GEOPHYSICAL TECHNIQUES FOR CO2 PLUME MONITORING

Author(s): Gasperikova, Erika; Daley, Thomas; Wang, Zan; Dilmore, Robert; Harbert, William; Huang, Lianjie; Gao, Kai; Chen, Ting; Zhang, Miao; Appriou, Delphine; Yang, Xianjin; Buscheck, Thomas; Mansoor, Kayyum; Carroll, Susan; Yonkofski, Catherine; Johnson, Timothy; Burghardt, Jeffrey; Strickland, Christopher; Brown, Christopher | Abstract: This report considers the application of number of different indirect (remote sensing) geophysical techniques for monitoring geologic sequestration of CO2 in brine-bearing formations. The time-lapse monitoring using seismic, gravity, electrical and electromagnetic techniques is described. Geophysical models used for numerical modeling are based on flow simulations of various CO2 sequestration scenarios. Different monitoring approaches are suitable for a site characterization prior to CO2 injection, for monitoring while injecting CO2, or for a post-injection stage. Basic principles of each technique are described. Workflows are described using various examples. Each of the techniques is sensitive to a different subsurface property. The seismic velocity depends on the bulk and shear modulus and density, the gravity response depends on density, and the electrical resistivity is sensitive to changes in formation properties such as porosity, pore fluid resistivity, and fluid saturation. For this reason these techniques are complementary to each other, and when used together they could provide improved characterization of the subsurface. In addition to individual techniques, incorporating an electrical resistance tomography (ERT) into DREAM (Designs for Risk Evaluation and Management) tool is also described.