高含硫气田套管腐蚀情况实验研究及建议

在我国近年对高温高压酸性气田的开发过程中，天然气中的H₂S和CO₂对套管造成了严重腐蚀，套管在服役过程中腐蚀穿孔和刺漏现象时有发生，对油气井安全生产威胁极大。为此，在实验室条件下采用自行设计的高温高压循环流动釜，模拟研究了四川盆地某气井中的套管在超高温高压高含H₂S和CO₂的条件下的腐蚀情况--井深4 944～5 738 m井段流速太低、套管壁会有水膜、元素硫附着、积水及腐蚀严重。实验以该气田在役使用的3种套管材料为研究对象，分别研究其在不同采气期（携水采气期和积水采气期）的腐蚀情况。根据实验获得的数据并结合API 579适用性评价方法，计算出被腐蚀套管的抗挤强度和抗内压强度，进而预测套管的安全服役寿命。结果表明：①该井的套管在携水采气期的腐蚀程度较积水采气期的腐蚀程度轻微；②随着开采年限的增加，套管的抗内压强度和抗外挤强度均呈直线下降；③在实验环境下根据剩余强度曲线图预测3种套管的安全服役寿命至少还有10年。建议在气田的开采过程中应尽量增加携水采气期的开采时间，从而延长套管的安全服役寿命。

An experimental study on casing corrosion in a high-H_2S gas field

During the development of HPHT sour gas fields in China in recent years,serious corrosion occurs so easily on casings by H2S and CO2 in the natural gas that corrosion perforation and corrosion piercing are rather common,which has posed a great threat to the safety of an oil/gas well.In view of this,a self-designed ultra-HPHT circulation flow kettle is thus developed for an experimental study to simulate the corrosion on casings in a gas well of a gas field in the Sichuan Basin under such conditions as high ...