Review of Waterflood Performance in the Fosterton Main Unit

Abstract The Main Roseray sand pool is one of three pools comprising the Fostertonfield in southwestern Saskatchewan. The pool was discovered in January, 1952, by Mobil Oil Canada, Ltd. Drilling continued until the middle of 1955, whendevelopment was considered complete. The pool was unitized on July 1, 1958, with Mobil Oil Canada, Ltd. as the operator. Pressure maintenance by means ofwater injection commenced during March, 1959. This paper presents basic dataand a review of reservoir performance under pressure maintenance bywaterflooding in the Fosterton Main Unit. Introduction The Main Roseray sand pool (Fosterton Main Unit) is one of three poolscomprising the Fosterton field. The Fosterton field is located in Township 17, Range 18, west of the Third Meridian in southwestern Saskatchewan (Figure1). The pool was discovered in January, 1952, by Mobil Oil Canada, Ltd., by thedrilling of Socony-Western Prairie Fosterton No. 1 in Lsd. 2 of Section 10, Township 17, Range 18, west of the Third Meridian. The pool produces from astratigraphic trap in the Roseray sand created by an erosional unconformitybetween it and the overlying Blairmore formation. Drilling continued until themiddle of 1955, when development was considered complete. Production from thispool is obtained from the Roseray I sand and the Roseray II sand. Table 1presents the reservoir properties for the pool. Figure 2 is an isopachmap of the Roseray I sand, which is the lower of the two producing sands. Thissand extends from the western edge of the pool and gradually thins out to theeast about midway through Section 11. It is underlain by water in the northwestcorner and along the southern portion. There are approximately 36 MMSTB oforiginal oil-in-place in this sand. Figure 3 is an isopach map of the Roseray II sand. This sand extends from the western to the eastern edge of thepool. Approximately one-third of the oil-in-place in this sand is underlain bywater in the eastern portion of the pool, as shown by the shaded area.