一种添加自交联环氧树脂乳液的防腐韧性水泥浆

An Anti-Corrosion Tough Cement Slurry Treated with Self-Crosslinking Epoxy Resin Emulsion

酸性气体中H_(2)S和CO_(2)要与硅酸盐水化物发生反应,导致水泥石的渗透率增大、抗压强度大幅降低,使油井水泥环受到严重腐蚀,影响井筒完整性。为此,合成一种自交联环氧树脂乳液,用于增强油井水泥耐H_(2)S和CO_(2)腐蚀的能力。在H_(2)S分压为2.0 MPa、CO_(2)分压为1.5 MPa下,对水泥石的防腐蚀性能和作用机理进行评价与分析。研究结果表明:①交联环氧树脂乳液加量增加,抗压强度增大,超过一定加量后抗压强度增加不明显甚至减小,而弹性模量降低显著,增幅逐渐减少;②自交联环氧树脂乳液能够提高油井水泥石耐H_(2)S和CO_(2)腐蚀的能力,随着自交联环氧树脂乳液加量的增大,水泥石受H_(2)S和CO_(2)的腐蚀深度、渗透率降低,抗压强度先增加后降低;③自交联环氧树脂乳液包裹水泥石的水化产物,阻隔了硅酸盐水泥石水化产物与H_(2)S和CO_(2)等酸性气体的接触,提高了水泥石对H_(2)S和CO_(2)等酸性气体的耐腐蚀能力;④自交联环氧树脂乳液防腐韧性水泥浆常规工程性能良好,固井水陈化时间、自交联环氧树脂加量、温度变化对稠化时间不敏感,现场应用可操作性强。在6口井开展了防腐韧性水泥浆试验,固井质量平均优质率达到90%以上,合格率为99%以上。结论认为,自交联环氧树脂乳液充填和成膜包裹水泥水化产物,使水泥石具有防腐韧性性能,在川东北高含硫区块具有良好的推广应用前景。

The reaction between the acid gases such as H_(2)S and CO_(2)with the hydrational products of silicates results in serious corrosion to the set cement,which is manifested in the increase in the permeability and dramatic reduction in the compressive strength of the set cement,negatively affecting the integrity of the wellbore.To deal with this problem,a self-crosslinking epoxy resin emulsion is developed to improve the ability of oil well cement to resist the corrosion by H_(2)S and CO_(2).In laboratory study,the performance and the mechanisms of set cement to resist corrosion are evaluated at H_(2)S partial pressure of 2.0 MPa and H_(2)S partial pressure of 1.5 MPa,and the results analyzed.The results of the study show that:1)Increase the concentration of the selfcrosslinking epoxy resin,the compressive strength of the set cement increases;when the compressive strength of the set cement increases to a certain value,further increase in the concentration of the epoxy resin does not cause the compressive strength of the set cement to increase any more,it,on the contrary,causes the compressive strength of the set cement to decrease.The elastic modulus in this process decreases significantly.2)As the concentration of the self-crosslinking epoxy resin increases,the corrosion depth caused by the H_(2)S and CO_(2)gases in the set cement and the permeability of the set cement decrease,the compressive strength of the set cement first increases and then decreases.3)The self-crosslinking epoxy resin can wrap up the hydrational products of the set cement,thereby isolating the set cement from being contacted with the acid gases and thus improving the corrosion tolerance of the set cement against acid gases.4)Cement slurries treated with the self-crosslinking epoxy resin have good engineering properties,leading to reduced sensitivity of the thickening time of a cement slurry to the aging time of cement water,the concentration of the self-crosslinking epoxy resin as well as changes in temperature,and these make the technology easy to use in field operation.The anti-corrosion tough cement slurry has been used in the cementing of 6 wells,more than 90%of the well cementing job is classified as“excellent”,and 99%of the well cementing job is classified as“qualified”.From the study and the field operation it is concluded that the self-crosslinking epoxy resin emulsion fills and wraps up as a membrane the hydrational products of cement,rendering the set cement good anti-corrosion performance and toughness,and this makes the anti-corrosion tough cement very suitable for cementing wells drilled in the high sulfide content blocks in northeast Sichuan.