关键词: 油井水泥石, 二氧化碳腐蚀, 有机防腐蚀剂, 微观结构, 防腐蚀机理

Abstract: At present,the main materials for improving the CO₂ resistance of cement mortar are active inorganic admixture,and the performance of which is limited,organic corrosion resistant materials are rarely reported. In order to improve the properties of cement's (ring) carbonation resistance,an environmental response type of cement stone was formed through adding an environmental response type of organic material. The changes of cement's compressive strength,permeability,pore structure and micro structure were studied at CO₂ environmental maintenance condition. The results showed that the environmental response type cement effectively inhibited the increase of compressive strength and permeability through carbonization corrosion. The pore size of cement was refined. The harmful hole (>100nm) was decreased. The gel hole (<50nm) was increased and the total porosity was decreased by 16.31%. The phase composition of the hydration product remained stable,and the membranous substance which has a continuous distribution and close texture was formed in the corrosion surface. By using scanning electron microscope (SEM) analysis,it is revealed that the carbonation resistance mechanism was the membranous substance with dense mesh structure formed through rust preventer crosslinking,and the formation of hydration layer with thickness increasing on the surface of cement stone blocked the erosion channel and reduced the contact chance of the product with the corrosive medium. The purpose of enhancing the CO₂ resistance of cement mortar was achieved. At the same time,it can be known by the SEM image of the cement with different adding amount of corrosion inhibitors that the quality of membranous substance may affect the ability of cement stone to resist the erosion of acid medium.

Key words: oil well cement, CO₂ corrosion, organic corrosion inhibitor, micro structure, corrosion protection mechanism