True triaxial hydraulic fracturing test and numerical simulation of limestone

Abstract

Hydraulic fracturing, as a key technology of deep energy exploitation, accelerates the rapid development of the modern petroleum industry. To study the mechanisms of hydraulic fracture propagation and rock failure mode of the vertical well hydraulic fracturing, the true triaxial hydraulic fracturing test and numerical simulation are carried out, and the influence of the principal stress difference, water injection displacement, perforation angle and natural fracture on fracture propagation is analyzed. The results show that the fracture propagation mode of limestone is mainly divided into two types: the single vertical fracture and the transverse-longitudinal crossed complex fracture. Under high displacement, the fracturing pressure is larger, and the secondary fracture is more likely to occur, while variable displacement loading is more likely to induce fracture network. Meanwhile, the amplitude of acoustic emission (AE) waveform of limestone during fracturing is between 0.01 and 0.02 mV, and the main frequency is maintained in the range of 230–300 kHz. When perforation angle θ=45°, it is easy to produce the T-type fracture that connects with the natural fracture, while X-type cracks are generated when 0=30°. The results can be used as a reference for further study on the mechanism of limestone hydraulic fracturing.

Keywords

true triaxial / hydraulic fracturing / acoustic emission / particle flow code (PFC) / perforation angle / natural fracture

References

[1] HuW-R, WeiY, BaoJ-W. Development of the theory and technology for low permeability reservoirs in China [J]. Petroleum Exploration and Development (English version), 2018, 45(4): 685-697

[2] VandenhoekP J, VandenbergJ T M, ShlyapoberskyJ. Theoretical and experimental investigation of rock dilatancy near the tip of a propagating hydraulic fracture [J]. International Journal of Rock Mechanics and Mining Science & Geomechanics Abstracts, 1993, 30(7): 1261-1264

[3] ZhangD-C, RanjithP G, PereraM S A. The brittleness indices used in rock mechanics and their application in shale hydraulic fracturing: A review [J]. Journal of Petroleum Science & Engineering, 2016, 143: 158-170

[4] PanD-D, LiS-C, XuZ-H, LiL-P, LuW, LinP, HuangX, SunS-Q, GaoC-L. Model tests and numerical analysis for water inrush caused by karst caves filled with confined water in tunnels [J]. Chinese Journal of Geotechnical Engineering, 2018, 40(5): 828-836

[5] LiuH-L, YangT-H, ChenS-K, YuQ-L, WangP-T. The mechanism of hydraulic fracturing and the engineering meaning of water outburst during rockmass failure [J]. Journal of Mining & Safety Engineering, 2010, 27(3): 356-362

[6] NaoiM, ChenY-Q, NishiharaK, YamamotoK, YanoS, WatanabeS. Monitoring hydraulically-induced fractures in the laboratory using acoustic emissions and the fluorescent method [J]. International Journal of Rock Mechanics and Mining Sciences, 2018, 104: 53-63

[7] WU Chen, GONG Feng-qiang, LUO Yong. A new quantitative method to identify the crack damage stress of rock using AE detection parameters [J]. Bulletin of Engineering Geology and Environment, 2020. DOI: https://doi.org/10.1007/s10064-020-01932-6.

[8] LiZ, JiaC-G, YangC-H, ZengY-J, GuoY-T, HengS, WangL, HouZ-K. Propagation of hydraulic fissures and bedding planes in hydraulic fracturing of shale [J]. Chinese Journal of Rock Mechanics and Engineering, 2015, 34(1): 12-20 in Chinese)

[9] WangH-Y. Hydraulic fracture propagation in naturally fractured reservoirs: Complex fracture or fracture networks [J]. Journal of Natural Gas Science and Engineering, 2019, 68: 102911

[10] ZhaoY, HeP-F, ZhangY-F, WangC-L. A new criterion for a toughness-dominated hydraulic fracture crossing a natural frictional interface [J]. Rock Mechanics & Rock Engineering, 2018, 52(8): 2617-2229

[11] GuoT-K, ZhangS-C, QuZ-Q, ZhouT, XiaoY-S, GaoJ. Experimental study of hydraulic fracturing for shale by stimulated reservoir volume [J]. Fuel, 2014, 128373-380

[12] MaG, ZhangF, LiuX, FengD, ZhangP-W. Experimental study of impact of crustal stress on fracturing pressure and hydraulic fracture [J]. Rock and Soil Mechanics, 2016, 37(S2): 216-222

