超深井用偏梯形螺纹套管适用性研究

针对我国西部超深井固并使用的偏梯形螺纹套管发生螺纹连接处泄漏、接箍及管体破裂与变形等事故，对西部两口超深井在用和拟用的φ177．8mmx13．72mmV-150和φ177．8mmx12．65mmNK-T140两种规格BTC螺纹套管进行了管柱设计验证试验研究。试验条件模拟井下预期的载荷和压力，试验项目包括上卸扣试验、密封试验（介质为水和气两种）、强度极限试验（拉伸、水压爆破、压缩和挤毁）等。结果发现，这两种套管在密封性和强度等方面均与使用条件存在一定差异，特别是难以满足一些异常复杂超深井的要求。建议在高压超深井中用气密封性较好的特殊螺纹接头套管。对于异常高压超深井，在设计时应进行密封设计，对套管进行必要的密封和强度评价试验。

Adaptability of buttress thread casing for ulthe-deep holes

In the light of the failure of buttress thread casing used in ultra-deep wells in west China oilfields, the authors make a verification test of string design of two kinds of casings, i. e. φ177.8mmx13 .72mm V - 150 and φ177.8mm x12.65mm NK - T140 casings which are used and will be used in two ultra-deep wells. Tests are made under the conditions of simulated downhole load and pressure, and the tests include makeup and breakout test, seal test(taking water and gas as media) and ultimate strength test(tension, burst, compression and collapse). The results of the tests show that, the strength and seal of these two casing cannot satisfy the operation requirements. The authors suggest using special thread casing with good gas-tightness in high pressure ultra-deep wells, and in the casing string design of unusual high pressure ultra-deep wells, seal design and appraisal test of casing seal and strength should be made.