Advantages of Gasification - Carbon Dioxide Enhanced Oil Recovery (CO2 EOR)
What is Carbon Dioxide Enhanced Oil Recovery (CO2 EOR)?
Carbon dioxide enhanced oil recovery (CO2 EOR) is a technique used to extract oil left underground following conventional oil drilling operations. CO2 is injected into an oil reservoir, where it serves to mobilize residual oil. Following CO2 EOR operations, the CO2 can remain underground, in the reservoir, and thereby be prevented from entering the atmosphere. CO2 EOR can extend the productive life of an existing oilfield by several decades, and it can lead to recovery of millions of barrels of additional oil.
How it Works
Under suitable temperature and pressure conditions, CO2 is mutually soluble with the crude oil in a geologic reservoir. This means that injected CO2 is able to dissolve and displace oil residue that is trapped in rock pores, just as a solvent is able to displace grease from a dirty bicycle chain. In a typical CO2 flood operation, a pipeline delivers CO2 to the oilfield, where it is directed to injection wells. These wells are strategically placed to optimize the areal sweep of the CO2 through the reservoir. As the injected CO2 moves through pore spaces in the rock, it encounters residual crude oil. The crude oil mixes with the CO2, forming a concentrated oil bank that is swept to producing wells. In this way, oil and gas companies are able to gain access to oil that would otherwise be left in the ground.
Background on CO2 EOR
CO2 EOR was first tested in the early 1970s in West Texas. Since then, it has been utilized successfully throughout the Permian Basin of West Texas and eastern New Mexico. It is currently being used in oilfields in Kansas, Mississippi, Wyoming, Oklahoma, Colorado, Utah, Montana, Alaska, and Pennsylvania. In the United States, there are currently 13,000 CO2 EOR wells in operation that produce a total of about 245,000 barrels of oil per day. Industry experts estimate that we have the potential to produce over 40 billion barrels of additional oil from existing domestic fields using advanced CO2 EOR techniques.
Until recently, most CO2 EOR has depended on naturally-occurring underground deposits as the source of the CO2. In recent years, however, industry has begun to utilize CO2 that has been captured as a by-product of fossil fuel combustion, gasification, or other industrial processes. Because a ton of CO2 costs $30, and each ton can yield 2-3 barrels of oil, there is a strong economic incentive to re-use industrially- sourced CO2 from gasification plants, gas processing facilities, and power generation plants.
CO2 EOR represents a win-win strategy for beneficial use of industrially-sourced CO2. From an economic standpoint, CO2 EOR is a highly effective tool for re-invigorating oil production from mature fields that might otherwise be abandoned. From an environmental standpoint, it represents a practical way to recycle and utilize CO2 while reducing overall atmospheric CO2 emissions.