The stress disturbance effect will significantly affect the propagation path of hydraulic fractures in the composite rock reservoir. To reveal the influence mechanism of stress disturbance effect on the hydraulic fracture propagation, several groups of laboratory tests and simulation tests were carried out. The test results showed that the hydraulic fracture tip formed a disturbing stress field because of the pore water pressure. Before the hydraulic fracture was extended to the bedding plane, the bedding plane had been damaged under stress disturbance, and the disturbed fracture zone was formed. The propagation mode of hydraulic fracture at the bedding plane was highly sensitive to the formation of the disturbed fracture zone. The sensitivity is mainly reflected from two aspects. (1) Under the action of the hydraulic fracture tip disturbance stress, many microfractures are generated and penetrated into the disturbance fracture zone on the bedding plane. This behavior is accompanied by energy dissipation causing the bedding plane material to be significantly softened, and the energy required for hydraulic fracture propagation is reduced dramatically. (2) The formation of the disturbed fracture zone improves the degree of fragmentation of the bedding plane, and the permeability of the local area increases significantly, forming the dominant circulation path. The higher the development of the disturbed fracture zone, the greater the hydraulic fracture propagation tendency along the bedding plane. According to the formation characteristics of the bedding plane disturbed fracture zone, the author proposed a nonlinear fracture model of the bedding plane disturbed fracture zone and established the hydraulic fracture propagation path criterion. This paper further analyzed the influencing factors of the disturbed fracture zone’s formation conditions and found that the bedding plane’s cementation strength was the main factor affecting the development degree of the disturbed fracture zone.

中文翻译：

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考虑扰动应力效应的复合岩石材料水力裂缝扩展规律的试验与数值研究

应力扰动效应将显着影响复合岩储层中水力裂缝的传播路径。为了揭示应力扰动效应对水力裂缝扩展的影响机制，开展了多组室内试验和模拟试验。试验结果表明，由于孔隙水压力，水力裂缝尖端形成了扰动应力场。在水力压裂延伸至层理面之前，层理面在应力扰动下已被破坏，形成扰动裂缝带。层理面水力裂缝的扩展方式对扰动裂缝带的形成高度敏感。敏感性主要体现在两个方面。(1) 在水力裂缝尖端扰动应力的作用下，产生许多微裂缝并侵入层理面上的扰动裂缝带。这种行为伴随着能量耗散，导致层理平面材料显着软化，水力裂缝扩展所需的能量显着降低。(2)扰动裂缝带的形成提高了层理面的破碎程度，局部区域渗透率显着增加，形成了主导循环路径。扰动裂缝带的发育程度越高，沿层理面的水力裂缝扩展趋势越大。根据层理平面扰动断裂带的形成特征，提出了层理平面扰动裂缝带的非线性裂缝模型，建立了水力裂缝扩展路径准则。进一步分析了扰动裂缝带形成条件的影响因素，发现层理面胶结强度是影响扰动裂缝带发育程度的主要因素。