Florida Department of Natural Resources A

STATE OF FLORIDA DEPARTMENT OF NATURAL RESOURCES Elton J. Gissendanner, Executive Director

DIVISION OF RESOURCE MANAGEMENT Art Wilde, Director

BUREAU OF GEOLOGY Walter Schmidt, Chief

INFORMATION CIRCULAR NO. 104

PART I - 1985 FLORIDA PETROLEUM PRODUCTION AND EXPLORATION

By Jacqueline M. Lloyd and Albert V. Applegate

PART II - THE BROWN DOLOMITE ZONE OF THE LEHIGH ACRES FORMATION (APTIAN) IN THE SOUTH FLORIDA BASIN - A POTENTIALLY PROLIFIC PRODUCING HORIZON OFFSHORE By

Albert V. Applegate

Tallahassee 1987 DEPARTMENT OF NATURAL RESOURCES

BOB MARTINEZ Governor

GEORGE FIRESTONE Secretary of State

BILL GUNTER State Treasurer

BETTY CASTOR Commissioner of Education

BOB BUTTERWORTH Attorney General

GERALD LEWIS State Comptroller

DOYLE CONNER Commissioner of Agriculture

ELTON J. GISSENDANNER Executive Director

ii (-.

LETTER OF TRANSMITTAL

BUREAU OF GEOLOGY TALLAHASSEE

Governor Bob Martinez, Chairman Sj Florida Department of Natural Resources Tallahassee, Florida 32301 Dear Governor Martinez: The Florida Geological Survey, Bureau of Geology, Division of Resource Management, Department of Natural Resources, is publishing a two-part report as its Information Circular 104. Part I - "1985 Florida Petroleum Production and Exploration" discusses 1985 oil and gas production, onshore and offshore exploration, and oil production and exploration statistics. This information is useful to the oil and gas industry and to the state in planning wise development of Florida's oil and gas resources.

Part IIof this report-- "The Brown Dolomite Zone of the Lehigh Acres Formation (Aptian) in the south Florida Basin - a potentially prolific producing horizon offshore" discusses the known extent of the Brown Dolomite Zone in the south Florida Basin and its possible future potential for producing oil. This information will be useful in planning future exploration programs and assessment thereof by the State of Florida.

Respectfully yours,

Walter Schmidt, Chief Bureau of Geology

iii Printed for the

Florida Geological Survey Tallahassee 1987

ISSN No. 0085-0616

Iv CONTENTS

Page

Part I - 1985 Florida Petroleum Production and Exploration .... 1

Part II - The Brown Dolomite Zone of the Lehigh Acres Formation (Aptian) in the South Florida Basin-A Potentially Prolific Producing Horizon Offshore...... 43

v PART I

1985 FLORIDA PETROLEUM PRODUCTION AND EXPLORATION

By Jacqueline M. Lloyd and Albert V. Applegate

vi TABLE OF CONTENTS

Page

Abstract ...... 1 1985 Production ...... 2 1985 Driling Activity ...... 2 Onshore Exploratory Drilling ...... 2 Offshore Exploratory Driling ...... 7 1985 Geophysical Exploration Activity ...... 9 Recent Florida Oil Field Discoveries ...... 11 Corkscrew Field ...... 11 Discovery ...... 11 Sunniland History ...... 16 Wells Drilled Near Corkscrew Field ...... 18 Stratigraphic Cross Section ...... 18 Conclusion ...... 20 Bluff Springs Field ...... 20 Discovery ...... 20 Historical and Geological Setting ...... 24 Conclusion ...... 26 McClellan Field ...... 26 Summary ...... 26 References ...... 27 Appendices ...... 28 I. 1985 and Cumulative Production Data ...... 29 II. 1985 Drilling Activity ...... 31 Table I. 1985 Field Wells Drilled ...... 32 Table II. 1985 Wildcat Wells Drilled ...... 34 Table III. Wells Drilled During 1985 in Eastern Planning Area, Gulf of Mexico...... 36

III. Discovery Well Data ...... 38 IV. 1985 Geophysical Exploration Activity ...... 40 V. Florida Oil and Gas Geology Related Theses ...... 42 ILLUSTRATIONS Figure 1. Production decline curve for Florida and for Jay field 1978 through 1985 ...... 3 Figure 2. Cumulative oil production through January 1986 for Florida oil fields ...... 4

Figure 3. Stratigraphic nomenclature, Middle Jurassic to Lower Cretaceous, Florida panhandle ...... 5

vii Figure 4. Stratigraphic nomenclature, Upper Jurassic to Lower Cretaceous, south Florida ...... 6

Figure 5. Leases and wells drilled in federal waters, offshore Florida ...... 8 Figure 6. 1985 geophysical exploration activity ...... 10

Figure 7. South Florida oil field location map ...... 12

Figure 8. Well location map with Sunniland structure, Corkscrew field ...... 13

Figure 9. Good porosity map of the Sunniland Formation ...... 14

Figure 10. Isopach of Sunniland dark carbonate ...... 15 Figure 11. Log information, P-314 (Sunoco Felda field; Sun Oil Co. Red Cattle No. 30-1) ...... 17 Figure 12. Stratigraphic cross section of Lake Trafford and Sun- nilard formations ...... 19

Figure 13. North Florida oil field location map ...... 21

Figure 14. Well location map with regional Smackover structure, Bluff Springs field area ...... 22 Figure 15. Log information, P-1136 (first offset, dry hole) and P-1125 (Bluff Springs discovery well) ...... 23

TABLES

Table 1. Production statistics, Bluff Springs field discovery well ...... 25

viii 1

1985 FLORIDA PETROLEUM PRODUCTION AND EXPLORATION

Jacqueline M. Lloyd and Albert V. Applegate

ABSTRACT

Florida petroleum production declined during 1985, as production from Jay field continued to decline. Onshore drilling activity main- tained a level similar to that of 1984, while drilling in federal waters off Florida showed an increase, with six wells completed during 1985. This peak in offshore drilling activity was presumably due to the fact that many offshore leases were close to expiration. Geophysical exploration activity also increased during 1985, including new exploration interest in the Apalachicola Embayment area and significantly increased exploration interest in south Florida. Wildcat drilling during 1985 yielded one success in south Florida with the discovery of Corkscrew field. The field is on the Sunniland trend and produces from the Lower Cretaceous Sunniland Limestone. Bluff Springs field in north Florida was actually discovered in 1984 but was not released from confidential status until December 1985. Pro- duction is from the Jurassic-age Smackover Formation. Drilling began in December, 1985, for another north Florida discovery, McClellan field. This field is located in Santa Rosa County and also produces from the Smackover Formation. The discovery well was completed on February 28, 1986, and is still confidential with the exception of a minimum of information released in F &A Oil Reports (April, 1986). Appendices of oil and gas information are presented. These include 1985 drilling activity, 1985 and cumulative production data, discovery well date, and 1985 geophysical exploration activity. In addition, a table listing theses held by the Florida Geological Survey library that are related to Florida oil and gas geology is presented. This should be of particular interest to those who are researching Florida oil and gas for academic as well as exploratory purposes. 2 1985 PRODUCTION

Florida oil production continued to decline in 1985 (figure 1 and Appendix 1). During 1985, Florida produced 11,457,913 barrels of oil compared to 14,461,969 barrels for 1984. This represents a 21 percent decrease in production. This is a lower percentage than the corres- ponding decrease for 1983 to 1984 (26 percent, Applegate and Lloyd, 1985). Figure 1 also illustrates the production decline for Jay field, indicating Jay Field's dominance in Florida oil performance. Smaller field discoveries continue to keep state-wide decline at a slightly lower rate than the Jay field decline; however, with Jay field accounting for 71 percent of the state's cumulative production through January 1986 (figure 2), only a discovery of a relatively large field would reverse the trend.

1985 DRILLING ACTIVITY Onshore Exploratory Drilling

Thirteen wildcat wells were drilled in Florida in 1985. Six of these wetls were Smackover-Norphlet tests (stratigraphic nomenclature shown on figure 3) in Santa Rosa and Escambia counties in west Florida; all were dry holes. Five wildcat wells were Sunniland tests (stratigraphic nomenclature shown on figure 4) drilled in Collier and Lee counties on the Sunniland trend. Four of these wells were dry holes, but R.K. Petroleum discovered the Corkscrew field in Collier County. This may well be the best field found in Florida since Exxon's Raccoon Point field was discovered in 1978. R.K. Petroleum has kindly waived the confidential status on this well and the Corkscrew field is discussed separately. Palmer Petroleum drilled a Paleozoic wildcat in north Florida on acreage leased by Star Petroleum. Star was one of the large lease- holders who assembled acreage in Madison, Taylor, Lafayette, Suwannee, and surrounding counties in the late 1970's. The well (Florida permit #1181), located in Section 2, T4S, R12E, in Suwannee County was drilled to a total depth of 6,888 feet and abandoned without testing. This is the sixth wildcat drilled to test the Paleozic section in north Florida since 1980. No shows have been found; as a result, much of the acreage acquired has been dropped. At present there are no out- standing drilling permits. Roy Roundtree (Star geologist, personal communication, 1985) stated that Star would probably keep its acreage position, but that it was extremely doubtful that any further drilling would be done until oil prices rebound. The Sabine Corporation drilled the Miccosukee No. 32-1 (Florida permit #1169) in Section 32, T49S, R35E in Broward County. This was the first oil well drilled in Broward County and was abandoned June 28, 1985, at a depth of 11,604 feet. The well was a Sunniland test well but was located approximately 10 miles to the east of the present producing trend. OIL PRODUCTION DECLINE 1978 THROUGH 1985 50

40-

2 -

15-

10-

5 i I I i I' I 1978 1979 1980 198-1 1982 1983 1984 1985

0 JAY FIELD + STATEWIDE Figure 1. Production decline curve for Florida and for Jay field 1978 through 1985 CUMULATIVEL PIRODUCTION THROUGH JANUARY, 1086 51 (7.8%)

S2 (3.8%) 532 (23)\8) (N3-5) (0.9%) S3 (2.3%) \ N2 (10.7%) S4 (1.9%), (s5-14) (1.5%)

KEY OIL FIELD

NE BlikjWk Creek N3 Nt. Cir 1 N4 huMwatar Creek N5 BlIff Springs B1 Weut Felda e2 Sumiland 93 Sunoco Felda 94 bar Island 55 Lahigh Park 96 Raccoo Point 87 Nid-Felda SB Lake Trafford 89 Tomumnd Canal SIG Seminolfe Sil Forty Nile Bend * S12 Corkicrme 913 BaNtr Island A 914 Pepper Hiamock

Nl-NWs North Florida Oil N1 (71.1%) sl-614. South Florida Oil * i Abandoned Figure 2. Cumulative oil production through January 1986 for Florida oil fields 5

GROUPS AND SERIES STAGES FORMATIONS

LOWER CRETACEOUS BERRIASIAN COTTON VALLEY TITHONIAN GROUP

UPPER HAYNESVILLE KIMMERIDGIAN FORMATION UPPER JURASSIC OBUCKNER MEMBER KIMMERIDGIAN (L. HAYNESVILLE)

OXFORDIAN SMACKOVER FORMATION

NORPHLET MIDDLE CALLOVIAN FORMATIQN JURASSIC BATHONIAN LOUANN SALT

Figure 3. Stratigraphic nomenclature, Middle Jurassic to Lower Cretaceous, Florida panhandle 6

SERIES STAGES GROUPS AND FORMATIONS

It RATTLESNAKE HAMMOCK FORMATION

O LAKE TRAFFORD FORMATION < SUNNILAND FORMATION

O PUNTA GORDA ANHYDRITE Z ( ______0 wz ABLE MEMBER 0 0 Cr W Cr ZO

< TWELVE MILE MEMBER -J

.) 0 uJ WEST FELDA SHALE

O 0 --I 2 PUMPKIN BAY FORMATION -J

0 BONE ISLAND FORMATION

,< WOOD RIVER FORMATION

Figure 4. Stratigraphic nomenclature, Upper Jurassic to Lower Cretaceous, south Florida 7 OFFSHORE EXPLORATORY DRILLING

