Radial Wellbore Cross-Layer Fracturing in Multi-Lithologic Superimposed Shale Oil Reservoirs:A Laboratory Study  

作　　者：Xiaoguang Wu Zhongwei Huang Tengda Long Gensheng Li Shouceng Tian Haizhu Wang Ruiyue Yang Kun Li Zikang Wang 

机构地区：[1]State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum(Beijing),Beijing 102249,China [2]Shanxi Key Laboratory of Carbon Dioxide Sequestration and Enhanced Oil Recovery,Xi’an 710075,China

出　　处：《Engineering》2025年第2期188-211,共24页工程(英文)

基　　金：supported by the National Natural Science Foun-dation of China(52421002,U24B6001,52204019,and 52192624);the Open Foundation of the Shanxi Key Laboratory of Carbon Dioxide Sequestration and Enhanced Oil Recovery。

摘　　要：Medium-high maturity continental shale oil is one of the hydrocarbon resources with the most potential for successful development in China.Nevertheless,the unique geological conditions of a multi-lithologic superposition shield the vertical propagation of hydraulic fractures and limit the longitudinal reconstruction in reservoirs,posing a great challenge for large-scale volumetric fracturing.Radial wellbore crosslayer fracturing,which transforms the interaction between the hydraulic fractures and lithologic interface into longitudinal multilayer competitive initiation,could provide a potential solution for this engineering challenge.To determine the longitudinal propagation behaviors of fractures guided by radial wellbores,true triaxial fracturing experiments were performed on multilayer shale-sandstone samples,with a focus on the injection pressure response,fracture morphology,and cross-layer pattern.The effects of the radial borehole length L,vertical stress difference K_(v),injection rate Q,and viscosity m of the fracturing fluid were analyzed.The results indicate that radial wellbores can greatly facilitate fracture initiation and cross-layer propagation.Unlike conventional hydraulic fracturing,there are two distinct fracture propagation patterns in radial wellbore fracturing:cross-layering and skip-layering.The fracture height guided by a radial wellbore is positively correlated with K_(v),Q,and m.Increasing these parameters causes a shift in the fracture initiation from a single root to an asynchronous root/toe end and can improve the cross-layer propagation capacity.Critical parameter thresholds exist for fracture propagation through and across interlayers under the guidance of radial boreholes.A parameter combination of critical cross-layering/skip-layering or alternating displacement/viscosity is recommended to simultaneously improve the fracture height and degree of lateral activation.The degree of correlation of different parameters with the vertical fracture height can be written as L>Q/m>K_(v).Increa

关 键 词：Hydraulic fracturing Continental shale oil Multi-lithologic superimposed reservoir Radial wellbore fracturing CROSS-LAYER 

分 类 号：TE357[石油与天然气工程—油气田开发工程] TE357.1