Abstract
This article presents a comprehensive overview of several recent theoretical results at Northwestern University and demonstrates them by new numerical simulations of branching of hydraulic fractures. To model the inelastic behavior and fracturing of shale as an inherently anisotropic material, the recently developed spherocylindrical microplane model is described. Regarding the spread and branching of hydraulic cracks during the fracking process, it is emphasized that two kinds of water flow must be simulated: (1) the Poiseuille flow through the hydraulic fractures and natural cracks and (2) the Darcy diffusion flow of leak-off water through the pores of intact shale. The body forces due to gradient of Darcy flow pressure must be taken into account. The crack opening width is computed by means of the crack band model, in which each finite element is imagined to contain at the outset a potential cohesive crack, one in each of three spatial orientations, with the fracking water flowing through if the crack gets opened. The use of this model to suppress problems of mesh sensitivity due to localization of distributed fracturing is explained. Computer simulations of the growth of branched hydraulic system are preformed in two dimensions (2D) only. The results illustrate the effects of anisotropy and natural cracks on the evolution of 2D fracture patterns during the fracking process. These effects are not large, but much stronger effects are expected in future three-dimensional simulations.
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Beckwith, R.: Hydraulic fracturing: the fuss, the facts, the future. J. Pet. Technol. 62(12), 34–40 (2010)
Bažant, Z.P., Salviato, M., Chau, V.T., Viswanathan, H., Zubelewicz, A.: Why fracking works. J. Appl. Mech.-Trans. ASME. 81(10), 101010-1–101010-10 (2014)
Xie, H.P., Gao, F., Ju, Y., Xie, L.Z., Yang, Y.M., Wang, J.: Novel idea of the theory and application of 3D volume fracturing for stimulation of shale gas reservoirs. Chin. Sci. Bull. 61(1), 36–46 (2016)
Mokhtari, M., Bui, B.T., Tutuncu, A.N.: Tensile failure of shales: impacts of layering and natural fractures. In: SPE Western North American and Rocky Mountain Joint Meeting, Society of Petroleum Engineers (2014)
Niandou, H., Shao, J.F., Henry, J.P., Fourmaintraux, D.: Laboratory investigation of the mechanical behaviour of Tournemire shale. Int. J. Rock Mech. Min. Sci. 34(1), 3–16 (1997)
Masri, M., Sibai, M., Shao, J.F., Mainguy, M.: Experimental investigation of the effect of temperature on the mechanical behavior of tournemire shale. Int. J. Rock Mech. Min. Sci. 70, 185–191 (2014)
Heng, S., Guo, Y.T., Yang, C.H., Daemen, J.J.K., Li, Z.: Experimental and theoretical study of the anisotropic properties of shale. Int. J. Rock Mech. Min. Sci. 74, 58–68 (2015)
Sone, H.: Mechanical properties of shale gas reservoir rocks, and its relation to the in-situ stress variation observed in shale gas reservoirs. Ph.D. thesis, Stanford University (2012)
Rassouli, F., Zoback, M.: A comparison of short-term and long-term creep experiments in unconventional reservoir formations. In: 50th US Rock Mechanics/Geomechanics Symposium, American Rock Mechanics Association (2016)
Tsai, S.W., Wu, E.M.: A general theory of strength for anisotropic materials. J. Compos. Mater. 5(1), 58–80 (1971)
Hill, R.: The Mathematical Theory of Plasticity, vol. 11. Oxford University Press, Oxford (1998)
Lee, Y.K., Pietruszczak, S.: Tensile failure criterion for transversely isotropic rocks. Int. J. Rock Mech. Min. Sci. 79, 205–215 (2015)
