低渗透油藏菱形反九点压裂井网两相渗流分析

Two-phase percolation of rhombus inverted nine-spot fracturing well pattern in low permeability oil reservoirs

依据低渗透油藏菱形反九点压裂井网不同流动区域的流动规律,建立了反映压裂开采过程物理本质的三区模型,推导出了考虑启动压力梯度的基质非达西渗流、椭圆渗流和裂缝非线性流动的三区两相渗流数学模型。研究表明:裂缝越长,累积产量越高,含水率增加越快;裂缝的导流能力越低,其累积产量越小,含水率也越小,随着导流能力的增加,累积产量的增加幅度变小;注水井排与裂缝的夹角对产量的影响不大;井排距对产量影响明显,对压裂井应采取较大的井排距。

According to flow characteristics of different flow area of rhombus inverted nine-spot fracturing well pattern in low permeability oil reservoirs,the three districts physical models that reflect physical nature of fracturing performance history have been built.Two-phase porous flow mathematical models of matrix non-Darcy flow with start-up pressure gradient,ellipse flow and fracture nonlinear flow in low permeability oil reservoirs are found.As the result indicates,the cumulative production and water content step up with the increase of fracture half length and flow conductivity;incremental scope of cumulative production decreases with the increase of flow conductivity;inclined angle of fracture and injection well row have a little influence on the cumulative production,and well row spacing influences cumulative production greatly.The major rational well row spacing are strongly recommended when put a hydraulic fracturing well into production.