气态二氧化碳对气井固井水泥石的腐蚀分析

通过分析和测量水泥石腐蚀后的微观结构、抗压强度、渗透率以及腐蚀量,研究了不同分压、时间、温度下CO2腐蚀对水泥石性能的影响。结果表明:CO2对水泥石产生腐蚀作用的本质在于CO2与水泥的水化产物相作用生成CaCO3等物质,破坏了水泥石的原有组成和微观结构,导致腐蚀后水泥石的抗压强度下降,渗透率增大;随着腐蚀时间、CO2分压和腐蚀温度的增加,腐蚀后的水泥石抗压强度降低、渗透率增大、腐蚀率增加。提出了设计抗CO2腐蚀性固井水泥浆体系的基本方法。研究气态CO2对水泥石的腐蚀规律,对于开发和设计抗CO2腐蚀性固井水泥浆体系、提高油气田开发效益等都具有重要意义。

An analysis of CO2 gas corrosion on the cement stone of gas wells

The performance of cement stone corroded by CO2 are investigated in this paper by analyzing or measuring the microstructure, compressive strength, permeability and corrosion amount under different pressures, temperatures, and time. From this study, the essence of CO2 corrosion on the cement stone is that the original composition and microstructure of the cement stone are destroyed by CaCO3 produced from the chemical reaction between CO2 and the hydration products of the cement, which results in the decrease of the compressive strength of the cement stone with a higher permeability.The compressive strength of the cement stone was thus decreased and the permeability is increased. With the increase of corrosion time, temperature and CO2 differential pressure, the compressive strength is further decreased, while the permeability and corrosion amount are further increased. Then a basic design method of anti CO2 corrosion slurry systems is proposed herein. The study on the corrosion rule of the gaseous CO2 to cement stone is significant for designing CO2 corrosion resistant slurry systems and improving the efficiency of oil/gas field development.