The potential for enhanced oil recovery in the United States is increasing continuously with advances in technology. Reservoir modeling, especially for CO2-EOR, has become extremely sophisticated with the increased capabilities of modern computers and with the development of advanced computer codes that are better capable of mimicking the physics and chemistry of enhanced oil recovery. Improved drilling and completion techniques are also contributing, providing better drilling efficiency and improved well control. New sensing devices and communication systems provide capability for real time analysis of field operations, including underground flow tracking and simulation, thus enhancing the ability to make intelligent decisions in a timely manner. The synergism of the advanced technologies allow a far better understanding and control of oil reservoirs, reservoir fluids, and the physics and chemistry of enhanced recovery.
CO2-EOR is the “universal” enhanced recovery system, applicable to most reservoirs except the very shallow and the reservoirs with heavier oils, for which thermal technologies are more applicable. DOE recently sponsored a study to determine the CO2-EOR potential for the reservoirs in 10 major U.S. basins (and essentially for the United States, since those basins hold the preponderance of U.S. oil resources). The results of the study are impressive, indicating that as much as 89 billion bbls of oil could be produced by applying modern and forthcoming advanced CO2-EOR technologies. These estimates are based on assumptions that require the application of the very best technologies available, something that is not likely to happen in every case. Even so, the remaining resources offer a large target for CO2-EOR, and even if only a portion of the 89 billion bbl estimate can be recovered, it is very much worth pursuing.
There are currently limited sources of low cost CO2 and delivery infrastructure (pipelines) to supply CO2 to the many oil fields in the United States with EOR potential. Coal to liquids and other alternative liquid transportation fuels production facilities are believed to be a key to unlocking the huge potential of U.S. EOR resources. These plants will be distributed across the United States, with many sited proximate to EOR-suited oil fields. CO2 will be a residual product of alternative liquid fuel plants, and capturing the gas for sale will not only create economic value but will also demonstrate environmental stewardship. Thus, it is anticipated that these new liquid fuels manufacturing plants will be a source of low cost CO2 for EOR operations.
The United States has limited existing CO2 sources and pipelines currently delivering this strategic EOR gas, and even in these regions, low cost CO2 is in short supply. Many of the basins showing large EOR potential have no existing supplies of CO2. With more than three decades of experience with the process, companies are becoming more comfortable with using CO2-EOR. If the price of oil remains high, there should be considerable incentive for companies to initiate new EOR projects, even though past experience has made investors leery of commitments to major projects.