Sale Number 94 was held forthe Eastern Gulf of Mexico in December, 1985. Figure 5 shows leases held prior to the bidding and leases acquired at the sale. It also shows the location of wells drilled in federal waters offshore Florida during 1985. Appendix II, table III is a review of the 1985 offshore drilling activity. Industry paid over $124 million for 82 leases (nine square miles, 5,760 acres per lease) out of total of 2,600tracts available. This marked lack of interest in the Eastern Gulf of Mexico was not unexpected, and no resumption of interest in the area is expected in the near future. Drilling in this area has been disappointing. The Destin Dome, which was once considered to be very attractive, was originally drilled in 1975. Over one billion dollars have been spent on leases and drilling and no appreciable reserves have been found. Sohio is rumored to have spent in excess of $20 million drilling their Gainesville lease. Drilling in the Charlotte Harbor area encountered basement at 10,000 to 12,000 feet on the Sarasota Arch. Drilling in the Pulley Ridge area has been postoned due to environmental studies, and this area will not be drilled before late-1986 at the earliest. In the Destin Dome and Pensacola areas, gas and condensate are the probable hydrocarbons to be encountered. These commodities are in oversupply at the present time. Forthese and other reasons, almost 100 blocks in the Eastern Planning Area expired in 1985 without being drilled. In sale no. 94, the highest bids went for tracts located on the Destin Dome. These bids were made by Shell Offshore Inc, and Amoco. Shell was high overall bidder, spending-$30.6 million for its interest in 30 tracts. Amoco spent $27.8 million forits. interest in 24 tracts. Both of these companies purchased drilling blocks outside of the Destin Dome area. In the Destin Dome and Pensacola areas, the principal drilling targets are the Norphlet and Smackover formations of Late Jurassic age. The former is capable of high volume gas production in the Mobile Bay area about 100 miles to the west, where wildcat and development drilling has been carried out by several companies since the original discovery by Mobil in 1979. The Norphlet is as much as 600 feet thick in the Mobile Bay area; unfortunately, it appears to thin rapidly to the east in Florida waters. The Smackover Formation is the principal producing formation in the Jay and Blackjack Creek fields which are approximately 100 miles to the northwest of the Destin Dome. In other areas in the Eastern Planning Area, Cretaceous limestones and dolomites are the principal wildcat targets. The exploratory drilling which took place offshore in 1985 was not encouraging. Four Smackover-Norphlet tests were drilled on the Destin Dome. Two of these unsuccessful wildcats were drilled by Shell in Block 160. Exxon drilled a Smackover-Norphlet dry hole in Block 284. Chev- ron did likewise in Block 422. It was rumored that Shell's first well in Block 160 had a good show, but no pipe was run in the well. In the Gainesville area (figure 5) Sohio is believed to have drilled 84ove64M 0.0"

8 y .._ ,,,,/[ ..

ci. Ri#i -q "MOO, S EASTERN \ RA innd a . ----- /

- Fiaure 5. Leases and wells drilled in federal waters, offshore Florida 9 through a thick Eagle Mills (Triassic) section before abandoning a well in Block 707 in Paleozoic rocks at 15,994 feet. Sohio drilled a wildcat in Pensacola Block 948 to a total depth of 18,958 feet. The well was drilled to test a Louann high and was located on the down-thrown side (southwest) of a regional fault. A seven-inch liner was cemented at 18,956 feet and the Smackover and Norphlet formations were tested. Test data are not available but the well was abandoned. Drilling in the offshore during 1986 (through June 1986) in the East- ern Planning Area of the Gulf of Mexico has been slow. As concessions granted by the federal government last for only five years without testing, Shell drilled one wildcat in Block 622 of Charlotte Harbor. This well was drilled to a total depth of 10,500 feet. Shell also drilled a test well in Block 512 of the DeSoto Canyon area to a total depth of 12,300 feet. Both wells were abandoned without testing.

1985 GEOPHYSICAL EXPLORATION ACTIVITY The implementation of Chapter 377, Part 1, Florida Statutes authoriz- ing the Florida Department of Natural Resources to regulate geophysical activities (Applegate and Lloyd, 1985), gives the Florida Geological Survey the opportunity to monitor not only areas of seismic activity in Florida, but also areas of interest to industry that, for one reason or another (i.e. economics, permitting problems, logistical problems) were not surveyed. Thirty-one applications for geophysical permits were received by the Florida Geological Survey during 1985. Of these 34 applications, 23 have been permitted, fourwerewithdrawn by the appli- cants, and four are still being processed. The areas covered by these permits are shown on figure 6. Only 18 permitted areas were actually surveyed during 1985; four permitted surveys were cancelled and the remaining one is "on hold" (presumably awaiting changes in economic conditions). As was the case in 1984, seismic activity for 1985 was greatest in the Florida panhandle. However, unlike 1984, panhandle activity was not strictly concentrated in Escambia and Santa Rosa counties but included seismic surveys in Liberty, Franklin, and Wakulla counties. Applications were also received which included, in addition to those counties listed above, proposed surveys in Okaloosa, Walton, Bay, and Calhoun counties. Surveys in these counties were not run, but the applications indicate an increased interest in Florida panhandle exploration. This apparently increased interest includes the Apalachicola Embayment area which was discussed by Applegate, et al. (1978) as an area with significant Smackover oil potential. The panhandle surveys completed in 1985 yielded 243 miles of shot-hole and 276 miles of Vibroseis lines, for a total of 519 miles. Only one application was received during 1985 for geophysical oper- ations in north peninsular Florida. This application was permitted and the survey was completed. It included 52 miles of shot-hole lines in Madison County. 10

- - -f"r ir -7 N-. I_. --,

STATE OF FLORIDA

F6. i-1 S

Figure 6. 1985 geophysical exploration activity 11

Geophysical exploration activity increased by an order of magnitude compared to 1984 in south Florida. A total of 392.25 miles (330 miles Vibroseis; 62.25 miles shot-hole) of seismic surveys were run in south Florida during 1985, compared to a total of only 22 miles for 1984. Surveys also covered a broader geographic area, including parts of Okeechobee, Collier, Hendry, Dade, Palm Beach, and Broward counties. 1985 seismic activity showed a general increase in exploration in Florida over more extensive geographic areas. The recent discoveries in both north (panhandle) and south Florida should encourage the con- tinuance of this trend.

RECENT FLORIDA OIL FIELD DISCOVERIES Corkscrew Field

DISCOVERY

The R. K. Petroleum Corp., Midland, Texas, completed 33-2 Rex Properties, the discovery well of the Corkscrew field on November 10, 1985.-The completion was made in the Sunniland formation of the Lower Cretaceous. The well is in Section 33, T46S, R28E, about 21/2 miles north and slightly west of the one-well Lake Trafford field in Collier County (figures 7 and 8). This location is favorable on both the equivalent good porosity map and the isopach of Sunniland dark carbonate (Applegate and Pontigo, 1984, and figures 9 and 10). The 6,000 acre driling block was assembled by Len W. Sipple, Naples, Florida, and John C. Sipple, Mobile, Alabama, owners of Southern Oil Exploration Inc., Mobile. Mike Cheeseman, consulting geologist, Pen- sacola, Florida, prepared geological and structural interpretations of the area from subsurface data. A conventional core was taken in the 11,536-564 feet interval of the Sunniland with 26.5 feet recovered. In the 11,550.25-559.5 feet interval (8.75 feet) average porosity was 15.25 percent; permeability, 106.2 milli- darcies (horizontal); water saturation, 37 percent of pore space; and oil saturation, 11.96 percent of pore space. The Analytical Logging Co. described the porous interval as a "fossil hash" of dolomitic limestone. The bottom 4.5 feet of core was described as an indurated, gray, crystalline limestone with no permeability. After logging, 7-inch casing was cemented at 11,547 feet, and an open hole completion was made in the 11,547-565 feet interval of the Sunniland Formation. Production is from unit 1 of the Sunniland Formation (figure 11). Units 1 and 2 produce in the Sunniland field to the southeast (Means, 1977). The Lake Trafford and Sunniland formations were encountered at 11,398 and 11,537 feet (E-log depths), respectively. A nine-hour swab test of the well produced 163.33 barrels of 260 gravity oil (A.P.I. at 60 degrees Fahrenheit) with no water, for a daily rate of 435 barrels. The well was placed on a pump and has produced about 12

OIL FIELDS IN SOUTH FLORIDA

b TOWNSENDCANAL

LEE CO. • -- rD HENDRY CO. PALM BEACH CO. WE3T3OCO - FELDA R30 R31E -P- 1170 jO CO.RKSCEWFIELE C r~l LAKETRAFD1F |P-222 I

AIN, kSEMINOLE£0

K" GLAND -- - T493

PEPPERHMOCK 0 BAXTERISLAND %LE3 I BROWARD CO.

COLLIER CO. RACOONPONT

DADE CO.

FORTYMLE BEND EXPLANATION , MONROE CO. * ACTIE OILFIELD SINACTNIVE0O. FELD0 10 KM S 10.o E3 SCALE 0

Figure 7. South Florida oil field location map 13

w R27E R28E

• \. 1 »P-t7•L P-1199°Drakocvrew afrordWld/

410

.0 2000 4000 6000 8000 FEET CONTOUR INTERVAL: 20 FT.

O NEW PERMITTEDLOCATION, P-1201 Corkscrew and Lake Trafford Fields * OIL FIELDS P-401;-117 LAKEnd P-11TRAFFORD CORKSCREW Structure Map Top of Sunnland

ABANDONED WILDCATS (1) P-408 (5) P-853 (2) P-1030 (6) P-849 13) P-1001 (7) P-477 (4) P-1050

Figure 8. Well location map with Sunniland structure, Corkscrew field 14

CnAlNLOTTI L A K E

------P A L M

L3 EEACH

SFIELD, P-1170

25+

EQUIVALENT -GOOD.-POROSITY *" M SUNNILAND FORMATION Cl * 5 FEET to o .,M

Figure 9. Good porosity map of the SunnhlandSunniland Formation 15

\^ \ "-60-^ -V }--- ^- LA E C ARLOTTE ' " ' 9L- .Eo •-90 - P LM

ORKSGBEW 1 60 FIELD P 170i

SB OWARD

ISOPACH : o SUNNILAND DARK CARBONATE C.I.10 FEET '

20 KM 0 A 0 E

0 80 MILES SCALE

PBiMM Y A.V.a PPLEMT

Figure 10. Isopach of Sunniland dark carbonate 16 220 barrels of oil per day, which is the pump capacity, with no water. Production through February 20, 1986, was 20,231 barrels of oil in 92 days, for an average of 220 barrels per day. Permits were secured to drill a west offset (P-1199) and a north offset (P-1201) to this well. The west offset (32-1) was completed as a producer with the top of the Sunniland encountered at 11,486 feet (figure 8).

SUNNILAND HISTORY

Sunniland field was discovered by Humble Oil and Refining Corp. (now Exxon) in 1943. Corkscrew field is about 11 miles to the northwest of the Sunniland field. The boulder zone, a cavernous dolostone in Tertiary age rocks encountered above 4,000 feet in the subsurface of south Florida, makes seismic interpretation difficult. For this reason, drilling of this trend has been limited even though many wells have produced a million or more barrels of oil. The Sunniland field, with a total of 18 producing wells, has yielded more than 18,300,000 barrels of oil and is currently producing more than 10,000 barrels/month from six wells. J. A. Means (1977) broke the Sunniland Formation into five units (figure 11). Following the end of the Punta Gorda Anhydrite deposition, unit 5, the "Rubble Zone," was deposited as the Sunniland sea advanced. It is a dark brown to dark gray, argillaceous, micritic limestone, which exhibits conchoidal fracturing and normally has a strongly petroliferous odor on a fresh surface. It is approximately 50 feet thick. The lower part of unit 4 has been called the "Black Shale." It is a dense argillaceous limestone about 40 feet thick. Directly above the "Black Shale" is a light brown, nonporous, miliolid-rich limestone, which is the upper part of unit 4. Directly above unit 4 are units 1,2, and 3, which are approximately 100 feet in total thickness, are located on the producing trend, and are composed of localized buildups of rudistids, algal plates, gastropods, Foraminifera, and other organic debris into mounds or pods which formed porous grainstones. Dolomitization of these grainstones has enhanced their porosity. These grade laterally into nonporous, miliolid-rich limestones. Mitchell-Tapping's 1984 and 1985 publications include excellent photographs of these carbonates. During and after deposition of the Sunniland Formation, the grainstones withstood compaction, and the laterally equivalent miliolid-rich lime muds were compacted (Means, 1977). This process began at the time of deposition, as the overlying Lake Trafford Formation thins over Sunniland highs. Additional compaction caused fractures and minor faulting around the edge of the oil fields. These fractures probably are responsible for the "Rubble Zone" in the lowermost Sunniland and may serve as a conduit for oil to migrate from the "Rubble Zone" (unit 5) and the "Black Shale" (lower part of unit 4) into the porous units 1, 2, and 3. Punta Gorda fm. Sunniland fm. Lake Trafford fnm. - lower anhydrite' - Unit 5 Unit 4 C Unit 2 Unit 1

