Geometry and reservoir heterogeneity of tertiary sandstones: a guide to reservoir continuity and geothermal resource development
External and internal continuity of Tertiary sandstones are controlled by various factors including structural trends, sand body geometry, and the distribution of mineral framework, matrix, and intersticies within the sand body. Except for the limits imposed by faults, these factors are largely inherited from the depositional environment and modified during sandstone compaction and cementation. Sandstone continuity affects energy exploration and production strategies. The strategies range in scope from regional to site-specific and closely parallel a sandstone hierarchy. The hierarchy includes subdivisions ranking from genetically related aquifer systems down to individual reservoirs within a fault-bounded sandstone. Volumes of individual reservoirs are 50% less to 200% more than estimated from conventional geologic mapping. In general, mapped volumes under-estimate actual volumes where faults are nonsealing and overestimate actual volumes where laterally continuous shale breaks cause reductions in porosity and permeability. Gross variations in these pore properties can be predicted on the basis of internal stratification and sandstone facies. Preliminary analyses indicate that large aquifers are found where barrier and strandplain sandstones parallel regional faults or where fluvial (meandering) channels trend normal to regional faults. Within these sand bodies, porosity and permeability are highest in large-scale crossbedded intervals and lowest in contorted, bioturbated, and small-scale ripple cross-laminated intervals.
- Research Organization:
- Texas Univ., Austin (USA). Bureau of Economic Geology
- DOE Contract Number:
- AC08-79ET27111
- OSTI ID:
- 6351948
- Report Number(s):
- CONF-811026-10; ON: DE81029782
- Resource Relation:
- Conference: 5. geopressured-geothermal energy conference, Baton Rouge, LA, USA, 13 Oct 1981
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GEOPRESSURED SYSTEMS
GEOLOGY
SANDSTONES
LITHOLOGY
AQUIFERS
GEOLOGIC FAULTS
PERMEABILITY
POROSITY
RESERVOIR ROCK
STRATIGRAPHY
TEXAS
ENERGY SYSTEMS
GEOLOGIC STRUCTURES
NORTH AMERICA
ROCKS
SEDIMENTARY ROCKS
SOUTHWEST REGION
USA
Geothermal Legacy
150201* - Geology & Hydrology of Geothermal Systems- USA- (-1989)
152002 - Geothermal Data & Theory- Properties of Minerals & Rocks