Conventional tieback techniques did not take into consideration annular gas channeling dur-ing liner cementing in high pressure wells .In this paper ,studies were conducted on critical techniques of tieback equipment for preventing gas channeling during liner cementing in ultrahigh pressure wells .Based on the analysis of critical techniques such as sealing elements of tieback stingers ,packer types ,and pre-vention from holding back and premature inflation of packers ,reliable tieback equipment with integral tie-back stinger and packer was designed ,with maximum sealing pressure up to 70 MPa .Considering the structural features of the tieback equipment and key issues in on site operation , applicable operation processes and techniques were defined .Technical requirements were addressed for some vulnerable sectors such as sweeping upper cement plug ,milling the tieback barrel and trial running ,and more accurate buoy-ancy change calculation methods were put forward .This tieback equipment was successfully used in 8 high pressure wells in the Sichuan Area .Those applications demonstrated that the new tieback equipment was simple ,safe ,reliable ,and well-performed in isolation ,and it would be an effective solution in preventing annular gas channeling during liner cementing in high pressure wells .%高压油气井尾管固井易发生环空气窜，采用常规回接技术不能解决环空气窜问题，为此，进行了超高压防气窜尾管固井回接装置关键技术研究。通过分析回接插头密封组件、封隔器类型、封隔器防退及防提前胀封等关键设计技术，设计了一种回接插头与封隔器一体、使用安全、密封能力达70 M Pa的超高压防气窜尾管固井回接装置。根据该回接装置的结构特点和现场施工关键环节，制定了合理的施工工艺和技术措施，提出了扫上水泥塞、磨铣回接筒、试插等易出问题关键环节的工艺要求，并给出了更精确的浮力变化计算方法。该回接装置在四川地区8口高压油气井尾管固井回接或短回接进行了应用，均未发生气窜。现场应用结果表明，该回接装置操作简便、安全可靠、封隔效果好，能够有效解决高压油气井尾管固井环空气窜的难题。
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