The 8 ° API gravity bitumen produced at Shell Canada's Peace River Oil Sands Project requires diluent addition to achieve liquid phase separation. Since it was too costly to supply diluent to each test satellite at this project, two-phase lest separators were installed and manually collected fluid samples were used to determine water cuts. This test method showed consistently poor repeatability and poor accuracy with respect to plant balances.
The use of an in-line, full-range (0–100%) net oil monitor capable of operating at the extreme temperature conditions encountered at Peace River has significantly improved well test accuracy.
The instrument utilizes the inherent differences in microwave energy absorption between water and a liquid hydrocarbon phase to differentiate between the relative amounts of each in a flowing medium. Several improvements to the unit's electronics and alterations to the installation / calibration have been implemented. Improved reliability of well test water cuts and increased operating safety during well testing are benefits that have resulted from the field-wide use of the net oil monitors.
Shell Canada's Peace River Complex is located in northern Alberta, 400 km northwest of Edmonton (Figure 1).
The Complex processes bitumen produced from the lower Cretaceous upper Bullhead formation. The produced bitumen is an 8 ° API gravity crude with a viscosity range of 200,000 cp at 20 ° C to 20 cp at 150 ° C. Shell Canada's efforts to investigate potential recovery strategies for extraction of the Peace River oil sands began in the early 1960's.
Extensive research, physical model experiments, numerical modelling and field tests led to the development of the Peace River In Situ Pilot (PRISP) in 1979. PRISP is presently entering its twelfth year of operations, 1979–1991.
The technical success of PRISP led 10 the development of the Peace River Expansion Project (PREP) in 1986. PREP is a commercial scale project consisting of 53 injection wells and 163 production wells directionally drilled from eight pad locations (Figure 2). PREP is presently entering its fifth year of operations, 1986–1991.
Although both PRISP and PREP continue to meet performance targets, significant potential exists to enhance bitumen recovery and thermal efficiency. One of the most valuable tools available for evaluating project performance is well test data.
Three-phase separators requiring the addition of a diluent to enable separation of the 8" API bitumen from water are utilized at PRISP. Well test data at PRISP has been very accurate within 5% of the plant lank balance. At the time of the field expansion in 1986, three-phase separators and diluent lines to the remote PREP satellites were deemed too costly. Less expensive two-phase separators were installed in the PREP field and manually obtained grab samples for water cut analysis were taken downstream of the separator. PREP well tests based on grab samples proved to have consistently poor repeatability, poor accuracy, limited frequency (one test per day) and operator safety concerns.
Alternate sampling techniques using mechanically obtained samples were investigated during 1987 in an effort to mitigate the shortcomings inherent in the grab sampling technique.