Injecting carbon dioxide in an oilfield to enhance oil recovery is proving to be an effective way of disposing of the greenhouse gas while extending the life of the Weyburn Oilfield in Saskatchewan, Canada, near the North Dakota border.
In a multinational project that includes the Department of Energy, more than 110 billion cubic feet of 95 percent pure CO2 have been injected in the field, producing more than 6 million barrels of oil. The effort, known as the Weyburn Project, is expected to store about 22 million tons of CO2 and produce 130 million barrels of oil over 20 years. Most of the injected CO2 comes from the Dakota Gasification Company’s synfuels plant in Beulah, N.D., via a 320-kilometer pipeline.
The idea is simple: Injecting compressed CO2, a greenhouse gas, into the oilfield creates a CO2 “flood” that forces the remaining oil into a well where it can be harvested; the CO2 remains behind, safely and permanently stored beneath the earth’s surface. The project’s overriding goal is to expand the knowledge of the capacity, transport rate, and storage of CO2 in geological formations associated with enhanced oil recovery—in other words, to make sure that “safe and permanent” are just that.
The Weyburn Project is a model of international cooperation. Since its launch in 1999 by the Petroleum Technology Research Centre in Regina, Saskatchewan, and EnCana Resources of Calgary, Alberta, Canada, the project has attracted 15 sponsors from governments and industry—including the U.S. Department of Energy, Natural Resources Canada, Alberta Energy Research Institute, Saskatchewan Industry and Resources, the European Community, and 10 industrial sponsors in Canada, the United States, and Japan.
Weyburn is one of several oilfields in the Williston Basin that first produced medium gravity crude oil in 1954. The field was produced by primary depletion until 1964 when an extensive water-flood scheme was introduced. By 1996 cumulative production had reached 328 million barrels of oil, or 23 percent of the 1.4 billion barrels originally trapped underground.
Data from the project, combined with the well’s historical data, are expected to provide specific insights on which a sound economic model of current and future sequestration efforts of this type can be based. It is expected that this and similar efforts would illustrate that combined enhanced oil recovery and sequestration projects are a viable and environmentally safe way of storing CO2 while obtaining oil that is difficult and expensive to extract through traditional methods.