--> Characterization of Reservoir Sandstones: Application of the Ichnofabric Index Method, by C. M. Tang, D. J. Bottjer, and M. L. Droser; #90986 (1994).

Datapages, Inc.Print this page

Abstract: Characterization of Reservoir Sandstones: Application of the Ichnofabric Index Method

Carol M. Tang, David J. Bottjer, Mary L. Droser

The degree of bioturbation in both siliciclastic and carbonate strata plays a role in the development of porosity and permeability, and hence reservoir potential. Systematic studies of variability in the amount of bioturbation present in reservoir rocks should provide significant information necessary for the realistic modeling of reservoir behavior.

The amount of bioturbation present in sedimentary rocks can be semi-quantitatively recorded using the ichnofabric index (ii) methodology.

Ichnofabric index values are determined by geologists scoring the relative amount of bioturbation present in a sedimentary interval. To test the reproducibility of the ii methodology, we applied non-parametric statistical tests and compared two readings of the ii values with each other. We found that in 86% of the cases, there were no statistical differences between the two readings. We also found no statistical differences between values generated by different operators. In addition, ii values obtained on core-sized materials are not statistically different from those obtained from larger fields-of-view. Ichnofabric index values were recorded from two nearshore sandstone deposits to investigate variability in bioturbation within a typical reservoir facies. In the Eocene Torrey Sandst ne (Solana Beach, California), we found large-scale variability along the 400 m of the studied outcrop. In addition, small-scale lateral variability within 2 m exists. In the Ordovician Watson Ranch Quartzite (Ibex, Utah), there was also large-scale variability in the amount of bioturbation along the studied 175 m outcrop. However, within 2 m no lateral variability was present.

Detailed studies recording ichnofabric indices from nearshore sandstones and other typical reservoir facies, when integrated with other sedimentary information, will provide important data for more realistic reservoir simulations in field development.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994