Ute Mountain Ute Indian Reservation Cortez R18W Karle Key Xu R17W T General Setting Mine Xu Xcu 36 Can y on N Xcu McElmo WIND RIVER 32 INDIAN MABEL ￿The Ute Mountain Ute Reservation is located in the northwest RESERVATION MOUNTAIN FT HALL IND RES Little Moude Mine Xcu T N ern portion of New Mexico and the southwestern corner of Colorado UTE PEAK 35 N R16W (Fig. UM-1). The reservation consists of 553,008 acres in Montezu BLACK 666 T W Y O M I N G MOUNTAIN 35 R20W SLEEPING UTE MOUNTAIN N ma and La Plata Counties, Colorado, and San Juan County, New R19W

Coche T Mexico. All of these lands belong to the tribe but are held in trust by NORTHWESTERN 34 SHOSHONI HERMANO the U.S. Government. Individually owned lands, or allotments, are IND RES Desert Canyon PEAK N MESA VERDE R14W NATIONAL GREAT SALT LAKE W Marble SENTINEL located at Allen Canyon and White Mesa, San Juan County, Utah, Wash Towaoc PARK PEAK T and cover 8,499 acres. Tribal lands held in trust within this area cov Towaoc River A S E M 33 1/2 N er 3,597 acres. An additional forty acres are defined as U.S. Govern THE MOUND R15W

SKULL VALLEY ment lands in San Juan County, Utah, and are utilized for school pur TEXAS PACIFIC 6-INCH OIL PIPELINE IND RES UNITAH AND OURAY INDIAN RESERVATION Navajo poses. W Ramona GOSHUTE 789 ￿The Allen Canyon allotments are located twelve miles west of IND RES T

UTAH 33 Blanding, Utah, and adjacent to the Manti-La Sal National Forest. Chipeta U T A H COLORADO N The White Mesa allotments are located nine miles south of Blanding, River C O L O R A D O 666 R13 1/2W Utah, on Utah Highway 47. These lands belong to known members 41 PAIUTE I R E D R E V Mancos

of the Tribe or their heirs; however, the titles are held in trust for River Mancos T A N N E R M E S A Mancos MONTEZUMALA PLATA COUNTY COUNTY T Farms these individuals by the U.S. Government. The Ute Mountain Ute Aztec Wash 32 W San Juan River N W MONTEZUMA Tribe also holds fee patent title to seven tracts of land located in Utah COUNTY COLORADO R20W R19W R18W R17W R16W NEW MEXICO SAN JUAN COUNTY

and Colorado totaling 595,647 acres. PAIUTE I R Barker UTE MOUNTAIN UTE Dome T INDIAN RESERVATION COLORADO ￿The topography of the reservation varies from approximately EXPLANATION 32 PAIUTE I R SOUTHERN UTE Oilfield X Prospect N 4,600 feet near the Four Corners to approximately 10,000 feet at the IND RES Gasfield cu- copper NEW MEXICO KAIBAB u- uranium Ute peak of the Sleeping Ute Mountain. The eastern half of the reserva IND RES Oil pipeline NAVAJO INDIAN RESERVATION W Sand and gravel pit Dome JICARILLA TAOS Gas pipeline IND RES APACHE TAOS INDEX MAP tion is characterized by a high mesa cut by the canyon of the Mancos IND RES IND RES Indian Reservation boundary Westwater Canyon HAVASUPAI I R PICURIS T River and numerous side canyons. The western half of the reserva SAN JUAN I R IND RES SANTA CLARA POJOAQUE I R 31 I R NAMBE I R 0 10 MILES HOPI INDIAN SAN ILDEFONSO I R 5 N RESERVATION TESUQUE I R Horseshoe- U.S. BUREAU OF MINES 4-INCH PIPELINE (HELIUM) tion, with the exception of the Sleeping Ute Mountain, is semi-desert JEMEZ I R Verde- HUALAPAI 0 5 10 20 KILOMETERS Gallop IND RES COCHITI I R Gallop ZIA SANTA DOMINGO I R grassland. NAVAJO IND RES IND RES SAN FELIPE I R NAVAJO I R LAGUNA SANTA ANA I R SANDIA I R R16W R15W R14W ￿The reservation ranges in elevations from about 4,600 feet along RAMAH NAVAJO IND RES ZUNI CANONCITO I R IND RES ACOMA ISLETA the San Juan River near Four Corners (the junction of the States of I R IND RES Figure UM-2. Geographic map of the Ute Mountain Ute Indian Reservation. LAGUNA I R Arizona, Utah, Colorado, and New Mexico) to 9,977 feet on Ute CAMP VERDE I R A R YAVAPAI I I R Z O N A PAYSON COMMUNITY I R ALAMO NAVAJO peak. Most of the western part of the reservation is semi-arid, eroded IND RES

FT APACHE N E W M E X I C O grasslands with some “badlands” topography near the Utah boun INDIAN RESERVATION

dary. North of the grasslands is the Sleeping Ute Mountain with a FT MC DOWELL IND RES SALT RIVER I R SAN CARLOS cover of scrub cedar, oak, and juniper. The eastern and southern INDIAN RESERVATION MESCALERO IND GILA BEND GILA RIVER RES IND RES IND RES parts of the reservation consist of the deeply-cut canyons and mesas MARICOPA PAPAGO IND RES IND RES of Mesa Verde and Tanner Mesa, and is covered by scrub cedar and juniper. PAPAGO INDIAN PASCUA YAQUI I R RESERVATION ￿The only paved highways in the reservation are U.S. Highways SAN XAVIER IND RES 160 and 666 and State Highways 41 and 789 (Fig. UM-2). Two YSLETA DEL SUR I R maintained gravel roads cross the reservation: one follows the Man cos River Canyon to the eastern part of the reservation, then south Figure UM-1. Location of the Ute Mountain Ute Indian Reservation (modified after U.S. ward toward Farmington and the other goes westward from Towaoc Department of the Interior, 1993). to the Cache oilfield then on to Aneth, Utah. Other roads are gener ally trails passable only to four-wheel-drive vehicles or pickup trucks. reservation in New Mexico are the towns of Shiprock, 30 miles from ￿Towaoc, the only town on the reservation, is the site of the Ute Towaoc, and Farmington, 29 miles east of Shiprock. Mountain Indian Agency and the residence of most of the people on the reservation. Cortez, Colorado, 16 miles northeast of Towaoc, serves as the principal market center for the area. South of the

UTE MOUNTAIN UTE RESERVATION Reservation Overview 1 COLORADO, NEW MEXICO Geology structural platform between the Monument Uplift, about 40 miles the maximum dip is about 9 ½ degrees. Except for the south side, faults are downthrown to the north, while others are downthrown to the The Ute Mountain Ute Indian Reservation is on the Four Corners to the west, and the San Juan basin immediately to the southeast. the flanks of the dome pass into a series of five anticlines, only south. Apparently the majority are high-angle normal faults. The two platform of the Colorado Plateau, and most of it is underlain by Superimposed on the platform are several smaller structures that two of which extend into the reservation. A moderately sharp anti longest faults southeast of Southern Ute Dome have curved traces ow gently dipping Mesozoic age sedimentary rocks (Fig. UM-3). give the reservation its own character; these are the Ute Dome, the cline plunges southeastward from McElmo Dome in the vicinity of ing to actual curves in the fault planes rather than to the effect of topog Most of the rocks exposed on the Reservation are sandstones, Mesa Verde Basin, and the Hogback Monocline, and even more Ute Peak. It is asymmetric, with a steeply dipping southwest side. raphy on dipping fault planes. Two miles southwest of Southern Ute shales, and mudstones of Cretaceous age; the oldest sedimentary locally, the McElmo Dome, the Barker Dome and Anticline, and A poorly defined anticline extends southwest from McElmo Dome Dome, two strike faults die out as small monoclinal flexures. formation exposed is of Jurassic age and the youngest consolidated the Southern Ute Dome (Figs. UM-3 and UM-4). about 4 miles, almost parallel to a graben that lies to the north. rocks are Tertiary. The oldest units crop out along the northern ￿Ute Dome is probably entirely the result of injection of mag The total area affected by McElmo Dome and its satellitie anti 112 111 110 109 108 clines is about 20 miles east to west 41 107 most boundary of the Reservation, and the exposed sedimentary ma and principally of three stocks at “The Knees,” Black Moun WYOMING WYOMING EXPLANATION UTAH 41 rocks become progressively younger toward the south and east, re tain, and Ute Peak. The dome is nearly circular in plan and aver and 10 miles north to south. COLORADO Monocline or steep limb of fold 0 8 16 32 48 64 Miles

￿Barker Dome and Anticline are on with direction of dip TA UPL NU IF flecting the higher topographic position of the Mesa Verde plateau. ages about 10 miles in diameter (Fig. UM-3). On its western side, I T 0 8 16 32 48 64 80 96 Kilometers the east flank of the Mesa Verde Basin, Crestal line of anticline, arch, uplift, up- The principal area of non-sedimentary rocks in the Reservation is the dome merges with west-and-southwest-plunging folds, and its warp, or swell, with direction of plunge SCALE AX at the east side of the reservation. The VERNAL I A the Ute Mountains, which are formed of Late Cretaceous or Terti western edge is poorly defined. The southwest flank of the dome Troughal line of syncline, basin, or sag L dome is slightly elongated north and with direction of plunge ary igneous rocks. may be underlain by a large intrusive mass, and an irregular-shap FO UINTA LD ￿Older sedimentary formations not exposed on the Reservation ed anticline that plunges westward from the northwest flank of the south, and extends northward for sev High-angle fault, with downthrown side BELT

40 R MEEKER

eral miles as the Barker Anticline. Thrust fault, with updrawn side E VR 40 but occurring in the subsurface include, in descending order, the C dome may also be underlain by an igneous mass, at least in part. I

R A Kayenta Formation and Wingate Sandstone of the Glen Canyon Maximum closure is at least 200 feet. WHITE

Other folds along the western flank do not appear to be closely re Boundary of tectonic division S

A RIVER ￿South Ute Dome is a small, nearly BASIN L UTAH UPLIFT Group of Jurassic age; the Dolores (Chinle), Shinarump, and lated to igneous activity. They are associated with zones of frac G U Uplift COLORADO RI round dome about a mile wide, imme PRICE O VE R Moenkopi Formations of Triassic age; the Cutler and Rico Forma D PICEANCE turing that may be tectonic in nature. G O D CARBONERA A diately southeast of Barker Dome (Fig. Basin L R CARBONDALE L O tions of Permian age; and the Paradox Formation of Pennsylvanian ￿The Mesa Verde Basin is a broad downwarp that is generally Y SA L O E SAG E C BASIN N L UM-3). Its eastern and southern flanks L W age. The Paradox Formation, characterized by its content of salt S EN reflected by the surface topography of Mesa Verde and occupies A

E JUNCTION BENCH L R are formed by a bend in the Hogback EV E G and gypsum, is significant because it is the producing horizon for most of the area between Ute Dome and the Hogback Monocline; A L

TL F K 39 ￿ BASIN E GR. S A GREEN U 39 Monocline, and its western flank is A R JUNCTION P oil wells in the northwest corner of the reservation. In that area it L the center of the basin coincides closely with the lowest part of the C RIVER UNCOMPAHGRE UPLIFT N I A F lies at depths of about 5,700 to 6,000 feet below the surface. Mesa Verde Upland in T 32 N, R 15 W. Structural closure on the formed by the eastern limb of a south S PARADOX FOLD T easterly plunging syncline that sepa GUNNISON UPLIFT Structure basin is probably on the order of 200-300 feet. Structural closure LA SAL MONTROSE SAG CAPITOL DOME O FOLDREEF BELT

MOAB D L rates South Ute Dome from Barker FAULT BELT O GUNNISON In broad aspect the Ute Mountain Ute Indian Reservation lies on a is limited due to the close proximity of the basin to the Hogback R E AND S 109 00' 45' Dome. Monocline. H 30' E ￿Steeply dipping normal faults oc N ￿The Hogback Monocline trends R 6750

McELMO Y E HENRY DOMES cur in the Ute Mountains area on the 38 HIGH PLATEAUS P DOME S northeasterly across the southeast part of O 38 6000 L A R S N J

I south, southwest and northwest flanks V WILSON SAN CIRCLE CLIFFS UPLIFT E the reservation, where it is reflected in N B DOME UAN

O A R

S Y

of Ute Dome, and to the southwest A

I N ABAJO small hogbacks formed by steeply dipping W N JICO S

A DOME P JUAN AG 6000 108 15' C DOME R flank of McElmo Dome. The greatest U E NEEDLE sandstone beds of the Pictured Cliffs IV E R T T LA PLATA DOME I N COLORADO ROCKIES H BLANDING DOME concentration of faults is on the north E Sandstone (Fig. UM-3). The dips in this KAIPAROWITS DOME W 37 15' M CORTEZ A RC UTE U R 5000 west flank of Ute Dome. Two sets of BASIN HUL E N V DOME area are mostly between 20 and 30 de DURANGO ETA I BASIN O R faults appear to have formed simulta M UTE

LORAD O DOME grees. The change in dip toward the San OC NAVAJO 37 DOME

SENTINEL PEAK 4000 neously in this vicinity; one set strikes A UTAH COLORADO

ES 37 E

DOME Juan Basin is relatively abrupt, and only a T ARIZONA FOUR CORNERS NEW MEXICO PIUTE

C C KAI CARRIED PLATFORM

nearly west, the other northeast. The H FOLDS H

K DOME B O N

short distance from the steepest part of the SAG AM A A A TYENDE OLUETO U

J B I

KAIBITO FARMINGTON AN

BA C

S

west-striking faults parallel west-trend SADDLE A

S monocline the dips in the basin are only 1 L Y RED ROCK I

UTE MOUNTAIN INDIAN RESERVATION N F BENCH C

5000 5000 F SADDLE ing folds and have displacements that L SAN JUAN I S or 2 degrees. On the northwest side of the N

3000 E PRESTON BASIN

U rarely exceed 30 feet. The northeast- P D monocline the beds flatten somewhat U L E P I BENCH F F L T trending faults appear to be extensions I I MESA VERDE more gradually to an essentially horizon F A BASIN T N

C BASIN A BLACK MESA R of a zone of faulting that cuts the E IUCIMIENTO UPLIFT C tal position, except at the Southern Ute H

37 00' 36 ARIZONA

NEW MEXICO 36 BARKER southwest flank and the central part of DOME and Barker Domes (Fig. UM-3). Between SOUTH CAMERON UTE McElmo Dome. This zone curves to a BENCH BASIN C the two areas of nearly horizontal beds, H DOME A

COCONINO U GO nearly east strike and continues toward P

EXPLANATION SALIENT H

which are only 2 to 4 miles apart, there L I

FT S G 3000 Cortez, Colorado. The faults along WUPATKI BENCH GALLUP LOPE

-1000 are several thousand feet of structural re LIT U T 2000 L Structure contours - drawn on 2000 E GALLUP ZUNI UPLIFT O base of Dakota Sandstone. MONOCLINE this zone form a graben on the south SAG 1000 lief. PUERCO E R D

Contour interval 250 feet 0 FAULT BELT N T G A west flank of McElmo Dome and have FLAGSTAFF R Near vertical fault ￿The McElmo Dome is immediately E

displacements of as much as 180 feet, 35 WINSLOW ACOMA ALBUQUERQUED

Anticline - showing plunge 3750 north of the Ute Mountains, and only the OL C D 35 ORA O N

the greatest known in the Ute Moun HOLBROOM A Syncline - showing plunge southernmost part of it lies within the res SAG MOGOLLON SLOPE R HOGBACK tain area. 0￿ 5 ￿ 10 ￿ 15 MILES G ervation (Fig. UM-3). Its structure is well R

