注水井环空带压统计分析及治理改进方向

Statistical Analysis and Improvement for Annular Pressure in Water Injection Wells

注水是油田开发的主要方式,油田绝大部分采取分层注水工艺,尤其是油田高含水阶段,分层注水精细程度要求更高。分层注水工艺管柱在井下受高温高压多因素影响,井下封隔器性能工况复杂,难以预测。一旦分层封隔器密封性能下降,注水压力经封隔器渗漏上窜至井口,井口套管环空则会聚集一定压力的气体或者液体,形成环空带压(套压)。带高套压注水,不利于套管长期工作,现场力求实效零套压生产。通过对分层注水工艺管柱的改进,研制的环空封隔器等工具,带套压水井呈现下降的趋势,改善了水井套管的工况,可以延缓其使用寿命。部分带套压井,仍需进一步优化封隔器胶筒性能及配套措施,以达到零套压生产目标。

Water injection is the main way of oilfield development,and most of the oilfields adopt layered water injection technology,especially in the stage of high water cut,which requires higher precision of layered water injection.The packers sealing property of separated layer water injection string are complex and difficult to predict with influence of many factors such as high temperature and high pressure.The water injection pressure will leak up to the wellhead through the packer while the sealing performance of the layered packer declining,and the annular pressure(casing pressure)will be observed when pressure of gas or liquid accumulated in the wellhead casing annulus.Annular pressure in water injection poses a serious hazard to the wellbore,requiring zero casing pressure in oilfield operation during injection.With improvements of the layered water injection string,development of annulus packer and other tools,the number of wells with casing pressure show a decreasing trend,improving the working condition of the well casing,which can prolong its service life.In order to achieve the goal of zero casing pressure production,it is still necessary to further optimize the packer performance and supporting measures.