Integrated Geologic/Engineering Study of Kurten Field Waterflood Project

Alison L. Gay

An integrated interpretation of petrographic, geochemical, engineering, and electric-log data is 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, SEM, 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. Engineering and production data sup ort 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 SP, allows the mapping of the sand facies. Water saturation and net oil-in-place maps reveal the best portions of the field on which to focus the revised waterflood project. This revision should concentrate on the quartz-rich bioturbated sand in the central portion of the original unit to result in a more efficient, economical, secondary recovery program.

AAPG Search and Discovery Article #91022©1989 AAPG Annual Convention, April 23-26, 1989, San Antonio, Texas.