高温高压含硫气井生产套管设计

DESIGN AND APPLICATION OF PRODUCTION CASING IN HTHP SOUR GAS WELL

川东北海相储层具有(超)深、高温、高压、含H2S/CO2特征,恶劣的井下工况使生产套管服役环境异常苛刻,易出现套管磨损、变形、泄露、破裂等事故,在有盐岩层等特殊地层存在时失效风险更大。从高温高压含硫气井复杂工况出发,分析了井深、H2S腐蚀、高温、盐岩层等特殊地层对生产套管设计的影响,浅析了管具下入、固井等对生产套管设计的特殊要求,提出了高温高压含硫气井可采用尾管固井后回接、增加管柱壁厚以及上大下小的复合套管柱结构,以降低上部管柱的应力水平、解决高强度与抗硫能力要求间的矛盾,此外,系统提出了高温高压含硫气井套管强度设计的方法,在川东北HBT1f3气井成功现场应用,对高温高压含硫气田生产套管安全经济设计具有重要的借鉴意义。

The marine facies reservoir in northeast Sichuan has the features of super deep, HTHP, contain H2S/CO2. The bad downhole conditions made the accidents such as the abrasion, deformation, break and leak of casing raise, and the failure risk of casing was bigger in salinastone formation. The influences of well depth, hydrogen sulfide corrosion, high temperature, salinastone reservoir on production casing design were analyzed, and the particular requirement of running of pipe and tool, as well as cementation to casing design was also discussed. In order to decrease the stress of upper case and resolve the contradiction between the high strength requirement and antisulphur capability, the extension pipe was tied back after cementation, and thick wall casing, along with combination string with bigger dimensions in upper case and lesser dimensions in lower case were used in HTHP sour gas well. Moreover, design methods of casing strength about HTHP sour gas well has been proposed and been used successfully in Heba gas well of northeast Sichuan.