Application of the Higgins-Leighton Waterflood Prediction Technique to L-lalfway Reservoirs In Northeastern British Columbia

Abstract

Abstract The history of the Peejay Unit No.1 waterflood project is summarized from inception to January. 1970. Various unusual performance aspects are discussed. The Higgins-Leighton waterflood prediction technique has been successfully applied to the Peejay Halfway Pool in northeastern British Columbia. Matching of pattern performance was attained by considering the adjustment of the laboratory-derived oil-water relative permeability relationships and ignoring stratification effects. These results are available to predict performance and ultimate recovery from undepleted patterns. INTRODUCTION THE MONITORING OF WATERFLOCD PROJECTS and continuing control of reservoir performance constitutes an important function for many reservoir engineers. This function becomes particularly critical when unsatisfactory results are noted. Peejay Unit No.1, which has been under waterflood since February, 1964, has exhibited some very unusual, and in some cases unsatisfactory, response, and has required close supervision to the present time. A paper by Rogan and Smith(l) described the initial phases of the waterflood project. The channel-flow technique for predicting pattern waterflood performance, developed by Higgins and Leighton(2,3,4,5) has generally proved to be of valuable assistance to reservoir engineers. In Peejay, the long period of time generally experienced to water breakthrough and the unusually sharp increase in water cut thereafter prompted investigation additional to that originally conducted. The Higgins-Leighton technique was used to predict the performance of individual patterns where various reservoir properties were adjusted until a match with actual well performance was achieved. The adjusted properties were then used to analyze performance at other locations. Location The Peejay Field is located about 50 miles north of the town of Fort St. John in northeastern British Columbia, specifically in NTS Block E-94-A-16 and H-94-A-15. Figure 1 shows the field location. The Triassic Halfway reservoir was discovered in March, 1959 by the drilling of the well Sinclair Pacific Doig River d-39-E. Development drilling was essentially completed by the end of 1962; however, considerable infill drilling has taken place since unitization in February. 1964. Figure 2 is a well location plat of the Peejay Field, including Peejay Unit No. 1, Peeja Unit No.3 and the Pacific-Sinclair Project. The reservoir underlying Peejay Unit No.1 has essentially no communication with Peejay Unit No. 2 to the east or Peejay Unit No.3 to tbe west. The present well count in Peejay Unit No. 1 is nineteen prooducing wells, four suspended oil wells and twelve water injection wells. RESERVOIR GEOLOGY The Peejay oil field is the largest of several highly productive oil pools in northeastern British Columbia which produce from the Halfway Formation, a basal unit of the Triassic. Schooler Creek Group. It is situated within the area of discontinuous Halfway deposition and distribution which trends northwest to southeast for 60 miles, near the eastern limits of the Schooler creek. The trap is stratigraphic, although structure is important- Oil production is limited laterally by discontinuity of deposition or deterioration of porosity and permeability. Water is present downdip and a relatively small gas cap is present updip. The Halfway Formation lies unconformably on Doig silt, shale and sand topographer and is overlain conformably by impermeable Charlie Lake siltstone, claystone and anhydrite.