Scholarlink

In recent years, conventional oil and gas resources are difficult to meet the increasing energy demand of human beings. Shale oil has huge reserves and is one of the unconventional oil and gas resources, which has attracted much attention in the world. However, shale oil reservoirs are usually buried deep, and there are a lot of complex natural fractures (NFs) in rock mass under the influence of tectonic stress and faults. Therefore, it is of great significance to clarify the height propagation law of the hydraulic fracture (HF) in shale oil reservoirs under the influence of NFs for the highly efficient development of shale oil reservoirs. Previous studies mainly focus on the 2D model and lacks of the 3D model. Based on the continuous-discontinuous element method (CDEM), a 3D fracture propagation model coupled with solid stress and fracture seepage is constructed in this paper. The fracture propagation model correctness is verified by the analytical solution of the classical Penny model. Then a 3D mine-scale transversely anisotropic shale reservoir with complex NFs is established to investigate the HF height mechanism under the influence of NFs. Results show that when the HF extends in the rock matrix, the HF is basically perpendicular to the minimum horizontal principal stress direction, and it mainly undergoes tensile failure. Once it approaches a NF, it mainly shows that the HF extends along the NF and bypasses the NF, and the shear failure occurs preferentially. Then the water pressure invades and gradually opens the NF, that is, the tensile failure occurs. Compared with the NFs containing only one primary direction, the fracture length, fracture height and fracture area only decreases slightly in the reservoir having random NFs. Additionally, the spread range of the HF has an obvious decline in the direction perpendicular to the minimum horizontal principal stress. Therefore, the primary development direction of NFs in a fractured reservoir is the decisive factor affecting the HF propagation. The results can provide a theoretical guidance for the optimization of fracturing design in fractured shale oil reservoirs.

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Research on the Propagation Mechanism of Hydraulic Fracture Height in a Fractured Shale Reservoir

  • 会议论文

  • 发表日期：

    2025年

查看全文
  • Bo Zhang,
  • Tian-kui Guo,
  • Ming Chen,
  • Zhan-qing Qu,
  • Ji-wei Wang,
  • Hai-yang Wang

摘要

In recent years, conventional oil and gas resources are difficult to meet the increasing energy demand of human beings. Shale oil has huge reserves and is one of the unconventional oil and gas resources, which has attracted much attention in the world. However, shale oil reservoirs are usually buried deep, and there are a lot of complex natural fractures (NFs) in rock mass under the influence of tectonic stress and faults. Therefore, it is of great significance to clarify the height propagation law of the hydraulic fracture (HF) in shale oil reservoirs under the influence of NFs for the highly efficient development of shale oil reservoirs. Previous studies mainly focus on the 2D model and lacks of the 3D model. Based on the continuous-discontinuous element method (CDEM), a 3D fracture propagation model coupled with solid stress and fracture seepage is constructed in this paper. The fracture propagation model correctness is verified by the analytical solution of the classical Penny model. Then a 3D mine-scale transversely anisotropic shale reservoir with complex NFs is established to investigate the HF height mechanism under the influence of NFs. Results show that when the HF extends in the rock matrix, the HF is basically perpendicular to the minimum horizontal principal stress direction, and it mainly undergoes tensile failure. Once it approaches a NF, it mainly shows that the HF extends along the NF and bypasses the NF, and the shear failure occurs preferentially. Then the water pressure invades and gradually opens the NF, that is, the tensile failure occurs. Compared with the NFs containing only one primary direction, the fracture length, fracture height and fracture area only decreases slightly in the reservoir having random NFs. Additionally, the spread range of the HF has an obvious decline in the direction perpendicular to the minimum horizontal principal stress. Therefore, the primary development direction of NFs in a fractured reservoir is the decisive factor affecting the HF propagation. The results can provide a theoretical guidance for the optimization of fracturing design in fractured shale oil reservoirs.