I R O V I E R LUCEROUPLIFT ￿Most of the faults in this area are O 0 5 10 ￿ 15 KILOMETERS exposed in McElmo Canyon, which cuts I concentrated on a bend in the Hogback 112 111 R through its southern flank. The dome is 110 109 108 107 Figure UM-3. Tectonic map of the Ute Mountain Ute Indian Reservation. Structure contour Monocline south of Southern Ute asymmetric, steepest on the south where Figure UM-4. Tectonic divisions of the Colorado Plateau (modified after Kelley, 1955). lines are drawn on the base of the Dakota Sandstone (modified after Anderson, 1995). Dome. The strikes of these faults range from N 70 W to N 90 W. Some UTE MOUNTAIN UTE RESERVATION Geology Overview 2 COLORADO, NEW MEXICO Basin Provinces (SOUTHWEST AND WEST) (NORTHEAST AND EAST 110 108 EXPLANATION The Ute Mountain Ute Indian Reservation is located on two SAN RAFAEL SWELL NORTHERN PARADOX BASIN UNCOMPAHGRE AND HENRY MOUNTAINS AND BOOK CLIFFS PLATEAU) Paradox Basin USGS designated Basin Provinces. The northwestern part of Province the reservation is located in the Paradox Basin Province and M.Y. TERTIARY WASATCH FORMATION 1800' 66 San Juan Basin the southeast part is located in the San Juan Basin Province FARRER FORMATION 1000' Province NELSEN FORMATION 600' (Fig. UM-5). (ERODED) MESAVERDE GROUP SEGO SANDSTONE 50-200' UNAMED BEDS Ute Mt. Ute Indian ? BUCK TONGUE 0-200' MESAVERDE FORMATION 300' CASTLEGATE SANDSTONE 0-300' 38 38 Reservation Paradox Basin Province MASUK MBR 700' BLACKHAWK (TYPE AREA) } EQUIVALENT UPPER MANCOS SHALE The Paradox Basin Province is in southeastern and south-cen EMERY SS 300' 4000' BLUE GATE SHALE MEMBER 1500' JUANA LOPEZ MEMBER ("FERRON MARKER") tral Utah and southwestern Colorado and encompasses much ? CRETACEOUS FERRON SS UT of the area from latitude 37° to 40° north and from longitude 0-400' CO GREENHORN LIMESTONE MEMBER 108° to 114° west (Fig. UM-5). It includes almost all of the TUNUNK SHALE MEMBER 600' DAKOTA SANSTONE 50-200' LOWER AZ NM Paradox Basin, the Uncompahgre and San Juan Uplifts, the BUCKHORN COL 138 ? CEDAR MNT FORMATION 100-250' BURRO CANYON FORMATION BRUSHY BASIN MEMBER San Rafael, Circle Cliffs, and Monument Uplifts, the Kaipar UPPER MORRISON FORMATION TIDWELL MEMBER 600-800' SALT WASH MEMBER owits and Henry Mountains Basins, and the Wasatch and SUMMERVILLE FORMATION Pausaugunt Plateaus (Fig. UM-4). Maximum dimensions of CURTIS FORMATION 0-200' CURTIS EQUIV. MOAB TONGUE WANAKAH FM MIDDLE SAN RAFAEL GROUP ENTRADA SANDSTONE 100-500' SLICK ROCK MEMBER ENTRADA SANSTONE } CARMEL FORMATION 100-300' DEWEY BRIDGE MEMBER the province area are approximately 280 miles long and 200 SCALE miles wide. It covers an area of about 33,000 square miles. JURASSIC LOWER GLEN CANYON NAVAJO SANDSTONE 0-450' The maximum thickness of Phanerozoic sedimentary rocks GROUP KAYENTA FORMATION 100-250' 0￿ 25 ￿ 50 miles 205 WINDGATE SS 300' 110 108 ranges from 5,000-8,000 feet in the central part of the prov CHURCH ROCK MBR OWL ROCK MBR ? ince to more than 15,000 feet in the Paradox Basin, Kaiparo UPPER PETRIFIED FOREST MBR CHINLE FORMATION 300-600' MOSS BACK MBR MONITOR BUTTE MBR Figure UM-5. Location of the Paradox Basin Province and the San Juan Basin wits Basin, and Wasatch Plateau. Rocks in the Paradox Basin SHINARUMPCGL MIDDLE Provinces (modified after Gautier, et al., 1996) range in age from Precambrian through Tertiary (Fig. UM-6). MOODY CANYON MBR ? PARIOTT MBR TORREY MBR TRIASSIC MOENKOPI FORMATION 0-800' HOSKINNINI MBR SEWEMUP MBR ￿Most of the production in the province has been from po LOWER SINBAD LS MBR BLACK DRAGON MBR ? SO PARADOX ALI BABA MBR 240 TENDERFOOT MBR NW SE rous carbonate buildups (mainly algal OCHOAN A A' GUADALUPIAN 180 MILES (290 KM) mounds) around the southwestern shelf LEONARDIAN WHITE RIM SS 0-500' ORGAN ROCK FORMATION 0-400' SHAFER TRAIL DOVE CREEK margin of the Paradox Basin. The giant EAST FLANK OF DURANGO CEDAR RIM SS 0-700' CUTLER FORMATION SAN RAFAEL SWELL MOAB AREA AREA AREA Aneth Field, with more than 1 BBOIP ac WOLFCAMPIAN OR GROUP (near I-70) (projected) UTAH￿ | COLORADO PERMIAN LOWER CUTLER 0-1500' 0-8000' 1500 counts for as much as two-thirds of the pro ? FERRON SANDSTONE MEMBER JUANA LOPEZ MEMBER 290 ven resources in the province, and other VIRGILIAN HONAKER TRAIL FORMATION MISSOURIAN CRETACEOUS MANCOS SHALE fields in this primarily stratigraphic play 0-3000' 4000 ? ISMAY DESERT CR CEDAR MOUNTAIN FORMATION K DAKOTA SANDSTONE (Porous Carbonate Buildup Play, 2102) ac BURRO CANYON FORMATION DESMOINESIAN CANE CR CYCLE OF AKAH PRODUCTION INTERVALS HERMOSA FORMATION PARADOX FORMATION count for much of the rest. Most of the oth OR GROUP THE ALKALI GULCH INTERVAL BARKER CR (SALT) 0-2000' (0-15,000' (Incl. salt flowage) MORRISON FORMATION er plays have a strong structural compo JURASSIC PENNSYVANIAN ATOKAN PINKERTON TRAIL FM 0-300' ? MOAB MBR. WANAKAH FM. MOLAS FM 0-100' SUMMERVILLE FM. J-5 ? nent, particularly the Buried Fault Blocks, MORROWAN 1000 ? 3000 JUNCTION CR. SS. 330 CHESTERIAN J-3 ? ? J-5 ? Older Paleozoic (2101), Fractured Interbed ENTRADA SANDSTONE SLICK ROCK MBR. ? MERAMECIAN ? ? TION DEWEY BRIDGE MBR. J-2 (2103), and Salt Anticline Flank (2105) OSAGEAN REDWALL LIMESTONE 500-800' AEL GP.

CURTIS FORMA MISS. LEADVILLE LIMESTONE 0-500' TION ONE KINDERHOOKIAN J-3 Plays. The Permian–Pennsylvanian Mar 360 CARMEL FORMA NAVAJO SANDST DOLORES QUARY LIMESTONE 100' SAN RAF TION FORMATION ginal Clastics Play (2104), Permo-Triassic UPPER ELBERT FORMATION 250' UPPER MBR A FORMA MC CRACKEN SS MBR 2000 KAYENT Unconformity Play (2106), and Cretaceous ANETH FORMATION (SO. PARADOX) PAGE SANDSTONE TE SANDSTONE DEV. MIDDLE WINGA TR-3 0-200' Sandstone Play (2107), as well as the hypo LOWER

ON GP. TRIASSIC 410 500 J-O SILURIAN CHINLE FORMATION thetical Lower Paleozoic/Proterozoic Play 435 TR-3 ORDOVICIAN UNDIFFERENTIATED (2403) which is described in Northern Ari 500 GLEN CANY LYNCH DOL 0-600' ? OCKS 1000 Vert. exag.=X146 UPPER MAXFIELD LS - MUAV LS 0-500' IGNACIO QTZITE TION TR-1 PERMIAN R zona Province (024), are combinations of OPI FORMA MOENK ONE MEMBER C.M. MOLENAAR both structure and stratigraphy. The Frac OPHIR SH - BRIGHT ANGEL SH 0-400' MIDDLE TINTIC QTZITE - TAPEATS SS 100-300' SINBAD LIMEST tured Interbed Play (2103) is an unconven tional, continuous-type play. CAMBRIAN LOWER 570 GRANITIC AND HIGH-RANK METAMORPHIC ROCKS 0 0 PRECAMBRIAN ET M Figure UM-7. Cross Section across the Paradox basin showing generalized stratigraphic relations of Triassic, Jurassic, and the lower part of Cretaceous formations (modified from Molenaar, 1981). Figure UM-6. Correlation Chart for rocks of the Paradox Basin and vicinity (modified after Molenaar, 1987).

UTE MOUNTAIN UTE RESERVATION Paradox Basin Province 3 COLORADO AND NEW MEXICO San Juan Basin Province northeast part of the structural basin where the Upper Devonian Elbert For ceous sandstones of the central basin is produced from AGE FORMATION OF GROUP mation overlies Precambrian basement rocks. Elsewhere in the province, stratigraphic traps. Around the flanks of the basin, some SW NE The San Juan Basin Province incorporates much of the area from latitude 35° Cambrian, Mississippian, Pennsylvanian, or Permian rocks may overlie the of the same Cretaceous units produce oil on many of the San Jose Formation to 38° north and from longitude 106° to 109° west (Fig. UM-5) and compris Precambrian. structures. TERTIARY Nacimiento Formation es all or part of four counties in northwest New Mexico and six counties in ￿Plays were defined primarily on the basis of stratigraphy because of the ￿Seven conventional plays were defined by the USGS Ojo Alamo Sandstone southwestern Colorado. It covers an area of about 22,000 square miles. strong stratigraphic controls on the occurrence of hydrocarbons throughout and are individually assessed in the province: Porous Car ￿Almost all hydrocarbon production and available subsurface data are re the province. In general, the plays correspond to lithostratigraphic units con bonate Buildup (2201), Marginal Clastics (2203), Entrada Kirtland Shale (Farmington Sandstone Member) stricted to the San Juan Basin. Also included in the province, but separated taining good quality reservoir rocks and having access to source beds. In the (2204), Basin Margin Dakota Oil (2206), Tocito/Gallup Fruitland Formation from the structural and topographic San Juan Basin by the Hogback Mono central part of the basin, porosity, permeability, stratigraphy, and hydrody Sandstone Oil (2207), Basin Margin Mesaverde Oil Pictured Cliffs Sanstone cline and Archuleta Arch, respectively, are the San Juan Dome and Chama namic forces control almost all production, whereas around the flanks, struc (2210), and Fruitland-Kirtland Fluvial Sandstone Gas Lewis Shale Basin, which contain sedimentary sequences similar to those of the San Juan ture and stratigraphy are key trapping factors. Although most Pennsylvani (2212) Plays. The Porous Carbonate Buildup Play (2201) Cliff House Sandstone Basin (Fig. UM-4). In much of the San Juan Dome area (Fig. UM-4) the an-age oil and gas is on structures around the northwestern margin, it com is assessed as part of play 2102 in the Paradox Basin; simi Menefee Formation sedimentary section is covered by variable thicknesses of volcanic rocks sur monly accumulates only in highly porous limestone buildups. Jurassic oil on lary, Permian–Pennsylvanian Marginal Clastics Gas Play LATE MesaverdeGroup Point Lookout Sandstone rounding numerous caldera structures. The stratigraphic section of the San the southern margin of the basin is stratigraphically trapped in eolian dunes (2203) is assessed as part of play 2104 in the Paradox Ba Upper Mancos Shale

Juan Basin attains a maximum thickness of approximately 15,000 feet in the at the top of the Entrada Sandstone. Almost all oil and gas in Upper Creta sin. CRETACEOUS A SAN JUAN BASIN Gallup Ss. (Torrivio Mbr.) Tocito Ss. Lentil SOUTH STRATIGRAPHIC CROSS SECTION NORTH A' Lower Mancos Shale Greenhorn Limestone Dakota Sandstone MAESTRICHTIAN Figure UM-9. KIRTLAND SHALE FM EARLY Burro Canyon Formation FRUITLAND FM Schematic north- SECTION REMOVED BY LATE PICTURED CLIFFS SS south cross section Morrison Formation (Todilto Limestone Member) TERTIARY TO QUATERNARY EROSION of Cretaceous JURASSIC Wanakah Formation stratigraphy in Entrada Sandstone northwest New LEWIS Mexico (modified TRIASSIC Chinle Formation CLIFF HOUSE SS SHALE CAMPANIAN after Molenaar, De Chelley Sandstone 1973,1983 a,b). Organ Rock Shale Cutler MESAVERDE PERMIAN Group Cedar Mesa Formation and related rocks GROUP MENEFEE FM POINT LOOKOUT SS Halgaito Formation Rico Formation Honaker Trail Formation Hermosa CREVASSE UPPER MANCOS SHALE SANTONIAN Paradox Formation and related rocks PENNSYLVANIAN Group CANYON FM Figure UM-8. Pinkerton Trail Formation Geochronologic BORREGO PASS SS Molas Formation chart for the San

DILCO MEMBER UPPER CRETACEOUS CONIACIAN Juan Basin MISSISSIPPIAN Leadville Sandstone A TOCITO SANDSTONE Province (modified TORRIVIO MEMBER B Ouray Limestone after Gautier, et al., DEVONIAN GALLUP 1996). Elbert Formation SANSTONE C TURONIAN JUANA LOPEZ MBR.LOWER MANCOS CAMBRIAN Ignacio Quartzite D SHALE GREENHORN LS MBR PRECAMBRIAN E CENOMANIAN ￿Eight unconventional plays were also assessed: five continuous-type plays and F three coal-bed gas plays. Continuous-type plays are Fractured Interbed Play(2202), DAKOTA SANDSTONE Dakota Central Basin Gas (2205), Mancos Fractured Shale (2208), Central Basin Me saverde Gas (2209), and Pictured Cliffs Gas (2211) Plays. Also present is the continu non-marine ss/sh estuarine ss (reservoir) ous-type Fractured Interbed Play (2103) which is described and assessed in Paradox Basin Province (021). Coal-bed gas plays are San Juan Basin– Overpressured (2250), shoreface sandstone muddy estuarine ss (largely non-reservoir) San Juan Basin–Underpressured Discharge (2252), and San Juan Basin – Underpres open marine shale estuarine open marine shale sured (2253).

marine limestone braided-fluvial sanstone

UTE MOUNTAIN UTE RESERVATION San Juan Basin Province 4 COLORADO, NEW MEXICO ? HALGAITO TYPE LOGS LOG 1 DAKOTA LOG 2 FORMATION SANDSTONE Ute Mountain Ute Indian Reservation BURROW CANYON RICO

Gamma Ray CRET. FORMATION FORMATION Two logs were chosen to represent the stratigraphy of the Ute Mountain Ute LEWIS Gamma Ray Indian Reservation. Cretaceous (upper Dakota-Lewis Shale) is shown in Log 1. SHALE Resistivity The Devonian-Cretaceous (lower Dakota) are shown in Log 2. The locations of Resistivity these wells are shown in Figure UM-10. MORRISON FORMATION HONAKER TRAIL FORMATION Well 1: Location: Sec 16, T32N, R12W, San Juan County, New Mexico (from Molenaar and Baird, 1989) WANAKH FM.

