Imperial's Steelman Unit IA And II Waterflood System

Abstract

Publication Rights Reserved Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and considered for publication in one of the two SPE magazines with the paper. Abstract In Jan., 1962, full-scale water flooding began in the Steelman field of southeastern Saskatchewan. The field has been developed on 80-acre spacing and the injection pattern is an inverted nine-spot. The main requirements of the flood are a high quality water and flexibility in injection rates and pressures. To accomplish these ends water from the high capacity Blairmore sand is distributed to the injection plants, where it is filtered and inhibitor-treated, before injection into high pressure lines radiating to the injection wells. The pressure and rate of injection to each well is controlled at the injection plant. Plant operation is semi-automatic and source well pumps, filters, engines and injection pumps are protected by safety controls. Corrosion throughout the injection system is controlled through coatings and inhibitor and bacteriacide injection. The design of the injection system was influenced by the results of a pilot operation which commenced in 1958. The use of dry gas engines and diatomaceous earth filters are some of the design improvements derived from pilot experience. This presentation discusses the design of surface facilities for the water floods in Steelman Units IA and II, which were installed by Imperial Oil, Ltd. in 1961. Introduction The Steelman field is on the northern rim of the Williston Basin in southeast Saskatchewan, approximately 15 miles north of the International Boundary, Fig. 1. The reservoir, at an average depth of 4,700 ft, is a stratigraphic trap of Mississippian limestone known locally as the Midale Beds. The zone is thin and heterogeneous with low permeability. To date, 760 wells have been drilled on 80-acre spacing. Recovery has been estimated at 16 per cent under natural depletion and 35 per cent under water flooding. Before fall-scale water flooding could be undertaken in Steelman, a pilot test was considered necessary because of the tight and heterogeneous nature of the reservoir, and the presence of hairline fractures which had been observed in cores throughout the field. To permit rapid evaluation, a closely spaced five-spot pilot pattern was selected with four injection wells drilled in the 10-acre area surrounding an existing producing well. Because of diverse lease ownership, a nine-section area was unitized to accommodate the pilot test. Unit negotiations were completed and water injection commenced in 1958. While essential reservoir data were being collected, the design and operation of the installed waterflood equipment was evaluated.