大庆深层气完井管柱CO_2腐蚀防护技术

CO_2 Corrosion Protection Technology for Deep Gas Well Completion Pipe in Daqing

针对大庆深层气田具有埋藏深、温度高、产出气含CO_2的特点,且CO_2分压多在0.2 MPa以上,井下油套管处于严重腐蚀状态。通过室内高温高压腐蚀评价实验,探索出P110管材在中等温度（60~100℃）条件下,局部腐蚀敏感性加强,出现明显的蚀坑形态。探索出在高温条件下13Cr-P110组合存在低电偶腐蚀,电偶腐蚀速率低于0.1 mm/a。并结合现场挂片腐蚀监测,建立了CO_2局部腐蚀速率三维发展模型,实现了局部腐蚀的定量计算分析。依据大庆深层腐蚀特征以及气井生产特征,兼顾气井安全与经济性,建立了全井13Cr、套管组配、缓蚀剂为主腐蚀防护技术,形成了3类6种完井工艺系列,保障气井管柱在10年生产周期内经济、安全生产。

The deep gas field in Daqing has the characteristics of deep buried depth,high temperature and with the partial pressure of CO_2 more than 0. 2 MPa,and so the underground tube is in a serious state of corrosion. Using the high temperature and high pressure corrosion evaluation experiment,the P110 tube is tested,the results show that the local corrosion sensitivity strengthens with a clear pit pattern under the medium temperature（ 60 ~ 100℃）,and together with low galvanic corrosion rate lower than 0. 1mm / a. in combination 13Cr-P110 under high temperature conditions. The three-dimensional development model of local corrosion rate of CO_2 was established with combining with the spot corrosion monitoring,and the quantitative calculation and analysis of local corrosion were realized. According to the Daqing deep corrosion characteristics and gas well production characteristics,considering safety and economy of gas well,the composition technology of the well with all 13 Cr,casing assembly,corrosion inhibitor was established,three kinds of six well completion technology series were formed with guarantee gas tubes in 10 years in the production cycle of economic and safety in production.