各向异性油藏水平井井网渗流场分析

Study on seepage field of horizontal well pattern in anisotropic reservoirs

为直观地反映各向异性油藏水平井井网地层压力分布及流体运动轨迹的特点,利用源汇理论、Newman乘积法及压降叠加原理,推导出各向异性油藏水平井井网不稳定渗流地层压力公式,提出流线生成方法,研究了水平井井网渗流场分布规律。结果表明:储层各向异性、生产时间和注采比对水平井井网渗流场影响较大。在布井时,水平井应垂直于最大主渗透率方向,以便形成线性水驱,提高驱替效果;生产时间越长,压力传播范围越广,采出程度越高;注采比越大,注入流体的波及范围越大,波及效率越高。利用该方法产生的流场图能够为各向异性油藏水平井开发井网设计及注入方案的优化提供科学依据。

This paper studies the distribution law of seepage field for horizontal well pattern, presents streamline construction method, and derives an equation of formation pressure for unsteady seepage flow of horizontal well pattern in anisotropic reservoir by using source-sink theory, Newman’s product method and pressure drop superposition principle in order to visually reflect the characteristics of pressure distribution and the flowing tracks of reservoir fluid. The result shows that the seepage field of horizontal well pattern is sensitive to reservoir anisotrophy, production time, and injection-production ratio. Horizontal well shall be placed vertical to the orientation of the maximum permeability in order to form linear water flooding and enhance displacement effect. The longer the production time is, the larger the pressure propagation area is, and the higher the degree of reserve recovery is; and the higher the injection-production ratio is, the larger the swept area of injected fluid is, and the higher the sweep efficiency is. The seepage field map generated by this method can provide a scientific basis for the design of horizontal development well pattern and the optimization of injection strategy in anisotropic reservoirs.