黄桥气田CO2腐蚀现状及完井选材评价研究

CO₂腐蚀是石油天然气工业中一种破坏力极强的腐蚀类型，自1983年在江苏黄桥苏174井钻获高产CO₂气流以后，随后完成了4口试采井，已探明黄桥CO₂气田为国内最大的CO₂气田。1985年投入开发以来，相继发生了气井套管断落、腐蚀穿孔、油管落井、采气树泄漏和地表泄漏等情况，正是由于腐蚀的影响，导致气田生产成本上升、生产时效降低，极大地影响了气田的开发效益。同时，CO₂腐蚀严重威胁着黄桥CO₂气田的安全生产，解决这类腐蚀问题已成当务之急。针对黄桥CO₂气田腐蚀现状和特征，分析了腐蚀异常的原因，并选用4种管材开展CO₂高温高压模拟试验，结果发现：现有的油套管材料P-110和N-80在高温、高压和CO₂环境下对管壁产生严重腐蚀；9Cr管材耐CO₂腐蚀性差，有轻微点蚀；13Cr管材基本不发生腐蚀，可以满足CO₂气井正常生产的要求。这些研究成果对新钻井的井下选材具有指导意义。

RESEARCH ON HUANGQIAO GAS FIELD CO2 CORROSION STATUS AND WELL COMPLETION MATERIAL SELECTION AND APPRAISAL

CO_2 corrosion is one severe type of corrosion in petroleum industry. Since CO_2 rich high gas flow was obtained in Su-174 in Huangqiao Jiangsu in 1983, four trial production wells have been completed and Huangqiao CO_2 Rich Gas Field has been proven to be the largest gas field with CO_2 content in China. Since its put into production in 1985, many kinds of serious incidents occurred one after another such as casing abruption and falling, corrosive pore, tubing falling, X'mas tree leakage and surface leakage, which have caused additional production cost, loss of production efficiency, and negative impact on economic effects of the gas field. Meanwhile, CO_2 corrosion is seriously threatening safe production of Huangqiao Gas Field and is imperative to cope with. Based on CO_2 corrosion status and characteristics of Huangqiao Gas Field, this paper analyzes the causes for corrosion abnormity and presents the results of CO_2 corrosion simulation test of four pipe materials under high temperature and high pressure. The test demonstrates that P110 and N80 casing and tubing currently in service suffer severe corrosion under the condition of high temperature, high pressure and presence of CO_2. 9Cr pipe shows bad CO_2 resistance and slight spot corrosion is to be seen; while 13Cr pipe is almost immune to corrosion and suitable for CO_2 service. The results of research may be used to direct material selection for downhole use.