关于内外压力对油井管柱稳定性影响问题的再讨论

Re-Discussion on Effects of Internal and External Pressures on Stability of Pipe String in Oil Wells

韩志勇

Han Zhiyong

中国石油大学(华东) 石油工程学院, 山东青岛 266580

School of Petroleum Engineering, China University of Petroleum(Huadong), Qingdao, Shandong, 266580, China

文献[1]（李子丰.内外压力对油井管柱等效轴向力及稳定性的影响[J].中国石油大学学报：自然科学版，2011，35（1）：65-67.）的结论可分为2部分：其一，否定传统理论，文献[2]（韩志勇.关于内外压力对油井管柱轴向力和稳定性影响问题的讨论[J].石油钻探技术，2013，41（6）：12-18.）已经对此进行了详细的分析和讨论；其二，给出了内外压力对油井管柱稳定性是否有影响的结论，认为“内外压力对悬挂油井管柱的稳定性没有影响；内外压力本身对两端固定油井管柱的稳定性没有影响；两端固定后内外压力的变化对油井管柱的稳定性有影响”。本文重点讨论第二部分结论。通过4个例题的计算，证明文献[1]关于悬挂管柱的结论仅仅适用于非梯度压力，而对液柱压力或液柱压力与非梯度压力的组合，则是不正确的。通过逻辑关系分析，认为文献[1]关于两端固定管柱的结论是自相矛盾的，“内外压力本身对固定管柱的稳定性没有影响”的结论是不正确的。研究发现，文献[1]在公式推导中有严重错误，认为两端固定管柱的下端仍然存在液压力，而且推导出的公式在应用中存在很大的局限性。文献[1]在公式推导中出现严重错误的根源在于不承认虚力的存在。

Reference[1]’s conclusions could be divided into two parts.First,traditional theory was negated,which had been analyzed and discussed in Reference[2].Second,conclusions wee given as follows:"internal and external pressures have no effect on the stability of suspended pipe string;internal or external pressure itself has no effect, but its changes has effect on the stability of pipe string fixed at both ends".Through four calculation examples,it was proved that Reference[1]’s conclusion regarding suspended pipe string was only applicable to non-gradient pressure,but not to fluid column pressure or the combination of fluid column pressure and non-gradient pressure.According to logical analysis,it was confirmed that the conclusion on the pipe string fixed at both ends was contradictory,and it was incorrect that "internal or external pressure itself has no effect on stability of pipe string fixed at both ends".There was a serious mistake in the derivation of formula in Reference[1],namely,"hydraulic pressure exists at the lower end of the pipe string fixed at both ends";the formula was very limited in use.Such mistake was attributed to non-recognition of the existence of fictitious force.

https://doi.org/10.3969/j.issn.1001-0890.2014.04.003