CLIFF HOUSE JURASSIC Well 2: SANDSTONE Location: Sec 18, T36N, R14W, Montezuma County, New Mexico ENTRADA SS. (from Molenaar and Baird, 1989 MENEFEE WINGATE SS. FORMATION

VERTICAL SCALE POINT LOOKOUT 0 SANDSTONE CHINLE PRODUCING FORMATIONS 100 FORMATION PARADOX 200 FORMATION AND 300 RELATED 400 ROCKS

500 feet TRIASSIC

WELL 2 PENNSYLVANIAN PENNSYLVANIAN CRETACEOUS CRETACEOUS MANCOS SHALE ORGAN ROCK FORMATION

UTE MOUNTAIN UTE INDIAN RESERVATION JUANA CEDAR PINKERTON WELL 1 LOPEZ MESA TRAIL MEMBER UT CO SANDSTONE FORMATION MOLAS FM. AZ NM

PERMIAN LEADVILLE LIMESTONE

HALGAITO MISS. FORMATION OURAY FM. UPPER MBR. DAKOTA ELBERT FM. Figure UM-10. Location of wells. SANDSTONE McCRACKEN SS. IGNACIO QUARTZITE DEVONIAN DEVONIAN

UTE MOUNTAIN UTE RESERVATION Type logs for the Ute Mountain Ute Indian Reservation 5 COLORADO, NEW MEXICO Table 1: Play Summary Chart Play Types Conventional Plays- Discrete deposits, usually bounded by a downdip water contact, from which oil, gas or NGL can be extracted using traditional development practices, including The United States Geological Survey identifies several petroleum plays in the San Juan and Paradox Basin Provinces production at the surface from a well as a consequence of natural pressure within the subsurface reservoir, artificial lifting of oil from the reservoir to the surface where applicable, and and classifies them as Conventional and Unconventional. The discussions that follow are limited to those with direct the maintenance of reservoir pressure by means of water or gas injection. significance for future petroleum development in the Ute Mountain Ute Indian Reservation. Unconventional Plays- A broad class of hydrocarbon deposits of a type (such as gas in “tight” sandstones, gas shales, and coal-bed gas) that historically has not been produced using traditional development practices. Such accumulations include most continuous-type deposits

Reservation: Ute Mountain Ute Total Production Undiscovered resources and numbers of fields are Geologic Province: Paradox and San Juan Basins ( by Province-1996) Paradox Basin San Juan Basin ￿Oil: 606,411 MBO 202,839 MBO for Province-wide plays. No attempt has been made Province Area: Paradox ￿ Basin (33,000 sq. miles), San Juan Basin (22,000 sq. miles) to estimate number of undiscovered fields within the ￿Gas: Reservation Area: 864 sq. miles (553,008 acres) 1,328,000 MMCFG 2,356,849 MMCFG Ute Mountain Ute Indian Reservation. ￿NGL: 66,206 MBNGL 39,074 MBNGL

USGS Undiscovered Accumulations > 1 MMBOE Play Probability Drilling depths Play Type Description of Play Oil or Gas Known Accumulations Pay Thickness Porosity/Permeability Designation Field Size and Number (chance of success) (min., mean, max.) Field Size (median, mean) Porous Carbonate Buildup Gas (10 BCFG, 131 BCFG) Mounds of algal limestone in the Gas Play Gas (448,740 MMCFG) Oil (4 MMBO, 6.3 MMBO) Paradox Formation of the Hermosa Both (4000, 6000, 14000)ft 2102 (Paradox) Oil (521,090 MBO) No. of Undiscovered Fields (min., median, max., mean) 1 10-50 feet 5-20%/9.1mD Group. Oil 2201 (San Juan) Gas (3, 7, 15, 7.8) (2500, 6000, 14000)ft 1 Oil (10, 20, 50, 24.2)

Tocito - Gallup Field Size (median, mean) Lenticular sandstone bodies of Gas (30 BCFG, 38.0 BCFG) Gas Both Gas (199,800 MMCFG) Oil (4 MMBO, 6.3 MMBO) Sandstone Oil Play Upper Cretaceous Tocito and Gallup 1 (4000, 6000, 8000)ft <50 feet 2207 Oil (174,135 MBO) No. of Undiscovered Fields (min., median, max., mean) 4-20%/0.5-150mD Sandstones. Oil Gas (1, 2, 5, 2.4) (1000, 5000, 8000)ft 2 Oil (2, 5, 8, 5.0) Mancos Fractured Shale Play 2208 Fractured organic rich marine Gas (94.42 BCFG, est. mean) Fracture Porosity/ Oil N/A 1 Oil Highly Variable 3 Mancos Shale. Oil (188.85 MMBO, est. mean) (1000, 3000, 7000)ft Unlimited Permeability

Central Basin Mesa- verde Gas Play Sandstone buildups associated 2209 Gas with stratigraphic rises in the Upper N/A 1 Cretaceous Point Lookout and Cliff Gas Gas (7,000 BCFG) (1000, 2600, 5000)ft 20-200 feet 10%/<2mD 4 House Sandstones.

Basin Margin Mesa- Intertonguing of porous marine sand- stone at the base of the Upper Field Size (median, mean) verde Oil Play Gas (7.8 BCFG, est. mean) Oil Cretaceous Point Lookout Sandstone Oil Oil (2 MMBO, 1.9 MMBO) 10-30 feet 2210 Oil (7.8 MMBO, est. mean) 0.8 (300, 2000, 4000)ft 23%/6mD with the organic-rich Upper Mancos No. of Undiscovered Fields (min., median, max., mean) 5 Shale. Oil (1, 5, 10, 4.2)

Field Size (median, mean) Basin Margin Dakota Gas Gas (10 BCFG, 12.1 BCFG) (1000, 2000, 2000)ft Oil Play Mostly upper marine part of the Gas (62,100 MMCFG) Oil (2 MMBO, 2.8 MMBO) Both 1 Oil 10-100 feet 2206 Dakota Sandstone. Oil (22,8559 MBO) No. of Undiscovered Fields (min., median, max., mean) <20%/0.55-400mD (600, 2000, 5000)ft Gas (1, 2, 5, 2.4) 6 Oil (5, 10, 20, 11.1)

Dakota Central Basin Coastal marine barrier-bar sand- Gas Play 2205 stone and continental fluvial sand- Gas Gas (8211.28 BCFG, est. mean) 1 Gas stone units, primarily within the N/A (5000, 6900, 8000)ft 30-70 feet 5-15%/0.1-0.25mD 7 transgressive Dakota Sandstone.

Buried Fault Blocks Field Size (median, mean) Gas (20 BCFG, 30.7 BCFG) Gas Older Paleozoic Play 39.4 feet Accumulations of oil in fault blocks Gas (59,518 MMCFG) (6000, 9000, 15000)ft Both Oil (4 MMBO, 7.3 MMBO) 1 2101 involving pre-Pennsylvanian rocks. Oil (53,700 MBO) No. of Undiscovered Fields (min., median, max., mean) Oil 5-25%/<0.01-272mD Gas (1, 4, 12, 5.1) (6000, 9000, 15000)ft 8 Oil (1, 4, 14, 5.1)

Fractured Interbed Play Gas (hyopothetical, continuous) Fractured organic rich dolomitic Gas (193.86 BCFG, est. mean) (8000, 9000, 10000)ft 1 <20 feet 1-5% 2103 shale and mudstone. Both Oil (242.32 MMBO, est. mean) N/A Oil 9 (8000, 9000, 10000)ft

Field Size (median, mean) Permian-Pennsylvanian Gas Gas (7 BCFG, 9 BCFG) Porous and permeable sandstone (3000, 7000, 20000)ft Marginal Clastics Play Gas (7.0 BCFG, est. mean) Oil (1 MMBO, 1.3 MMBO) intervals within the Permian Both 0.8 Oil N/A 2104 Oil (2.3 MMBO, est. mean) No. of Undiscovered Fields (min., median, max., mean) N/A Cutler Formation. (3000, 4500, 7000)ft Gas (1, 6, 15, 5.5) 10 Oil (1, 2, 4, 1.8)

Conventional play type Unconventional/Hypothetical play type UTE MOUNTAIN UTE RESERVATION Play Summary Table 6 COLORADO and NEW MEXICO Porous Carbonate Buildup Play kerogen from terrestrial plant material in black shale source rocks. are the Barker Creek, Akah, Desert Creek, and Ismay Stages (Fig. UM- Creek is bounded by the Chimney Rock and Gothic Shales 13). which represent transgressions (Fig. UM-13). Growth of the (USGS Designation 2102, 2201) Timing and migration: In the central part of the San Juan Basin, Pennsylvanian sediments entered the thermal zone of oil generation ￿ The Barker Creek Stage has a gross thickness of 500 feet. It is a Desert Creek carbonate bank occurred during slow subsidence General Characteristics during the Late Cretaceous to Paleocene, and the dry gas zone during fossiliferous, algal, dolomitic limestone with vuggy secondary dolo of the Paradox Basin. Source rocks for hydrocarbons are the The Porous Carbonate Buildup Play in the Paradox and San Juan Basin the Eocene to Oligocene. It also is probable that Pennsylvanian source mite. Most reservoir rock is algal, dolomitic limestone with enhanced Chimney Rock and Gothic Shales. Provinces (Fig. UM-11) is primarily a gas play and is characterized by rocks entered the zone of oil generation during the Oligocene porosity and permeability due to dolomitization and weathering. The ￿The Ismay Stage is divided into lower and upper units. oil and gas accumulations in mounds of algal (Ivanovia) limestone as throughout most of the Four Corners Platform. Updip migration and Barker Creek was deposited on paleostructural features related to the In the lower unit, bounded by the Gothic and Hovenweep sociated with organic-rich black shale rimming the evaporite sequences local migration from laterally equivalent carbonates and shale beds in Hogback Lineament. Shales, oil is produced from algal carbonate mound buildups. of the Paradox Formation of the Hermosa Group (Fig. UM-12). Most areas of favorable reservoir beds predominate, and remigration may ￿The Akah Stage is not considered to be an exploration objective The upper unit is bounded by the Hovenweep and Boundary developed fields within the play produce from combination traps in the have occurred in areas of faulting and fracturing. within the reservation because salt and anhydrite deposition was Butte Shales. Production there is from algal or fossiliferous dominant during this stage. The Akah Stage represents the maximum detrital bioclastic/biogenic reservoirs. The source rocks for Paradox Basin Province. Combination stratigraphic and structural trapping mechanisms Traps: extent of evaporite limits. the Ismay stage are the Gothic, Hovenweep, and Boundary are dominant among Pennsylvanian fields of the San Juan Basin and ￿The Desert Creek Stage carbonates were deposited in a definable Butte Shales. During the Ismay Stage the southern part of the Reservoirs: Almost all hydrocarbon production has been from vuggy Four Corners Platform. Most fields are located on structures, although limestone and dolomite reservoirs in five zones of the Hermosa Group. arcuate trend around the southeast terminus of the basin. The Desert basin was slowly subsiding. not all of these structures demonstrate closure. The structures o o o In ascending order they are the Alkali Gulch, Barker Creek, Akah, themselves may have been a critical factor in the deposition of 109 108 30' 108 EXPLANATION Desert Creek, and Ismay Stages (Fig. UM-13). The zones gradually bioclastic limestone reservoir rocks. Seals are provided by a variety of become less distinct toward the central part of the San Juan Basin. Net mechanisms, including porosity differences in the reservoir rock, pay thicknesses generally range from 10 to 50 feet and have porosities Ute Mt. Ute Indian overlying evaporites, and interbedded shales. Most production on the Reservation of 5-20 percent. Four Corners Platform is from depths of 5,100 to 8,500 feet, but minor Southern and eastern limit of halite Source rocks: Source beds for Pennsylvanian oil and gas are believed production and shows in the central part of the San Juan Basin are from 37 o30' to be organic-rich shales and laterally equivalent carbonate rocks within as deep as 11,000 feet. + + + + Isopach Contour the Paradox Formation. The presence of hydrogen sulfide (H S) and 2000 Line of the Surface 2 Exploration status and resource potential: Field sizes in the play + + 1200 appreciable amounts of CO at the Barker Creek and Ute Dome fields 1600 of the Paradox Fm. 2 vary considerably; most oil discoveries are in the 1–100 MMBO size + + + Contour interval is probably indicates high-temperature decomposition of carbonates, range and include associated gas production. The largest fields, Tocito + Cortez 1800 100 ft (Rice, 1983). Correlation of black dolomitic shale and mudstone units Dome and Tocito Dome North, have produced a total of about 13 of the Paradox Formation with prodelta facies in clastic cycles present MMBO and 26 BCFG. Eight significant nonassociated and associated + Location of drill 1400 1600 + in a proposed fan delta complex on the northeastern edge of the + Durango holes used for gas fields have been developed in the play, the largest of which, Barker + + Paradox Evaporite Basin helps to account for the high percentage of interpretation 1000 + + Creek, has produced 205 BCFG. The Pennsylvanian is o + + + + 110 108o EXPLANATION basically a gas play and has a moderate future potential + + for medium-size fields. UT + CO Paradox Basin + Province + + AZ + ++ + + + NM +++ + + Characteristics of Play + ++ + San Juan Basin + + + + + + Province In the Ute Mountain Ute Indian Reservation the Para 800 + ++ Southern and eastern limit dox Formation is conformably bounded by the Pinker + + Ute Mt. Ute. Indian + + + + + of anhydrite o o ton Trail Formation at its base and the Honaker Trail + 38 38 Reservation + + + Formation at its top (Fig. UM-14). It ranges from 800 + + + + ++ Play Boundary + + + + feet thick in the south to 1700 feet thick in the north + + 600 + (Fig. UM-14). The Paradox Formation was deposited + Farmington N + + A A during the Desmoinesian age of the Pennsylvanian Pe Location + + riod under strong cyclic conditions involving transgres + + + UT of Cross + o + CO + sive and regressive movements of the Pennsylvanian + 36 30' A' Section + + + + + + sea. The transgressive phase is represented by black or + + + + + + AZ NM + + ++ + ganic rich dolomitic muds while the regressive phase is + + + represented by carbonate mounds. Reservoirs within + + 400 + A' + + the reservation are biogenic/bioclastic carbonate SCALE mounds deposited in shoaling areas of an evaporite ba + ++ SCALE sin. The four main cycles of Desmoinesian deposition + 800 + + 0 25 miles + + 0 25 50 miles Figure UM-11. Location of Porous Carbonate Buildup 110o 108o Play (modified after Peterson, 1996). Figure UM-12. Isopach map of the Paradox Formation (modified after Huffman and Condon, 1993).

UTE MOUNTAIN UTE RESERVATION CONVENTIONAL PLAY: Porous Carbonate Buildup 7 COLORADO AND NEW MEXICO Analog Fields HONAKER TRAIL FORMATION Within or Near Reservation (*) denotes field lies within the reservation boundaries R-14-W R-13-W BARKER CREEK Boundary Butte ISMAY *Barker Creek Paradox Field (Fig. UM-15) PARADOX FIELD

STAGE Hovenweep Shale OSE Location of discovery well:￿SE¼, SE¼, NW¼, Sec 21, T32N, R14W, 36 31 Gothic Shale DESERT CREEK ￿ ￿ ￿ ￿NMPM ￿(March, 1945) STAGE Producing formation:￿ ￿Paradox Formation STRUCTURE MAP Chimney Rock Number of producing wells:￿5 (1977) 1 4 1 DATUM: TOP DESERT CREEK TION Production:￿ ￿ ￿215,279,080 MCFG (1996) OUP AKAH PARADOX ￿ ￿ ￿ ￿141,773 BO (1977) -2200' SAN JUAN CO., N.M. STAGE Gas characteristics:￿ ￿BTU 777 (dry basis) LA PLATA CO., COLO. Type of drive:￿ ￿ ￿Solution gas, fluid expansion, ineffective 6 ￿ ￿ ￿ ￿bottom water encroachment

-2000' X FORMA Average net pay:￿ ￿ ￿ ± 100 feet￿ T Porosity:￿￿ ￿ ￿2-10% 32 SP RES AHGRE CUTLER ARK

EVAPORITES Permeability:￿ ￿ ￿extremely variable N 7800 HERMOSA GR BARKER ISMAY

SWEET ARADO CREEK Heron North Field 21 -2200'7 1st P STAGE Location of discovery well:￿￿NE ¼, NW ¼, sec. 35, T41N, R25W LA PLATA CO., COLO.