Rao, K.S., Rao, G.V., Ramamurthy, T.: A strength criterion for anisotropic rocks. Ind. Geotech. J. 16(4), 317–333 (1986)
Jaeger, J.C.: Shear failure of anistropic rocks. Geol. Mag. 97(1), 65–72 (1960)
Hoek, E.: Strength of jointed rock masses. Geotechnique 33(3), 187–223 (1983)
Duveau, G., Shao, J.F., Henry, J.: Assessment of some failure criteria for strongly anisotropic geomaterials. Mech. Cohesive-Frict. Mater. 3(1), 1–26 (1998)
Jin, W.C., Xu, H., Arson, C., Busetti, S.: Computational model coupling mode ii discrete fracture propagation with continuum damage zone evolution. Int. J. Numer. Anal. Methods Geomech. 41(2), 223–250 (2016)
Levasseur, S., Welemane, H., Kondo, D.: A microcracks-induced damage model for initially anisotropic rocks accounting for microcracks closure. Int. J. Rock Mech. Min. Sci. 77, 122–132 (2015)
Jin, W.C., Arson, C.: Discrete equivalent wing crack based damage model for brittle solids. Int. J. Solids Struct. 110, 279–293 (2017)
Ravi-Chandar, K., Knauss, W.: An experimental investigation into dynamic fracture, III. On steady-state crack propagation and crack branching. Int. J. Fract. 26(2), 141–154 (1984)
Garagash, D., Detournay, E.: The tip region of a fluid-driven fracture in an elastic medium. J. Appl. Mech.-Trans. ASME 67(1), 183–192 (2000)
Bunger, A.P., Detournay, E., Garagash, D.I.: Toughness-dominated hydraulic fracture with leak-off. Int. J. Fract. 134(2), 175–190 (2005)
Detournay, E.: Propagation regimes of fluid-driven fractures in impermeable rocks. Int. J. Geomech. 4(1), 35–45 (2004)
Lecampion, B., Desroches, J.: Simultaneous initiation and growth of multiple radial hydraulic fractures from a horizontal wellbore. J. Mech. Phys. Solids. 82, 235–258 (2015)
Wang, H.: Poro-elasto-plastic modeling of complex hydraulic fracture propagation, simultaneous multi-fracturing and producing well interference. Acta Mech. 227(2), 507–525 (2016)
Waters, G.A., Lewis, R.E., Bentley, D.: The effect of mechanical properties anisotropy in the generation of hydraulic fractures in organic shales. In: SPE Annual Technical Conference and Exhibition. Society of Petroleum Engineers (2011)
Nagel, N.B., Sanchez-Nagel, M.A., Zhang, F., Garcia, X., Lee, B.: Coupled numerical evaluations of the geomechanical interactions between a hydraulic fracture stimulation and a natural fracture system in shale formations. Rock Mech. Rock Eng. 46(3), 581–609 (2013)
Chau, V.T., Bažant, Z.P., Su, Y.W.: Growth model for large branched three-dimensional hydraulic crack system in gas or oil shale. Phil. Trans. R. Soc. A. 374(2078), 20150418 (2016)
Chau, V.T., Li, C.B., Rahimi-Aghdam, S., Bažant, Z.P.: The enigma of large-scale permeability of gas shale: pre-existing or frac-induced? J. Appl. Mech.-Trans. ASME. 84(6), 061008-1–061008-11 (2017)
Li, C.B., Caner, F.C., Chau, V.T., Bažant, Z.P.: Spherocylindrical microplane constitutive model for shale and other anisotropic rocks. J. Mech. Phys. Solids. 103, 155–178 (2017)
Bažant, Z.P.: Comment on orthotropic models for concrete and geomaterials. J. Eng. Mech. 109(3), 849–865 (1983)
Brocca, M., Bažant, Z.P., Daniel, I.M.: Microplane model for stiff foams and finite element analysis of sandwich failure by core indentation. Int. J. Solids Struct. 38, 8111–8132 (2001)
Cusatis, G., Beghini, H., Bažant, Z.P.: Spectral stiffness microplane model for quasi-brittle composite laminates. I. Theory. J. Appl. Mech.-Trans. ASME 75(1), 021009-1–021009-9 (2008)