. I

a * * g ' S* : P3 ( no Feld field, S O . R d C t No. F 1og1 ior to P3 ( . Felda- Su Oi Co R C l

^M. J - U , Mr=_Ij .... I ' 18

WELLS DRILLED NEAR CORKSCREW FIELD

Wells drilled near Corkscrew field, which played a significant role in defining the geology and structure of the field, were the following (figure 8); 1. P-408 (Mobile Oil Henry Sanders Trustee 35-1). A drill stem test of the unit 5 "Rubble Zone" between 11,838 and 11,888 feet recovered 1,000 feet of water column, 1,166 feet of oil and gas cut water column. 2. P-1030 (NRM Audubon Society 1-1). Upper and Lower Sunniland had scattered odors and mineral fluorescence. 3. P-1001 (NRM Alico 31-2). Seventeen feet of good Sunniland "reef" rock (grainstone) encountered. 4. P-1056 (NRM Alico 31-4). This well tested 16 barrels of oil and 195 barrels of salt water in eight hours, from the Lake Trafford Formation. Also had good shows of oil in unit 1 of the Sunniland and shows of oil in fractures in unit 5 "Rubble Zone." The interval from 12,333 to 12,378 feet, units 1 and 2 in a directionally drilled hole, had an average porosity of 13.89 percent and horizontal permeability of 11.69 md. 5. P-853 (Total Bernice D. Pepper 2804). This well had shows of oil in the 11,555-560 feet interval of the Sunniland unit 1 with 15 percent porosity and horizontal permeability ranging from 0 to 67 md. In the 11,594-644 feet interval a core showed good porosity and permeability development in units 2 and 3, with porosity occasionally above 20 percent. The unit 5 "Rubble Zone" had excellent shows of oil but almost no porosity or permeability. 6. P-849 (Kanaba Oil and Gas Baron Collier 9-2). This well was drilled as a step-out to P-401, the discovery well of the Lake Trafford field. Only scattered porosity and permeability were noted in the upper three Sun- niland units. Unit 5 had many live shows of oil, but poor porosity and permeability. 7. P-401 (Mobile Oil Baron Collier 1). This well was the discovery well of the Lake Trafford field, which produces from the unit 5"Rubble Zone." The cumulative production through 1985 is more than 253,000 barrels with daily production of 34 barrels and no water. 8. P-477 (Exchange Oil & Gas Earl Ball 16-1). This is a south offset to the Lake Trafford discovery well. Completion was made in unit 5. The well produced about eight barrels per day of oil and was abandoned.

STRATIGRAPHIC CROSS SECTION

A stratigraphic cross section of the Sunniland and Lake Trafford formations was constructed from P-130 in Collier County to P-152 in Glades County (figure 12). This cross section was drawn approximately perpendicular to the producing trend (figures 7, 9, and 10). In the down-dip well, P-130, relatively thick Sunniland and Lake Trafford formations are composed principally of dark gray to black, nonporous limestones and anhydrite. In P-103, which is down-dip from the producing trend but 18 miles northeast of P-130, the Sunniland P-190(tiffs I) P*Ifl (Kft III) P-M5(09s 41r) P-i 10 Oft 40-) W.Iue is)

6p191 1 ap R96¶IYTI KP U s*I. Y A14MAMAY g6411mly 4AIft PAY 90A,0V1,MY

1 NUAC ;,OKP 11.1648

IK.MMIILAP URI 4 LMMfA

P411IN~fORAWNSY Figure 12.LStatg AphiCKcosscino aeTafodadSn adfrain 20 Formation is composed principally of dark micritic limestone and anhydrite. P-222 is on the producing trend; it produced some oil during a drill- stem test. but was abandoned as noncommercial. The thickening of the Sunnitand Formation and the thinning of the Lake Trafford Formation on the producing trend, as well as the development of porosity (an estimated 19 feet of porosity total) in units 1, 2, and 3 are as expected. Moving updip to P-133 and P-152, the Sunniland Formation has thinned to 215 feet and 168 feet, respectively. The porous Sunniland limestone in P-222 has disappeared, and in its place is chalky, nonper- meable limestone. The dark micritic limestone has thinned and almost disappeared in P-152 and is partially replaced by dolomite.

CONCLUSION

Corkscrew field is favorably located on both the good porosity and the dark carbonate Sunniland Formation maps. The location of the discovery well was based on geological and structural interpretations of the area from subsurface data. The discovery is consistent with calculations made by Applegate and Pontigo (1984). These calculations showed that 45 barrels of recoverable oil had been found for every foot of wildcat drilling between 1943 and 1980 In south Florida, and these reserve figures are very conservative. Additional calculations indicate that if drilling had been confined to the area of known porosity in the Sunniland Formation, the figure would have been more than 100 barrels of oil for every foot of wildcat drilling. These figures indicate that more drilling should be done in the future in south Florida.

Bluff Springs Field DISCOVERY

Bluff Springs field, a new oil field In the western panhandle of Florida, was discovered on March 25,1984. The discovery well, the Stone Petro- leum Corp. St. Regis Paper Co. No. 29-4 (Florida permit 1125), was released from confidential status in December, 1985. It was a rank wildcat located in Section 29, T5N, R31W, Escambia County, approximately 10 miles west-southwest of Jay field and approximately four miles southeast of the nearest previously drilled wildcat, Florida permit 1177 (figures 13 and 14). This area, west and southwest of Jay, is known to be underlain by Louann Salt with seismic studies indicating salt- induced fault structures in the overlying formations. Production is from Jurassic-age Smackover Formation dolomites from 16,332 to 16,339 feet (16,154 to 16,161 feet below MSL, figure 15). These dolomites are dark brownish-gray to brownish-black, fine grained micro-crystalline, and show evidence of recrystallization from originally oolitic and possibly pelletal facies. Examination of core chips from this interval (at 10x with binocular microscope) reveals primarily intercrystalline to vuggy porosity. Samples from the top of the produc- 21

NORTH FLORIDA OIL FELD LOCATION MAP

r7 RwR323w Ri0w R29W_ a .M2W R26W DISCOVIE UI . DICOVERY W= BLUFF«PROGa FW EETWATER1z

...--.- -. __ --______.___ ----•- - .i

EPLOCATIN O FIELDSACTIVE

SCALE CANTONMENT

. I V OACOLA

Figure 13. North Florida oil field location map 1n.S AmiEANUT CC*1h')Uh f0

AREA OF INTEREST . BLACKJ K CREEK FIELD

- LE AO SFIELD SPRINGSN SBLUFFRN

O PERMi L ED LOCATION

Smackover structure, Bluff springsSprings field area Figure 14. Well location map with regional Smackover , 3. ....

-1su.342 1 16 MSL..'MSI BUCKNER ANHYDRITE

5i MEAN!* POROSITY | .E|| g| SMACKOVER- --

Dual induction Focused Log BHC Acoustilog Compensated Neutron Lithe Density

Figure 15. Log information, P-1136 (first offset, dry hole) and P1 125 (Bluff Springs discovery well) 24 ing zone also appear to have retained some oomoldic porosity, although the oolites appear to have been replaced with dark brown, crystalline dolomite. Volumetric calculations based on log analyses by Dr. Charle H. Tootle of the Florida Bureau of Geology (personal communication, 1985) yielded the following values: pay thickness, 10 feet; mean porosity, 19.6 percent; mean oil saturation, 88 percent; original oil in place estimate, 1.3 million barrels; and recoverable oil estimate, 195,067 barrels. In an initial flowing test (assisted by nitrogen injection) on March 25, 1984, by Stone Petroleum Corp., the well produced 59.6 barrels of oil in three hours for an approximate daily rate of 477 barrels. Saltwater production was 170 barrels per day. Oil gravity was 57.0° A.P.I. at 60 degrees Fahrenheit. The first offset, Florida permit 1136 (the Stone Petroleum Corp. St. Regis Paper Co. No. 29-3), to the discovery well was also drilled by Stone Petroleum and is located approximately one-half mile northwest of the discovery well (figure 14). The Smackover was encountered at 16,342 feet (16,171 feet below MSL), structurally 17 feet lower than in the discovery well (figure 14). This is apparently too low on the structure as the well produced only salt water from two thin (three to four-feet thick) zones within the 16,354 to 16,363-foot interval (16,183-16,192 feet below MSL) of the upper Smackover. Core analysis by Location Sample Service, Inc. (LSS, Jackson, Miss.) yielded mean porosity estimates for these zones of 11.4 and 8.4 percent. Both zones had low permeability. LSS also found atrace of oil in only one sample from 16,356 feet (16,185 feet below MSL). On June 14th and 15th, 1985, Hughes Eastern Corp. retested the discovery well with results similar to those of Stone Petroleum's March 1984 test: 494 barrels of 54.50 A.P.I. gravity oil per day, 238 barrels of saltwater per day. Ownership of the discovery well was transferred from Stone Petroleum to Hughes Eastern following this test. Production from the well began in January, 1986. Monthly production reports for Janu- ary through June, 1986, indicate that the well Is producing an average of 555 barrels of oil and 221 barrels of water per day (see table 1). Permits have been issued to Hughes Eastern to drill two offsets, one east and one southeast of the discovery well (permits 1204 and 1205, figure 14). Given the results of the offset to the northwest, presumably Hughes Eastern expects to encounter the Smackover at structurally higher positions in these new offsets to the east and southeast.

HISTORICAL AND GEOLOGICAL SETTING

The discovery of Bluff Springs field brings the number of oil fields in north Florida up to five-four active and one plugged and abandoned (figure 13). The first of the north Florida fields to be discovered was Jay field in 1970. The discoveries of Mt. Carmel and Blackjack Creek fol- lowed in 1971 and 1972. Since then, a long series of dry wildcats (84 total) have been drilled in Florida's panhandle. With the exception of the discovery of the questionably commercial Sweetwater Creek field in 25 1977, the Bluff Springs discovery represents the first successful wildcat in west Florida in 12 years. Hopefully, renewed interest and improved technology will make this only the first in a series of similar successes.

Table I. Production statistics, Bluff Springs field discovery well.

MONTH OIL OIL WATER WATER GAS (1986) BARRELS BOPD* BARRELS BWPD* MCF January 18963 612 6466 209 8204 February 11945 427 5061 181 4608 March 17343 559 7110 229 10347 April 18415 614 5770 192 11047 May 18277 609 7311 244 12625 June 15319 511 8104 270 11258 *BOPD: Barrels of oil per day. *BWPD: Barrels of water per day.

North Florida (i.e. Florida panhandle) oil fields dominate Florida oil production (Applegate and Lloyd, 1985). These fields account for approximately 83 percent of the state's cumulative production through January, 1986 (figure 2). Jay field alone is responsible for 71 percent of the state's production. In all except Mt. Carmel field, production is from Jurassic-age Smackover dolomites and limestones (figure 3). Mt. Car- mel field produces from both the Smackover and the underlying Jurassic-age Norphlet Sandstone. Although a mixture of carbonates and clastics can be found within the Smackover, in the western panhandle producing area it is almost purely a sequence of dolomites and limestones. The underlying Norphlet Sandstone is primarily an arkosic sandstone. The Norphlet is underlain by the Louann Salt which is probably responsible for the structures found in the north Florida oil fields (except for Sweetwater Creek field which is believed to be located on a basement high). The Smackover is overlain by the Buckner Member of the Haynesville Formation. The Buckner is composed primarily of evaporites and forms the seal for some of the Smackover producing zones. Studies of the Jay field Smackover in Florida reveal complex networks of producing horizons (Lloyd and Parker, 1985; Lloyd, et al., 1986). Production is from dolomite horizons found at different levels in the Smackover; it is also from more than one porosity and facies type. Production can be from dolomitized oolitic facies with oomoldic porosity. More commonly, it is from dolomitized pelletal facies with intercrystalline, vuggy, and leached matrix porosity. Although core chip examination is not definitive, Bluff Springs field may be producing from both facies types. Florida's Smackover reservoirs appear to be the result of the complex interplay of porosity, paleoenvironment, diagenesis (primarily dolomitization), and the formation of networks of producing horizons. 26 CONCLUSION The possible complexity of undiscovered Smackover reservoirs located in north Florida makes their discovery all the more challenging. The discovery of Bluff Springs indicates that it can be done. Well coverage in much of the western Florida panhandle is sparse; there is a definite need for additional exploration within and adjacent to the known Smackover producing area in Florida.