UNCOMP SAN JUAN CO., N.M. ￿ ￿ ￿ ￿(1991) 7 12 2nd

Producing formation:￿ ￿Desert Creek Stage, Paradox Formation A ZONES 0'-180 P A R D O X

6 8000 ALKALI GULCH Number of producing wells:￿1 EET AKAH DESERT Production:￿ ￿ ￿0.31 BCFG CREEK

￿ ￿ ￿ ￿200,759 BO (January 1, 1996) -1800' Figure UM-13. Stratigraphic chart of the Pennsylvanian Hermosa Group illustrating the 11 0'-200 3rd Paradox facies change across the basin. Each stage is bounded by a time stratigraphic Average net pay:￿ ￿ ￿60 feet -2000' marker bed of sapropelic, dolomitic mud. These markers are continuous and mappable Porosity:￿￿ ￿ ￿15% throughout the basin (modified from Harr, 1996). Permeability:￿ ￿ ￿17.7 md 17 T 8200 A *Wickiup Field 32 DeChelly Sandstone (Upper) A' N Location of discovery well:￿￿SW ¼, SE ¼, Sec 24, T33N, R14W A' DeChelly Sandstone (Lower) -1800' ￿ ￿ ￿ ￿(March, 1972) -2000' Producing formation:￿ ￿Barker Creek Stage, Paradox Formation 31 31 36 BARKER CREEK R-14-W Number of producing wells:￿1 (1983) ZONES SOUR

Production:￿ ￿ ￿41,872 MCFG (1996) 8400 Organ Rock Formation E.P.N.G. Gas characteristics:￿ ￿BTU 914. E.P.N.G. SO. UNION 1st No. 6 Ute No. 11 Ute No. 17 Barker

Type of drive:￿ ￿ ￿Gas Expansion Cedar Mesa 1600' A' Average net pay:￿ ￿ ￿10 feet A Sandstone 2nd Halgaito Porosity:￿￿ ￿ ￿8% G-W CONTOUR Formation (-1840') 1st DATUM 2nd DATUM Rico Formation *Ute Dome Paradox Field 3rd G-W 8600 Location of discovery well:￿￿NE ¼, NE ¼, Sec 35, T32N, R14W Honaker Trail 2000' (-2000') ￿ ￿ ￿ ￿(September, 1948) Formation Phi 3rd Producing formation:￿ ￿Barker Creek Stage, Paradox Formation Number of producing wells:￿11 (1977) 1st Paradox Formation Phdc Production:￿ ￿ ￿93,589,058 MCFG (1996) G-W 2nd (-2300') Gas characteristics:￿ ￿BTU 777 (dry basis) Pha Type of drive:￿ ￿ ￿Primary Volumetric with limited water G-W 3rd (-2430') Molas Formation 1000 ￿ ￿ ￿ ￿drive in Barker Creek Zone 2500' Feet Phbc Average net pay:￿ ￿ ￿116 feet ￿ G-W ks PARADOX aleozoic roc Porosity:￿￿ ￿ ￿3.5% Phag (-2630') Pinkerton Trail Permeability:￿ ￿ ￿0.5 md (enhanced by fracturing) Figure UM-15. Structure contour map, type log, and cross section of Barker Creek Paradox Field (modified Formation Mississippian and lower P 0 from Matheny, 1978). 0 10 Miles Figure UM-14. Stratigraphic cross section through Ute Mountain Ute Indian Reservation (modified from Huffman and Condon, 1993).

UTE MOUNTAIN UTE RESERVATION CONVENTIONAL PLAY: Porous Carbonate Buildup 8 COLORADO, NEW MEXICO Tocito-Gallup Sandstone Oil Play o R14W (USGS Designation 2207) 110 108o EXPLANATION Figure UM-17. Location of Paradox Basin oil field discovery wells for General Characteristics Province fields producing from the T Tocito-Gallup Sandstone Oil The Tocito-Gallup Sandstone Oil Play is an oil and associated gas Ramora 33 play in lenticular sandstone bodies of the Upper Cretaceous Gallup San Juan Basin N Play. Province Chipeta Sandstone and Tocito Sandstone Lentil, associated with Mancos T Aztec 32 Shale source rocks lying immediately above an unconformity. The Ute Mt. Ute. Indian Wash N 38o 38 o UT CO play covers almost the entire area of the province (Fig. UM-16). Reservation AZ NM R19W Many Rocks T 32 Gallup North Many Rocks N Most of the producing fields are stratigraphic traps along a north Play Boundary Mesa Gallup Gallup west- trending belt near the southern margin of the central part of the T 31 San Juan Basin. Almost all production has been from the Tocito N Sandstone Lentil of the Mancos Shale and the Torrivio Member of A the Gallup Sandstone. Locations of oil field discovery wells produc A' Shiprock Gallup Horseshoe R14W UT North Gallup ing from the Tocito-Gallup Sandstone Oil Play are shown in figure CO Location A' of Cross UM-17. AZ NM Rattlesnake Jewet Waterflow Section Group Shiprock Valley Gallup Reservoirs: The Tocito Sandstone Lentil of the Mancos Shale is the Gallup Gallup South Totah major oil producing reservoir in the San Juan Basin. The name is ap Gallup plied to a number of lenticular sandstone bodies, commonly less than EXPLANATION Cha Cha 50 feet thick, that lie on or just above an unconformity and are of un Approximate location of discovery Gallup determined origin. Reservoir porosities in producing fields range SCALE well for named oil field from 4 to 20 percent and average about 15 percent. Permeabilities Limits of Ute Mountain Ute Indian N Reservation range from 0.5 to 150 Md and are typically 5 - 100 Md. The only 0 25 50 miles o o SCALE significant production from the regressive Gallup Sandstone is from 110 A 108 0 10 miles the Torrivio Member, a lenticular fluvial channel sandstone lying Figure UM-16. Location of the Tocito-Gallup Oil Play. Cross section A- SAN JUAN BASIN above, and in some places scouring into the top of the main marine A' is shown in Figure UM-18 (modified after Gautier, et al.,1996) A SOU TH STRATIGRAPHIC CROSS SECTION NORTH A' Gallup Sandstone. KIRTLAND SHALE FM MAESTRICHTIAN Source rocks: Source beds for Gallup oil are found in the marine acres and has estimated total ultimate recovery of 51 MMBO. FRUITLAND FM SECTION REMOVED BY LATE PICTURED CLIFFS SS Upper Cretaceous Mancos Shale. The Mancos contains 1-3 weight Gallup producing fields are typically 1,000-10,000 acres in area and TERTIARY TO QUARTERNARY EROSION percent organic carbon and produces a sweet, low-sulfur, paraffin- have 15-30 feet of pay. About one-third of these fields have an base oil that ranges from 38° to 43° API gravity in the Tocito fields estimated cumulative production exceeding 1 MMBO and 1 BCF of LEWIS CLIFF HOUSE SS SHALE and from 24°to 32° API gravity farther to the south in the Hospah associated gas. All of the larger fields produce from the Tocito CAMPANIAN and Hospah South fields. Sandstone Lentil of the Mancos Shale and are stratigraphically MESAVERDE controlled. South of the zone of sandstone buildups of the Tocito, GROUP MENEFEE FM Timing and migration: The Upper Mancos Shale of the central part POINT LOOKOUT SS of the San Juan Basin entered the thermal zone of oil generation in the regressive Gallup Sandstone produces primarily from the fluvial the late Eocene and gas generation in the Oligocene. Migration up channel sandstone of the Torrivio Member. The only large fields dip to reservoirs in the Tocito Sandstone Lentil and regressive Gallup producing from the Torrivio are the Hospah and Hospah South CREVASSE UPPER MANCOS SHALE SANTONIAN fields, which are combination traps. Similar, undiscovered traps of CANYON FM followed pathways similar to those determined by present structure BORREGO PASS SS because basin configuration has changed little since that time. small size may be present in the southern half of the basin. The DILCO MEMBER CONIACIAN UPPER CRETACEOUS future potential for oil and gas is low to moderate. A TOCITO SANDSTONE Traps: Almost all Gallup production is from stratigraphic traps at TORRIVIO MEMBER B depths between 1,500 and 5,500 feet. Hospah and Hospah South, the GALLUP SANDSTONE C TURONIAN largest fields in the regressive Gallup Sandstone, are combination JUANA LOPEZ MBR.LOWER MANCOS D SHALE stratigraphic and structural traps. The Tocito Sandstone is sealed by, GREENHORN LS MBR E encased in, and intertongues with the marine Mancos Shale, forming CENOMANIAN stratigraphic traps. Similarly, the fluvial channel Torrivio Member F DAKOTA SANDSTONE of the Gallup is encased in and intertongues with finer grained, or ganic-rich coastal-plain shales. Figure UM-18. Schematic south to north cross-section non-marine ss/sh estuarine ss (reservoir) Exploration status and resource potential: Initial Gallup field of the Cretaceous stratigraphy in northwestern New shoreface sandstone muddy estuarine ss (largely non-reservoir) discoveries were made in the mid 1920's, however the major Mexico with emphasis and detail on the late Turonian- Coniacian interval (modified after Molenaar, 1973, open marine shale estuarine open marine shale discoveries were not made until the late 1950's and early 1960's in 1983a,b). marine limestone braided-fluvial sandstone the deeper Tocito fields. The largest of these, Bisti, covers 37,500

UTE MOUNTAIN UTE RESERVATION CONVENTIONAL PLAY TYPE: Tocito- Gallup Sandstone Oil Play 9 COLORADO, NEW MEXICO Characteristics of the Tocito-Gallup Oil Play BEAUTIFUL MOUNTAIN SUBSURFACE 331/2N 331/2N In recent years a sequence stratigraphic framework has been applied OUTCROP 15W 13W 331/2N 0 to the Tocito and Gallup Sandstones near the Ute Mountain Ute In TST 19W dian Reservation (Jennett and Jones, 1995). This framework ex LST plains hydrocarbon occurrence and the stratigraphic traps associated TOCITO 0 UTE MOUNTAIN UTE TOCITO-4 SB 30 33N with these units. The northern extent of the Gallup Sandstone pro INDIAN RESERVATION 13W Torrivio duction is several miles south of the Indian reservation where it is 0 Nonmarine LST truncated by the Tocito Sandstone (Fig. UM-18). For this reason the 0 lithofacies TOCITO-3 SB 10 32N Gallup Sandstone will not be included in the following description. HST 32N 0 ￿Since the late 1950 ’s, 130 MMBOE have been produced from 19W COLORADO 13W TST the Tocito. The Tocito Sandstone marks a significant change from NEW MEXICO 32N LST shoreface/coastal plain depositional systems which prevailed TOCITO-2 SB 32N 13W 19W 10 MANY ROCKS VALLEY throughout Gallup deposition. The Tocito Sandstone is a transgres GALLUP TST/HST sive sequence set internally composed of four high- frequency se HORSESHOE VALLEY DOWNDIP LIMIT OF quences; in ascending order they are Tocito-1, Tocito-2, Tocito-3 and LST TOCITO-1 SB Shallow 31N RESERVOIR QUALITY SS Tocito-4 (Fig. UM-19). In the subsurface, the Tocito is distributed marine JUANA LOPEZ MBR. 18W into narrow and elongate bodies which trend northwest-southeast 0 (Figs. UM-20 to UM-23). (TRUNCATEDLIMIT OF BY TOCITO TOCITO 1 SEQUENCE2 SEQUENCE BOUNDARY BOUNDARY) 10 INTERFLUVE ￿The high-frequency sequences of the Tocito Sandstone contain 0 0 the lowstand, transgressive, and usually highstand systems tracts. RATTLESNAKE There are sequence boundaries at the base of each high-frequency se 0 quence represented by irregular erosional surfaces that truncate into open marine shale the underlying units. Above the erosional surfaces are incised valley JUANA LOPEZ MBR. shallow marine sandstone fill deposits representing the lowstand systems tracts. The tops of the fluvial/distributary/bay fill sandstone 29N HOGBACK 16W 0 valley fills represent transgressive flooding surfaces, the passage carbonaceous shale from valley-filling sedimentation to open-marine/shelfal sedimenta estuarine sandstone HST = high stand systems tract 0 tion, and the onset to the transgressive systems tracts. The transgres 10 TST = transgressive systems tract calcareous/fossiliferous sandstone 28N THE SHIPROCK sive systems tracts are overlain by distal marine shales of the high 19W LST = low stand systems tract 10 stand systems tracts (Tocito-1 and Tocito-2 only). Due to their close TOCITO 1 SEQUENCE vertical juxtaposition, the four Tocito sequences are collectively in Figure UM-19. Composite stratigraphic summary comparing the outcrop of the Gallup and Tocito INCISED VALLEY FILL ISOPACH terpreted as components of a sequence set. The four sequences are interval. Along Beautiful Mountain, a relatively complete Gallup section from the Juana Lopez to the CONTOUR INTERVAL 10 FEET Torrivio Sandstone occurs beneath the Tocito Sandstone Lentil. To the north in the subsurface, four 0 2 4 6 thought to reflect higher-order cycles in relative sea level which were ROCK RIDGE sequences compromise the Tocito interval, with the lowermost sequence boundary erosionally resting superimposed on a longer term cycle. MILES on beds of the Juana Lopez Member. The missing section is close to 400 feet. The sequence LEGEND ￿Hydrocarbon trapping is the result of stratigraphic relationships. boundaries merge toward the outcrop and form a composite surface which everywhere separates Tocito OUTCROP MEASURED SECTION Structural dip is uniformly toward the northeast and consequently strata from the underlying Gallup strata (modified after Jennette and Jones 1995). 26N provides only minor influence on the pooling of hydrocarbons. The INCISED VALLEY FILL 14W four main trapping elements are truncation by younger sequence PALEOCURRENT DIRECTION boundaries, arcuate bends in valleys, up-dip valley termination, and structural closure (Fig. UM-24). Figure UM-20. Isopach map of the Tocito-1 incised valley system. Two parallel valleys, the Horseshoe and Many Rocks valleys, are separated by a well defined interfluve. Note the position and paleocurrent patterns of the Mounds outcrop locality. Reservoir quality sandstone appears to be present farther down the Horseshoe valley (modified after Jennette and Jones, 1995).

