The bound growth of induced earthquakes could de-risk hydraulic fracturing
Ryan Schultz, Federica Lanza, Ben Dyer, Dimitrios Karvounis, Rémi Fiori, Peidong Shi, Vanille Ritz, Linus Villiger, Peter Meier, Stefan Wiemer
Abstract
The world's energy supply depends critically on hydraulic fracturing (HF) to access otherwise uneconomical resources. Unfortunately, HF also has the potential to induce larger earthquakes - with some projects being prematurely terminated because of perceived earthquake risks. To de-risk HF, we use a suite of statistical tests to discern if some physical process has restricted the growth of earthquake magnitudes. We show that all stage stimulations at both UK PNR-1z and Helsinki St1 indicate bound fracture growth, implying a more controllable operation. Contrastingly, stimulations at Utah FORGE and UK PNR-2 sequentially transitioned into unbound fault reactivation. The problematic stages (that ultimately led to the termination of PNR-2) are clearly distinguishable. We postulate that our research can discriminate fracture stimulation from fault reactivation, contributing to the de-risking of HF operations worldwide. Our statistical tests provide a framework for model falsification, which can guide physical insights into the bounding processes.