渤海油田注水井油套带压问题探析

Analysis on the Annulus Pressure in the Water Injection Wells of Bohai Oilfield

注水井环空带压已逐渐成为渤海油田开发面临的重要问题之一,较高的环空套压对井口设备和作业人员都构成较大的安全威胁。鉴于此,以渤海A作业公司为例,对其环空带压注水井进行了统计与分类,总结了注水井环空带压产生的原因,并通过数值计算、数据统计和室内试验等方法对具体原因进行了剖析。分析认为,注水管柱的变形和注水管材的结垢腐蚀是注水井环空带压的两大主要原因。结合注水管柱变形计算模型,研究了注水管柱变形造成环空带压的两种情况,提出了密封装置临界插拔次数和行程的概念,指出密封工具的疲劳损害是其密封失效的主要原因;通过注水水源的Sl值测量和金属挂片腐蚀试验,证实了地下水源会造成金属材质注水管柱结垢腐蚀。基于注水井环空带压原因分析,从事前预防、管理制度创新和事后补救等3个方面提出了应对措施及建议。研究结果对解决渤海油田注水井环空带压问题具有一定的指导意义。

Annulus pressure in water injection wells has gradually developed into one of the most important problems that impact the development of Bohai Oilfield.In order to solve this problem,this paper analyzed the cause of the annulus pressure in the water injection wells of Bohai Oilfield.Taking Bohai A operating company as an example,the water injection wells with annulus pressure were counted and classified,and the causes of the annulus pressure in water injection wells were summarized.In addition,the causes were specifically analyzed by means of numerical calculation,data statistics,indoor experiment and other methods.It is shown that the deformation and the scaling corrosion of water injection pipe string are two main causes of annulus pressure in water injection wells.Then,two situations of annulus pressure caused by the deformation of water injection pipe string were studied by virtue of the deformation calculation model of water injection pipe string.The concept of critical insertion times and process of sealing device was put forward,and the fatigue damage of sealing tools was considered to be the main cause of sealing failure.On the other hand,it was verified by measuring the Sl value of injected water source and carrying out coupon corrosion experiments that ground water sources can lead to the scaling corrosion of water injection pipe string made of metals.Finally,based on the analysis on the causes of annulus pressure in water injection wells,some countermeasures and suggestions were proposed from the aspects of pre-prevention,management system innovation and post remedy.The research results are of guiding significance to solve the annulus pressure problem of water injection wells in Bohai Oilfield.