UTE MOUNTAIN UTE RESERVATION CONVENTIONAL PLAY: Tocito-Gallup Sandstone Oil Play 10 COLORADO AND NEW MEXICO 331/2N 331/2N 331/2N 331/2N 331/2N 331/2N 331/2N 331/2N 331/2N 331/2N 331/2N 331/2N 20W 15W 13W 9W 20W 15W 13W 9W 15W 13W 9W 20W UTE MOUNTAIN UTE UTE MOUNTAIN UTE UTE MOUNTAIN UTE 33N 33N 30INDIAN RESERVATION 33N 33N 33N 33N 33N 20W 30 20W 9W INDIAN RESERVATION 13W 9W 20W 40 9W INDIAN RESERVATION 10 VERDE VALLEY 40

0 20 40 0 32N 32N 32N 32N 32N 32N 32N 30 32N 0 20W COLORADO COLORADO 20W 0 13W COLORADO 9W 9W 20W 13W 9W

32N 20 NEW MEXICO 32N 32N NEW MEXICO 32N 32N TOCIT 32N NEW MEXICO 32N 20 VERDE VALLEY INTERFLUVE 20W 20W 30 20W 13W 10W 13W 10W O 2 30 40 BY TR TOCIT UNCA 20 0 10 40 10 0 O 3 TED 31N T T 31N 31N OCIT 10 HIN 20W NED 20W 20 BY TOCITO 10W 10 4 TR O 2 TR UN 30 0 CATION INTERFLUVE UNCA 0 10 30N 30N 40 30N RATTLESNAKE 0 20W 30N 20W RATTLESNAKE 20W RATTLESNAKE TED BY INTERFLUVE 50 0 0 13W 60 TOCITO 4 SEQUENCE 20 10 TOCIT 20 INCISED VALLEY FILL ISOPACH 30 20 29N 29N 0 2 4 6 O 3 30 29N 15W 10W MILES 10W HOGBACK HOGBACK W T 20 10 A HOGBACK VALLEY OC T IT E OUTCROP MEASURED O R 0 3 RATTLESNAKE20 F SECTION TH LO 20 10 28N THE SHIPROCK IN 28N THE SHIPROCK W 28N N THE SHIPROCK INTERFLUVE CHA CHA VALLEY 20W ED 50 WATERFLOW VALLEY 20W VA INCISED VALLEY FILL 20W BY LL TO EY CIT 20 50 O 4 70 0 20 TR 30 20 UN 10 CA V TIO ALLEY WATERFLOW VALLEY ROCK RIDGE N ROCK RIDGE 40 ROCK RIDGE 0 10 TOCITO 2 TRUNCATED BY 10 0 TOCIT R O 2 TRUNCA 50 10 OCK RIDGE VALLEY TOCITO 3 10 INTERFLUVE0 20 26N 20 50 26N 17W 26N 17W TED BY 30 17W 10 BEAUTIFUL MOUNTAIN 0 TOCITO 3 BEAUTIFUL MOUNTAIN BEAUTIFUL MOUNTAIN BISTI VALLEY BISTI TOCITO 3 SEQUENCE 10 50 TOCITO 2 SEQUENCE VALLEY INCISED VALLEY FILL ISOPACH INCISED VALLEY FILL ISOPACH 0 2 4 6 10 10 INTERFLUVE CONTOUR INTERVAL 10 FEET TOCIT MILES 0 2 4 6 O 2 TRUNCA LEGEND 0 10 0 10 ? MILES OUTCROP MEASURED SECTION 24N 24N 24N TED BY 13W 13W LEGEND 13W TOCIT INCISED VALLEY FILL 0 OUTCROP MEASURED SECTION O 3 PARTIALLY TRUNCATED BY INCISED VALLEY FILL 23N ? 23N OVERLYING SEQUENCE 23N 23N 23N 10W 23N 18W 17W 10W 17W 10W Figure UM-23. Isopach map of the Tocito-4 incised Figure UM-22. Isopach map of the Tocito-3 sequence. Figure UM-21. Isopach map of the incised valley fill of valley-fill sequence. Valley fills make up the bulk of the The interval mapped is from the Tocito-3 sequence the Tocito-2 sequence. Four parallel valleys, each sepa map and are separated by narrow interfluvial areas. boundary to the Tocito-4 sequence boundary. A wider rated by interfluves, are evident. The Waterflow Valley The isopach patterns mapped in the subsurface cor array of valley shapes is evident: the broad Verde Val contains the thickest interval of sandstone. Note the over respond remarkably well with measured thickness of ley, the deep, V-shaped Waterflow Valley, and the asym all distribution of the lowstand systems tract is more the Tocito at the outcrop (C.V. Campbell, unpublished metric Bisti Valley. Note the areas thinned by truncation widespread than the Tocito-1 sequence. The Tocito-3 se Exxon Production Research data). Most of the Tocito by the overlying Tocito-4 sequence boundary, particular quence boundary incises and removes the Tocito-2 se in outcrop along Rock Ridge and Beautiful Mountain ly along the southern margin of the Waterflow Valley and quence along the southern margin of the Waterflow Val belongs to the Tocito-4 sequence (modified after Jen toward the outcrop area (modified after Jennette and ley and northern margin of the Bisti Valley. These narrow nette and Jones, 1995). bands of truncation correspond to axial thicks in the Toci Jones, 1995). to-3 sequence. This erosional relationship has led to a number of hydrocarbon traps in this vicinity (modified af ter Jennette and Jones, 1995).

UTE MOUNTAIN UTE RESERVATION CONVENTIONAL PLAY: Tocito-Gallup Sandstone Oil Play 11 COLORADO, NEW MEXICO Analog Fields Near the Reservation INCISED VALLEY TRAPPING MECHANISM R16W 1. VALLEY CHANGES DIRECTION MANY ROCKS GALLUP NORTH Many Rocks Gallup 10' (Figs. UM-25 - UM-27) MESA 0' Location of discovery well: ￿SE ¼, SW ¼, sec 27, T32N, R17W T GALLUP 15' 10' 0' ￿ ￿ ￿ ￿(1962) 32 0' Producing formation:￿ ￿Cretaceous Gallup Sandstone N Number of producing wells:￿62 (1977) U Horseshoe Field￿ ￿40 MOEB Production:￿ ￿ ￿9 MOEB (1995) Cha Cha Field￿ ￿14 MOEB D ￿ ￿ ￿ ￿1,047,270 MCFG (1977) Many Rocks Field￿￿9 MOEB Gas Characteristics:￿ ￿1,171 BTU Totah Field￿ ￿6 MOEB Oil Characteristics:￿ ￿40 ° API gravity 30' 5' MANY ROCKS 2. VALLEY TRUNCATED BY YOUNGER SEQUENCE BOUNDARY 10' GALLUP Type of drive:￿ ￿ ￿Solution gas with limited gas expansion T 20' Average net pay:￿ ￿ ￿Upper zone is 5 feet 31 HORSESHOE 30' 5' ￿ ￿ ￿ ￿Lower zone is 7.5 feet N GALLUP

Porosity:￿￿ ￿ ￿15% 0' Permeability:￿ ￿ ￿145 mD R18W Bisti Field￿54 MOEB MANY ROCKS Horseshoe Gallup Gallagos Field￿10 MOEB Figure UM-24. 0' HORSESHOE GALLUP AREA 40' Schematic summary Location of discovery well:￿￿NW ¼, SW ¼, sec 8, T32N, R17W of hydrocarbon SAN JUAN CO., N.M. 0' ￿ ￿ ￿ ￿(1961) trapping styles found 3. VALLEY TERMINATION ISOPACH MAP 20' Producing formation:￿ ￿Cretaceous Tocito Sandstone in the Tocito, stippled UPPER PAY SAND Number of producing wells:￿9 (1983) patterns indicate the ISOPACH INTERVAL 5', 10' position of oil R17W R16W Production:￿ ￿ ￿40 MOEB (1995) accumulations Oil characteristics:￿ ￿35 ° API gravity (modified after Figure UM-26. Isopach map of the “lower sand pay zone” for the Many Rocks Field (modified after Type of drive:￿ ￿ ￿water Jennette and Jones, Matheny and Little, 1978). Average net pay:￿ ￿ ￿15 feet 1995). TOCITO-3 SEQUENCE ABOVE Horseshoe Field Porosity:￿￿ ￿ ￿10 -15 % Permeability:￿ ￿ ￿unknown MANY ROCKS GALLUP FIELD Stratigraphic Cross Section R16W Cha Cha Gallup MANY ROCKS GALLUP NORTH CURTIS - LITTLE CURTIS - LITTLE CURTIS - LITTLE CURTIS - LITTLE CURTIS - LITTLE SKELLY SE 28-32N-17W SE 27-32N-17W SE 27-32N-17W SE 27-32N-17W SE 27-32N-17W SW 26-32N-17W Location of discovery well:￿￿NW ¼, SE ¼, sec 17, T28N, R13W MESA 1100 Producing formation:￿ ￿Cretaceous Gallup Sandstone T GALLUP 1100 Number of producing wells:￿42 (1977) 32 N 1600 Production:￿ ￿ ￿14 MOEB (1995) ￿ ￿ ￿ ￿17,965,301 MCFG (1977)

Oil characteristics:￿ ￿41 ° API gravity 1700

Type of drive:￿ ￿ ￿Solution Gas 1700

MANY ROCKS 1200 Average net play:￿￿ ￿Upper zone 10 feet GALLUP 1200 ￿ ￿ ￿ ￿Lower zone 10 feet T A 17 00 31 HORSESHOE A' Porosity:￿￿ ￿ ￿13.5% N GALLUP 5' Permeability:￿ ￿ ￿57 mD 0' GR IND. 5' SB JUANA GR IND. R18W GR IND. GR IND. 0' LST LOPEZ GR IND. GR IND. LOWER PAY SAND Many Rocks Horseshoe Gallup Area 10' 5' SAN JUAN COUNTY, NM Figure UM-27. Stratigraphic cross section of the “lower sand pay zone” for the Many Rocks Field. Figure UM-25. Isopach map of the “upper ISOPACH MAP 15' Hydrocarbons are trapped in the Tocito- 1 lowstand systems tract (Fig. UM-19) along updip bends in the sand pay zone” for the Many Rocks Field UPPER PAY SAND (modified after Matheny and Little, 1978). valley (modified after Jennette and Jones, 1995; Matheny and Little, 1978). ISOPACH INTERVAL 5' R17W

UTE MOUNTAIN UTE RESERVATION CONVENTIONAL PLAY: Tocito-Gallup Sandstone Oil Play 12 COLORADO, NEW MEXICO MANCOS FRACTURED SHALE PLAY developed parallel to the trend of the fold. They range in size from Figure UM-28. Location of o 110 108o EXPLANATION (USGS Designation 2208) hairline cracks to 1 ¾ inches wide. Mancos Fractured Shale Play ￿Oil reservoirs associated with the Mancos Fractured Shale Play (modified after Peterson, Paradox Basin General Characteristics depend on porosity and permeability provided by the fractures. The 1996) Cross section A-A' is Province shown in Figure UM-30. The Mancos Fractured Shale Play is a confirmed, unconventional, con reservoirs are lithologically controlled only to the extent that brittle San Juan Basin tinuous-type play. It is dependent on extensive fracturing in the organ competent interbeds capable of fracturing are present. The fractures Province ic- rich marine Mancos Shale. Most developed fields in the play are have greater lateral than vertical continuity. The basic tools used in Ute Mt. Ute. Indian o o associated with anticlinal and monoclinal structures around the eastern, exploration for fracture permeability are structure contour maps and 38 38 Reservation northern, and western margins of the San Juan Basin (Figs. UM-28 and lithofacies maps showing brittle interbeds in dominantly shaly sequen UM-29). ces. Play Boundary ￿Trap types are structural/stratigraphic-fracture traps. The reser Reservoirs: Reservoirs are comprised of fractured shale and interbed voirs are primarily driven by gravity drainage. ded coarser clastic intervals at approximately the Tocito Lentil strati UT graphic level. CO AZ A' NM A Location Source rocks: The Mancos Shale contains 1-3 weight percent organic of Cross carbon and produces a sweet, low-sulfur, paraffin-base oil that ranges Section from 33° to 43° API gravity. A' Timing: The Upper Mancos Shale of the central part of the San Juan R18W R17W A Basin entered the thermal zone of oil generation in the late Eocene and 6000 SCALE of gas generation in the Oligocene. Traps: Combination traps predominate. Traps are formed by fractur 0 25 50 miles 5000 o ing of shale and by interbedded coarser clastics on structures. 110 108o Exploration status and resource potential: Most of the larger dis coveries, such as Verde and Puerto Chiquito, were made prior to 1970, 4000 SW NE but directional drilling along the flanks of some of the poorly explored A A' structures could result in renewed interest in this play. T 42 T S 33 3000 N T lineMonoc Dalton Ss. Characteristics of Mancos Fractured Shale Play in 41 S Mancos Creek the Ute Mountain Ute Indian Reservation T Upper Mancos Shale UT CO 32 N Hogback Monocline Hogback ￿T he Mancos Fractured Shale Play produces oil from fractures in AZ NM MANCOS RIVER Borrego Pass lentil "Skelly zone" the Niobrara-Carlile age clastic sediments (Fig. UM-30) which repre T (Stray Ss) 41 Tocito Ss. lentil sent the first regressive wedge in the San Juan Basin. These sediments S Dilco LAPLATA have little or no effective porosity and permeability except that associ VERDE T GALLUP ated with fractures. The units of interest to oil exploration are the basal 40 Bisti field Niobrara (lower Tocito Sandstone), Niobrara-Carlile unconformity S Gallegos field (upper Carlile Shale-Tocito Sandstone contact), and Carlile Shale/silt Gallup stone contact interval above the Juana Lopez. The Niobrara-Carlile stage is laterally consistent with respect to siltstone content, cement content, and other observable stratigraphic phenomenon. EXPLANATION ￿The Hogback Monocline and Mancos Creek Monocline (Fig. UM- SCALE Approximate location of discovery well 200ft 29) are the structural features associated with fractures in the Mancos for named oil field 0 10 miles Shale. The Hogback Monocline is located in the northwest flank of the San Juan Basin in the southeast section of the Ute Mountain Ute Indian Limits of Ute Mountain Ute Indian Reservation N 0 Reservation. It has a dip as great as 60° and has up to 8000 feet of Structure contour line drawn on base of Dakota Sandstone. 0 10mi structural relief. The Mancos Creek Monocline is located south of the reservation and extends only a few miles. Fractures are mostly associ C. I. = 600 feet Figure UM-30. Subsurface stratigraphic cross section across the central San Juan Basin. Dashed ated with areas of maximum flexure and where anticlines and synclines Figure UM-29. Structure contour map of the basal Dakota Sandstone showing the Hogback Monocline, lines are time marker bentonites or calcareous silty zones (modified from Molenaar, 1973; Tillman, intersect the monoclines (Figs. UM-31 and 32). The fractures are best associated folds, and location of oil field discovery wells for fields producing from the Mancos Fractured Shale Play (modified after Anderson, 1995). 1985).

UTE MOUNTAIN UTE RESERVATION UNCONVENTIONAL PLAY TYPE: Mancos Fractured Shale Play 13 COLORADO, NEW MEXICO Analog Fields inside or near Reservation (*) denotes field lies within the reservation boundaries LA PLATA GALLUP FIELD *Verde Oil Field (Fig. UM-31) Location of discovery well:￿￿se ¼,sec. 14, T31 N, R15W, NMPM STRUCTURAL CONTOUR MAP BENSON- MONTIN-GREER DRLG. CORP. ￿ ￿ ￿ ￿(September 1955) La Plata Mancos No. P-31 Producing formation:￿ ￿Fractured interval in Niobrara age Mancos Shale se 31 - T32N - R13W Number of producing wells:￿27 (1978) CONTOURED ON ELECTRIC GAMMA RAY - INDUCTION Production:￿ ￿ ￿7,789,304 bbl. (1977) LOG MARKER "E" WITHIN Oil characteristics:￿ ￿38 ° - 42° API Gravity MANCOS SHALE Elev - R.K.B. 6075 Type of drive:￿ ￿ ￿Gravity drainage in entire field as a “unit” La Plata Gallup Field (Fig. UM-32) CONTOUR INTERVALS: 19 22 A Location of discovery well:￿￿se ¼, sw ¼, sec 5, T31N, R13W, NMPM 1000' ￿ ￿ ￿ ￿(April 1959) 100' T Producing formation:￿ ￿Fractured Mancos Shale. 32 Number of producing wells:￿4 (1978) BOUNDARY OF LA PLATA N GALLUP POOL Production:￿ ￿ ￿527,882 bbl. (1977) B 30 27 Oil characteristics:￿ ￿Sweet yellow-green, 30 ° API Gravity. Producing Dakota and Pennsylvanian Type of drive:￿ ￿ ￿Combination gravity and solution gas wells within mapped area are not shown. Mancos River Field Location of discovery well:￿￿E ½ Sec 15, T32N, R18W, NMPM Producing formation:￿ ￿Fractured Mancos Shale. C Number of producing wells:￿2 (1978) Production:￿ ￿ ￿22,750 bbl. (1982) 35 36 33 31 34 Oil characteristics:￿ ￿40 ° API Gravity P-31

5400 +42001 2 3

VERDE 5400 +2000 5200 T D FIELD 5000 T 31 N 4800 31 +4000 4400 N +4100 +1000 8 10 4000 +3000 E -0- N E I L C 3600 O -100 -200 N O Gamma Induction K M R14W R13W Ray AC TRIBAL INDIAN RESERVATION UTE MOUNTAIN GB 2400 O H

2200 Figure UM-32. Structure contour map and type log of the La Plata Gallup field. Structure contour lines are on the “E” marker within the Mancos Shale (top of the Niobrara Stage) which generally produces the highest electrical log resistivities in the Mancos Shale (modified after Greer, 1978).

