抽油泵凡尔罩可靠性分析及对策

Valve Cover of Oil Well Pump: Reliability Analysis and Strategy

石油开采过程中,抽油泵凡尔罩故障性断脱的频繁发生,不仅加大了采油作业工作量,增加了采油成本,同时也严重影响了原油产量。河南双河油田每年都有60～80口油井的抽油泵凡尔罩发生断脱。指出凡尔罩断脱主要表现为磨损、变形、腐蚀、脱扣等4种形式,分析归纳了造成凡尔罩断脱失效的主要影响因素有6个方面:凡尔罩材质选用不合适,油井深,凡尔罩结构不理想,柱塞上下往复运动所产生的交变应力对凡尔罩造成疲劳损坏,老油井含砂量高使凡尔罩内壁形成研磨划伤,加工工艺流程不合理。针对上述原因,提出了提高凡尔罩质量可靠性的4项主要技术措施:在修复泵时更换凡尔罩材质,将凡尔罩原热处理工序流程进行调整,运用渗氮技术对凡尔罩进行表面化学热处理,对凡尔罩的结构进行优化改进。采用以上措施所产生的积极效果在现场得到了验证:双河油田2003年以来,73口油井采用了改进后的凡尔罩,在保持产液量不变的状况下,投用至今未发生一起断脱事故,效果良好。

In the process of oil production, frequent dropout of pump's valve cover may not only increase work load of production operation and cost of production, but also heavily influence oil output. Every year, as many as 60 to 80 wells in Shuanghe Oilfield witness dropout of pump's valve covers. There are four forms of dropout: wear, de-formation, corrosion, and thread-off. The factors contributing to valve cover dropout are concerned with inappropriate selection of the material for valve cover, deep well, improper structure of valve caused by alternate stress resulting from the up-and-down reciprocal movement of plunger, abrasive wear of the internal wall of valve cover because of high content of sand in old oil wells, and irrational design of process flow. In view of these causes, technical measures proposed to increase quality reliability valve covers include substituting valve material when repaired, adjusting process flow of heat treatment of valve covers, applying nitridation to chemical heat treatment of the surface of valve covers, and optimizing the structure of valve covers. The positive results of adopting such measures are verified on the site, as no dropout has ever happened so far since the use of improved valve covers in 73 wells of Shuanghe Oilfield in 2003 provided that fluid yield remains unchanged.