By Robert Sabie, Jr., NM WRRI Research Scientist
Each month NM WRRI is featuring an eNews article describing an individual research focus of the ongoing New Mexico Universities Produced Water Synthesis Project (NMUPWSP). This month we are featuring the research project entitled, Monitoring of produced-waters-related seismicity and surface deformation in a three-dimensional geologic context in the Permian Basin, New Mexico, being performed by Drs. Alex Rinehart and Mairi Litherland and petroleum geologist, Joseph Grigg, from New Mexico Tech (NM Tech) in collaboration with Dr. Ronni Grapenthin, and PhD student Emily Graves from the University of Alaska at Fairbanks.
In New Mexico’s area of the Permian Basin, produced water that is co-produced during oil and gas extraction is separated out and is currently either treated and reused within the oil and gas industry, or reinjected through saltwater disposal wells into geologic formations containing brackish or brine aquifers. These brackish aquifers are deep under the surface, confined above and below by impermeable layers, and under pressure. As the formations are injected with produced water, the pressure increases. The injection of produced water into these formations and hydraulic fracturing near inactive faults has been linked to increases in seismic activity (Kerannen and Weingarten, 2018). As oil production in the Permian Basin has increased over the past few years, so has the need to understand the stress states of the injection horizons to ensure safe subsurface disposal of produced water.
The NM Tech research team is addressing this critical need identifying regions in the Permian Basin with increasing seismicity over the previous one to five years; identifying if these regions exhibit surface deformation using interferometric synthetic aperture radar (InSAR); identifying regions that experience aseismic surface deformation with InSAR; identifying wells undergoing injection operations in the region of interest and over the time period of interest; and, based on the detailed well construction and injection program information developed by other NMT collaborators, constructing a 1:100,000 scale three-dimensional geologic model in the form of a series of intersecting cross-sections of the formations injected in a region of heightened seismicity.
The overall goal of this project is to combine the results with other concurrent seismic and geodetic monitoring research in the region to establish an integrated monitoring program that will allow future researchers to infer when, where, and what volumes of produced waters may be injected and to ensure safe injection operations. This research may also guide future work on seismic risk in the region. As part of her core mission, Dr. Litherland will continue to monitor seismicity in the Permian Basin for the foreseeable future. Cross-sections, deformation maps, and correlations of seismicity to injection wells are forthcoming in the coming months.
Keranen, K.M. and Weingarten, M., 2018. Induced seismicity. Annual Review of Earth and Planetary Sciences.