T 2000

3000 30 CI - 200ft N

R15W 0 1 2 3 4 miles R14W

Figure UM-31. Generalized structure contour map of Verde field. Structure contours are on top of the Point Lookout Sandstone Member of the Mesaverde Group (modified from Hayes and Zapp, 1955).

UTE MOUNTAIN UTE RESERVATION UNCONVENTIONAL PLAY TYPE: Mancos Fractured Shale 14 COLORADO, NEW MEXICO Central Basin Mesaverde Gas Play ner grained paludal or marine sediments account for almost all of the A SAN JUAN BASIN (USGS Designation 2209) stratigraphic traps with a shale or coal seal. SOUTH STRATIGRAPHIC CROSS SECTION NORTH A' Exploration Status and Resource Potential: The Blanco Mesaverde KIRTLAND SHALE FM MAESTRICHTIAN General Characteristics field discovery well was completed in 1927, and the Ignacio Blanco FRUITLAND FM The unconventional continuous-type Central Basin Mesaverde SECTION REMOVED BY LATE PICTURED CLIFFS SS Mesaverde field discovery well was completed in 1952. Areally, these TERTIARY TO QUATERNARY EROSION Gas Play is in sandstone buildups associated with stratigraphic ris two closely adjacent fields cover more than 1,000,000 acres, encom es in the Upper Cretaceous Point Lookout and Cliff House Sand pass much of the central part of the San Juan Basin, and have produced LEWIS stones in the central San Juan Basin (Fig. UM-33). The major almost 7,000 BCFG and more than 30 MMB of condensate, approxi CLIFF HOUSE SS SHALE CAMPANIAN gas-producing interval in the San Juan Basin, the Upper Creta mately half of their estimated total recovery. Most of the recent gas ceous Mesaverde Group, is composed of the regressive marine discoveries range in areal size from 2,000 to 10,000 acres and have es MESAVERDE Point Lookout Sandstone, the nonmarine Menefee Formation, and GROUP MENEFEE FM timated total recoveries of 10 to 35 BCFG. POINT LOOKOUT SS the transgressive marine Cliff House Sandstone. Total thickness CEOUS of the interval ranges from about 500 to 2,500 feet, of which 20-50 percent is sandstone. The Mesaverde interval is enclosed by ma Basin Margin Mesaverde Oil Play CREVASSE UPPER MANCOS SHALE SANTONIAN CANYON FM rine shale: the Mancos Shale is beneath the interval and the Lewis (USGS Designation 2210) Shale above (Fig. UM-34). BORREGO PASS SS

DILCO MEMBER CONIACIAN UPPER CRETA General Characteristics A TOCITO SANDSTONE TORRIVIO MEMBER Reservoirs: Principal gas reservoirs productive in the Mesaverde The Basin Margin Mesaverde Oil Play is a confirmed oil play around B GALLUP interval are the Point Lookout and Cliff House marine sandstones. the margins of the central San Juan Basin (Fig. UM-35). Except for SANDSTONE C JUANA LOPEZ MBR. TURONIAN Smaller amounts of dry, nonassociated gas are produced from the Red Mesa field on the Four Corners Platform, field sizes are very LOWER MANCOS D SHALE thin, lenticular channel sandstone reservoirs and thin coal beds of small. The play depends on intertonguing of porous marine sandstone GREENHORN LS MBR E the Menefee. Much of this play is designated as tight, and reser at the base of the Upper Cretaceous Point Lookout Sandstone with the CENOMANIAN voir quality depends mostly on the degree of fracturing. Together, organic-rich Upper Mancos Shale. F the Blanco Mesaverde and Ignacio Blanco fields account for al DAKOTA SANDSTONE Reservoirs: Porous and permeable marine sandstone beds of the basal most half of the total nonassociated gas and condensate production Point Lookout Sandstone provide the principal reservoirs. The thick non-marine ss/sh estuarine ss (reservoir) from the San Juan Basin. Within these two fields porosity averag ness of this interval and of the beds themselves may be controlled to shoreface sandstone muddy estuarine ss es about 10 percent and permeability less than 2 mD; total pay (largely non-reservoir) some extent by underlying structures oriented in a northwesterly direc thickness is 20-200 feet. Smaller Mesaverde fields have porosities open marine shale estuarine open marine shale tion. ranging from 14 to 28 percent and permeabilities from 2 to 400 marine limestone braided-fluvial sandstone mD, with 6-25 feet of pay thickness. Source Rocks: The Upper Mancos Shale intertongues with the basal Point Lookout Sandstone and has been positively correlated with oil Figure UM-34. Schematic south to north cross section of the Cretaceous stratigraphy in the northern San Juan Basin (modified after Molenaar, Source Rocks: The carbon composition (C /C ) of 0.99-0.79 1973, 1983a,b). 13 1 1-5 produced from this interval (Ross, 1980). API gravity of Mesaverde and isotopic carbon (d C ) range of -33.4 to -46.7 per mil of the 1 oil ranges from 37° to 50°. o o nonassociated gas suggest a mixture of source rocks including 110 108o EXPLANATION 110 108o EXPLANATION Timing: Around the margin of the San Juan Basin the Upper Mancos coal and carbonaceous shale in the Menefee Formation (Rice, Paradox Basin Paradox Basin 1983). Shale entered the thermal zone of oil generation during the Oligocene. Province Province Timing and Migration: In the central part of the basin, the Man Traps: Structural or combination traps account for most of the oil pro San Juan Basin San Juan Basin Province Province cos Shale entered the thermal zone of oil generation in the Eocene duction from the Mesaverde. Seals are typically provided by marine Ute Mt. Ute. Indian Ute Mt. Ute. Indian shale, but paludal sediments or even coal of the Menefee Formation o o o o and of gas generation in the Oligocene. The Menefee Formation 38 38 Reservation 38 38 Reservation also entered the gas generation zone in the Oligocene. Because may also act as the seal. Play Boundary Play Boundary basin configuration was similar to that of today, updip migration Exploration Status and Resource Potential: The first oil-producing A would have been toward the south. Migration was impeded by hy area in the state of New Mexico, the Seven Lakes Field, was discov Location A drodynamic pressures directed toward the central basin, as well as ered by accident in 1911 when a well being drilled for water produced of Cross Location UT CO UT of Cross A' A' Section CO A' by the deposition of authigenic swelling clays due to de-watering oil from the Menefee Formation at a depth of approximately 350 feet. A' Section AZ NM AZ of Menefee coals. The only significant Mesaverde oil field, Red Mesa, was discovered in NM Traps: Trapping mechanisms for the largest fields in the central 1924. part of the San Juan Basin are not well understood. In both the Blanco Mesaverde and Ignacio Blanco fields, hydrodynamic forces are believed to contain gas in structurally lower parts of the SCALE SCALE basin, but other factors such as cementation and swelling clays 0 25 50 miles 0 25 50 miles 110o 108o 110o 108o may also play a role. Production depths are most commonly from A A 4,000 to 5,300 feet. Updip pinchouts of marine sandstone into fi Figure UM-33. Location of the Central Basin Mesaverde Gas Play Figure UM-35. Location of the Basin Margin Mesaverde Oil Play (modified after Gautier, et al., 1996). (modified after Gautier, et al., 1996).

UTE MOUNTAIN UTE RESERVATION CONVENTIONAL / UNCONVENTIONAL PLAY: Basin Margin Mesaverde Oil Play / Central Basin Mesaverde Gas Play 15 COLORADO, NEW MEXICO Basin Margin Mesaverde Oil Play 1HCMS 2HCMS and Central Basin Mesaverde Gas Play 109o00' 108o00' * 1 750 o Lower 1 Stratigraphy and Analog Fields 37 30' Cortez coastal 2 Lower The Cliff House and Point Lookout Sandstones are the producers of the Ba 160 plain 900 Durango 3 coastal sin Margin and Central Basin Mesaverde Plays in the Ute Mountain Ute In 800 plain Mesa Verde 4 dian Reservation. Foreshore 2 ￿The Point Lookout Sandstone is the most extensive regressive marine N.P. 950 3 5 Cretaceous sandstone in the San Juan Basin. The unit progrades from south SOUTHERN UTE 850 west to northeast in a series of imbricated sandstone units (Fig. UM-36). 4 6 Shoreface/ INDIAN RES. Upper 7 The depositional environments present in the Cliff House Sandstone are flu 5 delta front UTE MOUNTAIN UTE RESERVATION shoreface 1000 8 vial/estuarine, shoreface, and delta front. Reservoir characteristic studies COLORADO 1HCMS 6 900 have shown that the upper shoreface and shoreface/delta front have the high 7 9 est permeabilities at 10-80 mD. Permeabilities between 0.3 and 3 mD are 2HCMS 10 8 o 11 more common to lower shoreface sediments. The highest amounts of carbo 37 00' 1050 9 12 Middle to nate cement are present in the lower to middle shoreface. Varying deposi upper (?) 666 950 tional environments and their changing lithologies create distinctive divi 10 13 shoreface San Middle sions in the Point Lookout log responses (Figs. UM-37, -38, and -39). River 14 shoreface 1100 11 These divisions are used by exploration geologists to correlate productive Juan 12 1000 zones. 15 Distal 13 ￿Further work in the Mesaverde reveals the Point Lookout shoreface pro lower Shiprock 16 Animas 1150 14 shoreface graded in a staircase fashion across the basin, as a series of steps and risers Lower 17 until it reached its seaward depositional limit (Fig. UM-36). At this limit, River Farmington 15 1050 0 10 mi shoreface 18 there is a change in the stacking pattern of genetic sequences from seaward NEW MEXICO 16 19 17 stepping to landward stepping. This marks the beginning of the Cliff House 1200 18 shoreface aggradation. Reservoir-quality sandstones in the two vertically 20 1100 stacked shorefaces at the turnaround position are 70 meters thick. Figure UM-37. Index map showing location of drill holes 1HCMS and 2 HCMS referred to in Figure UM-38 Lower (modified after Keighin, Zech, and Dunbar, 1993). 21 shoreface 1250 1150 SW NE Innershelf 22

Cliff House Sandstone 1300

1200 Intershelf Lewis Shale transition

Figure UM-38. Comparison of depositional facies in the Point Lookout Sandstone, as Upper Menefee determined from cores, for core holes 1HCMS and 2HCMS (Fig. UM-37). Numbered arrows indicate locations of thin sections examined. (*) patterns indicate zones of Lower Menefee mineralogical similarity within depositional environments, as determined by modal point- count analysis (modified after Keighin, Zech, and Dunbar, 1993).

Point Lookout Sandstone

Sand-rich Coastal Plain Channelbelt Sandstones Marine Shelf Figure UM-36. Diagram of the stacking patterns of genetic sequences in the Mesaverde Group, and the temporal reflections among the five formations which compose it Mud-rich Coastal Plain Shoreface Ravinement surface (modified after Cross and Lessenger, 1997).

UTE MOUNTAIN UTE RESERVATION CONVENTIONAL / UNCONVENTIONAL PLAY TYPE: Basin Margin Mesaverde Oil Play / Central Basin Mesaverde Gas Play 16 COLORADO, NEW MEXICO JEROME McHUGH NENAHNEZAD MESAVERDE FIELD (OIL) SOUTHERN UTE NO. 3 Analog Fields within or near Reservation San Juan County, New Mexico nw nw sec 20 T32N R9W (Oil producing fields belong to Basin Margin Mesaverde Oil Play; Lewis Shale Gas producing fields belong to Central Basin Mesaverde Gas Play) R 15 W Nenahnezad Mesaverde 2300 5100 (Fig. UM-40)

4 Location of discovery well:￿￿nw sw, sec. 10, T29N, R15W (1970) 3 2 2 488 Producing formation:￿ ￿Cretaceous, Menefee Formation 2645 2400 2573 ￿ ￿ ￿ ￿(lower part) 2451 2290 5200 Cliff House Number of producing wells:￿0 2500 Production:￿ ￿ ￿1025 bbl (1983) 2600 2372 ATOM INCORPORATED transition T 2474 Type of drive:￿ ￿ ￿pumped 29 2700 2433 2421 #1 ATOM Average net pay:￿ ￿ ￿30 feet N 2800 2623 sw sec 10 T29N R15W 5300 Porosity:￿￿ ￿ ￿23% 2331 2000 2968 2344 2900 Twin Mounds Mesaverde 2367

5400 Location of discovery well:￿￿se sw sec. 4, T29N, R14W (1954) STRUCTURE CONTOUR MAP 2200 Producing formation:￿ ￿Cretaceous Point Lookout Sandstone Datum: Top Point Lookout Sandstone Number of producing wells:￿0 C. I. = 100' MENEFEE Production:￿ ￿ ￿654,884 MCFG (1983) 2474 Datum elevations from wells FORMATION drilled to deeper formations Gas characteristics:￿ ￿Btu 1,153 2400 5500 Type of drive:￿ ￿ ￿Volumetric with possibly partially active Discovery Well Menefee ￿ ￿ ￿ ￿water drive Well drilled to offset discovery Formation Average net pay:￿ ￿ ￿10 feet NENAHNEZAD Porosity:￿￿ ￿ ￿25% PAY ZONE 2 DATUM R 15 W 600 5600 Permeability:￿ ￿ ￿6 mD

0 POINT 4 2 2800 Point Lookout 16 3 0 LOOKOUT B Bench 5700 ? SANDSTONE Sandstone 5 8 0 C Bench T

32 8 3000 15 D Bench 29 5800 10 15 N 30 11 0 3 2 20 MANCOS

Transition 10 3200 SHALE 0 interval 5900 0 ISOPACH MAP Figure UM-40. Structure Figure UM-39. Log of the Lower Menefee Channel Sandstone contour map, isopach map, Upper Mancos Mesaverde pool stratigraphic Gamma Induction. and type log for the C.I. = 10' units. Well is in the Jerome Ray Shale Nenhnezad Mesaverde field 15 Channel thickness in feet McHugh Southern Ute NO. 3, NW, (modified after Meibos, 1983). TD 8048' DRL NW sec.20, T32N, R9W, La Plata Discovery Well County, CO (modified after Harr, Well drilled to offset discovery 1988, p. 123).