McCiellan Fleid

Exxon Corp. spudded a rank wildcat (Exxon Corp. State of Florida 33-1, Florida permit #1194) on December 31, 1985, in Section 33, T6N, R26W, Santa Rosa County (figure 13). This is approximately 3.25 miles north of the abandoned Sweetwater Creek field and 16 miles east of Mt. Carmel field which produces from both the Smackover Formation and the Norphlet Sandstone. The well found 152 barrels of 410 A.P.I. gravity oil per day from the Smackover through perforations from 14,072 to 14,090 feet (-13,828 to -13,846 feet MSL; F & A Oil Reports, 1986). Total depth of the discovery is 14,475 feet (-14,231 feet MSL). Two conventional cores and sidewall samples were taken with no details released (F & A Oil Reports, 1986). Seven-inch casing was run to 14,473 feet (-14,229 feet MSL) for completion on February 28, 1986 (F & A Oil Reports, 1986). The Sweetwater Creek field produced from the Houston Oil and Minerals Corp., W. M. Stokes 15-2, No. 1 well in Section 15, T5N, R26W, Santa Rosa County (Florida permit #881). In its initial test the well produced 624 barrels of 43.50 A.P.I. oil per day and only atrace of water from a Smackover limestone interval from 14,299 to 14,340 feet (-14,044 to -14,085 feet MSL). Hopes for a significant discovery proved false when the well began producing 100 percent water in December, 1980. The field produced a total of 13,695 barrels of oil during its entire lifetime. In its final year of production (1980) the well produced 1,465 barrels of oil. SUMMARY

As Florida oil production continues to decline, successful exploration efforts become more significant. Fortunately, recent oil exploration in Florida has yielded three new oil fields, two in the western panhandle of north Florida and one in south Florida. Unfortunately, it would require the discovery of a great number of such small fields to reverse the declining production trend which is primarily the result of declining production at Jay field. Despite this, exploration history indicates that there is room for additional discoveries within the known Smackover and Sunniland producing areas. In addition, although efforts have been unsuccessful to date, the offshore area and the Apalachicola Embay- ment area are relatively unexplored. The possibility of discovery of a new "Jay" should not be ruled out. Meanwhile, the chances for smaller field discoveries have been positively affirmed by recent history. 27

REFERENCES

Applegate, Albert V., F. A. Pontigo, Jr., and J. H. Rooke, 1978, Jurassic Smackover oil prospects in the Apalachicola embayment: Oil & Gas Jour., January 23, 1978, p. 80-84.

Applegate, Albert V. and F. A. Pontigo, Jr., 1984, Stratigraphy and oil potential of the Lower Cretaceous Sunniland Formation in south Flor- ida: Fla. Bur. of Geol. Rep. of Invest. No. 89, 40 p.

Applegate, Albert V. and Jacqueline M. Lloyd, 1985, Summary of Florida petroleum production and exploration, onshore and offshore, through 1984: Fla. Bur. of Geol. Inf. Cir. No. 101, 69 p. F & A Oil Reports, 1986, Florida, Vol. 13, No. 16, 4-16-86, p. 2.

Lloyd, Jacqueline M. and William C. Parker, 1985, Hydrocarbon reservoir formation: Paleoenvironment and structural interrelationship in the Jurassic Smackover, Jay field, Florida: abstract, Geol. Soc. Amer. Abstracts with Programs, 98th Annual Meeting, Orlando, Florida, p. 645. Lloyd, Jacqueline M., Paul C. Ragland, Joan M. Ragland,;and William C. Parker, 1986, Diagenesis of the Jurassic Smackoiver Formation, Jay field, Florida: Gulf Coast Assoc. of Geol. Societies Trans., Vol. 36, in press.

Means, John A., 1977, Southern Florida needs another look: Oil & Gas Jour., Vol. 75, No. 5, p. 212-225. Mitchell-Tapping, H. J., 1984, Petrology and depositional environment of the Sunniland producing fields of south Florida: Gulf Coast Assoc. of Geol. Societies Trans., Vol. 34, p. 157-173. Mitchell-Tapping, H. J., 1985, Petrology of the Sunniland, Forty Mile Bend and Bear Island fields of south Florida: G u IfCoast Assoc. of Geol. Societies Trans., Vol. 35, p. 233-242.

Ottman, R. D., P. L. Keyes, and M. A. Ziegler, 1973, Jay field- a Jurassic stratigraphic trap: Gulf Coast Assoc. of Geol. Societies Trans., Vol. 23, p. 146-157.

Sigsby, R. J., 1976, Paleoenvironmental analysis of the Big Escambia Creek-Jay-Blackjack Creek field area: Gulf Coast Assoc. of Geol. Societies Trans., Vol. 26, p. 258-278. 28

APPENDIX I 1985 AND CUMULATIVE PRODUCTION DATA 1985 AND CUMULATIVE PRODUCTION DATA-WITH 1984 DATA FOR COMPARISON (1)

FIELD (2) CUMULATIVE -1985 PRODUCTION- PRODUCTION -Number of Wells- Oil Gas Water Oil Gas PRO INJ SI TA TOT (Bbis) (MCF) (BbIs) (MBbls) (MMCF) NORTHWEST FLORIDA Bluff Springs 1 0 0 0 1 770 650 600 1 1 Jay 53 28 35 0 116 6358259 9440024 53651208 345740 435776 Blackjack Creek 9 7 8 0 24 1455467 1845391 8691150 51918 47903 Mt. Carmel 1 0 0 0 1 68416 101227 225661 4513 4726 Sweetwater Creek (3) 0 0 0 0 0 0 0 0 14 15 Subtotal 64 35 43 0 142 7882912 11387292 62568619 402186 488421 1984 Subtotal 60 38 44 0 142 11065623 13685980 55132481 SOUTH FLORIDA Sunoco Felda 10 6 11 0 27 188532 12253 2233681 11107 955 Mid-Felda 2 0 1 0 3 107639 0 234850 933 10 Townsend Canal 4 0 0 0 4 99866 0 255510 225 0 Lehigh Park 4 0 1 0 5 261720 26562 3526210 4536 457 West Felda 28 0 12 3 43 1146947 70630 8156504 38151 3020 Corkscrew 1 0 0 0 1 9472 0 0 9 0 Lake Trafford 1 0 0 0 1 11710 0 0 254 0 Seminole (3) 0 0 0 0 0 0 0 0 85 0 Sunniland 7 0 12 0 19 129841 12300 3162564 18327 1815 Bear Island 16 5 6 0 27 685248 58306 4274921 9201 721 Pepper Hammock 0 0 1 0 1 0 0 0 0 0 Baxter Island (3) 0 0 0 0 0 0 0 0 2 0 Raccoon Point 12 0 1 0 13 934026 109621 638923 1383 152 Forty Mile Bend (3) 0 0 0 0 0 0 0 0 33 2 Subtotal 85 11 45 3 144 3575001 289672 22483163 84246 7132 1984 Subtotal 84 15 37 2 138 3396346 256784 22228837 (Continued on next page.) FIELD (2) CUMULATIVE --1985 PRODUCTION-- PRODUCTION -Number of Wells- Oil Gas Water Oil Gas PRO INJ 81 TA TOT (Bbis) (MCF) (Bbls) (MBbis) (MMCF) STATEWIDE TOTAL 149 46 88 3 286 11457913 11676964 85061782 486432 496553 1904 TOTAL 144 53 81 2 280 14481960 13942764 77381318 1. Statistics compiled by Dr. Charles Tootle, Florida Bureau of Geology, Oil and Gas Section. 2. Fields are listed In order from north to south. 3. Plugged and abandoned oil fields. Abbreviations: PRO - Producing Wells Bbls - Barrels (42 US Gallons) INJ - Injection Wells MBbls - Thousand Barrels SI - Shut In Wells MCF - Thousand Cubic Feet TA - Temporarily Abandoned Wells MMFC - Million Cubic Feet TOT - Total No. Wells 31

APPENDIX II

1985 DRILLING ACTIVITY TABLE 1. 1985 FIELD WELLS DRILLED

Drill Floor 1 Waill and Opwetorf-Wll Completion Ele., Ft. Total Permit No. Name A No. Location Date Above M8L Depth. Ft. 8ta1m JAY FIELD4 Santa Ros W-15713 Exxon Corp.-Lawmon 2273' FNL A 2-26-86 247.5 15,686 Completed a a P-1146 Hawthorne No. 5-7 1606' FWL potential producer. See. & TSN. R29W Santa Ros• W-15a06 Exxon Corp.-E. a. 2282 FSL & 11-1445 25.6 15,780 Completed a a P-1180 Jeffreys, et. at 4' FEL (NOVO) potential producer. No. -4 Sea. TSN. R29W MT. CARMEL FIELD Santa Rosa W-15734 LL & E-Wolf- 191&2' FNL & 4-5-6 206 15,231 Plugged & abandoned P-114 Hendrcks No. 3884' FWL me a dry hole. 4-5-85. 36-1A Seac 36 T6N. R29W 8UNNILAND FIELD Ccoger W-15754 Exxon Corp.- 271.4A FNL & 3-15-5 42.5 11,780 Completed a- a P-1142 Colar Co. No. 2114.36' FWL potential producer. 19-2 Sec. 10 T48S, rOE BEAR ISLAND FIELD Collier W-15706 Exxon Corp.- SHLL 12-13-85 366 MD:12,000 Completed as a P61118A Collier Co. No. 1531.9 FSL & (NGVD) TVD:11,.66 potential producer. 2-10A 63&2r FWL See. 1 BHL: 272' FSL & 40W FEL Sac. 2 T498, R30E RACCOON POINT FIELD Collier W-15768 Exxon Corp.- SHL 3-15-85 34 MD:12.712 Completed as a P-1141 Collier Land & 723' FNL & TVD:11,464 . potential producer. Cattle Corp. 707 FWL No. 2-1 BHL* 1320' FNL & 1320' FEL Sec. 2, T52S, R34E Collier W-15718 Exxon Corp.- SHL: 1-3-85 35 MD:12,044 Completed as a P-1149 Collier Land & 1821.9' FSL & TVD:11,500 potential producer. Cattle Corp. 796.8' FEL No. 27-3 Sec. 28 BHL: 1320 FSL & 1320' FWL Sec. 27, T51S, R34E Collier No W-no.5 Exxon Corp.- SHL: 11-6-85 34.9 MD:11,654 Completed as a P-1150 Collier Land & 1651' FSL & TVD:11.600 potential producer. Cattle Corp. 809' FEL No. 28-4 BHL: 1320' FSL & 1320' FEL Sec. 28, T51S, R34E Collier W-15755 Exxon Corp.- SHL: 5-13-85 35 MD:12,370 Completed as a P-1162 Collier Land & 1985.5' FSL & TVD:11,513 potential producer. Cattle Corp. 745.1' FEL No. 27-2 Sec. 28 BHL: 1320' FNL & 1320' FWL Sec. 27, T51S. R34E Collier W-15859 Exxon Corp.- SHL: 12-6-85 35 MD:13,670 Completed as a P-1167 Collier Land & 2843' FNL & TVD:11,800 potential producer. Cattle Corp. 669 FEL No. 22-3 Sec. 28 BHL: 1320' FSL & 1320' FWL Sec. 22, T51S. R34E 1. Florida Bureau of Geology well number for samples (cuttings or core chips). Ca 2. For directionally drilled wells, SHL Is surface hole location. BHL Is bottom hole location. 3. MD: measured depth; TVD: true vertical depth (determined by directional survey). 4 Fields are listed In order from north to south. 5.,Well samples have not been submitted yet. TABLE II. 1985 WILDCAT WELLS DRILLED

