Seismic monitoring of steam-based recovery of bitumen

Since 1985, Imperial Oil has been using a recovery process, cyclic steam stimulation (CSS), to commercially produce bitumen from the Clearwater Formation near Cold Lake, Alberta, Canada (Figure 1). The Clearwater reservoir, an unconsolidated sand with a porosity of 32 percent and a permeability of 1 darcy, is saturated with an extremely viscous bitumen (viscosity about 150 000 cp). The CSS oil recovery process involves injection of steam at high temperatures and pressures (310° C and 10 MPa), followed by the production of bitumen from the same well. Twenty wells are directionally drilled from a single surface location or pad. More than 2000 wells are spaced on a regular 1.6 hectares grid, producing 100 000 b/d.