UTE MOUNTAIN UTE RESERVATION CONVENTIONAL / UNCONVENTIONAL PLAY TYPE: Basin Margin Mesaverde Oil Play / Central Basin Mesaverde Gas Play 17 COLORADO, NEW MEXICO o WEST TOE Basin Margin Dakota Oil Play mation (Fig. UM-43). This unconformity pro 110 108o EXPLANATION S 1/2 NE 1/4 and N 1/2 SE 1/4 A Sec. 7, T331/2N R16W A' (USGS Designation 2206) gressively truncates older units from northeast Paradox Basin DISTAL MARINE FACIES FOUR CORNERS to southwest. The upper boundary is con Province nw nw 23, T32N R20W General Characteristics formable with the Mancos Formation. San Juan Basin FOSSILIFEROUS Province FOSSILIFEROUS The Basin Margin Dakota Oil Play is both a structural and stratigraphic ￿Reservoirs in the Basin Margin Dakota FOSSILIFEROUS Ute Mt. Ute. Indian o o FOSSILIFEROUS play on the northern, southern, and western sides of the central San Oil Play are controlled by stratigraphic and 38 38 Reservation Juan Basin, and the southeastern part of the Ute Mountain Ute Indian structural trapping (Fig. UM-44). Successful Bridge Creek Limestone Member Reservation (Figs. UM-41 and UM-42). Because of the variability of exploration for lower Dakota Sandstone pro Play Boundary of the Mancos Shale depositional environments in the transgressive Dakota Sandstone, it is duction is accomplished by careful mapping difficult to characterize a typical reservoir lithology. Most production of channel sandstones and close attention to UT CO has been from the upper marine part of the interval but significant oil and gas shows in the thin porous sand Formation boundary AZ NM amounts of both oil and gas also have been produced from the nonmar stones that may develop into channels. burrows ine section. ? Reservoirs: The Late Cretaceous Dakota Sandstone varies from dom inantly nonmarine channel deposits and interbedded coal and conglom SCALE Lower shale member of the Mancos Shale erate in the northwest to dominantly shallow marine, commonly bur 0 25 50 miles ? rowed deposits in the southeast. Net pay thicknesses range from 10 to 110o 108o Formation Boundary 100 ft; porosities are as high as 20% and permeabilities are as high as Mancos Shale Fm. 400 mD. Figure UM-41. Location of Basin Margin Dakota Oil Play (modified Dakota FOUR CORNERS after Gautier, et al., 1996). Sandstone ne ne 22, T32N R20W Source rocks: Along the southern margin of the play, the Cretaceous ? MARINE GRYPHEA McELMO STACKED MUDSTONE marine Mancos Shale was the source of the Dakota oil. API gravities DOME DELTA PLAIN (?) 6000 (DISTRIBUTORY (?) FACIES CHANNEL OVERBANK range from 44° to 59°. On the Four Corners Platform to the west, non FACIES FACIES COAL marine source rocks of the Menefee Formation were identified as the 6000 Menefee CREVASSE source (Ross, 1980). The stratigraphically higher Menefee is brought SPLAY A Figure UM-43. FACIES COAL into close proximity with the Dakota across the Hogback Monocline. UTE STACKED DOME 5000 Correlation of uppermost (DISTRIBUTARY?) CHANNEL DELTA PLAIN ? Timing and migration: Depending on location, the Dakota Sandstone Jurassic to Mid- FACIES HL OVERBANK ? SENTINEL PEAK 4000 burrows FACIES and Lower Mancos Shale entered the oil window during the Oligocene DOME Cretaceous rocks in the CREVASSE Ute Mountain Ute Indian SPLAY FACIES to Miocene. In the southern part of the area, migration was still taking CLINKER 5000 UTE MOUNTAIN INDIAN RESERVATION Reservation (modified place in the late Miocene or even more recently. 3000 DELTA PLAIN ? from Aubrey, 1992). OVERBANK ? FACIES Traps: Fields range in size from 40 to 10,000 acres and most produc COAL MESA VERDE COAL BASIN tion is from fields of 100-2,000 acres. Stratigraphic traps are typically UT CO A' HL HL BARKER 1000 formed by updip pinchout of porous sandstone into shale or coal. AZ NM Middle SOUTH DOME UTE Structural traps on faulted anticlines sealed by shale form some of the Canyon DOME LACUSTRINE CHANNEL FACIES FACIES larger fields in the play. Oil production ranges in depth from 1,000 to 3000 OVERBANK 2000 -1000 AND 3,000 feet. MO NOCLIN E LACUSTRINE 0 FACIES CLINOPTILOLITE (?) Exploration status and resource potential: The first discoveries in Salt Creek the Dakota play were made in the early 1920's on small anticlinal Shiprock 3750 Burrow Canyon Fm. structures on the Four Corners Platform. Approximately 30% of the HOGBACK LACUSTRINE FACIES Rattlesnake Slickrock oil fields have an estimated total production exceeding 1 MMBO, and HL HL 758 m 26 km HL Hogback (16 mi) (2500 ft) the largest field (Price Gramps) has production of 7 MMBO. Future HL CLINOPTILOLITE HL Dakota oil discoveries are likely as basin structure and Dakota deposi HLCLINOPTILOLITE HL tional patterns are more fully understood. EXPLANATION Figure UM-42. Structure METERS FEET SANDSTONE & TROUGH CROSSBEDS 12 40 SCALE contour map of the basal CONGLOMERATE Stratigraphy Dakota Sandstone and SILTSTONE & TABULAR - PLANAR 9 30 Approximate location of discovery 0 12 miles MUDSTONE CROSSBEDS Horizontal distances are not to location of oil field 6 20 The Dakota Sandstone is a coastal plain deposit laid down in front of for named oil field LIMESTONE RIPPLE CROSSBEDS scale and facies relationships are discovery wells for fields only shown schematically. the advancing Mancos Sea. In the Ute Mountain Ute Indian Reserva 3 10 Limits of Ute Mountain Ute Indian Reservation producing from the Basin COAL COVERED tion the lower Dakota consists primarily of ribbon-type fluvial sand 0 0 Margin Dakota Oil Play UNCONFORMITY stone bodies and the upper Dakota consists of carbonaceous paludal Structure Contour line drawn on base of Dakota Sandstone BENTONITE 3000 (modified after Anderson, FACIES BOUNDARY shales deposited in coastal-plain or deltaic environments. The Dakota 1995). C. I. = 250 feet HL HARDLAYER (composed of silica and clay and locally unconformably overlies the fluvial deposits of the Burrow Canyon For contains feldspar)

UTE MOUNTAIN UTE RESERVATION CONVENTIONAL PLAY TYPE: Basin Margin Dakota Oil Play 18 COLORADO, NEW MEXICO Analog Fields Inside or Near Reservation (*) denotes field lies inside reservation boundaries AZTEC OIL & GAS AZTEC OIL & GAS AZTEC OIL & GAS No. 3 MIDDLE CANYON No. 1 MIDDLE CANYON No. 2 MIDDLE CANYON *Middle Canyon Dakota Field sw nw 14 T32N R15W ne sw 14 T32N R15W ne se 14 T32N R15W (Fig. UM-44) San Juan Co., New Mexico San Juan Co., New Mexico San Juan Co., New Mexico •Location of discovery well:￿NE ¼, SW ¼, sec. 14, T32N, R1 W ￿ ￿ ￿ ￿(September 1969) KB 6656 KB 6665 KB 6699 •Producing formation:￿ ￿Cretaceous Dakota Sandstone •Number of producing wells:￿1 •Production:￿ ￿ ￿4,886 BO (1971) •Type of drive:￿ ￿ ￿Water •Average net pay:￿￿ ￿20 feet •Porosity:￿ ￿ ￿12.1 % •Permeability:￿ ￿ ￿0.3 mD

Salt Creek Dakota Field DATUM Base - Greenhorn Ls DATUM •Location of discovery well:￿SW ¼, NW ¼, Sec 4, T30N, R17W ￿ ￿ ￿ ￿(July, 1958) •Producing formation:￿ ￿Cretaceous Dakota Sandstone Graneros Sh. •Number of producing wells:￿6 (1977) •Production:￿ ￿ ￿88,604 BO (1977) Top - Dakota •Gas characteristics:￿ ￿51.8 ° API Gravity Sandstone •Type of drive:￿ ￿ ￿Water •Average net pay:￿￿ ￿30 - 40 feet •Porosity:￿ ￿ ￿16 % •Permeability:￿ ￿ ￿0.8 mD.

Menefee Mountain Field

•Location of discovery well:￿NW ¼, NE ¼, Sec 16, T35N, R13W ￿ ￿ ￿ ￿(July, 1978) •Producing formation:￿ ￿Cretaceous Dakota Sandstone •Number of producing wells:￿3 (1981) •Production:￿ ￿ ￿33,356 BO (1981) •Gas characteristics:￿ ￿34 ° API Gravity •Type of drive:￿ ￿ ￿Water R 15 W •Average net play:￿ ￿15 feet ￿ •Porosity:￿ ￿ ￿12 - 14 % 9 10 11 12 •Permeability:￿ ￿ ￿Unknown ￿ Producting Zone: DAKOTA 3272-3370' IPP 123 BO. 7 BWPD 3 16 15 14 2 13 1 4 T Figure UM-44. Cross section 32 showing producing interval of N the Dakota Sandstone in the Middle Canyon Field (modified 21 22 23 24 after Stevensen, 1978). MIDDLE CANYON FIELD San Juan Co., New Mexico

UTE MOUNTAIN UTE RESERVATION CONVENTIONAL PLAY TYPE: Basin Margin Dakota Oil Play 19 COLORADO, NEW MEXICO DAKOTA CENTRAL BASIN GAS PLAY able. Non-associated gas in the Dakota pool was generated during the flanks and bottom of a large depression and is not o 110 108o EXPLANATION (USGS Designation 2205) late mature and postmature stages and probably had a marine Mancos localized by structural trapping (Fig. UM-46). The Shale source (Rice, 1983). fluid transmissibility characteristics of Dakota Paradox Basin Province GENERAL CHARACTERISTICS Timing and Migration: In the northern part of the central San Juan sandstones are generally consistent from the cen This Dakota Central Basin unconventional continuous-type play is Basin, the Dakota Sandstone and Mancos Shale entered the oil genera tral basin to the outcrop. Hydrodynamic forces, San Juan Basin Province contained in coastal marine barrier-bar sandstone and continental flu tion window in the Eocene and were elevated to temperatures appro acting in a basinward direction, have been suggest ed as the trapping mechanism, but these forces are Ute Mt. Ute. Indian vial sandstone units, primarily within the transgressive Dakota Sand priate for the generation of dry gas by the late Oligocene. Along the o o 38 38 Reservation stone. It is located in the northeastern part of the San Juan Basin prov southern margin of the central basin, the Dakota and lower Mancos en still poorly understood. The seal is commonly pro vided by either marine shale or paludal carbona ince and the southeastern corner of the Ute Mountain Ute Indian Res tered the thermal zone of oil generation during the late Miocene (Huff Play Boundary ervation (Figs. UM-45 to UM-47). man, 1987). It is not known at what point hydrodynamic forces ceous shale and coal. Production is primarily at depths ranging from 6,500 to 7,500 feet. Reservoirs: Reservoir quality is highly variable. Most of the marine reached sufficient strength to act as a trapping mechanism, but the ear A' A ly Miocene time is likely for the establishment of the present-day up Exploration status and resource potential: The Location sandstone reservoirs within the central basin field are considered tight UT in that the porosities range from 5% to 15% and permeabilies range lift and erosion pattern throughout most of the basin. Migration of the Dakota discovery well in the central basin was dril CO of Cross AZ A' Section from 0.1 to 0.25 mD. Fracturing, both natural and induced, is essential oil in the Dakota was still taking place in the late Miocene, of even led in 1947 southeast of Farmington, New Mexico. NM for effective field development. more recently, in the southern part of the San Juan Basin. The Dakota Basin Field, containing the Dakota gas pool, was formed February 1, 1961, by combining Source Rocks: Quality of the source beds for oil and gas is also vari Traps: The Dakota gas accumulation in the central basin is on the several existing fields. By the end of 1993 it had

DOME produced over 4.0 TCFG and 38 MMB condensate. 6000 Almost all of the Dakota interval in the central part SCALE of the basin is saturated with gas, and additional 0 25 50 miles o o 6000 future gas discoveries within the central basin field 110 A 108 and around its margins are possible. Figure UM-45. Location of Dakota Central Basin Gas Play (modified after Gautier, et UTE al., 1996). DOME 5000 N A NW SE A' SENTINEL PEAK 4000 DOME

5000 UTE MOUNTAIN UTE INDIAN RESERVATION Greenhorn Limestone 3000 Twowells Graneros Shale

Mancos Shale Twowells Mancos Shale MESA VERDE Twowells BASIN main UT CO Barker Creek Figure UM-47. body Paguate Sandstone AZ NM Dakota 1000 Schematic stratigraphic Dakota { Basin cross section of Clay Mesa Shale Dakota Ute Dome Cretaceous- Jurassic Strait Dakota rocks in the San Juan 3000 Burro Canyon Fm.Encinal Canyon Cubero Sandstone

-1000 Basin. Location of cross Canyon 2000 MONOCLIN E section is labeled on Dakota Saltwash member 0 Figure UM-45 (modified Oak Canyon Member after Walters, et. al., } Mancos Shale 1987). Brushy Basin Member 3750 Sandstone Dakota CK Jackpile Sandstone HOGBA Westwater Canyon Member EXPLANATION SCALE Recapture Member Approximate location of discovery Figure UM-46. Structure Lower Strata for named oil field contour map of the Dakota 0 12 miles Formation and location of Ute Mountain Ute Indian Reservation Boundary C. I. = 250 feet the discovery wells for fields in and near the Structure Contour line drawn on base of Dakota Sandstone reservation (modified after

3000 Anderson, 1995). Morrison Fm.

UTE MOUNTAIN UTE RESERVATION UNCONVENTIONAL PLAY TYPE: Dakota Central Basin Gas Play 20 COLORADO, NEW MEXICO Analog Fields in and near Reservation R131/2W (*) denotes field lies inside Reservation boundaries R14W 12 9 11

*Barker Creek Dakota (Fig. UM-48) CO ER NT Location of discovery well:￿￿se ne 16 - T32N - R14W (1925) AT A 2300 W C T AS T GREENHORN Producing formation:￿ ￿Upper Cretaceous Dakota Sandstone, G 14 16 L 14 ￿ ￿ ￿ ￿Paradox Formation 32 A + 3700' N Number of producing wells:￿5 (1977) I N IG + 3800' R Production:￿ ￿ ￿215,279,080 MCFG (1996) O GRANEROS 2400 Gas characteristics:￿ ￿Sweet gas

Type of drive:￿ ￿ ￿Gas expansion Pa 23 24 22 23 Mar Average net pay:￿ ￿ ￿40 feet 21 y Zone

Porosity:￿￿ ￿ ￿14% LA PLATA CO., COLO. ine

Permeability:￿ ￿ ￿0 - 1500 md, average = 16.5 md SAN JUAN CO., N.M. 2500

SURFA SURF DAKOTA

*Ute Dome Dakota Continental CE ACE Location of discovery well:￿￿se 35 - T32N - R14W (1921) FA F UL AULT Producing formation:￿ ￿Cretaceous Dakota Sandstone, A 17 T 15 + 3800'

￿ ￿ ￿ ￿Paradox Formation 2600

Number of producing wells:￿14 (1977) + 4000' Production:￿ ￿ ￿93,589,058 MCFG (1996) + 3700' Type of drive:￿ ￿ ￿Combination water drive and volumetric T Average net pay:￿ ￿ ￿30 feet 32 23

2700 Porosity:￿￿ ￿ ￿15% N MORRISON Permeability:￿ ￿ ￿10 md + 3900'

*Basin Dakota Location of discovery well:￿￿ne nw 4 - T27N - R10W NMPM ￿ ￿ ￿ ￿(April 1947) 26 E.P.G.N. #6 UTE Producing formation:￿ ￿Cretaceous Dakota Sandstone + 3800' sw sw 17 - T32N - R14W Number of producing wells:￿2395 R13W A' San Juan Co., New Mexico Production:￿ ￿ ￿Gas: 2,753,610,459 MCFG ￿ ￿ ￿ ￿Oil: 27,186,314 BO Characteristics￿ ￿ ￿Gas: 1100 BTU ￿ ￿ ￿ ￿Oil: 50 ° API Gravity Type of drive:￿ ￿ ￿Gas expansion (upper part), E.P.N.G. E.P.N.G. SO. UNION ￿ ￿ ￿ ￿Water drive (lower part) No. 6 Ute No. 11 Ute No. 17 Barker Average net pay:￿ ￿ ￿50-70 feet Porosity:￿￿ ￿ ￿5-15% Permeability:￿ ￿ ￿0.1 - 0.25 md +4200' A A' +4000'

Est. Gas - Water Contact GREENHORN +3800' GRANEROS Figure UM-48. Structure contour map of the top of the Graneros Shale, cross section, and type log +3600' Pay DAKOTA for the Barker Creek Dakota Field Zone (modified after Matheny, 1978) +3400' MORRISON

