USING EARTHQUAKE CATALOGS AND GEOLOGIC DATA TO ASSIST WITH CHARACTERIZING INDUCED SEISMICITY POTENTIAL FROM CCUS

As part of the Midwest Regional Carbon Initiative, a project funded by DOE and managed by Battelle, the potential for inducing earthquakes from future carbon capture, use, and sequestration (CCUS) is being assessed across a broad 20-state region of the northeastern U.S. Recent studies of induced seismicity (IS) in the project area, specifically in Illinois, Indiana, Ohio, Pennsylvania, and West Virginia, suggest that an injection zone’s proximity to crystalline basement is a major factor related to IS susceptibility. To assist with identifying candidate reservoirs for CCUS with low IS susceptibility, we are assessing this correlation in detail.

We developed an earthquake catalog that contains all known earthquakes of magnitude 2.2 and greater and all known events of any magnitude since 2009. The list includes events induced or likely induced by wastewater disposal and fracking gathered from the literature. We have also compiled relevant geological datasets including the tops and bases of the formations containing the reservoirs associated with IS and those suitable for CCUS, and we have developed a new, detailed topographic map of the top of the Precambrian crystalline basement. Consistent with the previous studies, our preliminary findings show that in all cases of IS but those in West Virginia, earthquakes were induced by fluid injections within ~1 km of basement. The probable IS cases in West Virginia, which occurred near the southeastern boundary of the Rome Trough, correlated with fluid injections at heights in the sedimentary strata from ~3.5 km to ~4.5 km above the Precambrian. The next steps in our assessment will involve: (1) developing an isopach map for depths below the supercritical CO₂ horizon and 1 km above basement (although a special case for the Rome Trough will need to be developed) and (2) characterizing relevant stratigraphy in regions of shallow (< 5 km) tectonic earthquakes with well-constrained focal depths, where there is potentially a greater risk of future induced seismicity.