高压CO2/O2环境中应力与缝隙耦合作用下不锈钢腐蚀行为研究

油气开采过程中注空气驱油技术导致井下管道螺纹连接处的腐蚀问题，不仅是油气安全开采的关键问题，同时也是应力与缝隙耦合作用下的腐蚀科学问题。本研究拟以油气开采中井下管道（13Cr不锈钢）为研究对象，针对管道螺纹连接处在应力与缝隙耦合作用下的腐蚀问题，探明高压CO2/O2地层水环境中缝隙内的水化学特性演化过程。建立高压CO2/O2环境中应力与缝隙耦合作用下的原位电化学测试系统，通过电化学测试和腐蚀产物/钝化膜的微观结构表征，同时应用第一性原理计算从原子尺度上揭示力学作用下钝化膜形成与破坏机制，探明不锈钢在应力与缝隙耦合作用下的腐蚀电化学机理与腐蚀产物膜/钝化膜结构特性演化机制的内在关系，揭示应力与缝隙的交互作用机制，从而为油气开采过程中井下管道螺纹连接处的腐蚀与防护提供理论依据。

Air injection enhanced oil recovery (Air-EOR) technique in the oil and gas exploration would cause severe corrosion of the thread joint of pipe. This issue is not only the key problem of the safety of oil and gas exploration, but also the fundamental issue of corrosion science under the synergistic effect of stress and crevice. In this project, thermodynamic model is established to determine the water chemistry characteristic inside the crevice at high pressure of CO2/O2 environment. In situ electrochemical measurement method under the synergistic effect of stress and crevice is also established. Electrochemical measurements and microstructure characterization of corrosion products/passive film, as well as First principles calculation which is used to determine the mechanism of the formation and damage of passive film under the applied stress, are carried out to reveal the relationship between the corrosion electrochemical mechanism and the evolution (damage and recovery) of passive film. The synergistic effect of stress and crevice is also clarified. It is anticipated that this research would provide an essential insight into establishing the protective method for the corrosion of thread joint of pipe in oil and gas exploration.