含气地层采卤井降咸配水管腐蚀严重原因分析

Analysis on the Serious Corrosion of Brine Reducing Water Distribution Pipe in Brine Extraction Well in Gas Bearing Formation

陕北盐田某盐矿采卤井组的配水管在生产后期腐蚀严重。本文从该区域地质情况,再结合现场检修、生产情况进行分析,认为配水管的腐蚀作用是多因素的,CO2对腐蚀起到重要的作用,配水管所处的高压、高温环境,以及气液多相流条件下,卤水中高浓度的Cl-、微量的H2S和接箍上液压管钳留下的咬痕加剧了腐蚀作用。针对腐蚀的原因,提出采取井组及时排除腔体内多余气体、选用耐CO2+H2S+Cl-腐蚀环境使用的管材、选用无牙痕或微痕管钳、改变介质pH值等应对措施,延长配水管的工作周期。

T he water distribution pipe of a brine mining well group in a salt mine in salt fields in the northern Shaanxi province corroded seriously in the late production period. Based on the analysis of the geological conditions in this area, combined with the on-site maintenance and production conditions, it is considered that the corrosion of the water distribution pipe is multifactorial, and CO2 plays an important role in the corrosion. The high pressure, high temperature environment, and gas-liquid conditions of water distribution pipes under multiphase flow conditions, high concentrations of Cl-in brine, traces of H2 S, and bite marks left by hydraulic pipe wrenches on the couplings aggravate the corrosion effect. In response to the cause of corrosion, it is proposed to timely remove excess gas in the cavity of well group, regularly turn over the well, select pipes resistant to CO2+ H2 S +Cl-corrosion, use toothless or micro-mark pipe wrenches, and change the pH of the medium, so as to extend the working cycle of water distribution pipes.