页岩气水平井分段压裂优化设计方法——以川西页岩气藏某水平井为例

页岩储层需要水力压裂才能获得理想的产能，压裂时在追求较大改造体积的同时也应注重形成与储层相匹配的缝网导流能力，以提高改造体积渗透率。基于Warren Root模型，将压裂后形成的缝网考虑为高渗透带，利用等效渗流理论建立了等效高渗透带模型，在地质模型中利用体积及等效渗透率对压裂缝网进行表征，通过产能模拟并借助净现值理论对高渗透带长度、等效渗透率等参数进行优选，并以优选的高渗透带参数为目标，结合缝网模拟便可得到目标条件下的最优施工参数。针对川西页岩气藏某水平井使用该方法得到最优高渗透带长度为200～220 m，最优等效渗透率为4～5 mD。结合缝网模拟得到目标条件下的施工参数为：总液量为1 600 m³，总砂量为53 m³，平均砂比为10%，最高砂比为28%，施工排量为10 m³/min。该设计为页岩气储层改造作业提供了技术支撑。

An optimal design of multi stage fracking for horizontal shale gas wells:A case study from the western Sichuan Basin

Hydraulic fracturing treatment is a major technique stimulating the field of a gas shale reservoir. While a large stimulated volume is pursued, the fracture network conductivity should be controlled so well to match the reservoir that the permeability of the stimulated volume is improved. Based on the Warren Root model and with the fracture network upon fracturing taken as the high permeability zone, the equivalent high permeability zone model was established by use of the equivalent seepage theory; secondly, the network was characterized in terms of volume and equivalent permeability in the geological model; thirdly, through performing capacity simulation while utilizing the net present value theory, such parameters were optimized as the length and equivalent permeability of the high permeability zone; and on this basis, optimal construction parameters were obtained under the objective condition combining the network simulation. In a case study from the western Sichuan Basin, the optimized high permeability zone length ranged from 200 to 220 m, and the optimized equivalent permeability from 4 to 5 mD. Combined with the network simulation, the construction parameters under the objective condition are: the total fluid volume of 1600 m³, the total sand volume of 53 m³, the average sand rate of 10%, the maximum sand rate of 28%, and construction displacement of 10 m³/min. This design provides a technical support for stimulating shale gas reservoirs.