Design Considerations For Carbon Dioxide Injection Facilities

Abstract

Abstract The first miscible carbon dioxide enhanced oil recovery project in Canada began in 1984 with the injection of CO2 into the Joffre Viking Tertiary Oil Unit by Vikor Resources Ltd. and the Alberta Oil Sands Technology and Research Authority (AOSTRA). Carbon dioxide injection facilities capable of injecting gaseous CO2 from a nearby petrochemical complex and liquid CO2 trucked to the site are discussed. The paper examines some process, instrumentation, material and operating considerations incorporated into the design of the project's carbon dioxide compression, dehydration, injection well and measurement equipment. Introduction Since the early 1970s considerable effort has been expended by industry in the research and field testing of miscible displacement of oil using CO2. In the United States, the number of CO2 miscible projects have blossomed to over thirty in the past two years. In the United States carbon dioxide miscible flooding is expected to contribute about 50 000 m3 I d of tertiary oil by 1995, and should develop dose to 500 million m3 of oil reserves. Although the potential a f miscible CO2 flooding is somewhat more limited in Canada than in the United States due to the lack of large natural occuring CO2 deposits, miscible CO2 flooding is still expected to contribute significantly to Canada's future oil reserves. A recent study by the National Energy Board (NEB) showed carbon dioxide miscible flooding to have an economic potential for recovering 50 million m3 of oil reserves, about 15% of Canada's anticipated 320 million m3 tertiary oil reserves. The first field testing of miscible CO2 technology in Canada is currently being operated by Vikor Resources Ltd. on behalf of the Alberta Oil Sands Technology and Research Authority (AOSTRA) and the Joffre Viking Tertiary Oil Unit in the Joffre Viking sandstone, approximately IS km northeast of Red Deer (Fig. 1). The project is located in an area of the reservoir which had been produced to its economic limit under water flood in the 1960s. The project consists of four water pre-pressure wells flanking two adjacent inverted five-spot CO2 injection patterns which are produced under a water alternating gas (WAG) process (Figs. 2 and 3). The project has been injecting CO2 since January 1984. Response to the CO2 injection has been observed, indicating the commercial potential of the process. This paper will deal with some of the process and mechanical design considerations of the CO2 injection system in Joffre; identifying potential problems specific to CO2 and commenting on recommendations to economically ameliorate each problem area. Injection System The CO2 injection system is shown schematically in Figure 4, It includes gaseous CO2 from Alberta Gas Ethylene Company (AGEC) and a liquid CO2 system located at the Central Battery. These two CO2 sources are comminglid at the Vikor Central Battery, and then distributed to the WAG injection wells. Separate water and CO2 injection systems to each WAG injection well are provided as corrosion in gaseous CO2 streams depends mainly on the presence of water.