UTE MOUNTAIN UTE RESERVATION UNCONVENTIONAL PLAY TYPE: Dakota Central Basin Gas Play 21 COLORADO, NEW MEXICO Buried Fault Blocks, Older Paleozoic Play Characteristics of the Buried Fault o Figure UM-49. Location of Buried Fault 110 108o EXPLANATION (USGS Designation 2101) Blocks, Older Paleozoic Play Blocks, Older Paleozoic Play and location of oil and gas discovery wells Paradox Basin General Characteristics In the Ute Mountain Ute Indian Reservation, the Buried Fault Blocks, for named fields (modified after Province The play is based on the occurrence of oil accumulations in fault Older Paleozoic Play consists of the Mississippian Leadville Limestone Peterson, 1996). San Juan Basin blocks involving pre-Pennsylvanian rocks, mainly in the salt anticline and the Devonian McCracken Sandstone Member of the Elbert Forma Province area of the Paradox Basin, and it covers an area of approximately Ute Mt. Ute. Indian tion. o o 38 38 Reservation 7,500 square miles (Fig. UM-49). Most of the structures are associat ￿The McCracken Sandstone (Figs. UM-51 and -53) is mainly a do ed with the salt anticlines themselves and were growing at the same lomitic sandstone, sandy dolomite, and dolomitic mudstone. Cyclical Play Boundary time that the salt was moving. fluctuations in relative sea level during McCracken time produced three McElmo coarsening-and thickening-upward intervals (parasequence sets) which Location of discovery well for Reservoirs: Reservoirs are in porous dolomite or dolomitic limestone correspond to the main reservoir units. Depositional environments UT CO named oil field beds of the Mississippian Leadville Limestone (Figs. UM-50, -52, and range from intertidal-supratidal carbonate flat to siliciclastic prodelta AZ Walker -53) and the Upper Devonian McCracken Sandstone Member (Figs. and delta front. Reservoir flow units are strongly dominated by silici Creek NM N. Tocito Hogback UM-51 and -53) of the Elbert Formation. Reservoirs are as thick as clastic lithofacies, whereas carbonate lithofacies compose major flow Dome Mississippian 200 feet, and porosity varies from 5 to as high as 25% in local cases. barriers and baffles. Table Mesa Permeability is generally low, but is as much as several hundred mD in ￿The Leadville Limestone (Figs. UM-50, -52, and -53) is Kinder places. hookian to Osagean in age and rests on top of shaly limestones of the Ouray Limestone. The Leadville is capped by a major unconformity SCALE Source Rocks: Probable source rocks are the organic-rich black dolo which has truncated the formation. Two well defined intraformational 0 25 50 miles mitic shales of the Pennsylvanian Paradox Formation. Migration into markers exist in the Leadville (Fig. UM-57). They are interpreted as 110o 108o Leadville or McCracken reservoirs occurred where fault blocks are in major erosional channels caused by upward shoaling cycles that include structural and (or) depositional contact with the black shale, which is a full suite of environments ranging from shallow marine tidal shelf commonly highly fractured. through lagoonal and supratidal. The markers represent time strati 2000 1000 o graphic lines which form the boundaries between depositional units and 0 37 30' Timing and Migration: Hydrocarbon generation began as early as separate facies of the Leadville. The Leadville has undergone complex Permian time and has continued to the present in some cases. Migra diagenesis. Moldic porosity and vuggy porosity are common. tion into pre-salt reservoirs was probably contemporaneous with the A McELMO DOME -1000 growth of salt structures. Migration pathways were enhanced by se Cortez -2000 vere fracturing of interbedded organic-rich shale during salt move Bluff 1000 ment. -3000 Durango -4000

Traps: Known traps are on uplifted fault blocks adjacent to salt anti -5000 clines or swells. Seals are Paradox Formation evaporite beds that Ute Mountain Ute -6000 overlie, or are in fault contact with, Mississippian or Devonian reser Indian Reservation -7000 o voirs. Drilling depths range from 7,000-8,000 feet at the Lisbon field, UTAH COLORADO 37 00' and to greater than 10,000 feet in other areas. ARIZONA NEW MEXICO San 0 Exploration Status and Resource Potential: Six oil and gas accu Juan River mulations produce from pre-salt structural blocks. The largest of these is the Lisbon field, which is approximately 43 MMBO and 250 BCFG 1000 -7000 Navajo Animas Reservoir in size. The remainder of the fields are noncommercial or marginally River Farmington commercial. The play is only moderately explored with respect to 2000 smaller structures. Future potential is low to moderate, and based on A' -5000 -6000 previous production history, undiscovered fields are estimated to be small to medium in size and have minimal oil columns. River Chinle -2000 SAN JUAN BASIN o 3000 -3000 36 30' Figure UM-50. Structure Contour Map of the top -4000 0 25 50 Miles of the Mississippian Leadville Limestone and 4000

location of cross section in figure UM-53 -1000 0 25 50 Kilometers (modified from Condon, 1995). DEFIANCE PLATEAU o o o o 109 30' 109 108 30' 108

UTE MOUNTAIN UTE RESERVATION CONVENTIONAL PLAY TYPE: Buried Fault Blocks, Older Paleozoic Play 22 COLORADO, NEW MEXICO 50 Figure UM-51. Isopach map of the

McCracken Sandstone Member of the Elbert 100 25 o 200 o 37 30' Formation. Contour intervals are 25 ft 37 30' 50 (modified from Condon, 1995).

50 400 100 Cortez 50 Cortez Bluff 25 Bluff 300 75 25 75 Durango n Juan 200 Durango Sa Rive an Juan R r S iver

200 0 0

Ute Mountain Ute Indian Reservation Ute Mountain Ute Indian Reservation 75 o o COLORADO 37 0' UTAH COLORADO 37 0' NEW MEXICO ARIZONA NEW MEXICO

100 75 River River 0 50 25 Navajo Navajo Animas Reservoir Animas 0 Farmington Farmington Reservoir 25 50 100 75 75 200 0 25 50 Miles Chinle River o Chinle River o 36 30' 36 30' 100 0 25 50 Kilometers 0 25 50 Miles

100 0 25 50 Kilometers o o o 109 0' o o o o o 109 30' 108 30' 108 0' 109 30' 109 0' 108 30' 108 0' 1 2 5 6 7 A' Figure UM-52. Isopach map of the Mississippian A 3 4 Leadville Limestone. Contour intervals are 100 ft Molas Formation (modified from Condon, 1995).

Leadville Limestone Ouray Limestone Upper member Precambrian McCracken Sandstone Elbert Member McCracken Ss Fm. Member Precambrian

Aneth Formation Precambrian 600 feet

Ophir Ignacio Precambrian Formation Quartzite Vertical scale Tintic Quartzite Figure UM-53. Stratigraphic section of Pre-Pennsylvanian units in the Ute Mountain Ute Indian Reservation and surrounding Precambrian area. All logs are gamma ray-neutron, except for log number 6 0 which consists of a spontaneous-potential and resistivity curves. Horizontal scale is variable (modified from Condon, 1995). Precambrian

UTE MOUNTAIN UTE RESERVATION CONVENTIONAL PLAY TYPE: Buried Fault Blocks, Older Paleozoic Play 23 COLORADO, NEW MEXICO Analog Field Near Reservation LISBON FIELD Lisbon Field STRUCTURAL CROSS-SECTION (Figs. UM-54 - UM-57) A LISBON B-615 LISBON C-910 LISBON D-810 LISBON D-610 (PROJ) A' Location of discovery well:￿￿nw ne ne, sec. 10, T30S, R24E (1959) SW KB 6307 KB 6255 KB 6643 KB 6642 NE Producing formation:￿ ￿McCracken Sandstone Member of the Elbert MOLAS ￿Formation, Leadville Limestone 8565 (-2265) N Number of producing wells:￿11 -1000 IO AT TUL LOWER ATOKA X SALT RM Production:￿ ￿ ￿1.465 BCFG, <1 MMBO McCracken FO S LEADVILLE PARADO LA ￿ ￿ ￿ ￿(1996) MO & -1400 AIL 8635 (-2335) ￿ ￿ ￿ ￿60 MMBO Leadville (1996) TR TON KER ONE . Oil characteristics:￿ ￿44 API PI N BR M NE Average net pay:￿ ￿ ￿39.4 Feet ALL LIMEST TO -1800 ONE S REDW D DOLOMITE Upper Osage - Meramec Porosity:￿￿ ￿ ￿0.3 - 16.9% AN T MBR. S OPHIR SHALE & Y LIMEST EN LYNCH Permeability:￿ ￿ ￿<0.01 - 272 mD CK IGNACIO FORMATIONS OURA RA ELEVATION (FEET) ELEVATION -2200 UPPER ELBERcC M "C" ANETH SHALE Marker -2600 TD 8895 PRECAMBRIAN

TD 9310 LISBON-McINTYRE FA TD 9050 EST. OIL-WATER CONTACT STRUCTURE MAP (-2340' SUBSEA) 0 2000 D Top - F2 Flow Unit FEET U Figure UM-55. Structure cross-section of Lisbon field (after Cole and Moore, 1996). Middle to Lower Osage McCRACKEN UNIT "B" BOUNDARY Marker LISBON D-810 CHRONOSTRATIGRAPHY ne/se ssc 10, 30S, 24E 9000

-2800 PARADOX BASIN GR SONIC D TERMINOLOGY PINKERTON SHALE -3000 U N WEST EAST 7659 MOLAS FORMATIONP (P) D A' U -1600-1400-1200 REDWALL LIMESTONE

LISBON-McINTYRE FAULT REDWALL LIMESTONE 7988 8000 Lower Osage or Kinderhook

-2600

MISSISSIPPIAN OURAY LIMESTONE OURAY LIMESTONE 8119 OURAY UPPER ELBERT MBR. UPPER ELBERT 9150 (-2850) -2000 ELBERT 8232 Kinderhook -1800 UPPER FORMATION McCRACKEN SS MBR. McCRACKEN -2200 )

0 ONIAN ANETH SANDSTONE 4 SHALE 8348 23 (- MIDDLE

T DEV ANETH SHALE -2400 C & 8422 DATA A NTA CO LOWER BREAK EST. OIL-WATE R SIL. Baren of Forams -2800 LYNCH DOLOMITE ORD. ELBERT U 3000 LYNCH DOLOMITE D 8785 9280 (-2980) CAMB. OPHIR SHALE IGNACIO FORMATION OPHIR SHALE Figure UM-57. Type log for Leadville Limestone unit at Lisbon Field (modified after PRECAMBRIAN 3000 8976 9000 0 5000 Fouret, 1996)

FEET IGNACIO FORMATION

CI = 200FT 9280

TD 9310 Figure UM-54. Structure contour map of the top of the F2 flow unit for Lisbon field and location of cross section in Figure UM- 55 (modified after Cole and Moore, 1996). Figure UM-56. Type log for McCracken unit at Lisbon Field (modified after Cole and Moore, 1996).

UTE MOUNTAIN UTE RESERVATION CONVENTIONAL PLAY TYPE: Buried Fault Blocks, Older Paleozoic Play 24 COLORADO, NEW MEXICO Fractured Interbed Play o Permian-Pennsylvanian Marginal 110 108o EXPLANATION (USGS Designation 2103) Figure UM-58. Location Clastics Gas Play of Fractured Interbed Play Paradox Basin (modified after Gautier, et (USGS Designation 2104) General Characteristics Province al., 1996). This unconventional continuous-type oil and gas play is oil prone General Characteristics throughout most of the Paradox Basin but is more gas prone to the San Juan Basin This hypothetical play, formerly known as the Silverton Delta Play east close to the ancestral Uncompahgre uplift (Fig. UM-58). The Province (Peterson, 1989), has been renamed to more accurately reflect the ge reasons for this change in character are increased depth of burial and Ute Mt. Ute. Indian o o ometry and depositional environment of the reservoir rocks. The Sil percentage of terrestrial organics to the east. 38 38 Reservation verton fan delta is limited to an area near the Colorado-Utah state Play Boundary line, but marginal clastic rocks extend the length of the ancestral Un Reservoirs: The play depends on extensive fracturing in the organ compahgre Uplift (Fig. UM-59). These clastics were deposited as co ic-rich dolomitic shale and mudstone in the interbeds between evap alesced outwash fans that intertongue with the cyclic marine deposits orites of the Pennsylvanian Paradox Formation or carbonate and of the Pennsylvanian Hermosa Group. clastic rocks of the related cycles on the shelf of the Paradox evapor ite basin. These shales and mudstones may be as thick as 130 feet UT CO Reservoirs: Gas shows have been encountered in porous and perme but are more commonly less than 20 feet thick. AZ NM able sandstone intervals within the generally arkosic Permian Cutler Formation in the vicinity of the ancestral Uncompahgre Uplift. Such Source rocks: These organic-rich black dolomitic shales and mud potential reservoir rock is present where feldspar and clay were winn stones are the source rocks for most, if not all, of the oil and gas in owed out by wave action or fluvial stream flow. For most of the area, the Paradox Basin. Total organic carbon commonly ranges from 1 the lower part of the Pennsylvanian interval is more likely to contain to 5% but may be as high as 20%. Oil produced by these source these beds than the upper part because of the lower original feldspar rocks typically has 40°-43° API gravity and low sulfur content. SCALE content of the lower part. In the upper part of the Pennsylvanian in terval, the southeastern Paradox Basin province is more likely to con Timing and migration: The thermal history of these rich source 0 25 50 miles o o tain such beds because of the presence of a large fan delta complex rocks is determined mostly by depth of burial and to a lesser degree 110 108 that provided the necessary depositional environments to clean the by the added effect of the Oligocene volcanic activity. Pennsylvani sandstone. an, Permian, Late Cretaceous, and early Tertiary sediments thicken 110o o EXPLANATION significantly to the east so that the Pennsylvanian section entered the 108 Source rocks: This play is dependent on the presence of Desmoinesian, thermal zone of oil and gas generation at different times depending Paradox Basin organic-rich, dolomitic shale and mudstone in contact or close prox on location. Close to the Uncompahgre Uplift, Pennsylvanian rocks Province imity to reservoir lithologies. Because this juxtaposition is necessari may have generated oil as early as the Permian; elsewhere these ly close to the ancestral Uncompahgre Uplift, the play is gas prone rocks may have entered the oil generation zone in the Late Creta San Juan Basin Province due to the preponderance of Type III kerogen from the uplift, as well ceous and the dry gas zone as late as the Oligocene. as the depth of burial in the deep trough along the basin margin. Ute Mt. Ute. Indian o o Traps: Fracturing of the shale on structures is a necessary attribute 38 38 Reservation Traps: Trap types are expected to be dominantly combinations of of this play, but the actual trapping and sealing mechanisms may be Play Boundary updip pinchouts of permeable sandstone lenses localized on folded stratigraphic as well as structural because the fractures die out into and faulted structures. Seals are provided by shale beds as well as by unfractured shale. Only certain intervals within the total shale thick reduced permeability due to clay. ness may be of sufficient richness or be sufficiently fractured for significant oil production. Depths to potential targets vary greatly Exploration status and resource potential: Little exploration has from more than 15,000 feet near the eastern basin margin to less UT CO taken place within this play and there is no production to date, but than 5,000 feet on the Four Corners Platform. AZ NM shows have been reported from Permian Cutler sandstone bodies. The presence of excellent source rocks and structures are factors in its fa Exploration status and resource potential: Until recently, the on vor. ly significant production from this play was from the Cane Creek Figure UM-59. Location of Shale in the Lone Canyon field discovered in 1962. Recently, near Permian-Pennsylvnian by Bartlett Flat field has been developed by directional drilling in Marginal Clastics Gas Play the Cane Creek Shale at a depth of approximately 9,000 feet. The SCALE (modified after Gautier, et al., Cane Creek, Chimney Rock, Gothic, and Hovenweep Shales have 1996). the most potential due to both organic content and thickness. 0 25 50 miles 110o 108o

UTE MOUNTAIN UTE RESERVATION CONVENTIONAL / UNCONVENTIONAL/HYPOTHETICAL PLAY: Fractured Interbed Play / Permian-Pennsylvanian Marginal Clastics Gas Play 25 COLORADO, NEW MEXICO