致密砂岩气藏压裂水平井裂缝参数的优化

Optimization of fracture parameters of fractured horizontal wells in tight sandstone gas reservoirs

为了解决压裂水平井的多参数综合优化问题,基于不稳定渗流原理,应用复位势理论、叠加原理和数值求解方法,建立了考虑裂缝干扰的压裂气藏水平井产量预测模型,研究了影响压裂水平井产量的单因素变化规律;结合正交试验设计方法和灰色关联理论,确定了影响压裂水平井产能的敏感因素排序,并实现了考虑多参数综合作用的压裂水平井参数优化设计。计算结果表明:算例中影响产量的重要性排序依次为地层渗透率、储层厚度、孔隙度、水平段长度、裂缝条数、裂缝长度和导流能力;优选区块水平井组合参数为水平段长度1 000m、裂缝条数10条、裂缝长度60m、导流能力10μm2.cm,按照优化参数施工后,无阻流量显著增加。

This paper aims to solve the problem of how to comprehensively optimize multiple parameters of a fractured horizontal well.First,based on the knowledge of unstable effluent seepage,complex potential theory,superposition principle and numerical method are adopted to develop aproductivity prediction model of fractured horizontal gas wells with the fracture interference taken into account.On this basis,the rules are discussed on how an individual factor will have an impact on fractured horizontal well production.Moreover,in combination with the orthogonal experiment design method and grey correlation theory,the ranking of sensitive parameters impacting fractured horizontal well productivity are determined,and thus an optimal design is accomplished for multiple parameters of fractured horizontal wells.The calculation results show that the importance of parameters influencing the well production ranks as follows : stratum permeability,reservoir thickness,porosity,and the length of the horizontal section,the number of fractures,fracture length and flow conductivity.The preferred combination of horizontal well parameters is as follows : horizontal section of 1000mlong,10fractures(60mlong) and conductivity of 10 μ m 2.cm.In an actual field practice according to the optimized parameters,a significant increase was finally found at the open flow capacity in that well.