Evaluation of a Conventional Steam Drive With Ancillary Materials: North Kern Front Field

Abstract

ABSTRACT Steam drive projects account for over 64% of all of the United States' Enhanced Oil Recovery (EOR) production, nearly 156,000 BOPD (24,000 m3/d). Even though steam drive is the most successful of all EOR processes, it is not without its problems. Gravity segregation and poor areal and vertical sweep efficiencies have limited recoveries in many heavy oil reservoirs. In many instances the injected steam prematurely breaks through into producing wells creating steam channels. If this steam channeling can be controlled to some degree and the steam is forced to contact more of the reservoir, overall recoveries can be improved. This paper documents efforts under a Department of Energy cost sharing contract to reduce steam channeling in a conventional steam drive using ancillary materials. A steam foam solution and a steam foam encapsulated in a polymer gel are being introduced in four steam injection patterns in the North Kern Front Field near Bakersfield, California. The ability of the ancillary materials to improve recovery will be determined through injection profiles, chemical tracer surveys, casing vent gas analyses, core and log data, and residual oil saturation data, as well as through temperature and production monitoring. It has been shown that in-situ steam foams can be used to alter the steam injection profiles to prevent excessive steam channeling. Results after injection of ancillary materials for approximately 18 months indicate that improvements in both the areal and vertical sweep efficiencies have been found in the four treated patterns when compared to the untreated control patterns. Several techniques are still under evaluation to determine the exact amount of incremental oil produced. Disscussion of production response will be limited to two of the four treated patterns, Witmer B2-3 and Witmer B2-5. A comparison of these two patterns to the Witmer control pattern, Witmer A2-7, indicates approximately 52 B/D (8 mv/d) of incremental oil is being produced as a result of the weekly chemical treatments.