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 cross-layer 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 nu 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 nu. 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/nu > K-v. Increasing the radial wellbore length can effectively facilitate fracture cross-/skip-layer propagation and reduce the critical threshold of injection parameters, which is conducive to maximizing the stimulated reservoir volume. (c) 2024 THE AUTHORS. Published by Elsevier LTD on behalf of Chinese Academy of Engineering and Higher Education Press Limited Company. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

关键字：Hydraulic fracturing; Continental shale oil; Multi-lithologic superimposed reservoir; Radial wellbore fracturing; Cross-layer

ISSN号：2095-8099

卷、期、页：卷45: 188-211

发表日期：2025-02-01

期刊分区（SCI为中科院分区）：一区

收录情况：SCI（科学引文索引印刷版）,EI（工程索引）,SCIE（科学引文索引网络版）

发表期刊名称：ENGINEERING

通讯作者：龙腾达,李琨,王子康

第一作者：武晓光,黄中伟,李根生,田守嶒,王海柱,杨睿月

论文类型：期刊论文

论文概要：武晓光,黄中伟,龙腾达,李根生,田守嶒,王海柱,杨睿月,李琨,王子康，Radial Wellbore Cross-Layer Fracturing in Multi-Lithologic Superimposed Shale Oil Reservoirs: A Laboratory Study，ENGINEERING，2025，卷45: 188-211

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