Simulation method of fracture propagation in fractured tight reservoir based on embedded mesh
XU Shiqian1，GUO Jiangchun1，YOUNIS Rami2，LU Cong1
(1. State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation，Southwest Petroleum University，Chengdu，
Sichuan 610500，China；2. Harold Vance Department of Petroleum Engineering，Texas A&M
University，Texas，College Station 77843，USA)
Abstract：To efficiently and accurately simulate fracture propagation in tight reservoirs with different types of natural fractures，a fully coupled hydro-geomechanical model based on embedded mesh is adopted. A time step adaptive adjustment strategy is proposed to improve the efficiency of main fracture propagation. The energy release rate method is employed to consider the effect of strongly cemented natural fractures. The damage model is applied to simulate the activation of weakly cemented natural fractures. After that，the influence of different types of natural fractures on the fracture propagation is investigated. The results show that：(1) the time step adjustment strategy can improve the computational efficiency of main fracture propagation by 50%. (2) If the orientation of strongly cemented natural fractures is relatively consistent，it is recommended to adjust the fracturing direction perpendicular or parallel to the natural fracture orientation appropriately. It can help reduce the likelihood of inter-well interference，making it suitable for closely spaced multi-cluster fracturing. (3) On a small scale，the hydraulic fracture geometry and fluid pressure field are greatly affected by the distribution of weakly cemented natural fractures. In addition，these natural fractures affect the tensile strength of the matrix rock. The lower the tensile strength，the larger the stimulated reservoir volume，the stronger the fluid loss effect，and the shorter the main fracture length. (4) On a large scale，when natural fractures of different cementation strengths exist，hydraulic fractures tend to form curved main fractures with damage zones. The method provides an efficient tool for fracturing simulation and optimization in fractured tight reservoirs.
[1] 邹才能，杨 智，何东博，等. 常规–非常规天然气理论、技术及前景[J]. 石油勘探与开发，2018，45(4)：575–587.(ZOU Caineng，YANG Zhi，HE Dongbo，et al. Theory，technology and prospects of conventional and unconventional natural gas[J]. Petroleum Exploration and Development，2018，45(4)：575–587.(in Chinese))
[2] 孙龙德，邹才能，贾爱林，等. 中国致密油气发展特征与方向[J]. 石油勘探与开发，2019，46(6)：1 015–1 026.(SUN Longde，ZOU Caineng，JIA Ailin，et al. Development characteristics and orientation of tight oil and gas in China[J]. Petroleum Exploration and Development，2019，46(6)：1 015–1 026.(in Chinese))
[3] 王小娟，洪海涛，吴长江，等. 四川盆地川中地区侏罗系沙溪庙组致密砂岩储层特征及成因[J]. 吉林大学学报：地球科学版，2022，52(4)：1 037–1 051.(WANG Xiaojuan，HONG Haitao，WU Changjiang，et al. Characteristics and formation mechanisms of tight sandstone reservoirs in Jurassic Shaximiao Formation，central of Sichuan Basin[J]. Journal of Jilin University：Earth Science，2022，52(4)： 1 037–1 051.(in Chinese))
[4] 李王鹏，刘忠群，胡宗全，等. 四川盆地川西坳陷新场须家河组二段致密砂岩储层裂缝发育特征及主控因素[J]. 石油与天然气地质，2021，42(4)：884–897.(LI Wangpeng，LIU Zhongqun，HU Zongquan，et al. Characteristics of and main factors controlling the tight sandstone reservoir fractures in the 2nd member of Xujiahe Formation in Xinchang area，Western Sichuan Depression，Sichuan Basin[J]. Oil and Gas Geology，2021，42(4)：884–897.(in Chinese))
[5] RU Z，HU J，MADNI A S，et al. A study on the optimal conditions for formation of complex fracture networks in fractured reservoirs[J]. Journal of Structural Geology，2020，135：104039.
[6] WANG H. Hydraulic fracture propagation in naturally fractured reservoirs：complex fracture or fracture networks[J]. Journal of Natural Gas Science and Engineering，2019，68：102911.
[7] ZHAO H，LI W，WANG L，et al. The influence of the distribution characteristics of complex natural fracture on the hydraulic fracture propagation morphology[J]. Frontiers in Earth Science，2022，9：784931.
[8] ZHANG H，CHEN J，ZHAO Z，et al. Hydraulic fracture network propagation in a naturally fractured shale reservoir based on the “well factory” model[J]. Computers and Geotechnics，2023，153：105103.
[9] ZOU J，JIAO Y，TAN F，et al. Complex hydraulic-fracture-network propagation in a naturally fractured reservoir[J]. Computers and Geotechnics，2021，135：104165.
[10] XIONG D，MA X. Influence of natural fractures on hydraulic fracture propagation behaviour[J]. Engineering Fracture Mechanics，2022，276：108932.
[11] LIU Z，PAN Z，LI S，et al. Study on the effect of cemented natural fractures on hydraulic fracture propagation in volcanic reservoirs[J]. Energy，2022，241：122845.
[12] WANG X，CHEN J，REN D，et al. Role of natural fractures with topology structure for hydraulic fracture propagation in continental shale reservoir[J]. Engineering Fracture Mechanics，2023，284：109237.