Drill Floor Well' and Operator-Well Completion Elev.,. Ft. Total 3 County Permit No. Name & No. Location 2 Date Above MSL Depth. Ft. Status NORTHWEST FLORIDA Escanbla W-15873 Cities Service 1628 FSL & 11-1-85 280 16800 Plugged & abandoned P-1172 Oil & Gas-Llzenby 1540 FWL (GL) as a dry hole, 11-5-85. No. 5-4 Sec. 5, TSN, R32W Escamblea W-15843 Primary Fuels, Inc. 1133.3' FNL & 11-8-85 270 16880 Plugged & abandoned P-1177 Robert O'Farell 1278.7' FWL as a dry hole, 11-8+85. No. 22-2 Sec. 22, T5N, R32W Santa Rosa W-15746 McMoran Oil & Gas 1032' FNL & 4-19-45 221 16,744 Plugged & abandoned P-1159 Co.-J. Ed Golden, 1029' FEL as a dry hole, 4-19-85. et al. No. 22-1 Sec. 22. T3N. R28W Santa Rosa W-15711 Smacko, Ltd.-R.W. 1165' FNL & 2-1-85 271 15.300 Plugged & abandoned P-1160 Blackmon, Jr. No. 1282' FEL as a dry hole, 2-1-85. 16-1 Sec. 16, TSN, RFl2W Santa Rosa W-15874 Spooner Petroleum 1047.7 FSL & 12-27-85 75 16,580 Plugged & abandoned P-1178 Co.-Champion Inter- 1083.9 FEL as a dry hole, 12-27-85. national No. 5-4 Sec. 5, T3N,R28W Santa Rosa W-15865 Tenneco Oil Co.- 1320WFSL & 12-20-85 221 17,050 Plugged & abandoned P-1185 Champion Interna- 1320' FEL as a dry hole, 12-20-85. tional No. 3-4 Sec. 3, T3N, R30W NORTH FLORIDA Suwannee W-15877 Palmer Petroleum, 563' FNL & 12-13-85 88.8 6,888 Plugged & abandoned P-1181 Inc.-Vining No. 1 752' FEL as a dry hole, 12-13-85. Sec. 2, T4S, R12E SOUTH FLORIDA Broward W-15765 Sabine Corp.- 1616' FNL & 6-28-85 24 11,604 Plugged & abandoned P-1169 Miccosukee No. 2310' FEL as a dry hole, 6-28-85. 32-1 Sec. 32, T49S, R35E Collier W-15841 Hughes Eastern 1382' FNL & 9-9-85 30 11,547 Plugged & abandoned P-1086 Petr., Ltd.-Collier 1567 FWL as a dry hole, 9-9-85. Co. No. 10-2 Sec. 10, T53S, R34E Collier W-15796 Hughes Eastern SHL: 10-15-85 37 MD:11.,632 Plugged & abandoned P-1140 Petr., Ltd.-Gerry 1295' FNL & TVD:11,591 as a dry hole, 10-15-85. Brothers No. 33-2 1040' FWL BHL: 695' FNL & 1040' FWL Sec. 33, T49S, R31E Collier W-15844 R. K. Petroleum 1440' FNL & 12-6-85 43.4 11,565 Completed as a P-1170 Corp.-Rex Proper- 952' FWL producer. ties No. 33-2 Sec. 33, T46S, R28E. Lee W-15756 Exxon Corp.-A. 1412' FNL & 5-19-85 52 11,800 Plugged & abandoned P-1165 Kaplan Trustees, 1208' FEL as a dry hole, 5-19-85. et al. No. 32-1 Sec. 32, T45S, R27E Lee W-15845 Hughes Enterprises- SHL: 11-15-85 34 MD:11,778 Plugged & abandoned P-1183 Hughes-Rutledge 1185' FNL & TVD:11,350 as a dry hole, 11-15-85. No. 9-4 2464' FWL BHL: 1640' FSL & 1564' FEL Sec. 9, T44S, R26E

1. Florida Bureau of Geology well number of samples (cuttings or core chips). 2. For directlonally drilled wells, SHL issurface hole location. BHL Is bottom hole location. 3. MD: measured depth; TVD: true vertical depth (determined by directional survey). TABLE III. WELLS DRILLED DURING 1985 IN EASTERN PLANNING AREA, GULF OF MEXICO N

DRILLER'S 1 WELL DEPTH, RTE, AREA NO. OPERATOR LOCATION FEET FT. MSL REMARKS Destin Dome OCS-G-6417 Shell Block 160 17761 105 Smackover-Norphlet well on Destln Dome. Well No. 1 Rumored to have had goo dahow In Norphlet. Shell-Amoco bids In sale 94, in December, 1985, support this belief. Set open hole plug. Abandoned 12-85.

Destin Dome OCS-G-6417 Shell Block 160 16993 105 Began drilling 5-9-85. Smackover-Norphlet Well No. 2 test. Abandoned 8-21-85 without testing. Destin Dome OCS-G-6428 Exxon Block 284 17500 73 Began driling 6-28-85. Smackover-Norphlet test drilled on Destin Dome. Abandoned 11-85 without testing. Destin Dome OCS-G-6438 Chevron Block 422 22222 83 Began drilling 7-2-85. Smackover-Norphlet test. Abandoned 12-85 without testing.

Gainesville OCS-G-6456 Sohlo Block 707 15994 100 Began drilling 6-3-85. T.D. In Paleozolcs(?). Well believed to have penetrated thick Eagle Mills (Triaasic) section. Abandoned without testing.

Pensacola Block OSC-G-6391 Sohlo Block 948 18958 85 Began drilling 2-18-85. Well drilled on Louann Salt structure. Seven Inch liner cemented at 18956 feet. Well tested In both Norphlet and Smackover. Abandoned 10-16-85.

1. RTE: Rotary Table Elevation. 37

APPENDIX III

DISCOVERY WELL DATA FLORIDA OIL FIELD DISCOVERY WELL DATA

Discovery Permit Perforations Total Name of Produc- Discovery Oil Gravity, Date No. Field County or Open Hole Depth Ing Formation Status Degrees API 9.26-43 42 Sunniland Collier 11,602-11,626 11,626 Sunniland Pumping 26 2-1-54 167 Forty Mile Bend Dade 11,322-11,339 11,577 Sunniland Pumping 21 7-22-64 315 Sunoco Felda Hendry 11,472-11,485 11,485 Sunnlland Pumping 25 6-2-66 371 West Felda Hendry 11,486-11,489 11,675 Sunnlland Pumping 26 3-30-69 401 Lake Trafford Collier 11,870-11,892 11,987 Sunnlland Pumping 26 6-15-70 417 Jay Santa Rosa 15,470-15,524 15,984 Smackover Flowing 51 12-19-71 504 Mt. Carmel Santa Rosa 15,260-15,280 15,399 Smackover Flowing 42 & Norphlet 2-14-72 523 Blackjack Creek Santa Rosa 15,790-15,900 16.,235 Smackover Flowing 51 & Norphlet 12-6-72 563 Bear Island Collier 11,589-11,595 11,817 Sunniland Pumping 26 11-14-73 662 Seminole Hendry 11,415-11,420 11,6051 Sunniland Pumping 25 7-30-74 712 Lehigh Park Lee 11,389-11,394 11,630 Sunniland Pumping 28 4-22-77 881 Sweetwater Creek Santa Rosa 11,299-14,340 14,611 Smackover Pumping 45 8-11-77 865 Baxter Island Collier 11,512-11,515 11,823 Sunniland Pumping 22 10-13-77 904 Mid-Felda Hendry 11,492-11,496 11,686 Sunniland Pumping 26 6-20-78 829 Raccoon Point Collier 11,410-11,414 11,658 Sunniland Pumping 23 9-28-78 897 Pepper Hammock Collier 11,629-11,633 11,897 Sunniland Pumping 27 6-27-82 1070 Townsend Canal Hendry 11,416-11,421 11,462 Sunniland Pumping 28 3-25-84 1125 Bluff Springs Escambla 16,332-16,339 16,800 Smackover Flowing 57 11-10-85 1170 Corkscrew Collier 11,547-11,565 11,565 Sunniland Swab Test 26 2-28-868 1194 McClellan Santa Rosa 14,072-14,090 14,475 Smackover Flowing 41 39

APPENDIX IV

1985 GEOPHYSICAL EXPLORATION ACTIVITY 1985 GEOPHYSICAL EXPLORATION ACTIVITY

COophysl- Surveyed Permit Expiration Energy Depth, Charge Shot Hole Survey Permit eel Co. For County Approved Date Status Source Ft. lise. Lbe polng, FPt Length, ml. Comments 0-31-86 Texaco Texaco Collier Application Seismic 10-20 0.25-2.5 220 107 Withdrawn Gelatin G-32-86 Seminole Seminole Collier Application Thumper N.A. N.A. NA. Not Expl. Expl. Pending Stated 0-33-88 Sela Pros Edwin & Collier 10-4-85 4-2-86 Survey Explosives 10-20 1 220 10 Berry Cox Cancelled G0-34-88 GFS Bel North Santa Rosa 3-6-85 9-3-85 Completed Seismic 150-180 10-15 330 7 Petrol. Gelatin 0-35-86 Western Western Esc., Sta Ra, Application Airgun N.A. N.A, N.A. 350 Offshore Geophys. Geophys, Oklsa, Wltn Pending G-36-88 GFS Inexco Santa Rosa 3-18-85 9-14-85 Completed Seismic 150-180 10-15 330 34.5 Gelatin G-37-88 Geco Geco Collier & 5-17-85 5-12-86 Partially Alrgun or N.A. N.A. N.A. 340 Only 50 miles Hendry Completed Vibrator Surveyed 0-38-85 GFS Arco Escamblea 3-27-85 9-23-85 Completed Seismic 80-100 2.5-5 330 57 Gelatin 150-180 G-39-85 GFS MC Moran Escambia 3-27-85 9-23-85 Completed Seismic 150-180 10-15 330 5 Gelatin 0-40-85 Selecom Arco Santa Rosa 3-29-85 9-25-85 Permit Seismic 80-100 5-10 165 30 Delta Untd. Expired Gelatin 150-180 G-41-85 Selscom Arco Santa Rosa 6-17-85 12-14-85 Completed Seismic 80-100 5-10 165 30 Delta Untd. Gelatin 150-180 G-42-85 Shell West- Shell West- Hendry 4-9-85 4-4-86 Completed Watergel 110 20 80 14.25 ern E & P ern E &P Explosive G-43-85 Geo Seism. Geo Seism. Walton Application Seismic 150-180 20 330 8 Serv. Serv. Withdrawn Gelatin G-44-85 Geco Geco Collier 9-24-85 3-23-86 Permit Vibrator N.A. N.A. N.A. 45.5 Partly Offshore Expired Comp. Air G-45-85 GFS Bel North Escambia Application Seismic 80-100 2.5 440 4.5 Petrol. Withdrawn Gelatin 150-180 7.5 G-46-85 GFS Union Oil Santa Rosa 7-19-85 1-15-86 Completed Seismic 80-100 2.5 440 4.5 Gelatin 150-180 7.5 G-47-85 Conoco Conoco Santa Rosa 7-12-85 1-8-86 Completed Vibrosels N.A. N.A. N.A. 22 Inc. Inc. G-48-85 Southern Southern Okeechobee 7-19-85 1-15-86 Completed Seismic 10 0.25 220 15 Seismic Seismic Gelatin G-49-85 Western Western Madison 7-10-85 1-7-85 Completed Dynamite 60 10 165 52. Geophys. Geophys. G-50-85 Shell West- Shell West- Dde, PIm 9-11-85 3-10-86 Completed Vibroseis N.A. N.A. N.A. 280 ern E & P ern E &P Bch, Cir, Brwd G-51-85 Seismic Cities Escambia & 9-24-85 9-19-86 On Hold Dynamite 100 20 440 11.3 Experts Service Santa Rosa G-52-85 J.M. J.M. Glades, 12-20-85 6-18-86 Cancelled Seismic 6 .55 110 66 Mini-holesurvey Huber Huber Highlands Gelatin 10 1.1 80-100 "Small" 5280 G-53-85 Western Western Escambia Application Dynamite 120 20 440 6 Geophys Geophys Withdrawn G-54-85 Geco Geco Bay, Calhoun, Application Vibrosels N.A. N.A. N.A. 420 Gulf, Liberty, Pending Franklin G-55-85 Southern Southern Hendry & Application Seismic 20 1 220 15.5 Seismic Seismic Collier Pending Gelatin G-56-85 Southern Gulf Coast Escambia 11-27-85 5-26-86 Completed Seismic 150 20 161 7.5 Seismic Geodata Gelatin G-57-85 Petty-Ray Petty-Ray Lib, Frank., 11-19-85 5-18-86 Completed Vibroesis N.A. N.A. N.A. 246 Geophys Geophys Wakulla G-58-85 GFS LA.Land Santa Rosa 11-8-85 5-7-86 Completed Vibroseis N.A. N.A. N.A. 8 & Expl. G-59-85 Shell West- Shell West- Hendry & 2-10-86 8-9-86 Completed Seismic 110 20 60 33 ern E & P ern E &P Palm Bch Gelatin G-60-85 GFS Mobil Escambla 12-23-85 6-21-86 Completed Seismic 80-150 10-20 330 22.5 Gelatin G-61-85 Western Tenneco Escambla & 2-4-86 5-5-86 Completed Dynamite 70 5 165 75 Geophylcal Oil E&P Santa Rosa

Total Miles In Applications 2327.05 Total Actual Surveyed 963.25 In South Florida 392.25 In North Florida, Panhandle 519.0 In North Florida, Peninsula 52.0 Total Pending 796.8 Total Withdrawn, Cancelled, or Expired 567.0 42 APPENDIX V

OIL AND GAS RELATED THESES HELD BY THE FLORIDA GEOLOGICAL SURVEY LIBRARY

Grinnell, Philip C., Jr., 1976, The Sunniland Limestone within the Forty Mile Bend Area, Monroe and Dade Counties, Florida: Tallahassee, FL, Fla. State Univ. Hearn, Frank P., 1984, Pre-Punta Gorda Sediments from the Bass, Collier Company, 12-2 Well, South Florida: Lafayette, LA, Univ. of Southwestern Louisiana.

