Anatomy of a lower Mississippian oil reservoir, West Virginia, United States
- West Virginia Geological Survey, Morgantown, WV (United States)
- West Virginia Univ., Morgantown, WV (United States)
Several lines of evidence indicate that the oil reservoir in Granny Creek field is compartmentalized due to internal heterogeneities: an analysis of initial open flows vs. year completed and well location; mapping of initial open flows and cumulative production; and the nonuniform behavior of injection pressures and rates in waterflood patterns. The Big Injun sandstones includes an upper, coarse-grained, fluvial channel facies, and a lower, fine-grained, distributary mouthbar facies. The bar facies is the main reservoir, and can be subdivided into crest, distal, and proximal subfacies. Low original porosity and permeability in the poorly sorted channel facies was reduced further by quartz cementation. In contrast, chlorite coatings restricted quartz cementation and preserved porosity and permeability in the proximal bar subfacies. Small, low-amplitude folds plunge northeastward on the flank of the main syncline in which the fields is located. These minor structural highs seem to match areas of high initial open flows and cumulative production. High production also occurs where the distal and marine-influenced, proximal mouth-bar subfacies pinch out against at least a few feet of the relatively impremeable channel facies. Lower production is associated with (1) thin areas of proximal mouth-bar subfacies; (2) a change from marine to fluvial dominance of the bar facies, which is accompanied by a reduction in porosity and permeability; and (3) loss of the less permeable channel facies above the porous reservoir sandstone, due to downcutting by regional erosion that produced a post-Big Injun unconformity.
- OSTI ID:
- 6851805
- Report Number(s):
- CONF-9310237--
- Journal Information:
- AAPG Bulletin (American Association of Petroleum Geologists); (United States), Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (United States) Vol. 77:9; ISSN 0149-1423; ISSN AABUD2
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
020200* -- Petroleum-- Reserves
Geology
& Exploration
ALLUVIAL DEPOSITS
COMPARTMENTS
CONCRETIONS
DEVELOPED COUNTRIES
GEOLOGIC DEPOSITS
GEOLOGIC STRUCTURES
GEOLOGY
HETEROGENEOUS EFFECTS
MAPPING
MINERALS
NORTH AMERICA
OXIDE MINERALS
PERMEABILITY
POROSITY
QUARTZ
RESERVOIR ROCK
ROCKS
SANDSTONES
SEDIMENTARY ROCKS
USA
WEST VIRGINIA