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Fault Reactivation Controlled by Elastic Stress Transfer during Hydraulic Fracturing at Preston New Road, UK
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 82nd EAGE Annual Conference & Exhibition, Oct 2021, Volume 2021, p.1 - 5
Abstract
Summary
We investigate the physical mechanisms that produced felt seismicity during hydraulic stimulation of the Preston New Road PNR-1z well in Lancashire, England in October – December 2018. While pore pressure increases are typically assumed to be the principal cause of induced seismicity, other factors such as poroelastic stress transfer and aseismic slip have also been proposed as alternative mechanisms. At PNR-1z, a downhole microseismic monitoring array detected and located over 38,000 events during the stimulation, which revealed the interaction between the hydraulic fractures and a pre-existing fault. Here we probe this interaction in more detail, focussing on the role played by elastic stress transfer produced by the tensile opening of hydraulic fractures. We generate stochastic models to simulate the impact of tensile fracture opening on the surrounding stress field, and find that the observed microseismic event locations occur predominantly in regions where these effects moved the stress conditions towards the failure envelope. We therefore conclude that elastic stress transfer from tensile opening of hydraulic fractures played an important role in controlling fault reactivation at this site.
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