Factors controlling reservoir quality in tertiary sandstones and their significance to geopressured geothermal production. Annual report, May 1, 1979-May 31, 1980
Differing extents of diagenetic modification is the factor primarily responsible for contrasting regional reservoir quality of Tertiary sandstones from the Upper and Lower Texas Gulf Coast. Detailed comparison of Frio sandstones from the Chocolate Bayou/Danbury Dome area, Brazoria County, and Vicksburg sandstones from the McAllen Ranch Field area, Hidalgo County, reveals that extent of diagenetic modification is most strongly influenced by (1) detrital mineralogy and (2) regional geothermal gradients. Vicksburg sandstones from the McAllen Ranch Field area are less stable, chemically and mechanically, than Frio sandstones from the Chocolate Bayou/Danbury dome area. Vicksburg sandstones are mineralogically immature and contain greater proportions of feldspars and rock fragments than do Frio sandstones. Thr reactive detrital assemblage of Vicksubrg sandstones is highly susceptible to diagenetic modification. Susceptibility is enhanced by higher than normal geothermal gradients in the McAllen Ranch Field area. Thus, consolidation of Vicksburg sandstones began at shallower depth of burial and precipitation of authigenic phases (especially calcite) was more pervasive than in Frio sandstones. Moreover, the late-stage episode of ferroan calcite precipitation that occluded most secondary porosity in Vicksburg sandstones did not occur significantly in Frio sandstones. Therefore, regional reservoir quality of Frio sandstones from Brazoria County is far better than that characterizing Vicksburg sandstones from Hidalgo County, especially at depths suitable for geopressured geothermal energy production.
- Research Organization:
- Texas Univ., Austin (USA). Bureau of Economic Geology
- DOE Contract Number:
- AC08-79ET27111
- OSTI ID:
- 6870346
- Report Number(s):
- DOE/ET/27111-1
- Country of Publication:
- United States
- Language:
- English
Similar Records
Feldspar diagenesis in the Frio Formation, Brazoria County, Texas Gulf Coast
Using presence of calcite cap rock in shales to predict occurrence of reservoirs composed of leached secondary porosity in the geopressured zone. Annual report, June 1, 1980-October 31, 1980
Related Subjects
GEOPRESSURED SYSTEMS
RESERVOIR ROCK
SANDSTONES
DIAGENESIS
CALCITE
CALCIUM OXIDES
CARBON ISOTOPES
CARBONATES
FELDSPARS
GULF COAST
IRON OXIDES
KAOLINITE
MAGNESIUM OXIDES
MINERALOGY
MODIFICATIONS
OXYGEN ISOTOPES
POROSITY
POTASSIUM OXIDES
PRESSURE GRADIENTS
QUARTZ
SODIUM OXIDES
STABILITY
TEMPERATURE GRADIENTS
TEXAS
ALKALI METAL COMPOUNDS
ALKALINE EARTH METAL COMPOUNDS
ALUMINIUM COMPOUNDS
ALUMINIUM SILICATES
CALCIUM CARBONATES
CALCIUM COMPOUNDS
CARBON COMPOUNDS
CHALCOGENIDES
IRON COMPOUNDS
ISOTOPES
MAGNESIUM COMPOUNDS
MINERALS
NORTH AMERICA
OXIDES
OXYGEN COMPOUNDS
POTASSIUM COMPOUNDS
ROCKS
SEDIMENTARY ROCKS
SILICATES
SILICON COMPOUNDS
SILICON OXIDES
SODIUM COMPOUNDS
SOUTHWEST REGION
TRANSITION ELEMENT COMPOUNDS
USA
Geothermal Legacy