Pressure Transient Tests In Fireflood Operations - Countess Field, Alberta

Abstract A research program supported by the Alberta Oil Sands Technology and Research Authority has been conducted for the 16 ha inverted five-spot fireflood pilot operated by PanCanadian Petroleum Limited in the Countess Field in Southeast Alberta. The pilot was initiated in 1983 to evaluate the fireflood process in a waterflooded Glauconitic sandstone reservoir of the Upper Mannville Group containing 28 ° API oil, and it is still continuing. A number of pressure transient tests were conducted, under this research program, during the period from 1984 to 1988. This paper summarizes these pressure transient tests and discusses the data obtained and analyses conducted. These tests have provided useful information on swept region, near wellbore conditions and advancement of the firefront in this pool. Estimates of cumulative burned volume from pressure falloff tests appear to be in reasonable agreement with calculations based on data obtained from combustion tube tests. Introduction The 16 ha inverted five spot fireflood pilot in the Countess Upper Mannville "B" pool in Southeast Alberta, operated by PanCanadian Petroleum Limited and jointly owned (50%) with LL&E Canada Limited, was initiated in 1983 to evaluate the fireflood process as a means for tertiary oil recovery. In Countess "B", oil production (28 ° API) is from a number of Glauconitic channel sands (Figure 1). The firefload pilot is located in the largest of these sands which is called Countess "B" - ParL. II, and which covers about 325 ha (800 acres). Average net pay thickness is 8.0 m and average porosity is 25%. Average sand permeability is 800 md. This highly permeable sand has been under water injection for several years and fluid transmissibility is excellent. Field pressures have been maintained near the bubble point. Details about the reservoir aspects of the pool and project performance were previously reported (1 to 3). In 1983, the Alberta Oil Sands Technology and Research Authority (AOSTRA) agreed to support the pilot project by funding an extensive research program in exchange for the project data. The program aimed at providing pertinent data and improved technology which could enhance fireflooding operations. Under this research program, a number of pressure transient tests were conducted. The main objective of these tests was to obtain reservoir parameters for both the burned and unswept regions, calculate the burned volume and monitor the progression of the firefront as suggested by many authors (4 to 8). The fundamental basis for interpretation of pressure transient data uses the composite-system theory; which considers a reservoir undergoing the fireflooding process as being made up of two regions (burned and unswept) having different Physical parameters. This paper summarizes these tests and discusses the results obtained. Pilot Project A detailed description of the pilot project has been previously reported (l to3). The pilot, as shown in Figure 1, consists of one inverted five-spot pattern (1 air injection well, 4 producers). The major facilities constructed for the pilot include a 600 HP main compressor, two 200 HP booster compressors, test and group separators, treater, flare knock out drum, flare stack and storage tanks.