含CO2天然气井筒腐蚀速率评价方法研究及应用

Research and Application of Evaluation Method for Corrosion Rate of CO2-Containing Natural Gas in Gas Well

天然气井筒CO2腐蚀问题严重影响了气井的正常生产,为了评估气井生产过程中井筒的安全性和使用寿命,需要对气井井筒腐蚀速率进行评价。气井井筒腐蚀环境复杂,常规的高温、高压腐蚀评价装置无法反映实际井筒内部流体对管柱的腐蚀状况,也不能研究含CO2天然气在井筒流动中温度、压力变化引起系统相态变化对腐蚀的影响。设计了一套可以循环注气的高温、高压腐蚀速率评价装置,用于研究井筒中气流对井筒的腐蚀规律。利用该装置测定了P110和N80钢在含CO2气体循环流动过程中的腐蚀速率,并对现场常用的几种气井缓蚀剂的性能进行了评价。

CO2 corrosion seriously affected normal production in the gas well. It was necessary to determine the corrosion rate in order to estimate the safety and service life of the wellbore. Due to complex environmental conditions, conventional high-temperature and high-pressure corrosion evaluation device could not reflect actual status of the internal pipelines, nor could it study the influences of phase change on the corrosion caused by fluctuation of temperature and pressure in the CO2-containing natural gas flow. Therefore, a set of high-temperature and high-pressure corrosion rate evaluation equipment which can recycle gas injection was designed. Corrosion rates of P110 and N80 steel in CO2 gas circulation were assessed by this device. Besides, performances of several commonly used corrosion inhibitors in the gas well were assessed. At last, a method for evaluating the corrosion rate of gas wellbore was developed.