Reservoir description of H. O. Mahoney Lease, Wasson (San Andres) Field, Yoakum County, Texas

Conference · Sun Feb 01 04:00:00 EST 1987 · AAPG Bulletin (American Association of Petroleum Geologists); (USA)

OSTI ID:5285304

Ballard, P D ^[1]

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1. Mobil Producing Texas and New Mexico, Inc., Midland, TX (USA)

Wasson field, a broad, domal structure, is located on the southeastern part of the Northwest shelf. Mobil Producing Texas and New Mexico, Inc., owns and operates the 640-ac H. O. Mahoney lease on the northeast flank of Wasson field. The lease produces from the Permian San Andres, Clear Fork, and Wichita-Albany Formations. The San Andres is a dolomitized carbonate deposited in an arid, tidal-flat environment with subtidal through supratidal facies in a regressive, shoaling-upward sequence. Production occurs from two intervals, the First Porosity and the Main Pay. Average reservoir parameters are 193 net ft, 13% porosity, and 6.2-md permeability. The first porosity interval, consisting of zones F1-F5, is 400 ft below the San Andres top and is comprised of porous supratidal and intertidal dolomites. These zones have a discontinuous, stringerlike geometry and display poorer reservoir development. The principal reservoir is the continuous Main Pay interval, which consists of zones M1-M8 and underlies the First Porosity at an average depth of 5,100 ft. The best porosity and permeability are developed within dolomitized pelloidal packstones of zones M1-M3 and F4. These packstones, deposited subparallel to the San Andres shoreline, exhibit excellent intercrystalline and leached-vuggy porosity with good permeability and lateral continuity. Understanding the depositional history allowed the identification of northeast to southwest porosity and permeability trends at Mahoney. Interbedded within the more porous zones are dolomitized mudstones displaying poor porosity and permeability. These laterally continuous layers restrict vertical fluid movement. Estimated original oil in place is 75,150 Mstb. About 80% of this volume is contained in zones F-4 and M1-M3 and represents most of the flow capacity. Carbon dioxide injection began October 17, 1985.

• OSTI ID: 5285304
• Report Number(s): CONF-8703189--
• Conference Information: Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (USA) Journal Volume: 71:2
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
Geology
& Exploration
020300 -- Petroleum-- Drilling & Production
ALKALINE EARTH METAL COMPOUNDS
CALCIUM CARBONATES
CALCIUM COMPOUNDS
CARBON COMPOUNDS
CARBON DIOXIDE INJECTION
CARBONATE MINERALS
CARBONATE ROCKS
CARBONATES
DEPOSITION
DIAGENESIS
DOLOMITE
ENERGY SOURCES
ENHANCED RECOVERY
FEDERAL REGION VI
FLUID INJECTION
FOSSIL FUELS
FUELS
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC FORMATIONS
MAGNESIUM CARBONATES
MAGNESIUM COMPOUNDS
MINERAL RESOURCES
MINERALS
MISCIBLE-PHASE DISPLACEMENT
NORTH AMERICA
OIL FIELDS
OIL WELLS
OXYGEN COMPOUNDS
PALEOZOIC ERA
PERMEABILITY
PERMIAN PERIOD
PETROLEUM
PETROLEUM DEPOSITS
POROSITY
RECOVERY
RESERVOIR ROCK
RESOURCES
ROCKS
SEDIMENTARY ROCKS
TEXAS
USA
WELLS