低渗透垂直补给油藏中水平井流态分析

The flow regimes of a horizontal well in a reservoir with a bottom weak feeding boundary.

采用ＧＲＥＥＮ函数方法，求出底部有低渗透层补给油藏中水平井的压力分布公式，绘制了典型水平井试井曲线；并利用压力分布公式，绘出了等压面随时间在地层中的传播过程。经分析，得出了有意义的结论：①在顶、底封闭性油藏中，水平井的流动期为井筒径向流→早期线性流（当无因次水平井半长ＬＤ较大时）→中期径向流；在底水油藏中，水平井流动期为井筒径向流→过渡流→稳态流；有低渗透补给油藏中的压力诊断曲线介于封闭性和有底水油藏的曲线之间。②在顶、底封闭性油藏中，当ＬＤ较大时，水平井相当于一口垂直裂缝井，在部署井网时，可以只考虑二维的情况。③底水及底部有低渗透层油藏中，必须考虑垂向上的不对称性。

This paper studies the transient pressure distributions of a horizontal well working in a reservoir with a bottom weak feeding boundary which includes one with non flow vertical boundaries and one with a bottom water boundary. The formulae of transient pressure distributions and well testing analysis are derived by using Green function method. Not only some typical well testing curves but also constant pressure curves versus time are drawn. By these curves, the authors analyse flow regimes of a horizontal well in a reservoir with bottom weak feeding boundary, and in conclude that: ①In a reservoir with non flow vertical boundaries, the flow regimes are: well bore radial flow → initial linear flow (as L D is large) → general radical flow; In a reservoir with a bottom water boundary, the flow regimes are: well bore radial flow → transitional flow → steady flow; In reservoir with a bottom weak feeding boundary, the flow regimes are between conditions of a reservoir with non flow boundaries and one with a bottom water boundary; ②A horizontal well can be regarded as a vertical fractural well as L D is large in a reservoir with non flow vertical boundaries; ③The vertical non symmetry must be considered in a reservoir with a bottom weak feeding or a bottom water boundary.