There is a great interest, especially in Western Canada, to capture carbon dioxide (CO2) from fossil fuel fired power plants and utilize it as a flooding agent for enhanced oil recovery (EOR) processes. This concept provides two important benefits:
captured CO2can be utilized as a flooding agent which would generate revenue from incremental oil production, and
CO2 emissions to the atmosphere are reduced, helping to alleviate global warming.
In the past few years, a number of feasibility studies and pilot projects on CO2 extraction from power plants have been performed. However, these results have shown that even though it is technically feasible to extract CO2from power plants, the EOR application cost is high in the current crude petroleum market. A major reason for the high cost is that the CO2extracting process requires a substantial amount of steam.
This paper will demonstrate how cogeneration concepts would help to reduce CO2 production costs by utilizing low pressure steams and waste heats from various sections of the power generation processes. The economics are based on the installation of a power generation plant and CO2 recovery facility in an existing oil producing facility.
Enhanced Oil Recovery (EOR) is becoming increasingly popular as primary production methods become less effective. Some typical EOR methods include waterfloods, steamfloods, firefloods, miscible floods and immiscible floods. Miscible and immiscible flooding techniques have proven to be both effective and popular. However, increasing demand for conventional flooding agents, such as propane, ethane, and other lighter end natural gas liquids, has limited its use. As an alternative, carbon dioxide (CO2) has been identified as a prime candidate for replacing these natural gas liquids. Although there is an abundant supply of CO2 being produced annually from various industrial sources, the capture and transportation cost is high for EOR applications.
Through the use of cogeneration concepts, this paper will demonstrate how CO2 production costs can be reduced. Cogeneration is the simultaneous production of power, either electrical or mechanical, and useful thermal energy from a single fuel source(1). The principle advantage of cogeneration systems lies in their efficiency and, hence, fuel savings compared to conventional thermal power stations. A typical utility generating station based on condensing steam turbine technology converts less than 40% of fuel energy in its boilers to electricity, with the remainder being rejected to the environment. In cogeneration, this waste heat is utilized as a sequential input into another process, for example, in the production of process steam. Therefore, a cogeneration system can convert 60 to 80% of the available fuel energy into electricity and useful heat.
Placing a cogenerating/C02 recovery plant in or near the EOR field can have numerous advantages(2). Some of these include:
Field operating costs can be reduced by utilizing produced electricity within EOR operations.
The cogeneration plant provides the EOR field operator a means by which shut-in natural gas can be used to produce CO2, electricity, and oil, thereby finding a marketplace for the shut-in gas.