Heron, Stephan D., III, 1982, Depositional and Diagenetic History of Selected Mesozoic Sediments of the South Florida Basin: Lafayette, LA, Univ. of Southwestern Louisiana.

Laird, John W., 1985, Diagenetic Controls on Reservoir Characteristics and Development in the Jurassic Norphlet Formation, Escambia County, Alabama: University, AL, Univ. of Alabama.

Pontigo, Felipe Antonio, Jr., 1982, Pre-Haynesville Stratigraphy and Structural Geology of the Apalachicola Embayment, Petrology and Paleoenvironmental Interpretation of the Smackover Formation: Talla- hassee, FL, Fla.State Univ.

Raasch, Albert C., Jr., 1954, The Sunniland Oil Field of Collier County, Florida: Tallahassee, FL, Fla. State Univ.

Vaughan, R. Lee, 1985, Diagenetic Effects on Reservoir Development in the Upper Jurassic Norphlet Formation, Mobile and Baldwin Counties, and Offshore Alabama: University, AL, Univ. of Alabama. 43

PART II

THE BROWN DOLOMITE ZONE OF THE LEHIGH ACRES FORMATION (APTIAN) IN THE SOUTH FLORIDA BASIN- A POTENTIALLY PROLIFIC PRODUCING HORIZON OFFSHORE

Albert V. Applegate 44 CONTENTS Page

Acknowledgements ...... 45

Abstract ...... 46

Purpose of study ...... 46

Method of study ...... 46

Metric conversion factors ...... 47

Lithology ...... 47

Stratigraphic relationships ...... 51

Geochemistry ...... 54

Structure ...... 55

Summary ...... 57

References ...... 58

Appendix I Summary of well data ...... 59

Appendix II Drill stem test data from Brown Dolomite Zone ...... 66

ILLUSTRATIONS

Figure 1 Isopach of the Brown Dolomite ...... 48 2 Structural map of the Brown Dolomite ...... 49 3 Isopach of the porous Brown Dolomite ...... 50 4 Generalized geological column Lower Cretaceous- Jurassic (?) rocks; south Florida Basin ...... 52 5 Control wells ...... 53 6 Structural features in Florida and offshore ...... 56 45

ACKNOWLEDGEMENTS

Geological Survey staff members reviewed and edited this report. Jim Jones and Ted Kiper drafted and photographed the figures. George Winston (consulting geologist, Coral Gables, Florida) provided geologic information and advice. 46

THE BROWN DOLOMITE ZONE OF THE LEHIGH ACRES FORMATION (APTIAN) IN THE SOUTH FLORIDA BASIN- A POTENTIALLY PROLIFIC PRODUCING HORIZON OFFSHORE by Albert V. Applegate

ABSTRACT

The best development of the Brown Dolomite onshore is in Charlotte and surrounding counties in the northern part of the South Florida Basin at a depth of approximately 12,000 feet. Here, the Brown Dolomite zone attains a maximum thickness of 100 feet, of which one-half is usually porous and capable of high volume fluid production. Offshore, the maximum thickness occurs near the Marquesas Keys, where approximately 400 feet of mostly porous dolomite has been encountered. Although very little oil staining has been found in the Charlotte County area, staining has been observed in two Marquesas wells. The best possibility for finding oil in the Brown Dolomite appears to be in the offshore portion of the South Florida Basin. Brown Dolomite is present in at least three wells on the Sarasota Arch and probably continues around the rim of the basin southeast to the Marquesas where thick vugular dolomite is present. Stratigraphic and structural traps associated with this dolomite, which is capped by dense limestone and anhydrite, may have led to the formation of giant oil fields.

PURPOSE OF STUDY

The potential economic importance of the Brown Dolomite in the offshore area of the South Florida Basin, as well as in the area where it was originally described, prompted this study. This information will help geologists to decide if the possibility of finding oil in this zone is worth the expense of drilling the additional 1,000 feet below the Sunni- land Formation.

METHOD OF STUDY

Core chips and cuttings of wells drilled through the Brown Dolomite zone were studied using a binocular microscope. Appendix I shows these wells. Information listed in Appendix I includes formation tops from the Punta gorda Anhydrite to total depth, net dolomite, porous dolomite, Jost circulation, and other pertinent data. from these data, an isopach map of the Brown Dolomite (Figure 1) was prepared. 47 Appendix 2 lists data on all drill stem tests. Water recoveries in these tests show that the wells tested had sufficient porosity and permeability to be capable of oil production. A structural map (Figure 2) using subsea depths to the top of the Punta Gorda Anhydrite was made. Wells penetrating the Punta Gorda Anhydrite were used in the preparation of this map. An isopach map (Figure 3) of the porous interval in the Brown Dolom- ite was prepared, utilizing available data. In early wells where sonic and neutron logs were not available, cores, cuttings, caliper surveys, drilling time logs, and lost circulation intervals were important factors in arriv- ing at estimates of the thickness of the porous interval as well as estimating the actual porosity. In those wells in which sonic or neutron- density logs were available, porosity calculations were found to be in fair agreementw.ith estimates made from cores and cuttings.

METRIC CONVERSION FACTORS

The Florida Bureau of Geology, in order to prevent duplication of parenthetical conversion units, inserts a tabular listing of conversion factors to obtain metric units.

Multiply by to obtain feet 0.0348 meters miles 1.6090 kilometers

LITHOLOGY

The texture of the Brown Dolomite varies from euhedral to anhedral, and from coarse to very fine grained. It is often vugular near the top of the section. Drill stem tests made in the Brown Dolomite show that it is capable of high fluid production. Much of the Brown Dolomite has fossil ghosts and other evidence of secondary origin. In general, the dolomite becomes less porous from top to bottom which may be partially due to porosity changes in the original limestone. In the Tribal Exxon Gulf Coast Realties 12-2 well (P-727) a core cutting the Brown Dolomite is predominantly limestone due to its downdip location in the basin. In this well the lowermost limestones exhibit the lowest porosity. Dolomite has an average porosity of nine percent in contrast to about four percent for the limestone. Permeability was low or non-existent in both the limestone and dolomite. This particular well was a key well in understanding the Brown Dolomite zone. It was cored through the Brown Dolomite zone with 100 percent core recovery. An analysis of each foot of the core was made by All Points, Inc., of Houston, Texas. Geophysical logs that were run included gamma ray, sonic, caliper, neutron-density and induction electrical. 48

FeOC X-^ OBcoEES-T LUCIE

L 0.-,, O MARTIN

LEE H Y OKEECHOBEE

COLLIER !BROWARD 1--"

"- too THICKNESS IN FEET ,D .

SCALE

Figure 1. Isopach of the Brown Dolomite. 49

/L-'"\ I___

0,00 MANATEE HARDEE HIGHLANDS 10,5 I OKEECHOBEE | ST. LUCIE

S 10,000 DEPTHBELDESOTOW MLI

MARTIN 10,900

PALM BEACH 11SCAE100 CHARLOTTE 11,300 HEN LAKE OKEECHOBEE 11,500 LEE

11,700

11,900 1 0 *

12,300

10,000 DEPTH BELOW MSL

gure 2.mapStructurALE of the Brown Dolomite. T -

Figure 2. Structural map of the Brown Dolomite. 50

SMAATMI I| AMDe |HmHLANO Y OIa I oOE -T. CMO* LUCIE

GLADES LANE -

COLLMM - a 0W I

Figure he porous Brown Dolomite. Figure 3. !sopach of the porous Brown Dolomite. 51 In wells drilled prior to the introduction of the compensated neutron density log it is mandatory to have cores or good cuttings in order to make a reliable estimate of net dolomite. Due to lost circulation in the more porous zones, samples may be of very poor quality, completely missing, or consist of little but lost circulation material. Another prob- lem in the better porosity zones is washout. When this occurs porosity calculations from geophysical logs are not reliable.

STRATIGRAPHIC RELATIONSHIPS

The term Brown Dolomite, or "CD Dolomite" as it was often called by Banks, was first used in two reports (Banks, 1964a and 1964b). Banks states (1964a, p. 3) that, "the Brown Dolomite occurs in the first few feet or the first few hundred feet of the Choffatella decipiens zone." In a stratigraphic section from Lee to Manatee counties (Banks, 1964b) the top of the Brown Dolomite lies 300 feet below the base of the Punta Gorda Anhydrite. The Choffatella decipiens zone was not described by Banks, but in various cross sections by Paul and Esther Applin (1965, plates 8, 9, 11), it has a thickness of approximately 1,000 feet in the area where the Brown Dolomite is present. The Applins considered the Choffatella decipiens zone to be lowermost Trinity age (lowermost Comanchean). It lies just above their Fort Pierce Formation of Late Jurassic (?) or Early Cretaceous age. Choffatella decipiens is a large benthic foraminifera which ranges throughout Early Cretaceous (Valanginian to Albian). It has been identified in limestone in the Caribbean region (Maync, 1950). The Applins (1965, plate 5) found the Choffatella decipiens in the upper 250 feet of the Fort Pierce Formation in their type well, the Amerada Cowles Magazine No. 2well (P-259) in St. Lucie County, Florida, and in several other wells penetrating this formation. A new nomenclature for the pre-Punta Gorda rocks in the South Florida Basin was introduced by Applegate, et al. (1981). In this nomenclature (Figure 4), the Lehigh Acres, an early Trinity age formation, lies beneath the Punta Gorda. This formation consists of three members, from youngest to oldest: the Able Member, 290-feet thick, composed principally of anhydrite and limestone; the Twelve Mile Member, 320- feet thick predominately limestone and dolomite, and the West Felda Member, 40-feet thick, composed of calcareous shale and dark gray, argillaceous limestone. The Brown Dolomite zone, which lies entirely within the Twelve Mile Member, is found at a minimum depth of about 50 feet below the top of the member. Onshore the Brown Dolomite zone is encountered only in the up-dip of the South Florida Basin. With the exception of its presence in the two Marquesas wells in the Florida Keys (Figure 5, P-275, P-284) it is not present in the area below the 11,900 foot contour of the Punta Gorda Anhydrite. The best onshore development of the Brown Dolomite occurs in northern Lee, northern Hendry, Charlotte, Glades, southeast De Soto 52

TT Tl FORMATION ...... SUNNILAND DLM LIMESTONE PUNTA GORDA 600' ANHYDRITE z . = m MEMBERABLE <\\\ , LIMESTONE S( c 290' - - -., ANHYDRITE Z us < TWELVE BROWN 2 z MILE DOLOMITE O O aJ MEMBER ZONE 0 o a -U-DOLO___° 320' ,- ,' ITE 0 WEST FELDA SHALE SHALE

ILl LIMESTONE O PUMPKIN BAY '. . NHYDRITE 1050 DOLOMITE

C T • ANHYDRITE 0 U BONE ISLAND LIMESTONE 1300 DOLOMITE

• > * ANHYDRITE ,n WOOD RIVER ... 0 <\• L\L\< DOLOMITE , 1700 ccS LIMESTONE : .BASAL CLASTIC ZONE

,*, : ; RHYOLITE TRIASSIC - JURASSIC N 1 ,. ,.•.,, 12., . ,''^^»*^\ 0 BASALT

Figure 4. Generalized geological column of Lower Cretaceous - Jurassic (?) rocks in the south Florida Basin. 53

MANATEE I HARDEE 1jHILANDS ~ _ E HA RD E E I I OK E E C H O BE E ST . LU C IE *236 1f62 i 259

22*2 I - MA TIN HoR ' 7 - TREADWELL I so -J HARLOTTEN5 ULGLADES LAKE PALMBEACH 7 750 5t GADE OKEECHOBEE 031 3 152 47 2 rLEE 2 I HENDRY 23, V -,_..^-,161 00R14COI *0767;314 I 3 4 5 14 24 265

