Testing Novel Reservoir Stimulation and Fracture Imaging Methods
Creating a well-connected network of fractures in hot, impermeable rocks is central to the performance of enhanced geothermal systems. The amount of heat that can be extracted is directly influenced by several properties, such as reservoir permeability and fracture surface area. Our ability to not only enhance, but also measure those fracture attributes is crucial to a better understanding of geothermal energy production in hot dry rocks.
The Department of Energy Subsurface Technology and Engineering R&D (SubTER) crosscut is currently funding research to explore novel reservoir stimulation approaches combined with methods for real-time imaging of fracture networks. Last month I traveled to Socorro, New Mexico and participated in a targeted field demonstration of this new technology with a team of researchers led by Sandia National Laboratory that included support from Pacific Northwest National Laboratory (PNNL) and Lawrence Berkeley National Laboratory.
A series of stimulation tests were performed using a novel explosive developed by Sandia that is designed to maximize permeability and at the same time minimize unwanted damage to the borehole. In addition, a suite of geophysical (electrical resistivity tomography, cross-borehole seismic, distributed acoustic, and ground penetrating radar) imaging technologies were deployed along with hydraulic tests and injection of signal enhancing contrast agents to characterize the newly developed fracture network. Novel real-time imaging capabilities developed by PNNL were also demonstrated during the integrated test. This technology will help provide critical information for operational control of the fracture generation process in the future, and could be a technology demonstrated at DOE’s Frontier Observatory for Research in Geothermal Energy (FORGE) site.
About the Author
Dr. Chris Strickland is a geophysicist at Pacific Northwest National Laboratory in Richland, WA.