大庆油田葡北Ⅱ断块降压开采技术数值模拟

Numerical simulation and insitu experiment of depressurization development of Pu-bei Ⅱ block reservoir in Daqing Oilfield

为改善大庆油田葡北Ⅱ断块累积注采比高、无效注水严重造成地层压力高,高液高含水井多现象,提出实施降压开采的水动力学调整方式.通过减少注水量,有效降低区块内过高的地层压力.改变系统压力有利于油水交换和相对低渗透层潜力的发挥,从而延缓油田产量的递减,抑制区块含水率上升速度.设计5种不同注采比降压开采方案.数值模拟结果表明,全面停注的降压开采效果最佳,随着注采比逐渐恢复,降压开采效果变差.确定不同注采比下的降压界限,在此基础上进行现场试验.试验结果表明,降压开采技术对于改善油田后期开发效果和提高采收率具有重要意义.

Pu-bei II block reservoir of Daqing Oilfield is faced with the problem of high pressure,high water cut and high liquid,caused by high injection and production ratio and invalid of injection.The depressurization development was applied to complete the regulation of water flooding region by numerical simulation research in this paper.Decreasing pressure and water cut is achieved by decreasing the injection and production ratio.Five different injection and production ratios were adopted to study depressurization development.The result indicated that completely stopping injection was most effective,and the effect of depressurization development became worse following the recover of injection and production ratio.Pressure drop limitation was obtained.Finally,this paper conducted insitu experiment of the depressurization development in Pu-bei II block reservoir.It is meaningful for improving developing effects and enhancing recovery ratios in late period.