PennsylvanianPennsylvanian ParadoxParadox FormationFormation Reservoir,Reservoir, ParadoxParadox BasinBasin –– OutcropOutcrop AnalogsAnalogs alongalong thethe SanSan JuanJuan RiverRiver

T T 35 40 S PARADOX FORMATION OUTCROP CHARACTERISTICS R 21 E R 22 E R 23 E R 24 E R 25 E R 26 E N 20 W R 19 W Caballo Bug Ucola T Papoose Canyon 36 Mustang Flat T S 39 Wild Station Squaw Creek Cahone N

Cherokee Alkali Point T Alkali Canyon Bradford Canyon 37 Dove Deadman Canyon Creek T S Patterson Canyon Deadman 38

Rock Canyon UTAH N Island Little Nancy Butte McCracken Spring Cave COLORADO T Squaw Point 38 Grayson Kachina Hatch T S Tin Cup Mesa Squaw Canyon 37 N Bannock Kiva T Cowboy Cajon Lake Cutthroat 39 (McClean) T S Bluff Monument 36 Broken Hills Cajon Mesa Runway N Tower Ismay T T 40 35 N S Bluff Bench Flodine Park Recapture Turner Bluff Greater Cache Ismay Sleeping Ute Gothic Mesa Aneth Desert Canyon T 34 N T McElmo 41 Heron Schematic diagram of Paradox Formation Jack North Mesa Marble Wash S Tohonadla Hogan T Desert Creek algal banks (from Brinton, 1986). Clay 331/2 Goosenecks of the San Juan River. Photograph Hill Roadrunner N Brown Hogan Rockwell Towoac by Tom Till, courtesy of the Utah Travel Council. Heron Flat T Cone Rock Anasazi 42 Blue Hogan Mule River Bank S Sage Hen Akah T Yellow Rock 33 N Chinle Wash T Anido Creek 43 T Location of Paradox Formation outcrops in the Eight-Foot Rapid S Cleft 32 Boundary Butte Rabbit Ears UTAH N area and The Goosenecks/Honaker Trail, San Juan River, southeastern Utah. ARIZONA T Boundary Butte East 41 N N UTAH

R 26 E R 27 E R 28 E R 29 E R 30 E 0 3 6 mi Ismay mound Northern Desert Desert Creek trend Creek beach/ shelf margin 0 3 6 9 km (predominantly mound trend trend limestone) (predominantly dolomite)

Map of Paradox Formation play area and fields within the Ismay and Desert Creek zones producing trends, Utah and Colorado.

Ismay zone algal banks near Eight-Foot Rapid Stacked complex of four phylloid-algal mounds in the Akah and Barker Creek zones of the PARADOX FORMATION RESERVOIR Paradox Formation, river mile 39.8. CHARACTERISTICS

• Net pay – 9 to 57 ft (3-17 m); 165 ft (50 m) at Greater Aneth field • Primary producing zones – Ismay and Desert Creek Paradox Formation algal bank/mound topography, morphology, and facies relationships as seen along the San Juan River, Utah • Depositional environments – shallow-shelf and shelf-margin marine, (from Brinton, 1986). carbonate buildups (phylloid algal and bryozoan mounds), oolitic banks, beach, and stabilized grain flats

• Carbonate fabrics – bafflestone, grainstone, packstone, and wackestone Photomosaic of a large phylloid-algal mound complex composed of algal bafflestone, skeletal grainstone, (limestone and dolomite) and packstone in the Barker Creek zone of the Paradox Formation, river mile 40.5. • Pore types – shelter, moldic, intercrystalline, vugs • Porosity - averages 8-12% • Permeability – less than 1 md to greater than 500 md, averaging 25 md • Diagenesis – early marine cementation, dolomitization (early and late), freshwater dissolution and cementation, and anhydrite and bitumen plugging

Type Log MERIDIAN Cherokee 33-14 NW SE Sec. 14, T37S-R23E KB 5,572 ft

GR Porosity 10% Typical cement-rich algal bafflestone exposed in a phylloid- Mound flank material – part of the large phylloid-algal algal mound, Ismay zone, Eight-Foot Rapid area. Original mound complex in the Barker Creek zone, river mile 40.5. 5600 sheltered pore spaces were filled with mud; cement rinds Well-developed cross-bedding in peloidal and oolitic grainstone in are developed around algal plates. the cap and intermound facies of the Barker Creek zone of the Paradox Formation along the Honaker Trail. Close-up shown in inset photo.

NPHI 5700 Upper Ismay

63 80

5800 09 CORE

43

Hovenweep Shale

5900 Lower Ismay

DPHI Gothic Shale Desert Creek 6000

Chimney Rock Shale Akah Schematic diagram of drilling targets in a Paradox carbonate 6100 Flooding surface (4th-order sequence boundary), Block diagram displaying depositional interpretation of a mound complex buildup by multilateral (horizontal) legs from an existing field well. Ismay zone along the Honaker Trail. Note and associated features in the Eight-Foot Rapid area. This interpretation is abundant intact and fragmented productid a composite of inferences made from outcrop and subsurface data. Completed 6/9/1987 TD 6,115 ft brachiopods in the medium gray limestone matrix. IPF 336 BO, 346 MCF, + 0 WTR Typical gamma ray-compensated neutron-litho density log of UTAH GEOLOGICAL SURVEY the Paradox Formation, Cherokee field, San Juan County, Utah. DEPARTMENT OF NATURAL RESOURCES