New technology will enable fast searches for leaky wells in depleted oil and gas reservoirs that are targeted for new life as CO2-sequestration areas.

The technology has been developed by the Department of Energy's National Energy Technology Laboratory (NETL) in Washington with Apogee Scientific Inc. of Englewood, Colorado, Fugro Airborne Surveys of Mississauga, Ontario, and LaSen Inc. of Las Cruces, New Mexico. The NETL is operated by the Office of Fossil Energy.

Efforts to curb global warming include storing CO2 emissions in depleted oil and gas reservoirs, but abandoned wells must be properly sealed, so the CO2 won't leak. For a trial run, equipment, called Sequre Well Finding Technology, was affixed to a helicopter and flown over Salt Creek oil field Natrona County, Wyoming. Discovered in the late 1800s, Salt Creek was one of the most prolific oil fields of the early 20th century. Typical well searches for proposed CO2 storage sites there are anticipated to cover hundreds of square kilometers.

The equipment consists of two detection systems: magnetic and methane. Magnetic sensors detect steel well casings that are subsequently depicted on maps used for ground reconnaissance. The magnetic sensors are able to detect some 95% of wells in oil and gas fields. During the test flight over Salt Creek, Sequre's magnetic sensors detected 133 of 139 wells. The other six wells were undetected due to corroded or missing casings, or because the casings were made of non-magnetic material, such as wood.

To locate the remaining, magnetically undetected wells, the methane sensors were used. The detectors locate leaking wells by detecting volatile components that have migrated to the earth's surface via the wellbore.

All potential leaks must be detected and sealed to assure complete and perpetual CO2 storage. "The Sequre technology is commercially available now," says Otis Mills Jr., a spokesman with NETL.

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