Washington, D.C. -- In a newly awarded project, researchers funded by the U.S. Department of Energy (DOE) are partnering with European scientists to track injected carbon dioxide (CO2) in the world's first and longest running carbon storage operation located at the Sleipner gas field in the North Sea. The researchers--from the Scripps Institution of Oceanography at the University of California, San Diego, and the Lamont-Doherty Earth Observatory (LDEO) in New York--will conduct surveys on the seafloor to monitor injected CO2 in the 1 kilometer-deep reservoir, where more than 10 million tonnes of CO2 have been stored to date.

"This international effort demonstrates the commitment of the United States, and other countries that produce or use fossil fuels, to decrease greenhouse gas emissions by finding new ways to capture and safely store CO2," said Dr. Victor Der, Acting Assistant Secretary for Fossil Energy. "The Office of Fossil Energy's Carbon Sequestration Program will benefit from this collaborative U.S.-European North Sea study by adding to our portfolio of successful technologies for CO2 monitoring, verification, and accounting in geologic reservoirs."

An ocean vessel will position sensitive gravity meters on the seafloor using a ship-tethered remotely operated vehicle carrying the instruments. Data from the instrument packages on the seafloor will be transmitted to operators aboard the ship. Academic researchers from Scripps and LDEO will collaborate with their Norwegian colleagues from StatoilHydro in the analysis of the results. The project will create approximately eight full-time jobs per year, which will be supported throughout the two-year project.

The technology to be used in the project recognizes that, as gas is injected into the sandstone reservoir, the density of the formation is altered as water in the pore spaces is displaced by lower density CO2. This density change affects the strength of the Earth's gravity field. Gravity surveys performed by the scientists at different times provide snapshots of the CO2 plume migration deep below the seafloor. Surveys performed by Scripps in 2002 and 2005 validated the gravity technique as an effective monitoring tool and assessed CO2 reservoir conditions for those years.

Since 1996, about one million tonnes of CO2 per year have been injected into the Sleipner reservoir. CO2 that is produced along with natural gas is separated on the production platform and re-injected into a sandstone formation at a depth of about 1,000 meters below sea level to prevent venting the gas to the atmosphere. A 80-meter-thick shale cap rock holds the CO2 securely in place.

From 2004 to 2006, DOE supported an earlier research project at the Sleipner field, the now-completed CO2STORE project, through its membership in the Carbon Sequestration Leadership Forum (CSLF). The CSLF, a voluntary, Ministerial-level international climate change initiative, facilitates the development and deployment of improved, cost-effective technologies for carbon capture and storage through collaborative efforts. The 22 members of the CSLF (21 nations plus the European Commission) account for 75 percent of all manmade CO2 emissions.

Lessons learned from monitoring the Sleipner CO2 sequestration project reservoir can be applied elsewhere in Europe, the United States, and worldwide. DOE sponsors research at other international CO2 storage operations, including the Australian Otway Basin project, Germany's CO2SINK project, the Algerian In Salah gas field storage project, and Canada's Weyburn-Midale CO2 storage and enhanced oil recovery project.

The project is managed by the Office of Fossil Energy's National Energy Technology Laboratory.