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Characterizing Permian upper Minnelusa sandstone reservoirs, Powder River basin, Wyoming, for enhanced oil recovery

Conference · · Am. Assoc. Pet. Geol., Bull.; (United States)
OSTI ID:7053895

Increasing oil production from sandstone reservoirs by enhanced oil recovery (EOR) techniques requires a knowledge of a sandstone's heterogeneity and its control on fluid-flow pathways within the sandstone. Both of these characteristics of upper Minnelusa sandstones are largely a function of sedimentologic and diagenetic effects. Upper Minnelusa sandstones comprise eolian dune, interdune, sabkha, and marine facies. For example, in the West Mellott field, dune strata are mainly high-angle, porous, avalanche deposits, whereas interdune strata are mainly low-angle to flat, thinly stratified, less porous ripple deposits. Sabkha and marine sandstones generally are wavy and ripple stratified, contain impermeable mudstone layers, and exhibit relatively low porosities. The juxtaposition and stacking of these clastic facies result in significant reservoir heterogeneity. Diagenetic alterations further enhance sandstone heterogeneity. Quartz, anhydrite, dolomite, and clays cement all facies but are distributed differently among facies: quartz occludes porosity preferentially in sabkha and interdune sandstones, whereas anhydrite pervasively cements the dune facies. Consequently, secondary porosity due to anhydrite dissolution is best developed in the dune facies. Authigenic clays and dolomite are most abundant in the interdune sandstones. In addition to sedimentologic and diagenetic effects, the intercalation of impermeable carbonates and evaporites with the sandstones, the presence of thin mudstone layers in some facies, the predominantly southward-directed paleocurrents of the cross-strata, and the differential erosion of the upper Minnelusa influence the pathways of fluids introduced into the reservoirs. Therefore, all will affect the performance of any EOR technique.

Research Organization:
Geological Survey, Denver, CO
OSTI ID:
7053895
Report Number(s):
CONF-8609129-
Journal Information:
Am. Assoc. Pet. Geol., Bull.; (United States), Journal Name: Am. Assoc. Pet. Geol., Bull.; (United States) Vol. 70:8; ISSN AAPGB
Country of Publication:
United States
Language:
English