LAYMAN II, JOHN M., Texas A&M University, Dept. of Geology Geophysics, College Station, TX

ABSTRACT: Pore Measurements by Petrographic Image Analysis: Implications for Rapid Identification and Ranking of Reservoir Flow Units, Happy Spraberry Field, Garza County, Texas

The Spraberry Formation (Permian, Leonardian) typically produces from siliciclastic turbidite deposits in the Midland Basin. The Spraberry Formation present at Happy Spraberry Field in Garza County, however, consists of a carbonate interval about 100 feet thick. Full diameter cores consist of oolitic-peloidal packstones and grainstones, rudstones and floatstones, in situ Tubiphytes bindstones, and siliciclastics. Standard petrographic analyses reveal that grain moldic, solution-enhanced intergranular, vuggy, and intraparticle pore types dominate the reservoir zones. However, only some of those genetic pore types correlate with optimum paired values of porosity and permeability, and those optimum paired values are associated with the best quality flow units. Pore data, including size, shape, and abundance was gathered using traditional petrographic methods. Repeat measurements were made on the slide set with automated image analysis equipment and Image-Pro^TM software. Statistical correlation of the two data sets suggests the reliability of the automated system in replacing tedious petrographic measurement of pore geometries. In some cases, the software may be used in differentiating genetic pore origins based on measurement data. Studies underway indicate that digital data on pore characteristics can be rapidly compared with petrophysical measurements and capillary pressure behavior. If so, this automated technique could be used to determine production characteristics of complex carbonate reservoirs.

AAPG Search and Discovery Article #90909©2000 AAPG Foundation Grants-in-Aid