Chapter 25: Passive Seismic and Surface Monitoring of Geomechanical Deformation Associated with Steam Injection
Shawn C. Maxwell, Jing Du, Julie Shemeta, 2010. "Passive Seismic and Surface Monitoring of Geomechanical Deformation Associated with Steam Injection", Heavy Oils: Reservoir Characterization and Production Monitoring, Satinder Chopra, Laurence R. Lines, Douglas R. Schmitt, Michael L. Batzle
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Monitoring injections is important for optimal reservoir management of any enhanced oil recovery. Monitoring is of particular importance in the case of steam injections, which often have small economic margins and where significant material property changes take place. Imaging can be used to optimize the injection, make informed reservoir engineering decisions, and help understand the mechanics of the injection.
Monitoring the steam chamber growth is critical in optimizing heavy-oil recovery; it ensures that the stimulation is confined to the reservoir and helps identify bypassed regions. Steam injection results in geomechanical strains associated with increased pore pressure, thermal stress changes, and dramatic changes in material properties associated with heating the reservoir sufficiently to mobilize the heavy oil/bitumen. This geomechanical deformation may be marked by seismic deformation and the release of seismic energy as fractures adjust to the strain field. Deformation may also be evident in surface expansion or subsidence. Monitoring the microseismic activity with sensitive seismometers and surface deformation with precise tiltmeters could allow the steam injection to be tracked with complementary technologies that respond to different expressions of the geomechanical deformation.
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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.