Economics of Carbon Dioxide Supplies For Use In Enhanced Oil Recovery In Alberta

Abstract

Abstract A study of the feasibility ojCO2, f1ooding in Alberta is discussed. The study includes a survey of potential CO2 supplies and a cost estimate for obtaining CO2 from each of the potential sources and for transporting the CO2 to the Pembina area in central Alberta. The economics of tertiary miscible flooding with CO2 are also evaluated, based on rough estimates of CO2 process performance. Introduction Enhanced oil recovery by gas injection has been practiced by the oil industry for years. In immiscible recovery projects, the injected fluid maintains reservoir pressures and drives the oil toward producing wells. In miscible projects, the injected fluid and oil dissolve in one another, reducing the residual oil saturation, which results in improved oil recovery. The Petroleum Recovery Institute has focused attention on CO2 as one of the fluids available as an injection agent in enhanced oil recovery processes. Use of the immiscible CO2 process has been investigated in a southeastern Alberta reservoir(1), and in Texas a full-scale commercial application has been in operation for several years(2). In addition, several other large CO2 injection projects are being initiated in the U.S. The Alberta Department of Energy and Natural Resources commissioned Saturn Engineering Ltd. to undertake a study of the supply of CO2, potentially available in Alberta, and the cost of processing, compressing and transporting it to applicableoil reservoirs which are suitable for miscible floodrecovery projects. The desired quantity of CO2 may range upward to 200 MMSCFD for full-scale projects, and for pilot scale field tests would be in the 10–20 MMSCFD range. The Pembina Cardium reservoir is considered a possibility for CO2 flooding, hence Drayton Valley was chosen as the delivery point for the CO2. The required quality of CO2 for this study was assumed at 98 plus per cent, the remainder being mainly N2 or H2, depending on source. This paper summarizes the results of the study completed in late 1977, of the cost of CO2 extracted from various sources and delivered to the wellhead. Also, a preliminary economic evaluation of CO2 flooding is presented for two potential projects in Alberta. Sources of CO2 The Petroleum Recovery Institute carried out an analysis of the potential CO2 sources in Alberta(3); the data with some modifications, were used in this study. The following sources were considered:power-plant flue gases;sour gas plants:ammonia plants;oil sands hydrogen plants. Only those sources with a minimum of 10 MMSCFD of CO2 were considered. A survey of ERCB data uncovered no large-scale natural reservoirs of CO2, other than those which also contain H2S and which are covered in the sour gas plants category. Power Plant Flue Gas Power plants are by far the largest individual source of CO2, but at the same time they represent the lowest quality source. The presence of ash and sulphur oxides in coal-fired plants results in significantly increased CO2 extraction costs. Two power-plant sources were considered: Calgary Power's Sundance coal-fired plant and Edmonton Power's Clover Bar gasfired plant.