Chlorite grain coats and preservation of primary porosity in deeply buried Springer Formation and lower Morrowan sandstones, southeastern Anadarko basin, Oklahoma
Petrographic studies of Upper Mississippian Springer and Lower Pennsylvanian (Morrowan) sandstones in six cores from the southeastern Anadarko basin, Caddo and Grady Counties, Oklahoma, reveal a complex diagenetic history that led to the destruction of much primary intergranular porosity. The Springer and lower Morrowan sandstones form prolific oil and gas reservoirs, despite the fine-grained nature of the rocks, the growth of authigenic clays, extensive cementation by quartz overgrowths and carbonate minerals, and burial depths of 11,500-14,800 ft. More than any other factors, the diagenetic creation and preservation of porosity are the major geologic controls on hydrocarbon production from these sandstones. Thin-section petrography and scanning electron microscopy show that porous intervals were formed mainly by extensive dissolution and leaching of detrital grains and authigenic cements. Locally, however, appreciable primary porosity was preserved in Cunningham (Springer Formation) and Primrose (Morrowan) sandstones (as much as 20% in one sample of Primrose sandstone) by the formation of chlorite grain coats on detrital quartz during the early stages of burial and diagenesis. The chlorite grain coats inhibited the occlusion of pore space by preventing pervasive cementation of the rocks by quartz overgrowths. Cross-plots of porosity versus the abundance of authigenic quartz and grain-coating chlorite document the relationship in two of the cores.
- Research Organization:
- Ecology and Environment, Overland Park, KS
- OSTI ID:
- 5905542
- Report Number(s):
- CONF-870916-
- Journal Information:
- AAPG (Am. Assoc. Pet. Geol.) Bull.; (United States), Vol. 71:8; Conference: American Association of Petroleum Geologists Mid-Continent Section meeting, Tulsa, OK, USA, 27 Sep 1987
- Country of Publication:
- United States
- Language:
- English
Similar Records
Influence of diagenesis on porosity development in reservoir sandstones - an overview
Diagenesis of upper Cretaceous Teapot sandstones, Powder River basin, Wyoming
Related Subjects
OKLAHOMA
PETROLEUM DEPOSITS
RESERVOIR ROCK
PETROGRAPHY
POROSITY
CHLORITE MINERALS
GEOLOGIC FORMATIONS
MISSISSIPPIAN PERIOD
SANDSTONES
FEDERAL REGION VI
GEOLOGIC AGES
GEOLOGIC DEPOSITS
MINERAL RESOURCES
MINERALS
NORTH AMERICA
PALEOZOIC ERA
RESOURCES
ROCKS
SEDIMENTARY ROCKS
SILICATE MINERALS
USA
020200* - Petroleum- Reserves
Geology
& Exploration