Šmilauer, V., Hoover, C.G., Bažant, Z.P., Caner, F.C., Waas, K.W., Shahwan, K.: Multiscale simulation of fracture of braided composites via repetitive unit cell. Eng. Fract. Mech. 78(6), 901–918 (2011)
Kirane, K., Salviato, M., Bažant, Z.P.: Microplane-triad model for elastic and fracturing behavior of woven composites. J. Appl. Mech.-Trans. ASME 83(4), 041006-1–041006-14 (2016)
Bažant, Z.P., Oh, B.H.: Efficient numerical integration on the surface of a sphere. ZAMM-J. Appl. Math. Mech. 66(1), 37–49 (1986)
Caner, F.C., Bažant, Z.P.: Microplane model M7 for plain concrete. I. Formulation. J. Eng. Mech. 139(12), 1714–1723 (2013)
Bažant, Z.P., Xiang, Y.Y., Prat, P.C.: Microplane model for concrete. I: stress–strain boundaries and finite strain. J. Eng. Mech. 122(3), 245–254 (1996)
Freeman, C., Moridis, G., Blasingame, T.: A numerical study of microscale flow behavior in tight gas and shale gas reservoir systems. Transp. Porous Media 90(1), 253–268 (2011)
Ilgen, A.G., Heath, J.E., Akkutlu, I.Y., Bryndzia, L.T., Cole, D.R., Kharaka, Y.K., Kneafsey, T.J., Milliken, K.L., Pyrak-Nolte, L.J., Suarez-Rivera, R.: Shales at all scales: exploring coupled processes in mudrocks. Earth-Sci. Rev. 166, 132–151 (2017)
Bažant, Z.P.: Crack band model for fracture of geomaterials. In: Eisenstein, Z. (eds.) Proceedings of 4th International Conference on Numerical Methods on Geomechanics, vol. 3. University of Alberta, Edmonton, pp 1137–1152 (1982)
Bažant, Z.P., Oh, B.H.: Crack band theory for fracture of concrete. Mater. Struct. 16(3), 155–177 (1983)
Červenka, J., Bažant, Z.P., Wierer, M.: Equivalent localization element for crack band approach to mesh-sensitivity in microplane model. Int. J. Numer. Methods Eng. 62(5), 700–726 (2005)
Bažant, Z.P., Planas, J.: Fracture and Size Effect in Concrete and Other Quasibrittle Materials. CRC Press, Boca Raton and London (1998)
Hull, K.L., Abousleiman, Y.N., Han, Y., Al-Muntasheri, G.A., Hosemann, P., Parker, S.S., Howard, C.B.: Nanomechanical characterization of the tensile modulus of rupture for kerogen-rich shale. SPE Journal. SPE-177628-PA (2017)
Sneddon, I.N.: The distribution of stress in the neighborhood of a crack in an elastic solid. Proc. R. Soc. A: Math. Phys. Eng. Sci. 187(1009), 229–260 (1946)
Dohmen, T., Zhang, J., Blangy, J.P.: Measurement and analysis of 3D stress shadowing related to the spacing of hydraulic fracturing in unconventional reservoirs. SPE Annual Technical Conference and Exhibition, Society of Petroleum Engineers (2014)
Acknowledgements
Partial financial support from the US Department of Energy through Subcontract No. 37008 of Northwestern University with Los Alamos National Laboratory is gratefully acknowledged. The simulation of fracturing damage also received some support from ARO Grant W911NF-15-101240 to Northwestern University. The first author wishes to thank the Department of Science and Technology of Sichuan Province (Nos. 2015JY0280, 2012FZ0124) and CSC for supporting him as a Research Fellow at Northwestern University. Collaboration with Sichuan University which led to important understanding of Longmaxi shale is deeply appreciated.
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This paper is dedicated to the memory of Franz Ziegler
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Li, C., Chau, V.T., Xie, H. et al. Recent advances in mechanics of fracking and new results on 2D simulation of crack branching in anisotropic gas or oil shale. Acta Mech 229, 975–992 (2018). https://doi.org/10.1007/s00707-017-2010-5
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DOI: https://doi.org/10.1007/s00707-017-2010-5