固井水泥石抗腐蚀性能的研究

许多油田在开发过程中,都遇到了地层中含有的诸如CO2和H2S等腐蚀性介质影响油井水泥环密封效果的问题,加强抗腐蚀水泥外加剂和水泥浆体系的研究变得至关重要.从水泥石腐蚀机理的研究出发,通过试验优选出了抗腐蚀性水泥填充料WG.WG的主要成分为非晶态SiO2,具有粒细(平均粒径约为0.1 μm)、比表面积大、活性高等特点.另外,选用不渗透剂G60S和硅粉,可以提高水泥石密实度,降低水泥石渗透率,从而提高水泥石的抗腐蚀性.通过对9种配方水泥浆固化体进行不同龄期的CO2、H2S腐蚀,测定水泥石腐蚀后的抗压强度、渗透率和腐蚀深度,进行反光显微镜、X-射线衍射分析,比较了填充料WG水泥浆、现场水泥浆、纯水泥浆固化体的抗腐蚀性,优选出了抗腐蚀高密度和低密度水泥浆配方.该抗腐蚀水泥浆体系不但具有抗腐蚀性,还具有良好的防气窜、降低自由水、稳定浆体等综合性能,可以满足不同井深条件下的固井作业需要.

Study on corrosion resisting of cement stone

Many oilfields in the world encountered the problem of oil cement sealing property ruined by corrosive mediums in the formation such as CO 2 and H 2S. To improve the structure integrity and sealing property of cement stone down hole for a long time period in acidic environment, research on corrosion resisting cement additives and relevant cement slurry systems becomes vital. Based on the study of corrosive mechanism to cement stone, anti-corrosion cement packing material WG was optimized, and 9 cement slurry were prepared. After different-period corrosion by CO 2 and H 2S to the 9 cured cement stones, parameters such as pressure strength, permeability and corrosive depth were measured. At the same time, the stone properties were analyzed by SEM and XRD methods. As a result, two corrosion resisting cement slurry compositions of high and low density were proposed. The system exhibits not only corrosion resistivity, but also good comprehensive properties such as anti-gas channeling, free water volume reducing andstable properties, which can satisfy cementing requirements for different depth operation.