Laboratory modeling of induced microseismicity in the Illinois Basin

The CarbonSAFE Macon County Project is evaluating the potential for injecting and geologically storing commercial quantities of CO₂ captured from large industrial emitters in the Illinois Basin. Determining the potential for induced seismicity is an important component of this evaluation. Microseismic activity recorded from previous demonstration projects appears to be related to development on planes of weakness in the low-permeable Precambrian crystalline basement that lies below the injection formation. To evaluate induced seismicity risk for the development of large commercial projects, detailed investigations of fault stability should be performed case specifically before injection starts. In the case of Illinois Basin, industrial scale projects could potentially involve carbon dioxide injection of several million tonnes CO₂ per year, so both the geomechanical properties of rocks and fault material and the stress state should be properly characterized. In this study, the cores of Precambrian rhyolite are recovered from more than 2 km depth in CarbonSAFE Macon County Well and preliminary X-ray CT scanning shows presence of sealed fractures in some of them, while others appear to be intact. The influence of fractures on rock's poroelastic and strength properties is investigated. Laboratory data is used in a numerical code to simulate the reservoir and basement response and explain the observed induced seismicity.