Reservoir characterization in the Spraberry trend, Midland basin, Texas: Delineation of target areas for additional oil recovery using old gamma-ray and neutron logs

Conference · Tue May 01 04:00:00 EDT 1990 · AAPG Bulletin (American Association of Petroleum Geologists); (USA)

OSTI ID:7091287

Guevara, E H ^[1]; Coates, G R ^[2]; Tyler, N; Graham, R L ^[3]

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1. Univ. of Texas, Austin (USA)
2. Schlumberger Well Services, Houston, TX (USA)
3. Exxon Co., U.S.A., Corpus Christi, TX (USA)

Correlation and lithological interpretation of more than 200 gamma-ray/neutron logs recorded mostly in the 1950s and 1960s, permitted mapping of submarine fan, sand-rich intervals (operational units) containing oil reservoirs of the Spraberry Formation (Lower Permian, Leonardian) in a 60-mi{sup 2} area in the east-central Spraberry Trend, Midland basin, west Texas. Isolith maps constructed using a fixed cutoff value on unnormalized gamma-ray logs indicate the reservoirs were deposited mainly in belts 1-3 mi wide subparallel to the basin axis. Log-facies maps suggest aggradational sand-rich channel and overbank facies transecting mud-rich, progradational fan facies. Sandstone shaliness and effective porosity maps were prepared using 90 of the logs that were standardized to a log chosen because of its easily identifiable markers, constant borehole environment, and areally representative log response. The data indicate that (1) sandstone thicknesses on isolith maps are higher than those on shaliness maps, partly reflecting different methodologies, (2) several thick, clean sandstones have low effective porosity, and (3) the best effective porosities appear to be related to intermediate clay contents. Petrographic data suggest that local discrepancies in areal distributions of sandstone depositional axes and effective porosities result at least partly from carbonate cementation and feldspar dissolution. The study indicates that combined isolith and porosity maps constructed using old logs (commonly main sources of data in mature fields) allow higher grading of prospective areas for additional recovery.

• OSTI ID: 7091287
• Report Number(s): CONF-900605--
• Conference Information: Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (USA) Journal Volume: 74:5
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
Geology
& Exploration
58 GEOSCIENCES
580000 -- Geosciences
EXPLORATION
FEDERAL REGION VI
GAMMA LOGGING
GEOLOGIC DEPOSITS
GEOLOGIC FORMATIONS
GEOLOGIC STRUCTURES
MINERAL RESOURCES
NEUTRON LOGGING
NORTH AMERICA
PERMEABILITY
PETROGRAPHY
PETROLEUM DEPOSITS
POROSITY
RADIOACTIVITY LOGGING
RESERVOIR ROCK
RESOURCES
ROCKS
SANDSTONES
SEDIMENTARY BASINS
SEDIMENTARY ROCKS
TEXAS
USA
WELL LOGGING