有机酸盐环空保护液在元坝海相气藏的应用

Application of organic acid salt annular protective fluid in Yuanba marine gas pool

元坝海相气藏具有埋藏深、高温、高压、高含硫化氢、中含二氧化碳等特性,气井生产中硫化氢、二氧化碳的存在使环空腐蚀环境极为恶劣。针对高含硫气井环空特殊的腐蚀环境,以有机酸盐为基液,添加高效咪唑啉类抗H2S和CO2缓蚀剂、铁离子稳定剂、除氧杀菌剂、助排剂、pH值调节剂,形成一套可控密度为1.59 g/cm3、抗温160℃有机酸盐环空保护液。室内评价实验表明:有机酸盐环空保护液抗高温稳定性强、腐蚀速率远低于设计要求0.076 mm/a,杀菌能力达99%以上。应用于元坝海相气藏3口超深井,取得较好效果,其中,元坝204-1H井酸压测试累计产气量133.92×104 m3/d,试气测试过程中,环空油、套管柱均无渗漏,环空保护液对油管外壁和套管内壁起到防腐作用,确保了油套管长期安全使用。

The marine gas pool in Yuanba is featured by great burial depth, high temperature, high pressure, high content of H2S and medium content of CO2, etc. The presence of H2S and CO2 in gas wells deteriorates the annular corrosion environment. In view of the special annular corrosion environment in high sulfur content gas wells, an organic acid salt protective lfuid with controllable density of 1.59 g/cm3 and temperature resistance of 160℃was generated by adding imidazoline H2S and CO2 inhibitors, ferrous stability, deoxidiz-ing bactericide, cleanup additive and pH modiifer. The indoor experiment shows that organic acid salt annulus protection lfuid is very stable in resisting high temperature and corrosion rate is far below the designed value of 0.076 mm/a and bactericidal ability is up to 99%. The protective lfuid was applied to three ultra-deep wells of marine gas pool in Yuanba, and the effectiveness was favorable. Among the wells, the Well Yuanba 204-1H had a cumulative gas production of 133.92×104 m/d by acid fracturing test;during gas testing, the tubing and casing in the annulus had no leaks, so the annulus protection lfuid functions very well to prevent corrosion of tubing external wall and casing internal wall and hence ensures safe and long-term service of tubing and casing.