Release Date: March 20, 2003

HOBBS, NM - Could depleted oil fields offer sites for "sequestering" greenhouse gas emissions? A field test in Hobbs, NM, co-sponsored by the U.S. Department of Energy, could give scientists their first "real-life" indication of whether this approach can be a future option in President Bush's Global Climate Change Initiative.

The project is the first major field experiment in the United States to test whether underground geologic formations might be used in the future to entrap carbon gases and isolate them permanently from the atmosphere.

Between December 20, 2002 and February 10, 2003, researchers injected approximately 2,100 tons of CO2 into Strata Production Company's West Pearl Queen reservoir near Hobbs. The quantity of CO2 injected in the New Mexico project is comparable to a single day of emissions from an average coal-fired power plant.

Now, researchers are monitoring the CO2 plume as it "soaks" into the reservoir rock. The objective is to determine whether the gases are likely to stay within the formation. This field experiment puts to the test what others have only studied in the laboratory.

Oil and gas reservoirs are thought to be promising targets for CO2 sequestration for several reasons.

First, oil and gas that originally accumulated in these reservoirs did not escape over geological time. Thus the reservoirs should also contain CO2, as long as pathways to the surface or to adjacent formations are not created by overpressuring of the reservoir, by fracturing out of the reservoir at wells, or by leaks around wells.

Second, the geologic structure and physical properties of most oil and gas fields have been characterized extensively. While additional characterization - particularly of the integrity and extent of the caprock - may be needed, the availability of existing data will lower the cost of implementing CO2 sequestration projects.

But scientists do not have good field data on how long the CO2 is likely to remain in the reservoir, or what physical or chemical changes might occur in the reservoir rock. The Strata project will begin providing answers to those questions.

For this project, an extensive 3-dimensional survey was conducted before the CO2 injection began, to provide the best possible subsurface geophysical image of the reservoir. As the CO2 entered the reservoir at a rate of about 40 tons per day and pressure of 1,400 psi, scientists used highly sensitive equipment to acquire microseismic signals to help track the movement of the plume.

The CO2 is now being allowed to "soak" into the reservoir rock for approximately 60-90 days. In early April, a second 3-D seismic survey will be taken. The before-and-after "snapshots" of the reservoir are expected to begin telling scientists the fate of the CO2 plume.

Scientists will continue to monitor the CO2 plume and any changes in the mineralization of the reservoir rock for the next year. Data from the field test will be used to determine the accuracy of various modeling and simulation tools that will be used to predict the storage capacity and any physical or chemical effects of the CO2 on the reservoir.

The project is being jointly sponsored by the National Energy Technology Laboratory, Sandia National Laboratory, Los Alamos National Laboratory, and Strata. The CO2 for the experiment is being provided by Kinder Morgan CO2 Company, LP.

The New Mexico project complements another similar and larger sequestration field test underway at the Weyburn oil field in southeastern Saskatchewan, Canada. Through a recently signed bilateral agreement between the U.S. Department of Energy and Natural Resources Canada, DOE is joining more than 15 government agencies, universities, and research institutions from around the world to monitor the capacity, movement, and fate of CO2 injected into a producing oil reservoir (the Strata project is taking place in a depleted, non-producing oil field).

In the Weyburn project, some 5,000 tons per day of nearly pure CO2 is being shipped from the Dakota Gasification Company's Great Plains Coal Gasification Plant outside Beulah, ND, through a 204-mile pipeline to the Weyburn field. Encana, the field's operator, is injecting the CO2 to extend the field's productive life, hoping to add another 25 years and as much as 130 million barrels of oil that might otherwise have been abandoned.

The Energy Department's contribution will be used for an intensive 3-year scientific mapping and modeling effort to trace the movement of the CO2 and determine whether it is likely to remain in the oil reservoir permanently.