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基于页岩气藏线性、非稳态流动特点,考虑未压裂区双重介质特点及其对产气的贡献,建立页岩气多级压裂水平井渗流模型并求得定压条件下Laplace空间解。数值模型验证表明解析解与数值解吻合度高,在此基础上推导新的页岩气双孔瞬态产量典型曲线,补充和发展原有页岩气SRV模型典型曲线,并进行参数敏感分析,将新建典型曲线与SRV模型、Brohi模型典型曲线进行对比。结果表明:新典型曲线流动阶段表现为线性流与过渡流交替,较Brohi单孔外区模型典型曲线更复杂;气藏尺寸、窜流系数、内外区裂缝渗透率比对典型曲线影响很大,而储容比的影响不明显;未压裂区天然裂缝对气井产量有积极作用,对页岩气藏进行产能预测时不可忽略。
Based on the characteristics of linear and unsteady flow in shale gas reservoirs, considering the characteristics of double media and the contribution to gas generation in un-fractured zone, a multi-stage fractured horizontal well model of shale gas is established and the Laplace space solution. Numerical model verification shows that the analytical solution has good agreement with the numerical solution. On this basis, a new typical transient curve of double porosity of shale gas is deduced to supplement and develop the typical SRV model shale gas curve, The new typical curve is compared with the typical curve of SRV model and Brohi model. The results show that the flow curves of the new typical curves show the alternation of the linear flow and the transition flow, which is more complicated than the typical curve of the Brohi single-hole outer zone model. The size of the reservoir, the channeling coefficient and the permeability of the fractures in the inner and outer zones greatly affect the typical curve. However, the effect of the ratio of storage to storage is not obvious. The natural fractures in the non-fracturing area have a positive effect on gas well production, and can not be neglected in productivity prediction of shale gas reservoirs.