Pre-existing natural fractures and other structurally weak planes are usually well-developed in unconventional reservoirs. When such fractures intersect with hydraulic induced fractures, they will redirect and propagate as an important mechanical principle of volume fracturing by the formation of complex fracture networks. Under the shadow effect of natural fractures and other structurally weak planes with hydraulic Supported fracture stress, hydraulic fractures do not fully propagate in the direction of the maximum horizontal-principal-stress. This paper computed the stress intensity factors of hydraulic fracture types I and II by integrating the various interactions, established universally-applicable mechanical principles for the propagation behavior when a hydraulic fracture propagating in an arbitrary direction intersects with a natural fracture at an arbitrary angle, and demonstrated the mechanical principles of the intersection between hydraulic induced fractures and pre-existing natural fractures. This study proved the following conclusions: as the intersection angle between the hydraulic fracture and the maximum horizontal-principal-stress increased, the possibility of the hydraulic fracture being captured by the natural fracture with an identical approaching angle first increased and then decreased; as the net stress increased, the intersection behavior between the hydraulic fracture and the natural fracture transitioned from penetration to capture.
Acknowledgements
Sponsored by National Science and Technology Major Projects (2016ZX05052, 2016ZX05014).
| [1] |
Qi Wu, Yun Xu, Xiaoquan Wang, et al., Volume fracturing technology of unconventional reservoirs: connotation, optimization design and implementation, Petrol. Explor. Dev. 39 (3) (2012) 352-358.
|
| [2] |
Haifeng Zhao, Mian Chen, Yan Jin, et al., Rock fracture kinetics of the fracture mesh system in shale gas reservoirs, Petrol. Explor. Dev. 39 (4) (2012) 465-470.
|
| [3] |
J.F. Gale, R.M. Reed, J. Holder, Natural fractures in the Barnett shale and their importance for hydraulic fracture treatments, AAPG (Am. Assoc. Pet. Geol.) Bull. 91 (4) (2007) 603-622.
|
| [4] |
M.W. McClure, R.N. Horne, Characterizing hydraulic fracturing with a tendency for shear stimulation test, SPE Reservoir Eval. Eng. 17 (2) (2014) 233-243.
|
| [5] |
Wan Cheng, Yan Jin, Mian Chen, et al., A Criterion for identifying hydraulic fractures crossing natural fractures in 3D space, Petrol. Explor. Dev. 41 (3) (2014) 336-340.
|
| [6] |
R. Offenberger, N. Ball, K. Kanneganti, et al., Integration of Natural and Hydraulic Fracture Network Modeling with Reservoir Simulation for an Eagle Ford Well[C], SPE Unconventional Resources Technology Conference, 2013 SPE-168683-MS.
|
| [7] |
Tiankui Guo, Shicheng Zhang, Zhanqing Qu, et al., Experimental study of hydraulic fracturing for shale by stimulated reservoir volume, Fuel 128 (2014) 373-380.
|
| [8] |
Jian Zhou, Mian Chen, Yan Jin, et al., Analysis of fracture propagation behavior and fracture geometry using a tri-axial fracturing system in naturally fractured reservoirs, Int. J. Rock Mech. Min. Sci. 45 (7) (2008) 1143-1152.
|
| [9] |
Mian Chen, Jian Zhou, Yan Jin, et al., Experimental study on fracturing features in naturally fractured reservoir, Acta Pet. Sin. 29 (3) (2008) 431-434.
|
| [10] |
Jian Zhou, Mian Chen, Yan Jin, et al., Experiment of propagation mechanism of hydraulic fracture in multi-fracture reservoir, Journal of China University of Petroleum 32 (4) (2008) 1-54.
|
| [11] |
S. Mohammad, Experimental and Numerical Study of Interaction of a Pre-existing Natural Interface and an Induced Hydraulic Fracture[D]. Ph.D. Curtin University, Faculty of Science and Engineering, Department of Petroleum Engineering, 2012.
|
| [12] |
C.E. Renshaw, D.D. Pollard, An experimentally verified criterion for propagation across unbounded frictional interfaces in brittle, linear elastic materials, Int. J. Rock Mech. Min. Sci. Geomech. Abstr. 32 (3) (1995) 237-249.
|
| [13] |
H. Gu, X. Weng, J. Lund, et al., Hydraulic fracture crossing natural fracture at nonorthogonal angles: a criterion and its validation and application, SPE Prod. Oper. 27 (1) (2012) 20-26.
|
| [14] |
D. Chuprakov, O. Melchaeva, R. Prioul, et al., Injection-sensitive Mechanics of Hydraulic Fracture Interaction with Discontinuities[C]// Us Rock Mechanics/Geomechanics Symposium vol. 1, (2013).
|
| [15] |
Tiantang Yu, The Extended Finite Element Method —— Theory, Application and Program[M], Science Press, Beijing, 2014.
|
| [16] |
C.L. Tu, The boundary collocation method and its application to fracture surface under external force, J. Hydraul. Eng. 7 (1983) 9-16.
|
| [17] |
T.L. Blanton, An experimental study of interaction between hydraulically induced and pre-existing fractures[C], SPE Unconventional Gas Recovery Symposium, 1982, pp. 559-571 SPE-10847-MS.
|
| [18] |
R.J. Nuismer, An energy release rate criterion for mixed mode facture, International Jornal of Fracture 11 (2) (1975) 245-250.
|
| [19] |
A.D. Taleghani, Analysis of Hydraulic Fracture Propagation in Fractured Reservoirs: an Improved Model for the Interaction between Induced and Natural Fractures[D], The University of Texas at Austin, Doctoral Thesis, Texas, 2009, pp. 28-150.
|
| [20] |
Hui Xiao, Research of Hydraulic Fracturing Dynamic Propagation in Fractured Reservoirs[D], Doctoral Thesis Southwest Petroleum University, Chengdu, 2014.
|
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