Twenty Years' Operation of an In-situ Combustion Project

Abstract

Abstract Amoco Canada Petroleum Company Ltd. has been testing in-situ combustion in the Athabasca Oil Sands since 1958.Field testing has resulted in the development of a technology package which may provide the key to recovering a significant portion of Alberta's 151 × 109 m3 (951 billion bbls) of bitumen within the oil sands. This paper reviews the many interrelated components involved in the combustion process, including the design and operation of the basic plant equipment, well pattern sizing, well completions, ignitions testing and analysis, and safety and ecological consideration. Sufficient successful test results were accumulated over this 20-year period to achieve all expansion to the multi-pattern test program now underway. Introduction Alberta's oil sand deposits, shown on Figure I, are among the largest in the world and contain some 151 × 109m3 (951 billion bbls) of bitumen in place. Eighty seven per cent of these deposits have more than 75 m (250 ft) of overburden associated with them. It is generally accepted that in-situ recovery techniques will be required to produce the bitumen from these deeply buried deposits. Amoco's leases within the Athabasca Oil Sands, shown on Figure 2, cover 42,500 hectares (105,000 acres) and contain an estimated 2.8 × 109m3 (18 billion bbls) of bitumen in place. It is on these leases that Amoco is developing the technology by which the unconsolidated oil sand can be thermally processed and the high-viscosity bitumen recovered leaving the fine sand in place. The commercial merit of this technology has yet to be determined, but it may be established by the current multi-pattern test project. Amoco has concentrated its efforts on developing a Combination of Forward Combustion and Waterflood process (COFCAW)* that has shown encouraging results and will be described later. From the ignition of the formation, through to the control of air injection rates and bottom-hole temperatures, to the production of sand-free fluids at high production rates, the in-situ combustion process has proven to be workable. The field experience generated over the past 20 years has enabled Amoco to reach a plateau requiring a multi-pattern field test. In 1958, Amoco Canada commenced actual field testing to develop an in-situ method for recovering bitumen from the oil sands. Experimental wells were drilled 40 Ian (25 miles) southeast of Fort McMurray on Test Site No. I (Fig. 2) and field tests were conducted from 1958 to 1962. A total of nine wells were drilled in this fust stage. In 1963, the project was moved to Test Site No.2 and from 1963 to 1976 over 50 experimental wells were drilled. Nearly $18 million was spent during the 20 years of experimental work. The basic testing of.the process design did not change over this period, however the technology and know-how of its application improved greatly. Failures were encountered, however each phase of testing was significant advancement toward developing a total process for the recovery of the bitumen by means of in-situ combustion. The technology developed during the 20-year test period will be discussed in this paper.