Where does the CO2 come from and where does it go? Today, most of the CO2 used in EOR operations is from natural underground ‘domes’ of CO2. With the natural supply of CO2 limited, man-made CO2 from the captured CO2 emissions of power plants and industrial facilities can be used to boost oil production through EOR.
Once CO2 is captured, it is compressed and transported by pipeline to oil fields. During EOR operations, CO2 is injected into the oil formation where it mixes with the oil and helps move the oil through the formation and to the production wells. CO2 that emerges with the oil is separated and re-injected into the formation. CO2-EOR projects resemble a closed-loop system where the CO2 is injected, produces oil, is stored in the formation, or is recycled back into the injection well.
Is CO2-EOR safe? CO2 is non-flammable and nonexplosive. It is not defined as a hazardous substance, but a Class L, highly volatile, nonflammable/nontoxic material (CFRg, CFRe, Appendix B, Table 4). (WRI, 2008)
Operating for 40 years, CO2 pipelines have an excellent safety record with no serious injuries or fatalities ever reported. Today there are over 3,900 miles of pipeline transporting CO2 for EOR use at wells producing 281,000 (MIT 2011) barrels of oil per day. The industry has operated for decades under existing policy and regulatory oversight at the local, state and federal level.
Geologic storage of CO2 is also regulated under existing policies and regulations. CO2 is contained by a series of physical and chemical trapping mechanisms over time. Most formations that hold oil for thousands of years also have the ability to contain CO2. As an example, research by the University of Texas Bureau of Economic Geology’s Gulf Coast Carbon Center on the SACROC oil field, where
CO2 has been injected for EOR since 1972, has found no evidence of CO2 leakage (TBEG). Experience from this decades-old CO2-EOR project and current commercial-scale CO2-EOR projects today shows that CO2-EOR can be performed in a manner that is safe for both human health and the environment.
- World Resources Institute, “Guidelines for Carbon Dioxide Capture, Transport, and Storage,” 2008.
- MIT Energy Initiative, “Role of Enhanced Oil Recovery in Accelerating the Deployment of Carbon Capture and Sequestration,” 2011.
- See the SACROC Research Project website for a complete list of studies. www.beg.utexas.edu/gccc/sacroc.php