Case History of Steam Injection Operations at Naval Petroleum Reserve No. 3, Teapot Dome Field, Wyoming: A Shallow Heterogeneous Light-Oil Reservoir

Abstract

ABSTRACT This paper summarizes the steam injection operations of the Naval Petroleum Reserve No. 3 (NPR-3), Teapot Dome field, Wyoming, a federally owned oilfield, located about 35 miles north of Casper, Wyoming. More than 24 million barrels of oil has been produced since initiation of production in 1922; more than 15 million barrels has been produced since full production began in 1976. The Shannon sandstone is the shallowest (350 to 500 ft) and most productive of nine producing zones and accounts for 55% of current production. The Shannon, composed of the Upper and Lower Shannon sandstones, was deposited as an offshore bar where bar margin, inter bar and bioturbated shelf sandstones are the reservoir. The reservoir is faulted and extensively fractured, with the two sandstone intervals separated by shaly non-productive siltstone. Maximum gross sand thickness is 100 ft with an average porosity of 18% and 63 mD air permeability. Since only 5% of the Shannon's 144 million barrels of original oil-in-place was estimated to be recoverable by primary means, a study of recovery technologies was conducted in 1980 resulting in implementation of a polymer-improved waterflood pilot and an in situ combustion pilot in 1981. The polymer pilot was unsuccessful, while the in situ combustion pilot was considered a technical success although marginally economic. Favorable response to steam preheating in the in situ combustion pilot led to the development of a steamdrive pilot in October 1985. Favorable response in the steamflood pilot led to recent rapid expansion. Currently 150 acres are being flooded using five 50MMBtu/hr steam generators. The history of the steamflood has been reviewed in an effort to document successful application of steamflooding in a shallow, very heterogeneous, low-permeability, light oil (32° API gravity) reservoir which defies conventional screening criteria.