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The AAPG/Datapages Combined Publications Database

AAPG Bulletin

Abstract


Volume: 69 (1985)

Issue: 5. (May)

First Page: 845

Last Page: 845

Title: Rock Types, Pore Types, and Hydrocarbon Exploration: ABSTRACT

Author(s): Edward B. Coalson, Dan J. Hartmann, John B. Thomas

Article Type: Meeting abstract

Abstract:

A proposed exploration-oriented method of classifying porosity in sedimentary rocks is based on microscopic examination of cores or Previous HitcuttingsNext Hit. Factors include geometry, size, abundance, and connectivity of the pores. The porosity classification is predictive of key petrophysical characteristics: porosity-Previous HitpermeabilityNext Hit relationships, capillary pressures, and (less certainly) relative permeabilities. For instance, intercrystalline macroporosity typically is associated with high Previous HitpermeabilityNext Hit for a given porosity, low capillarity, and favorable relative permeabilities. This is found to be true whether this porosity type occurs in a sucrosic dolomite or in a Previous HitsandstoneNext Hit with pervasive quartz overgrowths.

This predictive method was applied in three Rocky Mountain oil plays. Subtle "pore throat" traps could be recognized in the "J" Previous HitsandstoneNext Hit (Cretaceous) in the Denver basin of Colorado by means of porosity-Previous HitpermeabilityNext Hit plotting. Variations in hydrocarbon productivity Previous HitfromNext Hit a Teapot Formation (Cretaceous) field in the Powder River basin of Wyoming were related to porosity types and microfacies; the relationships were applied to exploration. Rock and porosity typing in the Red River Formation (Ordovician) reconciled apparent inconsistencies between drill-stem test, log, and mud-log data Previous HitfromTop a Williston basin wildcat. The well was reevaluated and completed successfully, resulting in a new field discovery. In each of these three examples, petrophysics was fundamental for proper evaluation o wildcat wells and exploration plays.

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Copyright 1997 American Association of Petroleum Geologists