超级13Cr油套管在含H_2S气井环境下的腐蚀试验

Laboratory tests for corrosion behaviors of Super 13Cr tubing and casing under sour downhole conditions

近20年来,在国内外H2S/CO2共存环境、高含Cl-的深井或复杂水平井中,为保障井筒寿命并控制耐蚀合金管柱成本,超级13Cr不锈钢油套管的应用逐步增多,而ISO等标准中对于超级13Cr油套管的适用条件规定严格,特别是在超级13Cr的抗硫化物应力开裂影响因素方面,不同学者研究认识不统一。为此,模拟陕北某区块含H2S气井腐蚀环境,利用电化学系统和高压腐蚀测试系统,评价了超级13Cr油套管的电化学和抗硫化物应力开裂能力。结果表明,在模拟环境下的超级13Cr电化学腐蚀速率为0.01mm/a,而传统13Cr的腐蚀速率为0.26mm/a。同时在抗硫化物应力开裂试验中,加载80%AYS和90%AYS下的超级13Cr没有出现NACE标准溶液试验下的开裂问题。该结果为类似气井环境下的超级13Cr应用提供了一定的参考。

Over the past two decades,Super 13Cr(Super Martensitic Stainless Steel) tubing and casing have been widely applied for the equilibrium of a gas well's lifetime and tubular goods inputs in the H2S/CO2 coexistence environment or high Cl-deep wells or complex horizontal wells,However,the application conditions for Super 13Cr steel are strictly limited in the description of the international standards like ISO;especially concerning its resistance to sulfide stress cracking(SSC) and the related influencing factors,different scholars always dispute with each other.In view of this,simulating the corrosion environment of a H2S gas well in a block in north Shaanxi province,China,we conducted laboratory tests to evaluate the resistance of Super 13Cr tubular goods to electrochemical corrosion and SSC by using the electrochemical system and high-pressure corrosion testing system.Under such simulated corrosion environment,the electrochemical corrosion rate of Super 13Cr steel was 0.01 mm/a,while that of the conventional 13Cr steel was 0.26 mm/a;unlike that in the NACE's standard solution test,there is no SSC sensitivity found when the test pressure reached 80% or 90% of AYS(Applied Yielding Strength).This study provides reference for the application of Super 13Cr tubular goods in such a similar sour downhole environment.