5|56B BROWARD " 727

0778 9280 - ----..- S DADE

NO BROWN DOLOMITE MONROE NOTED IN THESE WELLS IN LEHIGH ACRES FM. I

148 N 1 r 902 0

0 25 miles SCALE

284 5 o n

Figure 5. Location map of control wells. 54 and southwest Highlands counties. The best development encountered was in the Humble-Treadwell 1-A well, (Sec. 17, T42S, R23E) in southern Charlotte County, where there is at least 100 feet of dolomite. The thickest offshore section, with the exception of the previously discussed Marquesas wells, is found to the west-southwest in the two California-Coastal wells (P-289, P-297) in the FSL 224-B lease offshore from Lee County (Figure 5). Offshore the dolomite is known to continue to the west, where it has been found in at least three locations on or near the Sarasota Arch. From the Humble-Treadwell well, the thickest section of the Brown Dolomite zone closely follows the 11,600-foot structural contour of the Punta Gorda Anhydrite southeast to the Humble-Lehigh Acres well in Lee County, and then turns abruptly to the northeast, where it has an estimated thickness of 70 to 75 feet in southeast DeSoto County and southwest Highlands County. The occurrence of the rather thick section here may have been influenced by the Peninsular Arch. An estimated 38 feet of the Brown Dolomite zone is present in the Mobil-Phillips Seminole "C" well (P-565B) in Hendry County. No deep wells have been drilled to the southeast between this well and the Sinclair-Wiliams (P-148) and the Robinson-IIF well, both of which are located on Key Largo in eastern'Monroe County. Twenty-eight feet of very fine-grained anhydriticdolomite was found in the Sinclair-Williams well (P-148). Two wells in the Marquesas Keys which have a thick porous dolomite section are the Gulf-FSL 826Y well (P-275) and the Gulf-California OCS Block 28 well (P-284). Dolomite found in the Gulf 826Y well is highly porous and was considered by Banks (1964a and 1964b) to be the same Brown Dolomite which he had studied in Lee, Charlotte and Sarasota counties. The Gulf-California Block 28 well was found to have a consid- erably thinner dolomite section than the 826Y well. George Winston (personal communication, 1984) also believes that this dolomite is in the Twelve Mile Member of the Lehigh Acres Forma- tion. It is doubtful that a definitive correlation can be made until more deep control is available between the Florida Keys and the mainland.

GEOCHEMISTRY

The petroleum source rock study by Palacas (Palacas, et al., 1981) of pre-Punta Gorda rocks from widely scattered boreholes in the South Florida Basin revealed that the upper part of the Pumpkin Bay Forma- tion, and to a lesser extent, part of the Lehigh Acres Formation have the best source potential in the lower beds. The richest of these rocks studied to date are in the Humble-Lehigh Acres well (P-407) in Lee County and the Gulf FSL No. 373 well (P-22) on Big Pine Key (Figure 5). This is a favorable factor for the establishment of commercial oil production in the Brown Dolomite zone. 55 Another factor favoring possible oil generation in the Brown Dolomite is its depth. It lies approximately 1,000 feet below the Sunniland Forma- tion. The Sunniland is considered to be near the top of the "oil window," as it has a low gas-oil ratio (approximately 100 cubic feet of gas per stock tank barrel of oil) and a relatively low API gravityt250. This additional depth should ensure that, if oil is found in the Brown Dolomite, it wil be higher gravity oil with a higher gas-to-oil ratio than the oil presently being produced from the Sunniland Formation.

STRUCTURE

The South Florida Basin has experienced at least three major changes in size and shape since its formation following the separation of North America from Africa and South America. This division is thought to have occurred during the Triassic and Early Jurassic, peri- ods noted for red beds and volcanic activity in both north and south Florida (Barnett, 1975; Smith, 1982; Chowns and Wiliams, 1983; and Klitgord, et al., 1984). According to Winston (personal communication, 1983) the geographic extent of the South Florida Basin in early Comanchean time and during the deposition of Brown Dolomite was limited to atriangular area roughly 200 miles on each side. To the east, the basin was limited by the Cay Sal Arch, (Figure 6) which came into existence in early Coman- chean time. This feature extended north from Cuba through Cay Sal and east to Key Largo and up the present Florida Straits. The basin bends gently around the north side of Lake Okeechobee to the south side of the offshore Sarasota Arch. The Sarasota Arch extends in a southwest direction from Sarasota County across the west Floridashelf to the reef-capped Comanchean continental edge along the west Flor- ida escarpment. Along the arch, basement is encountered offshore at depths ranging from about 10,000 to 12,000 feet. This arch separates the South Florida Basin from the Tampa Basin, which lies to the north of the arch. After reaching the continental edge, the basin follows the escarpment to the southeast. Although later offshore drilling in the eastern Gulf of Mexico has changed the shape of the northern part of the South Florida Basin, as originally proposed by Oglesby (1965), many of his concepts appear to be valid. The Cretaceous section shown in his various South Florida Basin maps (based on seismic interpretation) thins significantly as it approaches the western edge of the Continental Shelf. If this general configuration of the basin is correct, it is probable that the Brown dolomite is present at the western edge of the basin and will provide a tempting target for exploratory drilling. This assumption is further bol- stered by the presence of a thick dolomite section in the Marquesas wells and the lack of dolomite in the Gulf-FSL 373 well (P-22) to the east on Big Pine Key. This area was structurally low during the Early Cretaceous. 56

0• SOUTH EAST .o" GEORGIA EMBAYMENT

3 0^ %o 1 BLAKE . , BASINPLATEAU

as LAKE OKEECHOBEE

SO UTH F ORIDA I BAHAMASBA -" STUARTSUAT I t BASIN B ASIN CITY REEF . M SA CAY SAL ARCH . / MARQUESAS CAY SAL

•0 L\ CAYO COCO

S,€ X ^~CUBA I

A" STRUCTURAL FEATURES YUCATAN PEN. IN FLORIDA AND OFFSHORE

SCALE 100 0 100 200 300 400 500 miles IFigure 6.I StructuralI featuresda Iandoffshore.

Figure 6. Structural features in Florida and offshore. 57 SUMMARY

Interest in the Brown Dolomite zone of the Lehigh Acres Formation and other dolomites in the geologic column is certain to increase as attention focuses on the petroleum potential in the offshore portion of the South Florida Basin. Because of porosity and permeability enhancement accompanying the chemical processes that transform limestone into dolomite, sucrosic dolomites are by far the most important of the carbonate reservoir rocks. In the northern part of the South Florida Basin, centering around Charlotte County, no reserves or good shows have been found, even though the geochemistry appears to be favorable. One explanation is that, since these beds have a gentle southwest dip with no known faulting, any oil in the Brown Dolomite could have migrated updip to the northeast and out of the dolomite into basal clastics. Another possibility is that no structure has been drilled. It is doubtful that further drilling in the northern area will be forthcoming until better seismic tools are developed or new discoveries are made in other areas of the South Florida Basin. The best possibility at present for new discoveries appears to be offshore Florida where thick porous dolomites are believed to exist. Such dolomites in a stratigraphic or structural trap could have led to the formation of giant fields. Any exploration program would have at least two attractive targets before reaching the Brown Dolomite zone. The Dollar Bay Formation, lying about 2,000 feet above the Sunniland Formation, has had very good heavy oil shows in the Lake Okeechobee area. However, the oil, because of low formation temperature, is not sufficiently maturated at this updip location. In the offshore, where the same Dollar Bay Formation could be present, formation temperatures and resulting API gravity could be consid- erably higher. The same reasoning applies to the Sunniland Formation. This formation produces oil of 25-26 degrees API gravity, with a gas-to- oil ratio of approximately 100 onshore. In the offshore, if the formation is present, it could be deeper and have a higher gas-to-oil ratio and a higher API gravity. This relatively unexplored offshore part of the South Florida Basin, with its thick Cretaceous and Jurassic (?) dolomites, coupled with numerous anhydrite seals, offers a tempting target. Ready markets for oil and gas, together with benign weather in the offshore, all point to the need for a sustained driling program to thoroughly test this area. 58

REFERENCES

Applegate, A. V., Winston, G. 0., and Palacas, J. G. 1981, Subdivision and Regional Stratigraphy of the Pre-Punta Gorda Rocks (Lowermost Cretaceous-Jurassic ?) in South Florida: Supplement to Gulf Coast Assoc. Geol. Soc. Trans., v. 31, p. 447-453.

Applin, P. L. and Applin, E. R., 1965, The Comanche Series and Asso- ciated Rocks in the Subsurface in Central and South Florida: U.S. Geological Survey Prof. Paper 447.

Banks, J. E., 1964a, Oil and Gas Prospects of the Englewood Area of Lee, Charlotte and Sarasota Counties, Florida: unpublished report for Coastal Pet. Corp. placed in Bureau of Geology Library in Tallahassee, Florida.

Banks, J. E., 1964b, Geologic Investigation for Petroleum in the Area of State of Florida Drilling Lease 224-B: unpublished report for Coastal Pet. Corp. placed in Bureau of Geology Library in Tallahassee, Florida.

Barnett, R. S., 1975, Basement Structure of Florida and its Tectonic Implications: Gulf Coast Assoc. of Geol. Socs. Trans., v. 25, p. 122-142.

Chowns, T. M., and Williams, C. T., 1983, Pre-Cretaceous Rocks Beneath the Georgia Coastal Plain-Regional Implications: in Studies Related to the Charleston, South Carolina Earthquake of 1886 - Tec- tonics and Seismicity: U.S. Geological Survey Prof. Paper 1313, p. 42. Klitgord, K.D., Popenoe, P., and Schouten, H., 1984, Florida: a Jurassic Transform Plate Boundary: Journal of Geophysical Research, vol. 89, no. B-9, p. 7753-7772. Maync, W., 1950, The Foraminiferal Genus Choffatella schlumberger in the Lower Cretaceous (Urgonean) of the Caribbean Region (Venezuela, Cuba, Mexico, and Florida): Eclogae Geol. Helv., Lausanne, 1950, v. 42 (1949), No. 2, p. 539. Oglesby, W. R., 1965, Folio of South Florida Basin, a Preliminary Study: Map Series 19, Florida Geological Survey (out of print).

Palacas, J. G., Daws, T. A., and Applegate, A. V., 1981, Preliminary Petroleum Source-Rock Assessment of Pre-Punta Gorda rocks (lowermost Cretaceous-Jurassic?) in South Florida: Gulf Coast Assoc. Geol. Socs. Trans., v. 31, p. 369-376. APPENDIX I SUMMARY OF WELL DATA Company Punta Lehigh Twelve Brown Net West Bone Wood & Gorda Acres Mile Dolo Dolo Felda Pumpkin Island River T.D. Fee Name Fm. Fm. Mbr. Zone (ft.) Mbr. Bay Fm. Fm. Fm. ft. Elev. Brown Dolomite Porosity, etc. CHARLOTTE COUNTY B-5 This well has best dolomite HORC 12456- seen in any onshore well with Treadwell 11684 12160 12365 12581 100 12720 12800 NR 13300 20 much vugular porosity noted, especially in upper part of section. Twenty feet porosity from core and resistivity log.

Samples worthless. All tops are questionable. No Gamma P-178 or Sonic log in this well. No Gulf 12290- drilling breaks. High re- Vanderbilt 11442 11940 12370 80 12495 12615 NR- 12725 22 sistivity in zone.

Porosity 7 percent from sonic log. Some vugular porosity noted in study of core, No trace of oil staining noted. P-310 Dolomite probably wopld pro- Gulf duce because of vugs. Well Stevens 12290- produced salt water on drill Estate 11528 11985 12215 12370 55 NR 12395 25 stem test.

P-373 Some spotty fair porosity in Mobile upper part of Brown Dolomite Babcock 11930- Zone. Generally poor porosity, 6 Ranch 11290 11675 11825 12010 70 12164 12230 NR 12500 55 percent or less. Sonic log use- less because of washout.

P-375 Samples worthless. Estimate Mobil from Gamma Ray, Sonic, and Offshore 11920- comparison nearest wells. No FSL-224 B.11150 11640 11882 12000 70? 12170 12220 NR 12931 21 porous dolomite. Porosity estimated from sonic .1 P-459 approx, 8 percent. Finely cry- (o Exchange 11760- stalline, dense. Best porosity Payson 11151 11512 11652 830 60 11900 12050 12760 NR 13432 81 at base of Interval. APPENDIX I (Con't.) SUMMARY OF WELL DATA

Company Punts Lehigh Twelve Brown Net West Bone Wood T.D. & Gorda Acres Mile Dolo Dolo Felda Pumpkin Island River Fee Name Fm. Fm. Mbr. Zone (ft.) Mbr. Bay Fm. Fm. Fm. ft. Elev. Brown Dolomite Porosity, etc. P.-472 Dolomite very fine-grained Exchange throughout this Interval, No Oil & Gas commercial porosity, Sonic Babcock 12050- log shows approx. 4 percent Florida Co. 11366 11780 11940 12158 70 12360 12440 NR 13000 47 porosity.

