The influence of fault reactivation on injection-induced dynamic triggering of permeability evolution
Abstract
Mechanisms controlling fracture permeability enhancement during injection-induced and natural dynamic stressing remain unresolved. We explore pressure-driven permeability (k) evolution by step-increasing fluid pressure (p) on near-critically stressed laboratory fractures in shale and schist as representative of faults in sedimentary reservoirs/seals and basement rocks. Fluid is pulsed through the fracture with successively incremented pressure to first examine sub-reactivation permeability response that then progresses through fracture reactivation. Transient pore pressure pulses result in a permeability increase that persists even after the return of spiked pore pressure to the null background level. We show that fracture sealing is systematically reversible with the perturbing pressure pulses and pressure-driven permeability enhancement is eminently reproducible even absent shear slip and in the very short term (order of minutes). These characteristics of the observed fracture sealing following a pressure perturbation appear similar to those of the response by rate-and-state frictional healing upon stress/velocity perturbations. Dynamic permeability increase scales with the pore pressure magnitude and fracture sealing controls the following per-pulse permeability increase, both in the absence and presence of reactivation. However, initiation of the injection-induced reactivation results in a significant increase in the rate of permeability enhancement (dk/dp). These results demonstrate the role of frictional healing and sealing of fractures at interplay with other probable processes in pore pressure-driven permeability stimulation, such as particle mobilization.
Additional Information
© The Author(s) 2020. Published by Oxford University Press on behalf of The Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model). Accepted 2020 August 3. Received 2020 August 2; in original form 2019 December 6. All experimental data are available as supplementary material. E.C. Yildirim acknowledges the financial support from Turkish Petroleum for her M.S. studies upon which this work is based.Attached Files
Published - ggaa382.pdf
Supplemental Material - ggaa382_supplemental_files.zip
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Additional details
- Eprint ID
- 105435
- Resolver ID
- CaltechAUTHORS:20200917-101103858
- Turkish Petroleum
- Created
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2020-09-17Created from EPrint's datestamp field
- Updated
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2021-11-16Created from EPrint's last_modified field