History Match of the UTF Phase A Project with Coupled Reservoir Geomechanical Simulation

Abstract Field operation of the Underground Test Facility (UTF) Phase A SAGD project started in November 1987 and terminated in October 1990. In order to understand the interactions between fluid flow and geomechanical behaviour of the reservoir during the SAGD operation, the coupled reservoir geomechanical simulation methodology was applied to history match the measured performance of the project. Reservoir and geomechanical responses were available from an extensive instrumentation program designed for this project. Reservoir pressure, temperature, horizontal displacement, vertical strain and volumetric strain from the coupled simulation were compared with the data obtained from the field survey. These comparisons show that the coupled reservoir geomechanical simulation methodology has the potential to capture both reservoir and geomechanical responses during SAGD. In addition, the steam chamber propagation modes, both in the field and in the simulation, were also discussed. Introduction The coupled reservoir geomechanical simulation methodology (called "coupled simulation" in this paper) has been developed and tested successfully(1). The UTF Phase A project provided a variety of data measured in the field during the SAGD operation which can be used to history match the SAGD process and verify this methodology. The objective of this paper is to establish the reservoir model and geomechanical model based on the available and assumed reservoir properties. Then, to conduct the coupled reservoir geomechanical simulation and compare the simulation performance with that obtained from the field. Finally, sensitivity analyses were conducted to examine the influence of reservoir parameters on the SAGD simulations. Project and Reservoir Description The UTF Phase A project is located 60 km northwest of Fort McMurray, Alberta, Canada. Field operation started in November 1987 and terminated in October 1990. Rottenfusser et al.(2) performed a detailed reservoir characterization. The bottom Clearwater Formation and the McMurray Oil Sands Formation were informally divided into units of A to H. Units D, E and G consist of the major pay zone. Unit F is located between Units E and G and is dominantly shale, grey to light brown in colour, and thinly bedded. Unit F is continuous across the pilot area. It separated the injectors and producers of well pairs Al and A3. Well pair A2 was deliberately drilled so that both wells were above the Unit F barrier(3). The effect of Unit F on the SAGD production performance will be discussed later. The typical reservoir properties are as follows: average porosity is 35%, horizontal permeability is 1 to 10 darcy, bitumen saturation is about 85% and initial reservoir pressure and temperature are 550 kPa and 8 °C, respectively. Bitumen viscosity at reservoir temperature is 5 ? 106 cP and can be reduced to 7 cP at 220 °C(4). Geotechnical Instrumentation In total, 14 dedicated thermocouples (AT series), 4 inclinometers (AGI series), 3 extensometers (AGE series) and 5 piezometers (AGP series) were installed (Figure 1). AT1 and AT7 were also used as inclinometer wells. Piezometers were installed in wells AT4, AT9, AT12 and AT14, and a traversing thermocouple string was used to measure temperature in wells AGI1, AGI2, AGI3 and AGI4.