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页岩气储层纳微米孔隙、裂缝结构复杂,存在多尺度流动,气体的流动规律不同于常规气藏.本文对多孔介质内气体流动进行了研究,利用努森数划分不同尺度下气体流态,阐明了不同区域的流动机理和流动特征;综合考虑达西渗流、滑移扩散效应、井筒附近高速非达西效应等多重非线性效应,建立了页岩气储层多尺度统一流动模型.引入页岩气储层基质-压裂缝耦合两区模型,建立了页岩气储层压裂井定压条件下的两区压力分布和产能预测方程,并结合生产实例进行了参数敏感性分析.结果表明:随着滑移扩散系数、分形系数、压裂半径的增大,页岩气井产能增加,且增加幅度减小;考虑高速非达西效应较不考虑高速非达西效应时,页岩储层产能偏低,且高速非达西效应的影响小于滑移扩散对产能的影响.该模型为体积压裂页岩气产能预测及开发指标优化提供了理论依据.
The shale gas reservoir has nanometer micropores and complex fractures with multi-scale flow, and the gas flow is different from conventional gas reservoirs. In this paper, the gas flow in porous media is studied. Using Knudsen’s number of gas flow regimes , And clarifies the flow mechanism and flow characteristics in different regions. A multi-scale unified flow model for shale gas reservoir is established by considering multiple non-Darcy effects such as Darcy flow, slip diffusion and high-speed non-Darcy effect near the wellbore. The shale gas reservoir fractures and fractures are coupled with the two-zone model, and the pressure distribution and capacity prediction equation of two zones under the constant pressure of shale gas reservoir fracturing well are set up, and the parameter sensitivity analysis is carried out with the production example.Results The results show that with the increase of slip diffusion coefficient, fractal coefficient and fracturing radius, the production capacity of shale gas wells increases and the increase amplitude decreases. Considering the high-speed non-Darcy effect and the high-speed non-Darcy effect, Layer production capacity is low, and the impact of high-speed non-Darcy effect is less than that of slip diffusion on production capacity.The model provides a theoretical basis for the prediction of volumetric production of shale gas and optimization of development index.