Reservoir Heterogeneity Within Bartlesville Sandstone, Glenn Pool Oil Field, Creek County, Oklahoma

Michael D. Kuykendall

The extent of reservoir heterogeneity within the Middle Pennsylvanian (Desmoinesian) Bartlesville Glenn sandstone in the 160-ac William Berryhill unit was established using more than 70 modern well log suites and 18 cores.

Reservoir characterization of genetic sandstone units within the Bartlesville is based on differences in lithologic characteristics, sedimentologic features, porosity, permeability, and log-response characteristics. The upper delta-plain depositional setting of the Bartlesville was such that short-distance changes in facies created many small-scale heterogeneities. Recognition of laterally continuous distinct units in the Bartlesville sandstone requires integration of well log signatures and rock properties. Although thin intervals of interbedded sandstone and shale, and calcite-cemented sandstone are discontinuous laterally, they tend to compartmentalize portions of the reservoir.

The Bartlesville sandstone is presently a sublitharenite-litharenite, even after its composition has been influenced strongly by diagenetic processes. Porosity is mostly secondary owing to the dissolution of unstable framework grains. Distribution and general trends of porosity are affected by changes in composition and pore geometry in particular rock units as well as local changes in depositional trend.

Moderately complex short-distance changes in the sandstone units and pore geometries result in reservoir heterogeneity, with imprecise correlation of individual units. However, continuity of these units can be estimated, with a fair degree of confidence, over small areas after logs and rock features are integrated.

Porosity and permeability, along with diagenesis, petrophysical, and depositional environmental features, aided in reservoir characterization and contributed to improved implementation and prediction of enhanced recovery.

AAPG Search and Discovery Article #91025©1989 AAPG Midcontinent, Sept. 24-26, 1989, Oklahoma City, Oklahoma.