Study Reveals How Pre-existing Fractures Control Hydraulic Fracture Propagation Through Stress Redistribution
Researchers conducted laboratory experiments and computer simulations to understand how natural fractures influence the path of hydraulic fractures in rock formations. The study found that stress redistribution around pre-existing fractures determines whether hydraulic fractures are attracted to or deflected away from them. These findings have implications for optimizing hydraulic fracturing in oil and gas extraction and subsurface storage applications.
A new study published on arXiv investigates the interaction between hydraulic fractures (HF) and pre-existing natural fractures (NF) in rock formations using coupled laboratory experiments and numerical simulations. Researchers tested PMMA specimens under various stress conditions while using digital image correlation to measure displacement and strain during hydraulic fracturing. The key finding is that the trajectory of hydraulic fractures is governed by shear stress and shear strain components generated by the orientation of natural fractures relative to the far-field maximum principal stress. When shear deformation promotes compressive stress near a natural fracture, the hydraulic fracture deflects away; conversely, when shear deformation reduces normal stress along the natural fracture, the hydraulic fracture is attracted to it. The numerical simulations revealed that hydraulic fractures in pre-fractured specimens require mixed-mode fracture criteria to accurately model their curved propagation, whereas intact specimens propagate in pure tensile mode. These mechanistic insights could improve prediction and control of fracture trajectories in subsurface stimulation and storage applications.
What's missing
The study's limitations regarding the use of PMMA as a rock analog material and the applicability of plane-strain laboratory conditions to three-dimensional field scenarios are not discussed in the abstract. Additionally, the abstract does not specify the range of natural fracture orientations tested or discuss how results may vary with different rock types, fluid properties, or in-situ stress regimes encountered in real subsurface applications.
What different sources said
- arXiv physicsCenter
Local Stress Redistribution Controls Interactions between Hydraulic Fractures and Pre-existing Fractures
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