我国海上油井管腐蚀与防护研究进展

总结了我国海洋环境油井管的防腐实践,为类似油气田开发提供技术参考。指出了我国海上油气井的环境与腐蚀状况,针对腐蚀环境特征,分仅含二氧化碳井下环境、含硫井下环境及热采井高温环境进行防腐技术总结。海洋环境油井气井内、外腐蚀均较严重,外腐蚀主要为海洋环境大气腐蚀,内腐蚀失效的原因多为CO2引发的腐蚀,此外因作业需要,井筒内流体性质的变化也加剧了内腐蚀失效。针对单独CO2腐蚀环境,建立了海上特色的防腐图版,并提出三种低成本防腐策略;针对H2S腐蚀环境,开展了不同材质的腐蚀规律研究与服役寿命预测;针对热采井高温腐蚀环境,开展了氧含量、高温腐蚀与热应力叠加强度变化研究。研究认为,海洋环境油气井外腐蚀可采取涂敷、牺牲阳极、阴极保护,井下CO2腐蚀可以采用防腐选材图版选择合适材质,为降低成本可以采用组合管柱防腐,含H2S环境可采用碳钢或低铬钢,以降低硫化物应力开裂(SSC)和应力腐蚀(SCC)风险,热采井宜控制含氧量及热强度衰减的影响。

Research Progress on Corrosion and Corrosion Protection of Offshore Oil Well Tubing in China

This article summarizes the practice of oil well pipe corrosion protection in marine environment in China and provides technical reference for similar oil and gas field development.The environments and corrosion status of offshore oil and gas wells in China are pointed out,and the anti-corrosion technologies are summarized according to the characteristics of the corrosion environments which can be divided into carbon dioxide downhole environment,sulfur downhole environment and high temperature environment of thermal production wells.Both the internal and external corrosions of oil and gas wells in the marine environment are serious.The external corrosion is mainly caused by atmospheric corrosion in marine environment,while the internal corrosion is mainly caused by CO2 corrosion.In addition,the change of fluid properties in the wellbores due to the operation needs also aggravates the internal corrosion.For CO2 corrosion environment,a marine anti-corrosion chart is established,and three low-cost anti-corrosion strategies are proposed.The research on the corrosion law of different materials and prediction of their service life are studied for H2S corrosion environment.The changes of the superimposed strength of oxygen content,corrosion at high temperature and thermal stress are studied for high temperature environment of thermal production wells.It is considered that the external corrosion of oil and gas wells in marine environment can be protected by coating,sacrificial anode and cathodic protection;CO2 corrosion in the wells can be handled by using the anti-corrosion material selection chart to select suitable materials,while combined string corrosion protection strategies can be used to reduce cost;H2S environment can use carbon steel or low chrome steel to reduce the risk of SSC and SCC;thermal production wells should control the influence of oxygen content and heat intensity attenuation.