The Role Of Geophysics In Developing Strategies For Co2 Sequestration In Geologic Formations

Abstract

Global Climate Change has been attributed to emissions to the atmosphere of greenhouse gases (GHG), with a major constituent being anthropogenic CO2 emissions from coal-fired power plants and the transportation sector. Many approaches have been proposed to mitigate CO2 emissions. Among the most promising is capture and sequestration in geologic formations. This option has the advantage of being able to cope with the large volume of CO2 involved, which will continue to increase because of the growing energy demand. Consequently, an important component of the United States Department of Energy’s (DOE) research and development program is dedicated to reducing CO2 emissions from power plants by developing technologies for capturing and sequestering CO2 in geologic formations. This paper presents an overview of DOE’s research program in the area of CO2 sequestration and storage in geologic formations. Geophysical field techniques are playing a major role in current field demonstrations of CO2 sequestration and have the potential to play an even greater role as geologic sequestration becomes a reality in a future “carbon constrained world.” The role of geophysical techniques in studying the processes involved in the CO2 geologic sequestration life cycle are discussed. These processes include CO2 capture, transport, injection, and measurement, monitoring, and verification (MMV) of the permanence of storage in a geologic reservoir with an effective caprock seal. Techniques, including seismic surveys using a variety of data acquisition and processing strategies (2D seismic surveys, seismic tomography, and others), microseismic monitoring, microgravity surveys, electrical and electromagnetic methods, and geophysical well logging all can, potentially, provide valuable subsurface stratigraphic and structural imaging data, as well as information on subsurface properties such as the location of fractures and faults that could serve as migratory pathways for escape of injected CO2. Advanced field operations and field studies sponsored by DOE are utilizing a variety of geophysics in the life cycle of CO2 geologic sequestration. Examples include the Sleipner field operations in the North Sea, the Canadian Weyburn Enhanced Oil Field, the pilot CO2 injection into the Texas Frio Formation saline aquifer, the pilot CO2 injection in the West Pearl Queen depleted oil reservoir in New Mexico, and the characterization of potential reservoirs for the Ohio River Valley at the AEP Mountaineer Power Plant in Virginia. Geophysics is also important relative to the President’s initiative for a ten year, $1billion dollar FutureGen project to develop a power plant with “zero emissions.” This may be achieved, in part, by geologic sequestration of CO2.