P-475 Dolomite is fine-grained, Por- Exchange osity approx. 8-10 percent Oil & Gas from density log. Porosity State Lease 11930- from sonic log approx. 2448 11175 11585 11852 12000 80 12034 12120 12786 NR 13232 38 10-12 percent

COLLIER COUNTY P-346 Much lost circulation noted HORC in 12810-12830 Interval. No noted. Gulf Coast dolomite Realties 12803- #24-1 11840 12462 12742 12816 0? 13036 13072 14070 NR 14500 38

P-727 Gamma log misleading. This Tribal well Is below Punta Gorda Exxon (-11800') structure contour of Gulf Coast and on southeast edge zone. See Realtles 12803- "Brown Dolomite" text #12-4 11870 12490 12780 12872 7 13070 13110 14150 15480 17254 40

DESOTO COUNTY

P-609 Shell 28' of 8 percent porosity and Punts 11260- balance 5 percent or less. Gorda 10745 • 11060 11210 11340 70 11400 11550 12190 NR 13000 77 APPENDIX I (Con't.) SUMMARY OF WELL DATA

Company Punta Lehigh Twelve Brown Net West Bone Wood & Gorda Acres Mile Dolo Dolo Felda Pumpkin Island River T.D. Fee Name Fm. Fm. Mbr. Zone (ft.) Mbr. Bay Fm. Fm. Fm. ft. Elev. Brown Dolomite Porosity, etc. P-679A Brown Dolomite Zone very AMOCO sandy. Dolomite fine-arained, Knight non-porous with interbedded 10280- light gray limestone. Sand 9916 10130 10264 10340 35? Not present 11655 121 below 10,340 ft.

GLADES COUNTY

P-152 Information from lithology log Coastal of Banks. Very low porosity Tledke in Interval. Trace dead oil. No 11605- samples through this Interval 11048 11340 11540 11705 30 11815 11860 12760 NR 13424 30 in sample library.

HARDEE COUNTY

P-62 Redbeds 11382'. Lack of por- HORC 10570- osity, a 20' sampling Interval, Keen 10134 ? ? 10640? 30 10770 10835 Not Pre. 11934 63 and quartz sand in the Brown Dolomite Zone make all estimates very questionable in HENDRY COUNTY this well.

P-314 * Extremely poor samples. Drill Sun Oil 12440- stem test shows porosity and Red Cattle 11648 12160 12378 12520 50? 12618 NR 12680 54 permeability in interval. Poor P-424 suite of logs. Much of interval probably chalk. Exchange Approximately 6' in upper part Oil & Gas of zone with 8 percent por- Fla. Land 12350- 1 33 osty. Very rapid decrease In & Timber 11552 12052 12246 12364 10 NR 1244 dolomite in this well. May be oi close to eastern edge of zone. -* APPENDIX I (Con't.) SUMMARY OF WELL DATA

Company Punta Lehigh Twelve Brown Net West Bone Wood A Gorda Acres Mile Dolo Dolo Felda Pumpkin Island River T D. Fee Name Fm.r Fm, Mbr. Zone (Ift) Mbr Bay Fm. Fm. Fm. ft. Elev. Brown Dolomite Porosity, etc. P-•858. Dolomite fine-grained with Mobil no visible porosity. Density Phillips 12446- log shows washout, Much Seminole C11600 12190 12400 12500 15 12690 12720 13750 15100 17025 35 chalk In Interval.

P-758 25' of fair porosity in upper Shell 12272- part of Interval (7-11 percent) Alico 11560 11990 12240 12328 45 12515 12552 13490 14840 16000 45 with some well cuttings misl- Ing. Porosity 6 percent or less In lower part of interval. P-789 Variable porosity. Approx. Shell Oil one-half of Brown Dolo- Consol. mite has porosity up to 24 Tomoka 12132- percent. Samples Indicate this Co. 11484 11870 12090 92 22? 12374 12416 NR 12423 44 Interval is a porous chalk.

P-951 22' coarselv crystalline dolo- Ashland Oil mite. Balance of dolomite A. Duda & 12400- has low porosity of 5 percent. Sons 11578 12078 12292 486 58 NR 12603 44 Much lost circulation material but excellent samples.

HIGHLANDS COUNTY

Dolo 10796-10808, silty and B-1 lacks porosity. Some vugular HORC 10796- porosity to 20 percent. Por- Carlton 10380 10622 10758 10880 75 10990 11052 11722 12985 114 osity 10832-10880, variable with some good vugular. No sonic log. Est. 25' porous. APPENDIX I (Con't.) SUMMARY OF WELL DATA

Company Punts Lehigh Twelve Brown Net West Bone Wood & Gorda Acres Mile Dolo Dolo Felds Pumpkin Island River T.D. Fee Name Fm. Fm. Mbr. Zone (ft.) Mbr. Bay Fm. Fm. Fm. ft. Elev. Brown Dolomite Porosity, etc. P-225 No ditch or core samples. Es- Continental 10818- timated only from electric log Carlton 10640 10740 10895 75? 11025 11100 NR 12630 88 and mud log In comparison. with HORC Carlton well. Micro-log shows no porosity. No drilling break.

P-862 Approx. 8' of porosity from AMOCO 10856- neutron-density log with bal- Jackson 10450 10686 10792 10898 30 11036 11106 11750 12625 25 ance of dolomite low porosity. Samples confirm this.

LEE COUNTY

P-161 Porosity to 15 percent. Some Humble 12830- Vugular porosity. Some slight Kirchoff 11855 12450 12734 54 24 NR 12877 22 oil staining in upper 10' of dolomite,

P-289 Dolomite microcrystalline to California finely crystalline. Some test Coastal 12485- circulation material. Drill stem FSL 224B. 11564 12152 12410 12598 103 12748 12800 13772 NR 13975 39 that produced water. Neutron log and drilling time log indicate porosity. Samples comminuted.

P-297 Dolomite comminuted. Much California lost circulation material. Coastal 12445- Microcrystalline to finely FSL 224B. 11524 12104 12380 12560 110 NR 12600 40 crystalline. Estimated 40' porous. _O APPENDIX I (Con't.) SUMMARY OF WELL DATA 2

Company Punts Lehigh Twelve Brown Net Wesl Bone Wood & Gorda Acres Mile Dolo Dolo Felda Pumpkin Island River T.D. Fee Name Fm. Fm. Mbr. Zone (ft.) Mbr. Bay Fm. Fm. Fm. ft. Elev Brown Dolomite Pority, ste P-407 Eleven feet of poroeity from HORC sonic log. Reet of Interval 4-6 Lehigh percent porosity. Samples Acres 12588- show very fine-grained Well No. 1 11700 12250 12460 12684 70 12760 12800 13660 14672 15710 58 dolomite.

P-758 No porosity found In cuttlngs. Exxon Porosielty 4-5 percent from City of logkna•yse. Ft. Myers 12528- #16-2 11578 12112 12506 78 50 NR 12599 43

MANATEE COUNTY

P-236 Dolomite 11020-1105 calc., MagnolIa 10966- Not fine-grained. Very little Schroeder 10371 10710 10905 11038 10 11115 Present 11228 70 porosity in dolomite.

MARQUESAS KEYS

P-275 Oil stain 14670-14680, tar Oil Gulf 14620- 14754-14760. Much lost circ. FSL-826Y 12860 14270 14550? 15036 400 14955 NR 15475 58 material This zone of dolomite has much good porosity highly vugular. P-264 Oil stain 14563,1457614578. Gulf-Cal- Variable poroelty in the Brown Ifomrnl Co. 14420- Dolomite, but approx. 14 per- BIk 28 OCS12740 14105 14310 14640 240 14790 14806 NR 15294 72 cent average. APPENDIX I (Con't.) SUMMARY OF WELL DATA

Company Punts Lehigh Twelve Brown Net West Bone Wood & Gorda Acres Mile Dolo Dolo Felda Pumpkin Island River T.D. Fee Name Fm. Fm. Mbr. Zone (ft.) Mbr. Bay Fm. Fm. Fm. ft. Elev. Brown Dolomite Porosity, etc.

MONROE COUNTY

P-22 Dolomite very fine-grained, Gulf calcftic. No porosity. FSL 373 Big Pine 14590- Key 12710 14220 14500 14740 30 14865 14910 NR 15455 23

P-148 Dolomite, very fine-grained, Sinclair 11090- anhydritic, calcitic, Inter- Williams 10162 10805 11045 11124 20 11280 11318 NR 11968 20 bedded S, light brown, forams, No trace of oill or tar sand. No porosity.

PALM BEACH COUNTY

P-47 All tops tentative, Brown dol- HORC Not omite not present. This zone TUCSON 10757 10770 10770 Present 11040 11075 11790 13110 13375 34 possibly 10900-1000 inter- of buff colitc.,mllolitic limestone. Punta Gorda and Able member believed to be 10757-10770 anhydrite bed.

P-265 Limestone cream to brown to HORC gray. Some algal piates, State 12438- millolids, anhydrite. Dolomite Lease 1004 11624 12712 12380 12478 8 12700 12730 NR 12810 34 very fine-gralned with no visible porosity. Trace tar oil in limestone. NR = Not Reached APPENDIX 1II DRILL STEM TEST DATA FROM BROWN DOLOMITE ZONE

Chlorides Permit Operator & Interval Duration of Cushion Total IFBHP ISIBHP Total County Fee Name Tested ft. Test (hrs.) Chokes Recovery FFBHP FSIBHP Solids (ppm) P-310 Gulf Oil 500 ft. 11750 ft. salt '3027 '5489 - Charlotte No. 1 Stevens 12184-12459 1 10/64" & 3/8" water. No show, "532 N"5489 -

P-289 Cal-Coastal Lee No. 1 Fla, state 1000 ft. 9372 ft. salt 1081 5315 140,000 224B 12463-12494 2 1/4" & 5/8" water. No show. 4730 5803 256,600

P-161 HORC 11700 ft. salt 1273 - - Lee No. 1 Kirchoff 12824-12877 71 1/4 water. No show. 3499 4732 -

P-275 Gulf Oil Corp. 127 bbls. offshore No. 1 state of 21.3 bbls, salt water. LOST PACKER AND PRESSURE RECORDS IN HOLE Monroe Fla, 826Y 14642-14702 5 1/3 1/4" & 1" No show.

P-314 Sun Oil Co, 2000 ft. salt 1100 ft. mud HRIry No. 1 Red water and 9000 ft. 3782 - 131,000 Cattle 12475-12680 1 1/2 1/4" & 5/8" salt water. 5539 5566 271,000

P-'84 Gulf 9350 ft. black offshore California Co. 3600 ft. fresh salt water 5514 6940 - Monroe OCS BIk 28 14409-14508 2 1/2 water and 560 ft. mud. 6460 6940 - * Initial flowing bottom hole pressure. *' Final flowing bottom hole pressure. " Initial shut-In bottom hole pressure, " Final shut-in bottom hole pressure. VA1CT5 SCIENCE LIBRARY 3 1262 04707 0882

FLORIDA DEPARTMENT OF NATURAL RESOURCES A BUREAU OF GEOLOGY FLORIDA GEOLOGICAL SURVEY 903 WEST TENNESSEE STREET SCIENCE TALLAHASSEE, FLORIDA 32304-7795 LBRY Walter Schmidt, Chief Peter M. Dobbins, Admin. Asst. Alison Lewis, Librarian Jessie Hawkins, Custodian Sandie Ray, Secretary

GEOLOGICAL INVESTIGATIONS SECTION

Thomas M. Scott, Senior Geologist/Administrator Albert V. Applegate, Geologist Ed Lane, Geologist Ken Campbell, Geologist Margaret Lehey, Staff Asst. Cindy Collier, Secretary Jacqueline M. Lloyd, Geologist Richard Howard, Laboratory Tech. John Morrill, Core Driller Richard Johnson, Geologist Albert Phillips, Asst. Driller Jim Jones, Draftsman Frank Rupert, Geologist Ted Kiper, Draftsman Wei Wuchang, Research Asst. OFFICE OF MINERAL RESOURCE INVESTIGATIONS AND ENVIRONMENTAL GEOLOGY SECTION J. William Yon, Senior Geologist/Administrator Paulette Bond, Geologist Ron Hoenstine, Geologist Shelton Graves, Research Asst. Steve Spencer, Geologist OIL AND GAS SECTION

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