Abstract In this chapter, seismic-attribute spectral decomposition (SD) is used for understanding heavy-oil and bitumen sand reservoir behavior and comprehending their heterogeneities for future reservoir simulation. Spectral decomposition is performed on the migrated stack and on amplitude-versus-offset (AVO) attributes (P- and S-wave impedance reflectivity). Examples provided in this chapter are from reservoirs with cold and thermal production. The observed differences between SD performed on P- and S-wave impedance reflectivity are explained with the solid state of the oil sands at their preproduction reservoir condition. The interpretation of the seismic attributes is based on the poroelastic and viscoelastic behaviors of the heavy oil and/or bitumen. The reservoir characteristics identified on the spectrally decomposed AVO attributes can be summarized as follows: (1) higher energy at the top and base of the reservoir is associated with shale; (2) medium to high energy is an indication of water sand; (3) low energy in the middle of the reservoir is commonly associated with thick bitumen zones that have high absorption; and (4) the bitumen-water interface is identified.

Introduction Heavy-oil reservoirs are an abundant resource, particularly in Canada, Venezuela, and Alaska. By some estimates, heavy oils represent as much as 6.3 trillion barrels of oil in place. This matches available quantities of conventional oil. More than 50% of Canada's oil production is now from heavy oil (Batzle et al., 2006). Much of the heavy-oil recovery in Western Canada involves steam injection, called “hot production.” An alternative to thermal heavy-oil production in the field is known as “cold production,” which is a primary nonthermal process in which reservoir temperature is not affected. The cold production process has been economically successful in several unconsolidated heavy-oil fields in Alberta and Saskatchewan, Canada (Sawatzky et al., 2002). During the cold production process, sand and oil are produced simultaneously by progressive cavity pumps, generating high-porosity channels termed “wormholes.” The development of wormholes causes reservoir pressure to fall below the bubble point, resulting in dissolved gas coming out of solution to form foamy oil. Foamy oil and wormholes are believed to be two key factors in the enhancement of oil recovery (Metwally et al., 1995; Maini, 2004). The development of wormholes and the formation of foamy oil will disturb fluid properties in the reservoir during heavy-oil cold production. Batzle et al. (2006) showed that the bulk modulus of heavy oil drops to near zero very quickly from approximately 2.6 GPa after pressure is lower than the bubble point line at approximately 2 MPa. This disturbance will probably be detectable for seismic survey.

Introduction Heavy-oil reservoirs are an abundant hydrocarbon resource, which will in all probability comprise a significant portion of long-term world oil production. The world’s heavy-oil reserves have been estimated to be approximately 6 trillion barrels — roughly equivalent to conventional reserves. The largest heavy-oil reserves are in Canada, Venezuela, the United States, Norway, Indonesia, China, Russia, and Kuwait. Cold production is a low-energy production method that has been widely used in Western Canada. Although the primary recovery rates are relatively modest, cold production of heavy oil requires much less energy than hot production methods such as cyclic steam injection (CSS) or steam-assisted gravity drainage (SAGD), and as a consequence it results in much less hydrocarbon use in the recovery stage.