Importance of Core in Understanding Carbonate Reservoirs

Xavier Janson, Julia F. Gale, James W. Jennings, Charles Kerans, 
Robert G. Loucks, F. Jerry Lucia, Stephen Ruppel, and Fred P. Wang
Bureau of Economic Geology, Jackson School of Geosciences, University of Texas at Austin

Core material is essential in conducting a geological reservoir description and producing a reservoir model. Core is the best veritable data that shows what a reservoir is composed of and it is required to calibrate wireline-logs and seismic for defining reservoir architecture, flow units, and petrophysical properties. Sequence stratigraphic and facies based core analyses define parameters for determining dimensions, lateral variability, and internal heterogeneity of flow units. Pore-type descriptions and diagenesis analysis of core samples define reservoir quality. Special core analyses, such as capillary pressure analysis, provide understanding of fluid distribution and other performance parameters. Accurate wireline-log analysis requires core-based calibration. 

Cores do not only answer questions, but also propose questions. A series of cores from different depositional and diagenetic environments are presented at this poster session that demonstrates not only the value of core in producing a reservoir description, but also demonstrates that core descriptions of a reservoir propose new questions. These questions would not be recognized without rock material.

Cores from the following depositional diagenetic environments are displayed: (1) shelf-edge reef, (2) platform-interior bioherm, (3) ramp-crest dolomitized grainstone shoals, (4) dolomitized peritidal deposits, (5) deep-water fractured chalks, and (6) collapsed-paleocave deposits.