Sequestering CO2 in geologic formations in the earth is a promising approach to reducing CO2 in the atmosphere and thereby slowing global warming. In these formations, it is important to understand where the CO2 is going and to assure that the sequestered CO2 is permanently contained. Seismic methods can assist in understanding why the CO2 has flowed into certain formations. Unfortunately, seismic methods are only weakly influenced by fluid properties that are essential in discriminating locations of high CO2 saturation. Electroseismic methods, which depend on injecting an electrical current into the earth and measuring the seismic response using electroseismic conversions, can provide for direct hydrocarbon indication and direct measurement of CO2 saturation. However, surface electroseismic measurements exhibit very weak signals. This project will determine the feasibility of using a crosswell geometry to enhance the signal-to-noise ratio (SNR) of the electroseismic conversions. In this configuration, travel paths would be shortened by placing receivers in the very quiet borehole environment.
Commercial Applications and Other Benefits as described by the awardee: Crosswell seismic/electroseismic measurements would allow CO2 to be characterized as it moves through the thin reservoir intervals that are typical in many reservoirs proposed for sequestration. These measurements also would allow for a much more complete look inside the reservoir to discover bypassed oil, target infill locations, and enhance the geologic and reservoir models used in oil and gas development. The anticipated market for crosswell electroseismic imaging is $100 to $200MM annually.
