--> ABSTRACT: Depositional Environments of Upper Morrow Sandstone in Southeast Tracy and Southeast Eva Fields, Texas County, Oklahoma, by Harvey O. Vick; #91039 (2010)

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Depositional Environments of Upper Morrow Sandstone in Southeast Tracy and Southeast Eva Fields, Texas County, Oklahoma

Harvey O. Vick

Southeast Tracy field, Texas County, Oklahoma, produces gas from an upper Morrow sandstone. The field has produced over 33 bcf of gas and a negligible amount of oil from 12 wells, since its discovery in November 1958. Development drilling on the southern end of the Southeast Tracy field has extended its boundary to within 1.4 mi of the Southeast Eva field, which produces from stratigraphically equivalent upper Morrow sandstones. The Southeast Eva field has produced over 188,000 bbl of oil and 1 bcf of gas from 7 wells since its discovery in February 1978.

The upper Morrow sandstone in the Southeast Tracy field has a shoestring geometry, characterized by a north-south trend 8 mi long and 1.5 mi wide. The sandstone has a broad, U-shaped base and is more than 70 ft thick. The shale interval between the base of the sandstone and underlying marker beds progressively thins from north to south. The sandstone in the Southeast Tracy field has a blocky to bell-shaped, electric-log profile, and is interpreted as a channel-fill. The channel trend extends southward from the Postle field, a thick upper Morrow fluvial and deltaic complex to the north.

Well-log profiles and a study of drill cuttings suggest the presence of a clean, well-sorted coarsening-upward sandstone in the southern part of Southeast Tracy field. In Southeast Eva field, the upper Morrow interval, equivalent to the channel sandstone in Southeast Tracy field, is characterized by four sandstones and intervening shales. These sandstones are each less than 30 ft thick, have limited areal extent, and have no distinct directional trend. These characteristics suggest change in depositional environment. Sandstones at Southeast Eva are interpreted, at this stage of development drilling, as shoreline-reworked, channel-mouth sands.

Drill cuttings from most wells in the Southeast Eva field contain calcite, dolomite, pyrite, and scattered glauconite grains. The occurrence of these materials may account for calculated water saturations as high as 60% in some producing wells.

AAPG Search and Discovery Article #91039©1987 AAPG Mid-Continent Section Meeting, Tulsa, Oklahoma, September 27-29, 1987.