大庆外围特低渗透油藏非线性渗流周期注水研究

大庆外围某特低渗透试验井区平面非均质性严重,周期注水利于驱动低渗透区原油。由于特低渗透油藏压力敏感性强,文中根据非线性渗流规律,进行数值模拟研究,优化周期注水方式。采用矿场实际数据,选取矩形五点井网,建立平面非均质模型,分析"增注—减注"方式与"增注—停注"方式的含水率、采出程度、有效驱动体系的建立及地层压力保持情况。结果表明,"增注—减注"方式比"增注—停注"方式采出程度高、驱油波及系数大、低渗区非线性及储层伤害影响小。分析结果对低/特低渗透油藏注水开发具有指导意义。

Study on cycle water injection considering non-linear flow of ultra-low permeability reservoir in periphery part of Daqing Oilfield

The plane heterogeneity is serious in the test area of ultra-low permeability reservoir in periphery part of Daqing Oilfield.The cycle water injection can help to drive crude oil from the low permeability area.Considering the strong pressure sensitivity,this paper followed nonlinear seepage rule and made numerical simulation study to optimize the cycle water injection mode.Using the actual data and five-spot well pattern,this paper established a plane heterogeneity model.The comparative analysis of the cycle injection mode such as increasing water injection and decreasing water injection is done,getting the water cut,recovery rate,pressure gradient and formation pressure.Analysis shows that the recovery degree obtained by increasing water injection and decreasing water injection is higher than that of increasing water injection and stopping water injection,the sweep efficiency of oil displacement is high and the damage of nonlinear flow and stress sensitivity is small,which has an instructive significance for the water injection development of ultra-low permeability reservoir.