A time-lapse CSEM monitoring study for hydraulic fracturing in shale gas reservoir

Hydraulic fracturing has been widely used in shale gas production. During the hydraulic fracturing, microcracks are open and filled with the conducive fluid, which enhances the overall hydraulic conductivity of the shale formulation. Undoubtedly, the monitoring of the fracturing process is crucially important for shale gas production. The controlled source electromagnetic method (CSEM) is sensitive to the electric conductivity change and can potentially be used for monitoring hydraulic fracturing. In this paper, we carried out numerical modeling and a field test on the CSEM monitoring of hydraulic fracturing at the Fuling shale gas field in southern China. Firstly, we perform the numerical modeling based on a synthetic model derived from the logging data of the field test site to investigate the effect of the steel-cased well on EM responses. Then, we investigate EM responses at the surface caused by the shale gas reservoir for different configurations to optimize survey parameters. Subsequently, the optimal broadside survey system is applied to investigate the effectiveness of CSEM monitoring on a synthetic hydraulic fracturing process. Finally, a real application is applied to carry out the time-lapse CSEM monitoring of the hydraulic fracturing during the shale gas production. Both the modeling results and the field data show the optimistic potential of use CSEM monitoring on the hydraulic fracturing process applied in the shale gas production.