Waterflood Pressure Maintenance of the Peejay Field - British Columbia

Abstract

Abstract The Peejay field, located approximately 50 miles north of Fort St. John, British Columbia, was unitized and placed under waterflood pressure maintenancein April, 1964. This field is unique in that it is the first oil and gas unitto be formed in British Columbia for the purpose of initiating secondary recovery. The Peejay field contains an estimated 36,000,000 stocktank barrels of oil-in-place. The predominant primary depletion drive mechanism was internal gas expansion, which was expected to yield approximately 6,000,000 STB ofrecovery or only 16 per cent of the original oil-in-place. A line-drive waterflood in the down-dip water zone is expected to yield an additional9,000,000 bbls of recovery or a total of 42 per cent of the original oil-in-place. Reservoir characteristics are such that full replacement of the5,800-B/D field production can be achieved by water injection into one well. Important secondary benefits of the pressure maintenance and unitization scheme are:deferment of large capital expenditures for artificial lift equipment;reduction of operating costs in a remote muskeg area;conservation of reservoir energy through flexibility of production; and increased allowable production rates through the application of a better recovery mechanism. The securing of a satisfactory water supply was complicated by the lack of subsurface acquifers and by the seasonally poor water quality in the adjacent Doig river. These problems were overcome by the construction of a 900,000-barrel pit for off-stream storage. Construction and the operation of supply and treating facilities were generally complicated by deep muskeg in the field area. Introduction The Peejay oil field is located approximately 50 miles north of the town of Fort St. John, British Columbia (Figure 1). Access to the field is by anall-weather road, constructed for exploration in the general area. The producing zone in the field is the Halfway formation of Triassic age. Development to July, 1963, had resulted in the completion of nineteen producing oil wells and two suspended wells in the pool. The proven developed surface area is 4,300 acres (Figure 2).