页岩气藏综合渗流模型建立及影响因素分析

Establishment of A Comprehensive Seepage Model for Shale Gas Reservoir and Analysis on Its Influential Factors

为了定量分析扩散、滑脱及应力敏感对页岩气藏压裂水平井生产的影响,在三线性渗流模型的基础上,重新建立了多因素综合渗流数学模型,并对模型进行了解析推导,得到了综合影响因素下的产能方程。综合模型中,扩散和滑脱作用于基质孔隙提高渗透率以增加产量,应力敏感作用于裂缝网络损失渗透率以降低产量,多重因素的综合影响取决于孔隙大小、储层压力和裂缝宽度等因素。应用得到的产能方程进行了威201-H1井的实例分析,得到了不同孔隙直径和不同裂缝开度下各因素的综合作用效果。结果表明,与未考虑综合因素模型的产量相比,随着基质孔隙直径的增加,综合渗流模型的产量由增加会转变为减少,并且当遇到裂缝开度较大时,转折的孔隙阈值会相应减少。

In order to analyze quantitatively the comprehensive influence of diffusing,slippage and stress sensitivity on the production of the fractured horizontal well in the shale gas reservoirs,a multi-factor model was rebuilt based on the three linear seepage models and also the productivity equation was obtained with the integral effect factors.In this model,the effects of diffusing and slippage could enhance the production with the increase of matrix permeability,but the effect of stress sensitivity of rock reduced the production with lowering the fracture permeability.And the multi-factor effect depended on the pore size,reservoir pressure and the fracture width.The derived equation was applied for case study in Well Wei 201-H1,the multi-factor effect for different pore diameters and the different fracture widths was obtained.The results show that contrasted with original model without considering these factors,with the increase of matrix pore diameter,the production rate of the model would be turned to reduction from enhancement,when the aperture of fracture is bigger,the turning threshold would be reduced correspondingly.