页岩自支撑裂缝导流能力预测方法研究

页岩气井的产能主要取决于支撑剂充填层裂缝和储层剪切滑移形成的自支撑裂缝提供的导流能力，目前对页岩自支撑裂缝导流能力变化规律和影响机理的认识仍不够充分，采用分形理论方法，引入裂缝开度分形维数和迂曲度分形维数对裂缝空间进行定量表征，建立了考虑闭合应力作用的自支撑裂缝导流能力数学模型。开展自支撑裂缝导流能力实验，结果显示初期裂缝导流能力可达30~50 D·cm，在40 MPa的闭合压力下仍可保持在1 D·cm以上；理论模型预测的结果与实验测试结果基本吻合；模型敏感性分析表明，裂缝开度分形维数与导流能力呈正相关关系；迂曲度分形维数与导流能力呈负相关关系。利用此方法可实现自支撑裂缝导流能力的快速、准确预测，为合理预测气井产能提供支撑。

Method to Predict the Self-supporting Fracture Conductivity of Shale

The production capacity of shale gas wells primarily depends on the conductivity of the proppant filling layer fracture and the self-supporting fracture formed by the shear slip of the reservoir. Currently, our understanding of the variation law and mechanism that influences the self-supporting fracture conductivity of shale is insufficient. The fractal theory method was used to introduce the fractal dimensions of fracture aperture and tortuosity to characterize the fracture space quantitatively, and a mathematical model of self-supporting fracture conductivity was established that considers the effect of closure stress. An experiment of self-supporting fracture conductivity was conducted. The results show that the initial fracture conductivity reached 30~50 D·cm and could be maintained above 1 D·cm under a closure pressure of 40 MPa. The theoretical model prediction results agree well with the experimental test results. The sensitivity analysis shows that the fractal dimension of fracture aperture is positively correlated with the conductivity, while the fractal dimension of tortuosity is negatively correlated with the conductivity. The proposed method can quickly and accurately predict the self-supporting fracture conductivity of shale and provide support for rational prediction of gas well productivity.