Facies and reservoir characterization of an upper Smackover interval, East Barnett Field, Conecuh County, Alabama

Conference · Sat Sep 01 00:00:00 EDT 1990 · AAPG Bulletin (American Association of Petroleum Geologists); (USA)

OSTI ID:6131093

Bergan, G R ^[1]; Hearne, J H ^[2]

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1. Reservoirs, Inc., Houston, TX (USA)
2. Coastal Oil and Gas Corp., Jackson, MS (USA)

Excellent production from an upper Smackover (Jurassic) ooid grainstone was established in April 1988 by Coastal Oil and Gas Corporation with the discovery of the East Barnett field in Conecuh County, Alabama. A structure map on the top of the Smackover Formation and net porosity isopach map of the producing intervals show that the trapping mechanism at the field has both structural and stratigraphic components. Two diamond cores were cut from 13,580 to 13,701 ft, beginning approximately 20 ft below the top of the Smackover. Two shallowing-upward sequences are identified in the cores. The first sequence starts at the base of the cored interval and is characterized by thick, subtidal algal boundstones capped by a collapse breccia facies. This entire sequence was deposited in the shallow subtidal to lower intertidal zone. Subsequent lowering of sea level exposed the top portion of the boundstones to meteoric or mixing zone waters, creating the diagenetic, collapse breccia facies. The anhydrite associated with the breccia also indicates surface exposure. The second sequence begins with algal boundstones that sharply overlie the collapse breccia facies of the previous sequence. These boundstones grade upward into high-energy, cross-bedded ooid beach ( ) and oncoidal, peloidal beach shoreface deposits. Proximity of the overlying Buckner anhydrite, representing a probable sabkha system, favors a beach or a very nearshore shoal interpretation for the ooid grainstones. The ooid grainstone facies, which is the primary producing interval, has measured porosity values ranging from 5.3% to 17.8% and averaging 11.0%. Measured permeability values range from 0.04 md to 701 md and average 161.63 md. These high porosity and permeability values result from abundant primary intergranular pore space, as well as secondary pore space created by dolomitization and dissolution of framework grains.

• OSTI ID: 6131093
• Report Number(s): CONF-9010204-; CODEN: AABUD
• Journal Information: AAPG Bulletin (American Association of Petroleum Geologists); (USA), Vol. 74:9; Conference: Gulf Coast Association of Geological Societies and Gulf Coast Section of SEPM (Society of Economics, Paleontologists, and Mineralogist) meeting, Lafayette, LA (USA), 17-19 Oct 1990; ISSN 0149-1423
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
03 NATURAL GAS
58 GEOSCIENCES
ALABAMA
NATURAL GAS DEPOSITS
PETROLEUM DEPOSITS
RESERVOIR ROCK
DEPOSITION
ANHYDRITE
DIAGENESIS
GEOLOGIC FORMATIONS
GEOLOGIC HISTORY
GEOLOGIC TRAPS
NATURAL GAS WELLS
OIL WELLS
PERMEABILITY
POROSITY
ALKALINE EARTH METAL COMPOUNDS
CALCIUM COMPOUNDS
CALCIUM SULFATES
FEDERAL REGION IV
GEOLOGIC DEPOSITS
MINERAL RESOURCES
MINERALS
NORTH AMERICA
OXYGEN COMPOUNDS
RESOURCES
SULFATE MINERALS
SULFATES
SULFUR COMPOUNDS
USA
WELLS
020200* - Petroleum- Reserves
Geology
& Exploration
030200 - Natural Gas- Reserves
Geology
& Exploration
580000 - Geosciences