MARTINEZ, GUILLERMO, Univ. of Tulsa, Department of Geology, Tulsa, OK

ABSTRACT: Reservoir Heterogeneity in a Portion of the Bartlesville Sandstone

The Bartlesville Sandstone has been one of the most impotent oil-producing intervals in Northeastern Oklahoma, since its discovery in theearly 1900s. Many fields have produced from thin sandstone; most are in advanced stages of recovery, and some are faced with possible abandonment. As oil-field maturity increases, reservoir characterization becomes critical.

In order to characterize reservoir heterogeneities, a roadcut between the cities of Claremore and Pryor was selected for detailed study. The roadcut is 70 ft high and 350 ft long. Twelve wells, penetrating the Bartlesville Sandstone have been drilled, cored and logged behind the roadcut face.

Four levels of heterogeneity are identified at the study site. The first level (largest scale) is represented by multistoried channel fills, plus laterally associated facies. At this level, changes in texture, sedimentary structures and permeability contrasts of 1 to 2 orders of magnitude are found between rocks underlying and overlying erosion surfaces The second level is the individual "story" or genetic interval represented by a collection of contiguous facies (channel fill, levee, splay). The third level is represented by individual facies such as an individual channel fill. The fourth level for the channel-fill facies contains four subfacies: lower fill, chute-modified lateral accretion bars, complex laminated strata and mud fills. Preliminary results indicate that permeability c ntrasts are also present among channel fill subfacies.

The outcrop-based model will be used in the definition of reservoir heterogeneities and potential compartments in the prolific Bartlesville Sandstone (Glenn Sand) of Glenn pool field.

AAPG Search and Discovery Article #90987©1993 AAPG Annual Convention, New Orleans, Louisiana, April 25-28, 1993.