--> ABSTRACT: Geologic Reservoir Characterization of Humphreys Sandstone (Pennsylvanian), East Velma Field, Oklahoma, by M. K. McGowen; #91030 (2010)

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Geologic Reservoir Characterization of Humphreys Sandstone (Pennsylvanian), East Velma Field, Oklahoma

M. K. McGowen

East Velma field is located in the Ardmore basin, Stephens County, Oklahoma, on the north flank of a truncated anticline with dips that range from 30°-60°. The discovery well of the Humphreys sand unit was drilled in April 1951 and an original oil in place of 32.7 million bbl was calculated. Primary depletion was by solution gas drive with gas reinjection and gravity drainage which was enhanced by the steep structural dip of the field. A waterflood that was initiated in 1983 and a proposed CO2 miscible displacement program to further enhance field recovery prompted the need to develop a detailed geologic description of the reservoir.

Core studies indicate that the Humphreys sandstone was deposited in a shallow marine, tidally dominated environment. Subfacies include sand-rich tidal flat and tidal channel deposits. The unit is primarily composed of very fine to fine-grained, moderately to well-sorted quartzarenites. Dominant sedimentary structures include bidirectional and unidirectional current ripples, cross-laminations, common slump structures, and zones abundant and scattered burrows.

Four types of heterogeneities have been identified within the Humphreys sandstone that affect reservoir quality and continuity: carbonate cemented zones; a mudstone interval that divides the sandstone unit into two lobes in the northeastern part of the field; two mud-filled, abandoned tidal channels that disrupt continuity in the southeastern part of the field; and filled fractures. Results of the geologic description are currently being used in reservoir simulation studies.

AAPG Search and Discovery Article #91030©1988 AAPG Annual Convention, Houston, Texas, 20-23 March 1988.