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<p>Layered argillaceous limestone, prevalent in continental shale reservoirs, is characterized by rich organic matter and favorable oil-bearing conditions. Nevertheless, the interaction mechanisms between hydraulic fractures (HFs) and bedding planes (BPs), which significantly influence hydraulic fracturing and stimulated reservoir volume (SRV), remain inadequately understood. In this study, true triaxial hydraulic fracturing experiments were carried out using acoustic emission (AE) monitoring and three-dimensional computed tomography (CT) scanning to investigate the effects of bedding plane density (<i>D</i><sub><i>bp</i></sub>) on vertical fracture propagation modes, AE responses, and fracture characteristics. Additionally, we established a response surface methodology (RSM) integrating a finite element model based on flow-stress-damage coupling with Box–Behnken design to analyze how in-situ stress, bedding mechanical properties, and construction factors affect hydraulic fracture behavior and SRV. Results reveal that four complex non-planar propagation modes occur when HFs interact with BPs. Increased <i>D</i><sub><i>bp</i></sub> results in a fracturing curve with multi-peak fluctuations and heightened high-frequency and dense AE activity. Significant interfacial activation and mineral particle displacement lead to an upward trend in the proportion of shear failure events. Key factors impacting SRV include <i>D</i><sub><i>bp</i></sub>, injection rate, vertical stress difference, and fluid viscosity, with vertical stress difference demonstrating high sensitivity to fracture height. Optimizing injection rate and fluid viscosity is essential for effective fracture network optimization and height control. These findings provide critical insights into the vertical propagation mechanisms of HFs and strategies for optimizing SRV in the layered shale reservoirs of the Jiyang Depression.</p>

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Vertical Propagation Behavior of Hydraulic Fractures and Multi-factor Optimization of Layered Shale Models Using CT Technology and the Response Surface Method

  • 期刊论文

  • 发表日期：

    2025年8月20日

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  • Jian Lu,
  • Lianchong Li,
  • Tianle Lu,
  • Jisheng Sui,
  • Liming Liu,
  • Zilin Zhang

摘要

Layered argillaceous limestone, prevalent in continental shale reservoirs, is characterized by rich organic matter and favorable oil-bearing conditions. Nevertheless, the interaction mechanisms between hydraulic fractures (HFs) and bedding planes (BPs), which significantly influence hydraulic fracturing and stimulated reservoir volume (SRV), remain inadequately understood. In this study, true triaxial hydraulic fracturing experiments were carried out using acoustic emission (AE) monitoring and three-dimensional computed tomography (CT) scanning to investigate the effects of bedding plane density (Dbp) on vertical fracture propagation modes, AE responses, and fracture characteristics. Additionally, we established a response surface methodology (RSM) integrating a finite element model based on flow-stress-damage coupling with Box–Behnken design to analyze how in-situ stress, bedding mechanical properties, and construction factors affect hydraulic fracture behavior and SRV. Results reveal that four complex non-planar propagation modes occur when HFs interact with BPs. Increased Dbp results in a fracturing curve with multi-peak fluctuations and heightened high-frequency and dense AE activity. Significant interfacial activation and mineral particle displacement lead to an upward trend in the proportion of shear failure events. Key factors impacting SRV include Dbp, injection rate, vertical stress difference, and fluid viscosity, with vertical stress difference demonstrating high sensitivity to fracture height. Optimizing injection rate and fluid viscosity is essential for effective fracture network optimization and height control. These findings provide critical insights into the vertical propagation mechanisms of HFs and strategies for optimizing SRV in the layered shale reservoirs of the Jiyang Depression.