Sedimentary facies and petrophysical characteristics of cores from the lower Vicksburg gas reservoirs, McAllen Ranch field, Hidalgo County, Texas

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

OSTI ID:5917428

Langford, R P; Maguregui, J ^[1]; Howard, W E; Hall, J D ^[2]

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1. Univ. of Texas, Austin (USA)
2. ResTech, Houston, Inc., TX (USA)

As part of an effort funded by the Gas Research Institute, the Department of Energy, and the State of Texas, and with the cooperation of Shell Oil Co., sandstones in the Vicksburg S (Oligocene) reservoir were cored in the McAllen Ranch gas field in the A. A. McAllen B- 17 and B- 18 wells. Detailed correlation of the cores with petrophysical data illustrates the controls of deposition and diagenesis on reservoir quality. The cores were drilled using oil-based mud, and special care in handling minimized evaporation. Core-derived water saturations were compared with log-calculated water saturations. Special core analyses of cementation factor, saturation exponent, and relative permeability were performed. Thin-section petrography and X-ray diffraction were used to determine mineralogy. The cores consist of prodelta and delta-front facies. Permeability and porosity generally increase with increasing grain size and are greatest in 1 to 2 ft thick zones within massive and laminated beds in the uppermost delta front. Porous intervals increase in abundance upward within the delta-front sandstones. Permeability variation over two orders of magnitude within the reservoir sands corresponds to diagenetic facies within the core. High permeability occurs only within thin bands. Trough cross-stratified sandstone is commonly porous only near the tops of the foresets. Differences in the character of the microresistivity curve of the high-resolution dipmeter log correlate with differences in cementation and with different depositional facies within the cores. Comparison of microresistivity logs and cores allows extrapolation of facies and cement characteristics and resulting reservoir properties to uncored intervals with the objective of maximizing recovery of natural gas.

• OSTI ID: 5917428
• Report Number(s): CONF-9010204--
• Conference Information: Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (USA) Journal Volume: 74:9
• Country of Publication: United States
• Language: English

Related Subjects

03 NATURAL GAS
030200* -- Natural Gas-- Reserves
Geology
& Exploration
58 GEOSCIENCES
580000 -- Geosciences
ALLUVIAL DEPOSITS
CENOZOIC ERA
COHERENT SCATTERING
DEPOSITION
DIAGENESIS
DIFFRACTION
DRILL CORES
FEDERAL REGION VI
GEOLOGIC AGES
GEOLOGIC DEPOSITS
MINERAL RESOURCES
NATIONAL ORGANIZATIONS
NATURAL GAS DEPOSITS
NATURAL GAS WELLS
NORTH AMERICA
PERMEABILITY
PETROGRAPHY
POROSITY
RESEARCH PROGRAMS
RESERVOIR ROCK
RESOURCES
ROCKS
SANDSTONES
SCATTERING
SEDIMENTARY ROCKS
SHALES
SILTSTONES
TERTIARY PERIOD
TEXAS
US DOE
US ORGANIZATIONS
USA
WELLS
X-RAY DIFFRACTION