Mark McCullum, 2010. "Crosswell Seismic Imaging — A Critical Tool for Thermal Projects", Heavy Oils: Reservoir Characterization and Production Monitoring, Satinder Chopra, Laurence R. Lines, Douglas R. Schmitt, Michael L. Batzle
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The goal of any operator involved in heavy oil whether flowing or not is to maximize production and minimize costs. With the rapid growth of projects in oil sands, the SAGD process has become commonplace. Although widespread, SAGD is still a relatively new process and operators are discovering that developing an adequate steam chamber requires careful planning. An integral part of this planning process is detailed characterization of the reservoir. With the current operating experience, it is apparent that relatively small features in the reservoir, once thought to be of little or no concern, have been a major impediment or permanent barrier to steam chamber development. The lack of steam chamber growth or inconsistent growth along the horizontal wells is a major contributor to underperforming wells. Therefore, upfront reservoir characterization and the identification of baffles and barriers to steam growth are critical to the process. This chapter details how operators are utilizing crosswell seismic imaging to increase reservoir knowledge and plan SAGD well pair placement and assess overall performance of the steam injection process.
Heavy oil is characterized by an American Petroleum Institute (API) gravity of less than 22.3°. Bitumen at 8–10° API will not flow at normal reservoir conditions. The API gravity of the oil in the reservoir predicates the production methods. Various production methods are now being used in heavy-oil reservoirs. They range from cold heavy-oil production with sand (CHOPS), cyclic steam injection (CSS), steam-assisted gravity drainage (SAGD), steam-assisted gas push (SAGP), vapor extraction (VAPEX), fire flood, and Toe-to-Heel Air Injection (THAITM). With the exception of CHOPS and VAPEX, the other methods rely on heat to mobilize the oil. In the case of fire flood and THAI, heat is generated internal to the reservoir by active combustion, and the other methods rely on steam injected from the surface. It is these processes that will be focused on here.
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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.