An Electrical Resistivity Tomography System Using Borehole Casing as Electrode (ERT-BCE) with Variable Depth to Track Movement of Subsurface CO2

Statement of the Problem: Carbon Capture and Storage (CCS) is a set of technologies used to reduce greenhouse gas emissions from large point sources, such as power plants and industrial facilities. CCS involves capturing carbon dioxide (CO2) emissions from these sources before they are released into the atmosphere, transporting the CO2 to a storage location, and securely storing it deep underground in geological formations. During the lifetime of such projects, continuous monitoring of subsurface CO2 concentrations helps to detect any potential leaks from storage sites, ensuring the safe and secure storage of CO2. DOE’s Carbon Transport & Storage Program is focusing on developing novel electromagnetic (EM) sensors to accurately and affordably monitor carbon dioxide (CO2) injected into the subsurface over the lifetime of such programs. Proposed Solution: To address this critical need, X-wave Innovations, Inc. (XII) along with our collaborator, Energy & Environmental Research Center (EERC) at University of North Dakota, proposes a novel electrical resistivity tomography (ERT) system using borehole casing as a variable-length electrode to map the subsurface above commercial-scale deep carbon storage reservoirs for the presence CO2. The proposed system is based on smart borehole casings that are designed to function as capacitively coupled electrodes with built-in rugged switches. This would solve two crucial issues related to deep downhole ERT measurements; first, capacitively coupled electrodes are not prone to corrosion like galvanic electrodes, and second, in-built switching capability significantly reduces the total length of wiring required for installation > 10000 ft deep. This reduces the cost of long-term CO2 monitoring and would ensure the permanence of the geological storage site. This method can be configured to work in borehole-to-borehole and borehole-to-surface configurations. Phase I work: During the Phase I program, XII and EERC will demonstrate the feasibility of the proposed ERT-BCE system. XII will use the EM/geophysical model of deep carbon storage reservoir provided by EERC to design the smart borehole casing electrodes using numerical simulations for use in deep downhole conditions. XII would develop a prototype of the smart electrodes including the built-in switching system. XII would also focus towards inverting EM data into 3D conductivity profiles using in-house expertise in deep learning-based AI and leveraging the geophysics expertise at EERC.Commercial Applications: The proposed technology is capable of monitoring CO2 content in the subsurface around deep carbon storage reservoirs using electrical conductivity measurements using novel smart electrodes. In addition to the application in CCS projects, the low-cost and rugged nature of the system is likely going to be of interest to several other fields which require long-term geophysical surveys. Mineral, hydrocarbon and groundwater exploration and engineering geology are fields which can benefit from the proposed sensor system. In Phase I, we will approach the experts from these fields to better understand the specific requirements.