Wireless Electrical Resistivity Tomography System for CO2 Sequestration Monitoring

An effort is underway by the U.S. DOE to develop cost-effective and environmentally sound technologies in order to help to stabilize atmospheric concentrations of CO2 and to reduce greenhouse gas emissions. There is a significant need for economical methods to characterize potential sequestration reservoirs as well as determine the extent, location and nature of leaks from reservoirs both to assure that CO2 is effectively sequestered for long periods of time, and to reduce the likelihood of local environmental impacts. Electrical Resistivity Tomography (ERT) is a geophysical tool that has been used successfully to image the electrical resistivity of the subsurface, and is especially sensitive to pore fluid content. ERT is capable of monitoring movement of sequestered CO2 by measuring the change in the electrical resistivity of the subsurface, both in the saturated and vadose zones. Our ERT system under development consists of many, inexpensive, self-contained units that communicate with each other through a distributed wireless network. The capital expense of such a system would be relatively small. The operating expenses, once the system is automated, would also be small. In the Phase I project, the prototype system design was completed, a preliminary version of a new survey design strategy was implemented and a strategy for employing multiple, simultaneous current sources was developed. The new strategy will increase signal to noise levels and enhance target resolution. In Phase II Year 1 we will complete fabrication of the prototype system and operation software and adapt imaging routines for the multi-source strategy. We will complete all design upgrades and perform unit as well as full scale field tests in Year 2. Commercial Applications and Other Benefits There is a significant need for cost-effective methods to monitor CO2 sequestrationreservoirs in order to reduce the likelihood of local environmental impacts. This project will develop a cost-effective method of monitoring sequestration reservoirs for potential leakage pathways and for reservoir integrity using a geophysical method, Electrical Resistivity Tomography (ERT)