Shale gas zipper fracturing interference model influenced by natural fractures-fault zones
WANG Qiang1，YANG Yu1，SONG Yi2，SHEN Cheng2，ZHAO Jinzhou1，HU Yongquan1，WANG Yufeng1
(1. State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation，Southwest Petroleum University，Chengdu，Sichuan 610500，China；2. Shale Gas Research Institute，PetroChina Southwest Oil and Gas Field Company，Chengdu，Sichuan 610051，China)
Abstract：In order to solve the problem of fracture intersection interference between deep shale gas wells in southern Sichuan，a numerical model of shale gas zipline fracturing is constructed based on finite-discrete element method，which considers the influence of natural fracture-fault structure. The model uses joint units with different mechanical properties to characterize natural fractures and faults，which can realize continuous simulation of multiple operation processes of“response well fracturing，response well shut-in，and excited well fracturing”，so as to accurately characterize physical behaviors such as fracture intersection，pressure and stress interference. The KGD analytical solution model of single fracture propagation and the experimental data of intersection between hydraulic fracture and natural fracture are used to verify the proposed model. Furthermore，a comparative case study has been conducted for typical well sections. The research results show that compared to natural fractures，the pressure drop response dynamics are more significant when intersecting with faults and hydraulic fractures. Under high stress difference，natural fractures are mainly subject to shear failure，while the matrix is mainly subject to tensile failure. At the initial stage of shut-in，natural fractures or faults continue to extend due to the net pressure of the remaining fluid in the fractures. After the fracture intersects between wells，the high pressure fluid of the exciting well preferentially flows into the response well through the high diversion channel，resulting in the increase of the response well pressure，the increase of filtration loss and the repeated reconstruction of some fractures，which will lead to the slow increase of the fracture length and the decrease of the overall fracturing efficiency.
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2025, Vol. 44 
