Chapter 6: Seismic Rock Physics of Steam Injection in Bituminous-oil Reservoirs
Evan Bianco, Sam Kaplan, Douglas Schmitt, 2010. "Seismic Rock Physics of Steam Injection in Bituminous-oil Reservoirs", Heavy Oils: Reservoir Characterization and Production Monitoring, Satinder Chopra, Laurence R. Lines, Douglas R. Schmitt, Michael L. Batzle
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This case study explores rock physical properties of heavy-oil reservoirs subject to the steam-assisted gravity drainage (SAGD) thermal-enhanced recovery process (Butler and Stephens, 1981; Butler, 1998). Previously published measurements (e.g., Wang et al., 1990; Eastwood, 1993) of the temperature-dependent properties of heavy-oil saturated sands are extended by fluid substitutional modeling and wireline data to assess the effects of pore fluid composition, pressure, and temperature changes on the seismic velocities of unconsolidated sands. Rock physics modeling is applied to a typical shallow McMurray formation reservoir (135–160 m depth) encountered within the bituminous Athabasca Oil Sands deposit in Western Canada to construct a rock-physics-based velocity model of the SAGD process. Although the injected steam pressure and temperature control the fluid bulk moduli within the pore space, the effective stress-dependent elastic frame moduli are the most poorly known yet most important factors governing the changes of seismic properties during this recovery operation. The results of the fluid substitution are used to construct a 2D synthetic seismic section to establish seismic attributes for analysis and interpretation of the physical SAGD process. The findings of this modeling promote a more complete description of 11 high-resolution, time-lapse, 2D seismic profiles collected over some of the earliest steam zones.
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Heavy oil is an important global resource with reserves comparable to those of conventional oil. As conventional resources get thinner, attention is being focused on heavy oil and bitumen, which hold the promise of becoming useful fuels. Already more than 1 million barrels of oil are being produced from the oil sands in Canada; heavy oil represents half of California’s crude oil production in the United States and is a major production in Mexico. With demand for global energy soaring, heavy oil will undoubtedly be an important resource to be exploited in a big way in the near future.
The SEG Development and Production Committee held its Heavy Oil Forum in Edmonton, Alberta, in July 2007. This was a joint research forum cosponsored by the Canadian Society of Exploration Geophysicists (CSEG) and SEG and hosted by the University of Alberta. Preceding the forum, a field trip took the participants to the vast Athabasca Oil Sands region where they observed the outcrops, open pit mining, and steam injection operations, followed by a tour of the steam-assisted gravity drainage projects. Topics of the well-attended forum included the definition of heavy oil; where is heavy oil found; how it is produced; heavy-oil reservoir characterization; fluid and rock properties; electrical, tilt, and gravity techniques; borehole, surface seismic measurements; and microseismicity.