Controlled Source Electromagnetic Monitoring of Hydraulic Fracturing

Controlled Source Electromagnetics (CSEM) have been used as a direct hydrocarbon indicator since the 1960s, with a resurgence in marine conventional settings in the new millennium, with many studies revolving around detecting a thin resistive layer such as a reservoir at 1m-3km depth. The presence of the resistive layer is characterized by a jump in electric field amplitude recorded at the boundary between the layer and the host sediments. Here the lessons learned from these studies are applied to terrestrial unconventional settings. However, unlike in marine settings where resistive hydrocarbon-charged fluids comprise a conventional reservoir, on land we are interested in electrically conductive injected fluids. The work shown here is a means to develop further methods to enable more reliable terrestrial CSEM monitoring of the flow of injected fluids associated with hydraulic fracturing of unconventional reservoirs and to detect subsurface fluids based on their CSEM signature and in turn, to infer the subsurface flow of electrically conductive injected fluids. Overall this project attempts to create more efficient fracturing, by determining fluid pathways, hence making projects more cost effective by reducing the cost of extraction. The predictive model developed focuses on the mapping of fluid flow in from a horizontal pipe in a uniform halfspace using a long in-line Horizontal Electric Dipole (HED) with electric field amplitude recorded by an array of electric field sensors. The code provided has been edited to include a long-dipole source in addition to the half dipole source originally in place in order to align with current CSEM field practices. The well casing has also been included due to its large effect on CSEM response.