[13] WuJ-J, ZhangS-H, SunP-H, CaoH, ChenJ-Z. Experimental study on acoustic emission characteristics in coal seam pulse hydraulic fracturing [J]. Journal of Central South University (Science and Technology), 2017, 48(7): 1866-1874(in Chinese)

[14] FanY, ZhaoY-L, ZhuZ-M, ZhouC-L, ZhangX-S. Theoretical study of break down pressures and fracture initiation angles based on model containing wellbore and perforations [J]. Journal of Central South University (Science and Technology), 2019, 50(3): 669-678(in Chinese)

[15] RuedaC J A, MejiaS E C, RoehlD, PereiraL C. Hydro-mechanical modeling of hydraulic fracture propagation and its interactions with frictional natural fractures [J]. Computers and Geotechnics, 2019, 111: 290-300

[16] LinH, DengJ-G, LiuW, XieT, XuJ, LiuH-L. Numerical simulation of hydraulic fracture propagation in weakly consolidated sandstone reservoirs [J]. Journal of Central South University, 2018, 25(12): 2944-2952

[17] PakzadR, WangS Y, SloanS W. Numerical simulation of hydraulic fracturing in low-/high-permeability, quasi-brittle and heterogeneous rocks [J]. Rock Mechanics & Rock Engineering, 2018, 51(4): 1153-1171

[18] TangC-A, ThamL G, LeeP K K, YangT-H. Coupled analysis of flow, stress and damage (FSD) in rock failure [J]. International Journal of Rock Mechanics & Mining Sciences, 2002, 39(4): 477-489

[19] LiZ-C, LiL-C, LiM, ZhangL-Y, TangC-A. A numerical investigation on the effects of rock brittleness on the hydraulic fractures in the shale reservoir [J]. Journal of Natural Gas Science & Engineering, 2017, 50: 22-32

[20] ShiG-H. Discontinuous deformation analysis: A new numerical model for the statics and dynamics of deformable block structures [J]. Engineering Computations, 1992, 9(2): 157-168

[21] VahabM, KhaliliN. Numerical investigation of the flow regimes through hydraulic fractures using the X-FEM technique [J]. Engineering Fracture Mechanics, 2016, 169: 146-162

[22] FarzinH, AliM. A new three dimensional approach to numerically model hydraulic fracturing process [J]. Journal of Petroleum Science and Engineering, 2014, 124: 451-467

[23] GAO Cheng-lu, ZHOU Zong-qing, LI Zhuo-hui, LI Li-ping, CHENG Shuai. Peridynamics simulation of surrounding rock damage characteristics during tunnel excavation [J]. Tunnelling and Underground Space Technology, 2020, 97. DOI: https://doi.org/10.1016/j.tust.2020.103289.

[24] ZhouZ-Q, RanjithP G, YangW-M, ShiS-S, WeiC-C, LiZ-H. A new set of scaling relationships for DEM-CFD simulations of fluid-solid coupling problems in saturated and cohesiveless granular soils [J]. Computational Particle Mechanics, 2019, 6(4): 657-669

[25] WangT, HuW-R, ElsworthD, ZhouW, ZhouW-B, ZhaoX-Y. The effect of natural fractures on hydraulic fracturing propagation in coal seams [J]. Journal of Petroleum Science & Engineering, 2017, 150: 180-190

[26] YoonJ S, ZangA, StephanssonO, HofmannH, ZimmermannG. Discrete element modelling of hydraulic fracture propagation and dynamic interaction with natural fractures in hard rock [J]. Procedia Engineering, 2017, 191: 1023-1031

[27] Itasca Consulting Group Inc. PFC2D-particle flow code in two dimensions [M]. Ver. 4.0 User’s Manual. ICG, Minneapolis.

[28] GuoT-K, QuZ-Q, GongD-G, LeiX, LiuM. Numerical simulation of directional propagation of hydraulic fracture guided by vertical multi-radial boreholes [J]. Journal of Natural Gas Science and Engineering, 2016, 35: 175-188

[29] ChengY-G, LuY-Y, GeZ-L, ChengL, ZhengJ-W, ZhangW-F. Experimental study on crack propagation control and mechanism analysis of directional hydraulic fracturing [J]. Fuel, 2018, 218: 316-324