Movement of injected carbon dioxide plume in an underground Cranfield Oilfield is being tracked by installing Electric Resistance Tomography (ERT). The project, being executed at Cranfield Oilfieldnear Natchez, Miss., is a part of the ‘Southeast Regional Carbon Sequestration Partnership (SECARB) initiative that aims to store carbon dioxide in underground formations in quantities in excess of one million tons.
Vertical electrode arrays, configured in a cross-well arrangement, are utilized by ERT for performing four-electrode based measurements of electrical resistance’s variations in the subsurface formation. The resistance of carbon dioxide in the Cranfield site is five times more in comparison with its surroundings. Due to this, the ERT was able to depict considerable changes in resistance during movement and growth of the carbon dioxide plume. ERT is able to develop an electrical resistivity distribution image by transforming many such resistance measurements. The distribution is related to the carbon dioxide oil plume.
The ERT technology was developed for geological and environmental applications during the 1980’s at Livermore and is akin to the scanning process of a computed tomography scan. It is able to image the resistivity of the soil, for providing soil related information to scientists like saturation, temperature, and type of soil. It is able to provide critical information to the Cranfield project, related to the reactions on carbon dioxide during its storage underground.
Initially utilized for monitoring contaminants flow into shallow groundwater supplies, the technique was later modified for monitoring carbon dioxide pumped into deep under ground storage systems.
The Cranfield ERT project’s 10,000 feet deep subsurface application that uses this technique has surpassed the earlier European sequestration project’s 2,400 feet record near Potsdam, Germany.
The SECARB partnership includes the private sector, a Native American enterprise, Southern States Energy Board, the Tennessee Valley Authority, geological surveys from eleven states, regulatory agencies, the Electric Power Research Institute, southern utilities, and academic institutions.
Source: http:// www.llnl.gov