Sandstone Petrology and Diagenesis of Lower Tuscaloosa Formation Reservoirs in McComb and Little Creek Field Areas, Southwest Mississippi

Kenneth H. Hamlin, Christopher P. Cameron

Two major depositional facies characterize producing lower Tuscaloosa Formation (Upper Cretaceous) sandstone reservoirs in the McComb-Little Creek field areas: a lower fluvial sequence ("Denkman sand") topped by nearshore marine deposits ("McComb sand"). Petrographic studies reveal that the sandstones of both fields were deposited as very fine to medium-grained quartzarenites and quartz litharenites. Petrographic and x-ray diffraction analyses of the clay mineral content of the sandstones indicate that most of the clays are authigenic and comprise a suite which includes chlorite, kaolinite, mixed-layer illite/smectite, and illite. Mixed-layer illite/smectite appears to be considerably more abundant in the McComb reservoir sandstones than at Little Creek. The reservoir san stones in the McComb and Little Creek fields are highlighted by good secondary porosity (3-27%, average 19%) developed through dissolution of rock fragments and carbonate cements.

AAPG Search and Discovery Article #91042©1987 GCAGS and GC-SEPM Section Meeting, San Antonio, Texas, October 28-31, 1987.