The Plains CO₂ Reduction (PCOR) Partnership, one of seven in DOE’s Regional Carbon Sequestration Partnership program, collaborated with Eagle Operating Inc. to complete the test in the Northwest McGregor Oil Field in Williams County, N.D.

The huff-and-puff method of enhanced oil recovery proceeds in three phases: injection (the huff stage); “soaking” for a short period of time; and production (the puff stage). Compared to other huff-and-puff operations, the PCOR Partnership test was unique for several reasons:

• The depth (approximately 8,050 feet), was among the greatest.
• Pressure (3,000 pounds per square inch) and temperature (180 °F) were among the highest.
• The formation was a carbonate rather than clastic reservoir.

The test was conducted utilizing a producing oil well in the Mission Canyon Formation, part of the Madison Group of Mississippian-age carbonate rocks in the western United States. During the test, 440 tons of liquid CO₂ were injected into the well to a depth at which CO₂ is miscible and blends with residual in-place oil. Following 2 weeks of “soaking,” the well was placed back into production.

Production more than doubled over the course of a 3-month period, increasing from a baseline rate of 1.5 stock tank barrels (STB) per day to 3-7 STB per day. The percentage of oil in the produced fluid, commonly referred to as the oil cut, also increased, more than doubling from less than 3% to 6%.

In addition to demonstrating the feasibility of combining CO₂ storage along with enhanced oil recovery in carbonate rocks deeper than 8,000 feet, the test determined that two Schlumberger technologies—a reservoir saturation tool (RST) and vertical seismic profiling (VSP)—may be effective tools for detecting and monitoring small-volume CO₂ plumes in deep carbonate reservoirs to ensure safe and permanent sequestration. Project outcomes may be applicable to many other sites in the PCOR Partnership region and in similar settings globally.

The Regional Carbon Sequestration Partnerships initiative is a government-industry effort that is determining the best approaches for capturing and storing gases that can contribute to climate change. The PCOR Partnership brings together more than 80 partners—consisting of public agencies, utilities, oil and gas companies, engineering firms, nonprofit organizations, and universities—in a region that includes all or part of nine US states and four Canadian provinces. Led by the Energy and Environmental Center in Grand Forks, North Dakota, the PCOR Partnership has completed four small-scale validation tests and is currently conducting two large-scale development tests.

The Regional Carbon Sequestration Partnerships initiative is managed by the Office of Fossil Energy’s National Energy Technology Laboratory.