ABSTRACT:
Hyrdocarbon production from deep oil sands deposits relies on thermal processes such as steam stimulations to overcome the viscosity of the bitumen and make its flow to surface possible. These processes put well casings under fatigue and thermal stresses and can lead to their sudden failure. Microseismic monitoring has been undertaken over the last decade in order to detect such failures in the Cold Lake oil field in Alberta operated by Imperial Oil Resources. This paper describes results of the application of a seismic model in the detection of well casing failures and a new approach for such detections. Seismic energy was found to be a very reliable parameter for such detections through the comparison of seismic energies of P and S waves and, particularly, those of SH and SV components of seismic signals originating from casing failures.
1 INTRODUCTION
Imperial Oil Resources is one of Canada''s largest producers of hydrocarbon liquids and their Cold Lake oil field is one of the largest sources of crude oil production in Canada (Fig. 1). The oil sands at Cold Lake, like the majority of Canada''s oil sands deposits, are too deep to be mined from surface and too viscous to be exploited using conventional extraction techniques. Thermal recovery processes such as Cyclic Steam Stimulation (CSS) are employed to overcome the viscosity of the bitumen and allow it to flow to surface. The extraction process consists of injecting large volumes of steam under high pressures and temperatures (300°C) into the oilbearing Clearwater formation (CW), located at the depth range 400-450m (Fig. 2). Steam injection is alternating with oil and water production for as many cycles as economic conditions permit (e.g. Kry 1989) and the process uses the same well for steam injection and bitume
