胜利断块油藏细分注水技术界限研究

老油田进入特高含水期后,剩余油分布更加零散,各种地质因素也因长期注水开发而发生了一定的改变.此时稳油控水难度进一步加大,为了进一步挖掘剩余油,控制含水上升速度、减缓产量递减,必须对注水井采取进一步的细分调整.基于水湿油藏注水井注水层段吸水效果,从注入水受力分析入手,运用达西定律推导出了水驱油藏水驱油全过程中的单位体积注入水沿竖直、地层两个方向运移的渗流速度公式,明晰了水驱油藏注水层段不同开发阶段砂岩吸水机理.研究结果表明,水驱油藏细分注水效果与岩石绝对渗透率、水相相对渗透率、注入水黏度、水动力压力梯度、注水井启动压力梯度、含水饱和度、地层倾角、油水密度差等参数有关.结合胜利油田断块油藏地质特征及细分注水工艺要求,制定了一套适合胜利油田不同断块区的细分注水技术政策界限:层段内渗透率变异系数小于0.3,砂岩条带宽度极比小于2.5,且东辛油区断块油藏层段内砂岩厚度小于6m,小层数小于4个;现河油区断块油藏层段内砂岩厚度小于5m,小层数小于5个;临盘油区断块油藏层段内砂岩厚度小于6m,小层数小于6个.矿场试验证实,该细分注水技术政策界限是合理、实用的,其为胜利断块油藏注上水、注够水、注好水,实现多层断块油藏的高效开发提供了技术保障,对类似油藏细分注水技术界限研究具有一定的借鉴意义.

Study on Technology Policy Limitation of Subdivision Water Injectionin Complex Fault Block Reservoirs of Shengli Oil Field

Old oilfields in China have successively entered into middle to late stage of oil production.Because the oil fields have entered into ultrahigh water cut production period,resulting in water out extent and thickness increased respectively and residual oil decreased as well as residual oil distribution scattered,which makes the oil fields development become more difficult.Meanwhile,the different geological factors have also been changed by water flood for so long term.The development area of water injection is now facing great challenge in producing more oil and less water.Therefore,it is necessary to accomplish water injection with fine layer classification to develop more residual oil,control water cut rise and reduce decline rate of water drive.On the basis of the effect of water absorption in water-wet reservoir,by means of force analysis,using Darcy's Law,the formulae of the whole water driving oil course about unit volume injected water seepage velocity formula of formation direction and vertical migration were deduced first.The formulae clarify the absorbing mechanism of sand stonein different development stages,and provides a theoretical basis for injection potential evaluation in water driving oil reservoir.The research results show the main control factors of subdivided injection have to do with absolute permeability,water phase relative permeability,injected water viscosity,hydrodynamic pressure gradient,injection start-up pressure gradient,dip,water saturation,Oil/water density difference,etc.Combining with field practice,the main control factors of subdivided injection were sift out.Using reservoir numerical simulation technology and mathematical statistics method,the influence law of different factors influencing water absorption effect were carried out.Finally,the results obtained a rational policy limitation of Subdivision Water Injection Technique,which apply to Complex Fault Block Reservoirs of Dongxin,Xianhe,and Linpan Oilfiled.The technology policy limitations include the permeability variation coefficientand Less than 0.3 and the Oil-bearing belt width differential Less than 2.5 in a certain water injection interval.At the Same time,the sandstone thickness is less than 6 m,the layer number is less than 4 in Dongxin fault block oil reservoir,the sandstone thickness is less than 5 m,the layer number is less than 5 in Xianhe fault block oil reservoir,the sandstone thickness is less than 6 m,the layer number is less than 6 in Linpan fault block oil reservoir.The field application indicates that the technology policy limitation is reasonable and practical.The research result has guide importance to water injection,water injection enough,and well water injectionduring the fine water injection work,and provides the technical support for high-efficient developing multi-layer fault block oil reservoir in Shengli Oil Field.At the same time,The research has certain reference significance to similar reservoir.