聚合物驱防地层流体返吐分注工艺的研究与应用

Research and Application of Single Flow Separate Layer Polymer Injection Technology

目前大庆油田常用的聚合物驱单管多层分注工艺在注入井关停时,由于地层压力高于井筒压力,地层流体携带泥砂返吐至井筒中,形成堵塞,导致了洗井周期过短的问题。新研制的聚合物驱防地层流体返吐分注工艺可以有效解决这个问题,其内部采用轻质球结构设计,通过轻质球和注聚通道空间上的相互配合,实现流体单向控制功能,有效地防止地层流体返吐。工具外径为20mm,可放置在聚合物驱单管多层分注工艺偏心配注器的偏孔内,实现工艺上的全面兼容。通过室内水力特性实验,防返吐压力调节器压力调节能力为1.43MPa,黏度损失小于5.5%,反向承压达到15MPa。在萨北某区块开展现场试验,测试工作用时0.5d,流量测试调配用时1d,平均洗井周期由173d提高至286d,截至2018年年底,已现场应用328口井,有效地防止了聚合物驱分注井地层流体的返吐问题。防地层流体返吐分注工艺可靠,并可与聚合物驱单管多层分注工艺相互兼容,达到了方便管理、降本增效的目的,具有极大的推广空间。

Single-tube separate layer polymer injection technology is commonly applied in Daqing oilfield.The formation fluid carries the sediment back into the wellbore and blocks the space of the wellbore because of higher formation pressure than wellbore pressure when the injection well stops working,which results in much shorter well washing period.Single flow separate layer polymer injection technology was developed to solve this problem.Spherical resin ball was designed for matching the polymer injection channel so as to realize the flow in one-way instead of flowing back.Its outside diameter is 20 mm.The new technology is compatible be-cause the ball can be put into eccentric hole of the eccentric flow regulator.Laboratory experiments of hy-draulic characteristics show that the choke pressure difference is 1.43 MPa,the rate of viscosity loss is less than 5.5% and the single flow pressurization is 15 MPa.It was applied to a block of north Saertu.The test and flow regulation finished in 0.5 day and one day respectively.The average purge period increased from173 days to 286 days.By the end of 2018,the technology was applied to 328 wells and effectively prevents flowing back of the fluid in wells with separate layer polymer injection.This technology is reliable and match-es to the single-tube separate layer polymer injection technology,and has broad application prospects with more benefit,low cost and convenient management.