[13] 李 军，翟文宝，陈朝伟，等. 基于零厚度内聚力单元的水力裂缝随机扩展方法研究[J]. 岩土力学，2021，42(1)：265–279.(LI Jun，ZHAI Wenbao，CHEN Zhaowei，et al. Research on random propagation method of hydraulic fracture based on zero-thickness cohesive element[J]. Rock and Soil Mechanics，2021，42(1)：265–279.(in Chinese))
[14] ZHENG H，PU C，SUN C. Study on the interaction between hydraulic fracture and natural fracture based on extended finite element method[J]. Engineering Fracture Mechanics，2020，230：106981.
[15] RASHID H，OLORODE O，CHUKWUDOZIE C. An iteratively coupled model for flow，deformation，and fracture propagation in fractured unconventional reservoirs[J]. Journal of Petroleum Science and Engineering，2022，214：110468.
[16] ZHOU Y，YANG D，ZHANG X，et al. Numerical investigation of the interaction between hydraulic fractures and natural fractures in porous media based on an enriched FEM[J]. Engineering Fracture Mechanics，2020，235：107175.
[17] LI Z，LI X，YU J，et al. Influence of existing natural fractures and beddings on the formation of fracture network during hydraulic fracturing based on the extended finite element method[J]. Geomechanics and Geophysics for Geo-Energy and Geo-Resources，2020，6：1–13.
[18] DONG Y，TIAN W，LI P，et al. Numerical investigation of complex hydraulic fracture network in naturally fractured reservoirs based on the XFEM[J]. Journal of Natural Gas Science and Engineering，2021，96：104272.
[19] SUO Y，CHEN Z，RAHMAN S S，et al. Numerical simulation of mixed-mode hydraulic fracture propagation and interaction with different types of natural fractures in shale gas reservoirs[J]. Environmental Earth Sciences，2020，79：1–11.
[20] ZHANG B，GUO T，QU Z，et al. Numerical simulation of fracture propagation and production performance in a fractured geothermal reservoir using a 2D FEM-based THMD coupling model[J]. Energy，2023，273：127175.
[21] ROTH S N，LÉGER P，SOULAÏMANI A. A combined XFEM- damage mechanics approach for concrete crack propagation[J]. Computer Methods in Applied Mechanics and Engineering，2015，283：923–955.
[22] AYATOLLAHI M，SEDIGHIANI K. Mode I fracture initiation in limestone by strain energy density criterion[J]. Theoretical Applied Fracture Mechanics，2012，57(1)：14–18.
[23] SEWERYN A. A non-local stress and strain energy release rate mixed mode fracture initiation and propagation criteria[J]. Engineering Fracture Mechanics，1998，59(6)：737–760.
[24] BOULENOUAR A，BENSEDDIQ N，MAZARI M. Strain energy density prediction of crack propagation for 2D linear elastic materials[J]. Theoretical Applied Fracture Mechanics，2013，67： 29–37.
[25] DUMSTORFF P，MESCHKE G. Crack propagation criteria in the framework of X-FEM-based structural analyses[J]. International Journal for Numerical Analytical Methods in Geomechanics，2007，31(2)：239–259.
[26] MARSHALL D，COX B. A J-integral method for calculating steady- state matrix cracking stresses in composites[J]. Mechanics of Materials，1988，7(2)：127–133.
[27] REN G，YOUNIS R M. Efficient co-solution of time step size and independent state in simulations of fluid-driven fracture propagation with embedded meshes[J]. International Journal for Numerical Methods in Engineering，2022，123(10)：2 262–2 289.
[28] WANG X，SHI F，LIU C，et al. Extended finite element simulation of fracture network propagation in formation containing frictional and cemented natural fractures[J]. Journal of Natural Gas Science Engineering，2018，50：309–324.
[29] DAHI-TALEGHANI A，OLSON J E. How natural fractures could affect hydraulic-fracture geometry[J]. SPE Journal，2013，19(1)： 161–171.
[30] XIE L，MIN K B，SHEN B. Simulation of hydraulic fracturing and its interactions with a pre-existing fracture using displacement discontinuity method[J]. Journal of Natural Gas Science and Engineering，2016，36：1 284–1 294.
[31] DAHI-TALEGHANI A，OLSON J E. Numerical modeling of multistranded-hydraulic-fracture propagation：accounting for the interaction between induced and natural fractures[J]. SPE Journal，2011，16(3)：575–581.
[32] WU K，OLSON J E. Mechanics analysis of interaction between hydraulic and natural fractures in shale reservoirs[C]// Proceedings of SPE/AAPG/SEG Unconventional Resources Technology Conference Denver，Colorado，USA：[s. n.]，2014：1 824–1 841.
[33] ZHANG X，JEFFREY R G. Role of overpressurized fluid and fluid-driven fractures in forming fracture networks[J]. Journal of Geochemical Exploration，2014，144：194–207.
[34] MAZARS J，PIJAUDIER-CABOT G. Continuum damage theory- application to concrete[J]. Journal of Engineering Mechanics，1989，115(2)：345–365.
[35] GUNN R M. Non-linear analysis of arch dams including an anisotropic damage mechanics based constitutive model for concrete[Ph. D. Thesis][D]. Brighton：University of Brighton，1998.
[36] CHEN L，LIU X，LIANG L，et al. Experimental study on rock mechanical properties of tight oil reservoirs in JM area[C]// Proceedings of 2nd SEG Rock Physics Workshop：Challenges in Deep and Unconventional Oil/Gas Exploration. Qingdao，China：[s. n.]，2019：41–44.
2025, Vol. 44 
