Fordoche: An Enhanced Oil Recovery Project Utilizing High-Pressure Methane and Nitrogen Injection

Abstract

ABSTRACT The Fordoche Field, Pointe Coupee Parish, Louisiana contains several high pressure retrograde condensate and volatile oil reservoirs. Since July, 1971, Sun Exploration and Production Company has maintained an extremely successful enhanced oil recovery program in two (2) of the volatile oil reservoirs, namely the Wilcox 8 and Wilcox 12 reservoirs. This paper reviews the reservoir performance and operational aspects of the EOR program. The injection of dry natural gas with nitrogen at high pressures is predicted to result in a miscible displacement of reservoir fluids. Extensive reservoir modeling efforts predict that oil recovery will increase by an average of 19.5% over that of primary depletion due to the miscible displacement mechanism, the maintenance of reservoir pressure over 7000 psig, and due to highly successful operational practices. Operational difficulties addressed are: the proper allocation of methane and nitrogen between producers/injectors, the ever increasing percentage of nitrogen in the gas stream which necessitates modifying plant and production facilities in order to keep equipment operating efficiently, the initiation of and monitoring of a radioactive tracer survey which commenced in January of 1985, and the evaluation of nitrogen rejection techniques for removal of nitrogen from the producing gas streams.