Log-Derived evaluation of shaly sandstone reservoirs
Significant natural gas resources are known to exist in the United States in tight, low-permeability sandstones that cover a prospective area of 1,000,000 mi/sup 2/ (2,590,000 km/sup 2/). Characterization and reliable estimation of their production potential based on well logs are important although difficult task. Proper evaluation of low permeability sands based on conventional log-interpretation techniques is frequently inadequate. Furthermore, while empirical rules of thumb assist in the evaluation of localized conditions, they only provide guidelines. Recent developments in quantitative log-analysis techniques incorporate natural-gamma-ray spectral data and application of the Waxman-Smits model for detailed reservoir description. Quantitative correlations of cation exchange capacity (CEC), water salinity, porosity, and conductivity of water- and hydrocarbon-bearing shaly sand reservoirs are based on resistivity, density, neutron and natural-gamma-ray spectral data. These correlations provide important information about clay volume, reservoir porosities (total, effective) and fluid-saturation distribution (total, effective), type of clay minerals (smectite, illite, chlorite/kaolinite), their distribution in the reservoir (dispersed, laminated, structural), and log-derived indicators of potential formation damage. Field experiences are reviewed for logging and evaluating tight formations in south Texas; the Jurassic Cotton Valley trend in east Texas, Louisiana, and Arkansas; and the Tertiary Fort Union and Cretaceous Mesaverde Formations of the Piceance basin in Colorado.
- Research Organization:
- Dresser, Atlas, Houston, TX
- OSTI ID:
- 6570552
- Report Number(s):
- CONF-8405216-
- Journal Information:
- Am. Assoc. Pet. Geol., Bull.; (United States), Vol. 68:4; Conference: AAPG annual convention, San Antonio, TX, USA, 20 May 1984
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
NATURAL GAS DEPOSITS
RESERVOIR ROCK
WELL LOGGING
ARKANSAS
CLAYS
COLORADO
EVALUATED DATA
JURASSIC PERIOD
LOUISIANA
PERMEABILITY
POROSITY
SANDSTONES
SEDIMENTARY BASINS
SHALES
TEXAS
DATA
FEDERAL REGION VI
FEDERAL REGION VIII
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC STRUCTURES
INFORMATION
MESOZOIC ERA
MINERAL RESOURCES
NORTH AMERICA
NUMERICAL DATA
RESOURCES
ROCKS
SEDIMENTARY ROCKS
USA
030200* - Natural Gas- Reserves
Geology
& Exploration