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Open AccessArticle

Investigation of Hydraulic Fracturing Behavior in Heterogeneous Laminated Rock Using a Micromechanics-Based Numerical Approach

by 1,2,3,*, 3, 1,2, 1,2 and 1,2
1
Key Laboratory of Shale Gas and Geoengineering, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
2
Institutions of Earth Science, Chinese Academy of Sciences, Beijing 100029, China
3
School of Engineering, University of British Columbia, Kelowna, BC V1V 1V7, Canada
*
Author to whom correspondence should be addressed.
Energies 2019, 12(18), 3500; https://doi.org/10.3390/en12183500
Received: 3 July 2019 / Revised: 8 August 2019 / Accepted: 10 September 2019 / Published: 11 September 2019
(This article belongs to the Section Geo-Energy)
Understanding hydraulic fracturing mechanisms in heterogeneous laminated rocks is important for designing and optimizing well production, as well as for predicting shale gas production. In this study, a micromechanics-based numerical approach was used to understand the physical processes and underlying mechanisms of fracking for different strata orientations, in-situ stresses, rock strengths, and injection parameters. The numerical experiments revealed a very strong influence of the pre-existing weakness planes on fracking. Geological models for rock without weakness planes and laminated rock behave very differently. Most simulated fractures in the rock without weakness planes were caused by tensile failure of the rock matrix. In an intact rock model, although a radial damage zone was generated around the injection hole, most of the small cracks were isolated, resulting in poor connectivity of the fracture network. For rock models with pre-existing weakness planes, tension and shear failure of these structural planes formed an oval-shaped network. The network was symmetrically developed around the injection well because the strength of the pre-existing weakness planes is generally lower than the rock matrix. The research shows that the angular relations between the orientation of the structural planes and the maximum horizontal stress, as well as the in-situ stress ratios, have significant effects on the morphology and extent of the networks. The strength of the pre-existing weakness planes, their spacing, and the injection rate can dramatically influence the effectiveness of hydraulic fracturing treatments. View Full-Text
Keywords: hydraulic fracturing; laminated rocks; micromechanics; coupled fluid-mechanical model; heterogeneity; anisotropic behavior hydraulic fracturing; laminated rocks; micromechanics; coupled fluid-mechanical model; heterogeneity; anisotropic behavior
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MDPI and ACS Style

Zhao, H.; Tannant, D.D.; Ma, F.; Guo, J.; Feng, X. Investigation of Hydraulic Fracturing Behavior in Heterogeneous Laminated Rock Using a Micromechanics-Based Numerical Approach. Energies 2019, 12, 3500.

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