页岩气压裂水平井生产数据分析方法

气井生产数据分析是评价气井动态储量、储层物性、水力裂缝等参数的有效方法，但在页岩气藏中，气体解吸、多段压裂、体积压裂区(SRV)的存在使得常规的评价模型不能满足现场需要。笔者在充分考虑了气体解吸、裂缝干扰、边界影响的基础上，利用Laplace变换和压力叠加原理求解压裂水平井的不稳定产能动态，并利用渐进分析给出新的无量纲物质平衡时间和产量，绘制页岩气压裂水平井Agarwal-Gardner型产量递减图版。图版可分为两大阶段：在不稳定递减阶段，页岩气的吸附特性会对发散的曲线产生显著影响；在拟稳态递减阶段，递减曲线归一，呈现Arps调和递减规律。矿场实例表明，通过拟合实际的生产数据，可以得到气藏有效泄流面积、天然裂缝渗透率及水力裂缝长度等参数，以此评价页岩气藏地质储量和水力压裂效果。

A method of production data analysis for multi-fractured horizontal well in shale gas reservoir

Production data analysis is an effective method of evaluating gas in place, parameters of reservoir and hydraulic fractures. Current model of production data analysis fails to make sense because of the existence of absorption, multi-fracturing, and stimulated reservoir volume (SRV). Considering the effect of desorption, fracture interacting and closed boundary, the authors calculate the productivity of multi-fractured horizontal well in shale gas by Laplace transform and pressure superposition principle. Then theoretical charts of Agarwal-Gardner production decline curves are presented by employing new definition of dimensionless material balance time and dimensionless production, which is based on asymptotic approximations. The result shows that Agarwal-Gardner curves can be divided into two parts where they are scattered in early transient period, and where their shape was influenced by parameters relevant to adsorption, position of each fracture and reservoir geometry, and then drawn to Arps harmonious decline in pseudo steady state period. Reservoir parameters, hydraulic fracture characteristics and gas in place are evaluated by using the type curve matching with actual production data.