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页岩气藏开发中基质、天然微裂缝、人工裂缝同时参与渗流,且其内部还存在着吸附、解吸与滑脱特性,渗流机理复杂,分形理论对复杂系统恰好能比较精确地描述,因此本文引入分形理论,分别运用分形迂曲毛束管模型、分形面缝二叉树模型、分形面缝三叉树模型推导出基质、天然微裂缝、人工裂缝的分形孔隙度及分形表观渗透率,建立分形三重介质页岩气藏数学模型,绘制拟稳态与非稳态下的压力及压力导数响应曲线,划分渗流阶段。结果表明,分形因素影响渗流总径向流阶段,由于分形特征的影响,总径向流阶段压力导数曲线上翘;拟稳态窜流可分为早期纯井筒储集、天然裂缝与人工裂缝窜流、裂缝线性流、基质-天然裂缝窜流及总体径向流5个渗流阶段,非稳态窜流可分为早期纯井筒储集、过渡段、非稳态窜流段、系统线性流段及总径向流5个渗流阶段。
In the development of shale gas reservoirs, matrix, natural microcracks, and artificial fractures also participate in seepage, and there are also adsorption, desorption and slippage characteristics inside the shale gas reservoir. The seepage mechanism is complex and the fractal theory can precisely describe the complex system precisely. Therefore, Fractal theory, fractal tortuous tuft tube model, fractal surface stitch binary tree model and fractal stitch trigeminal model were respectively used to derive the matrix, natural microcracks, fractal porosity and fractal apparent permeability of artificial fractures. Fractal triple media sheets The mathematic model of gas reservoir is plotted with response curves of pressure and pressure derivative under quasi-steady state and unsteady state, and the seepage stage is divided. The results show that fractal factors affect the total radial flow of seepage. Due to the influence of fractal characteristics, the pressure derivative curve of the total radial flow is upturned. The quasi steady-state channeling can be divided into early pure wellbore storage, natural fractures and artificial fissures Flow, fissure linear flow, matrix - natural fissure channeling and total radial flow 5 seepage stage, non-steady channeling can be divided into early pure wellbore reservoir, transitional section, non-steady channeling section, the system of linear flow section And total radial flow 5 seepage stage.