高酸性气田金属材料的实验室评价方法研究

IN LAB. EVALUATION METHODS OF METAL MATERIALS FOR HIGH SOUR GAS FIELDS

国际标准ISO15156—2认为碳钢和低合金钢在硫化氢分压大于0.1MPa的湿气环境中,抗硫化物应力开裂性能具有不确定性;美国腐蚀工程师协会的标准NACEMR0175也没有表明其所列材料在硫化氢体积分数大于10%时具有可靠性。这成为川东北高含硫化氢气田开发必须解决的关键技术难题之一。通过实验室对常用的90、95级井下管材和地面管线用钢材料20G和16Mn材料的常压三点弯曲和在高压釜中的高硫化氢分压三点弯曲腐蚀试验研究,证明了硫化氢分压大于1.0MPa时,碳钢和低合金钢抗硫化物应力开裂性能有不同程度的下降。为此,文章提出了硫化氢分压大于1.0MPa以上的气田是高含酸性气田,以及高酸性气田抗硫化物应力开裂金属材料在实验室的试验评价原则和试验室评价方法。在模拟现场环境时,要注意模拟原位pH值、温度和硫化氢分压。

International standard ISO15156 2 believes that the ability of sulfide resistant stress rupture is un certain for carbon steel and low alloy steel in the wet gas environment when the partial pressure of hydrogen sulfide is more than 0.1 MPa. American standard of Corrosion Engineer Association(NACEMR0175) also doesn't indicate the reliability of its listed materials when the volume fraction of hydrogen sulfide is more than 10%. It is one of the key technical problems to solve for developing the northeast Sichuan gas fields with high content of hydrogen sulfide. With the in lab. 3 pointbending experiments under atmospheric pressure and the in lab. 3 pointbending experiments under high partial pressure of hydrogen sulfide in autoclave for the general down-hole tubing of grades 90 & 95, and the surface tubing of steel 20G & 16Mn., it is demonstrated that the ability of sulfide resistant stress rupture decreases at different levels when the partial pressure of hydrogen sulfide is more than 1.0 MPa So, the article suggests the gas fields with more than 1.0 MPa of partial pressure of hydrogen sulfide should be called high sour gas fields, and proposes the in lab. evaluation criteria and methods of metal materials of sulfide resistant stress rupture for high sour gas fields. When simulating field situation, more attention should be paid to simulating the in situ pH value, temperature, and partial pressure of hydrogen sulfide.