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ABSTRACT: Integrated Geologic/Engineering Study of the Kurten Field Waterflood

Alison L. Gay

An integrated interpretation of petrographic, geochemical, engineering, and electric-log data was used to evaluate a current waterflood project in Kurten field, Brazos County, Texas. Petrographic studies reveal three sand facies deposited in a dynamic sand ridge environment. Although electric-log porosity is relatively constant throughout the sand body, scanning electron microscope thin section, and engineering profile studies reveal the clean well-sorted sand facies to be impermeable due to quartz overgrowths. A quartz-rich bioturbated sand is identified as the reservoir facies, having fewer quartz overgrowths and more authigenic clays. The third sand facies, a clay-rich bioturbated sand, is impermeable due to an overabundance of authigenic and detrital clays. Engineerin and production data support this interpretation.

A comparison of hydrocarbon composition of the oils, using capillary gas chromatography, supports the conclusion that the well-sorted clean sand contains many permeability barriers and is not a continuous reservoir conducive to waterflooding.

Interactive computer interpretation of electric logs, using a combination of sonic and density porosities, deep resistivity, and spontaneous potential, allows the mapping of the sand facies. Water saturations and net oil in place maps reveal the best parts of the field on which to focus the revised waterflood project. This revision should concentrate on the quartz-rich bioturbated sand in the central part of the original unit to result in a more efficient, economical, secondary recovery program.

AAPG Search and Discovery Article #91003©1990 AAPG Annual Convention, San Francisco, California, June 3-6, 1990