loading page

Coupled poroelastic modelling of hydraulic fracturing-induced seismicity: Implications for understanding the post shut-in ML 2.9 earthquake at the Preston New Road, UK
  • Wenzhuo Cao,
  • James P. Verdon,
  • Ming Tao
Wenzhuo Cao
Imperial College London

Corresponding Author:w.cao15@imperial.ac.uk

Author Profile
James P. Verdon
University of Bristol
Author Profile
Ming Tao
School of Resources and Safety Engineering, Central South University
Author Profile


Post-injection seismicity associated with hydraulic stimulation has posed great challenges to hydraulic fracturing operations. This work aims to identify the causal mechanism of the post shut-in ML 2.9 earthquake in August 2019 at the Preston New Road, UK, amongst three plausible mechanisms, i.e., the post shut-in pore pressure diffusion, poroelastic stressing on a non-overpressurised fault, and poroelastic stressing on an overpressurised fault. A 3D fully-coupled poroelastic model that considers the poroelastic solid deformation, fluid flow in both porous rocks and fracture structures, and hydraulic fracture propagation was developed to simulate the hydromechanical response of the shale reservoir formation to hydraulic fracturing operations at the site. Based on the model results, Coulomb stress changes and seismicity rate were further evaluated on the PNR-2 fault responsible for the earthquake. Model results have shown that increased pore pressure plays a dominant role in triggering the fault slippage, although the poroelastic stress may have acted to promote the slippage. Amongst the three plausible mechanisms, the post shut-in pore pressure diffusion is the most favoured in terms of Coulomb stress change, seismicity rate, timing of fault slippage and rupture area. The coupled modelling results suggested that the occurrence of the post shut-in ML 2.9 earthquake was a three-staged process, involving first propagation of fracture tips that stimulated surrounding reservoir formations, then hydraulic connection with and subsequent pore pressure diffusion to the partially-sealing PNR-2 fault, and eventually fault activation primarily under the direct impact of increased pore pressure.
Mar 2022Published in Journal of Geophysical Research: Solid Earth volume 127 issue 3. 10.1029/2021JB023376