硫化氢对固井水泥石腐蚀研究

Research on Corrosion of Oil Well Cement Stone by H_2S

以SEM、X-ray和化学分析等方法,通过比较水泥石腐蚀前后抗压强度、渗透率、微观结构、水泥石腐蚀率的变化,研究了在不同H2S气体总压力、浓度(分压)等条件下H2S腐蚀不同渗透率、钙硅比的水泥石的规律。实验结果表明:H2S与水泥石中水泥水化产物反应生成CaS、FeS和Al2S3等没有胶结性的物质,会严重破坏水泥石的结构、增大水泥石的渗透性,使腐蚀进一步加速进行;1.5MPa下纯H2S腐蚀10天后水泥石的强度损失达到73.74%以上,渗透率增大63.47倍;在一定总压力下,H2S浓度越大,水泥石的渗透率增加倍数越大,强度损失率越大;水泥石的渗透率越大,水泥石腐蚀越严重;钙硅比越大,水泥石腐蚀越严重;水泥石的渗透率和钙硅比是控制H2S腐蚀水泥石的关键因素。

With X-ray, SEM, and chemical analysis, by comparing the compressive strength, permeability, microstructure and corrosion rate of the cement stone（CS） before and after corrosion, the corrosion law of the CSs with different permeability and Ca/Si ratio was studied under different H2S gas total compression, concentration. The results showed that substances without cementation power, such as CaS,FeS and A12S3 , were produced as a result of corrosion of the CS by H2S,which damaged seriously the structure of the CS, increased the permeability of the CS and hastened the corrison of the CS. The loss of 73.74% cement strength and 63.47 times higher the permeability were caused under the pressure of 1.5 MPa for 10 days by pure H2S gas corrosion. Under a given total pressure, the higher the H2 S concentration, the higher the corrosion rate of the CS, the higher the increase times of the permeability of the CS, the weaker the cement strength. The greater the permeability of the CS or the higher the Ca/Si ratio of the CS, the more serious the corrosion. The key factors controlling the corrosion were permeability and Ca/Si ratio.