高浓度CO_(2)环境下高温防腐防窜水泥浆体系研究

Study on high temperature anti-corrosion and anti-channeling cement slurry system in high concentration CO_(2) environment

恩平区块油田是南海东部第一个含CO_(2)气顶的油田,其气顶CO_(2)含量高达95.67%~96.78%,高温高浓度CO_(2)环境使水泥石长效封固能力降低,井筒完整性保障难度增大。在较高的压力环境下,CO_(2)呈现低黏度、高扩散性和高压缩性的超临界特性,使水泥石的腐蚀加剧,给开发井固井作业带来极高的挑战。研发了一类高温防腐剂C-FC和C-FA,通过无机材料和有机材料的协同作用以及优化颗粒级配技术,构建了在高浓度CO_(2)环境下密度在1.9~2.2 g/cm3高温防腐防窜水泥浆体系。室内体系评价实验表明,不同密度的高温防腐防窜水泥浆体系下水泥石结构致密,具有良好的防腐能力,室内在150℃、35 MPa、70%CO_(2)分压下水泥石腐蚀深度小于1.3 mm,抗压强度衰退率小于11%,渗透率增大率小于18%,具有良好的流变性能和防气窜性能。

Enping block oilfield is the first oilfield with CO_(2)gas cap in the east of South China Sea.The content of CO_(2)in gas cap is as high as 95.67%~96.78%.The long-term sealing capacity of cement stone is reduced and the guarantee of wellbore integrity is more difficult under the environment of high temperature and high concentration of CO_(2).Under high pressure environment,CO_(2)presents the supercritical characteristics of low viscosity,high diffusion and high pressure shrinkage,which aggravates the corrosion of cement stone and brings great challenges to the cementing operation of development wells.A class of high temperature preservatives C-FC and C-FA were developed.Through the synergistic effect of inorganic and organic materials and the optimization of particle gradation technology,a high temperature anti-corrosion and anti-channeling cement slurry system with density of 1.9~2.2 g/cm3 in high concentration CO_(2)environment was constructed.The indoor system evaluation test shows that under the high temperature anti-corrosion and anti-channeling cement slurry system with different densities,the cement stone has compact structure and good anti-corrosion ability.Under 150℃,35 MPa and the 70%partial pressure of CO_(2),the corrosion depth of cement stone is less than 1.3 mm,the decline rate of compressive strength is less than 11%,the increase rate of permeability is less than 18%,and has good rheological properties and anti-channeling properties.