Thermal Techniques for the Recovery of Heavy Oil and Bitumen

Abstract

Abstract Over 90% of the world's heavy oil and bitumen (oil sands) are deposited in Canada and Venezuela. Alberta holds the world's largest reserves of bitumen and the reserves are of the same order of magnitude as reserves of conventional oil in Saudi Arabia. Up to 80% of estimated reserves could be recovered by in-situ thermal operation. As the resources available for conventional crude in Canada continue to decline, further development of heavy oil and oil sands in-situ recovery technologies is critical to meeting Canada's present and future energy requirements. Sophisticated technologies have been required to economically develop Canada's complex and varying oil fields. Various existing in-situ technologies such as hot water injection, steam flooding, cyclic steaming and combustion processes have been successfully applied in Venezuela and California. Most recently, advances made in directional drilling and measuring while drilling (MWD) technologies have facilitated development of new in-situ production technologies such as the steam assisted gravity drainage (SAGD), expanding solvent-SAGD (ES-SAGD) and solvent vapor extraction (VAPEX) that have significantly improved well-bore reservoir contact, sweep efficiencies, produced oil rates and reduced production costs. This paper provides an overview of existing and new thermal in-situ technologies and current projects. Potential of new technologies are assessed and compared to various existing in-situ thermal processes. Critical issues affecting production performance are discussed. Canadian Bitumen Resource The Canadian bitumen deposits are almost entirely located in the province of Alberta. Three major deposits are defined as Athabasca, Cold Lake and Peace River. Figure 1 shows the major oil sands deposits of Canada. The average depths of the deposits are 300, 400 and 500 m, respectively. Table 1 is a summary comparison of the initial bitumen volume-in-place for the three deposits1. The Alberta Energy and Utilities Board (AEUB)[1] estimate the total initial volume-in-place of bitumen to be 259.1 billion m3. This estimate could ultimately reach 400 billion m3 by the time all exploratory developments are completed. This shows that Canada has the world's largest bitumen deposits. Out of the total volume, 24 billion m3 are available for surface mining techniques. Athabasca deposit is the only deposit with surface mineable reserves. About 376 billion m3 lie too deep to be surface-mined and are exploitable by in-situ technologies. However, approximately 12%, or ~ 50 billion m3 of the total volume-in-place is estimated to be ultimately recovered by existing technologies. That percentage is expected to increase as more advances in recovery technologies are made. Figure 2 shows reservoir characteristics for the three deposits[2]. The Athabasca deposit has Alberta's largest reserve of bitumen that lies in the McMurray formation. The deposit has three layers of oil sands (McMurray, Clearwater and Grad Rapids) separated by shale layers. The deposit is covered by a sand stone overburden and has an area of ~41,000 square kilometers. The Cold Lake deposit is made up of four separate reservoirs that lie in McMurray, Clearwater, Lower Grand Rapids and Upper Grand Rapids and covers an area of approximately 21,000 square kilometers. The oil deposits lie under a thick overburden that prohibits surface mining and can only be produced by in-situ techniques. Most of the Peace River deposit lies under the deepest overburden as compared to Athabasca and Cold Lake deposits. The rich Peace River deposit is contained in the Bluesky and Gething formations. Figure 3 compares Canada's proven oil reserves with those of the world deposits[3]. Table 2 shows existing and planned in-situ heavy oil and oil sands projects[4]. Table 3 and Figure 4 display the forecast of Canadian crude oil production to the year 20155. This paper focuses on the in-situ production technologies for heavy oil and oil sands (bitumen).