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<p>During large-scale multistage hydraulic fracturing of shale gas horizontal wells, disturbances to the non-uniform in-situ stress and the wellbore thermal stress can lead to integrity issues such as casing damage and cement sheath failure. Based on the principles of elastic mechanics and thermal stress theory, considering the coupling effects of non-uniform in-situ stress and thermal stress to establish a coupling stress model for the casing-cement sheath-formation system, and the influence of wellbore temperature, non-uniform in-situ stress and casing eccentricity on the coupling stress in shale gas horizontal wells is analyzed. When considering the coupling of non-uniform in-situ stress and thermal stress, the peak values of the system’s radial, circumferential, axial, and Von Mises stresses increase by 12.87%, 13.64%, 28.69%, and 13.24%, respectively, compared to the system where thermal stress is not considered. The peak stress positions occur at the cement sheath first interface and the inner wall of casing, and the failure risk of cement sheath first interface is higher. As the temperature of inner wall of the casing wall decreases, the shear stress at the cement sheath first and second interfaces remains unchanged, while the circumferential stress gradually diminishes, and the radial stress, axial stress, and Von Mises stress progressively increase. With the minimum horizontal stress increases, the maximum shear stress and maximum Von Mises stress at the cement sheath first and second interfaces gradually decrease, while the radial, circumferential, and axial stresses steadily rise, leading to a more uniform distribution of casing-cement sheath-formation system stress. As the casing eccentricity increases, the maximum circumferential stress, axial stress, and Von Mises stress at the cement sheath first and second interfaces gradually rise, the maximum radial stress at the first interface and the maximum shear stress at the second interface also increase, the maximum radial stress at the second interface decreases., while the maximum shear stress at the first interface first slightly increases and then slightly decreases.</p>

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Coupling stress analysis of deep shale gas horizontal wells under non-uniform in-situ stress and thermal stress

  • 期刊论文

  • 出版模式：

    开放获取

  • 发表日期：

    2026年4月29日

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  • Honglin Xu,
  • Shilin Xiang,
  • Yang Qing,
  • Nian Peng,
  • Xiaodong Yang,
  • Bin Yang,
  • Zhi Zhang

摘要

During large-scale multistage hydraulic fracturing of shale gas horizontal wells, disturbances to the non-uniform in-situ stress and the wellbore thermal stress can lead to integrity issues such as casing damage and cement sheath failure. Based on the principles of elastic mechanics and thermal stress theory, considering the coupling effects of non-uniform in-situ stress and thermal stress to establish a coupling stress model for the casing-cement sheath-formation system, and the influence of wellbore temperature, non-uniform in-situ stress and casing eccentricity on the coupling stress in shale gas horizontal wells is analyzed. When considering the coupling of non-uniform in-situ stress and thermal stress, the peak values of the system’s radial, circumferential, axial, and Von Mises stresses increase by 12.87%, 13.64%, 28.69%, and 13.24%, respectively, compared to the system where thermal stress is not considered. The peak stress positions occur at the cement sheath first interface and the inner wall of casing, and the failure risk of cement sheath first interface is higher. As the temperature of inner wall of the casing wall decreases, the shear stress at the cement sheath first and second interfaces remains unchanged, while the circumferential stress gradually diminishes, and the radial stress, axial stress, and Von Mises stress progressively increase. With the minimum horizontal stress increases, the maximum shear stress and maximum Von Mises stress at the cement sheath first and second interfaces gradually decrease, while the radial, circumferential, and axial stresses steadily rise, leading to a more uniform distribution of casing-cement sheath-formation system stress. As the casing eccentricity increases, the maximum circumferential stress, axial stress, and Von Mises stress at the cement sheath first and second interfaces gradually rise, the maximum radial stress at the first interface and the maximum shear stress at the second interface also increase, the maximum radial stress at the second interface decreases., while the maximum shear stress at the first interface first slightly increases and then slightly decreases.