Discussion on Effects of Internal and External Pressure on Axial Force and Stability of Pipe String in Oil Wells

Reference1raised objection to the traditional theory of determining pipe stability established by A.Lubinski and H.B.Woods etc,and reached the conclusion that the determining method and formulas of traditional theory were improper.Looking into reference1carefully,the author found that some wordings of reference1are inconsistent with the historical facts and it has some misunderstandings to the traditional theory,the actual model proposed in it is not real enough,and an apparent error exists in the derivation,i.e.the pressure force on the lower end face of the tube has not been included in calculating the axial force.After analyzing the historical development process of the traditional theory,the paper confirms the correctness of the traditional theory and its application,and analyzes the apparent error in the derivation of reference1.It is concluded that the denying of fictitious force,Woods Model,traditional method and formulas for calculating stability of pipe string in oil wells does not hold water.Not recognizing the existence of fictitious force in reference1,the hydraulic pressure on the lower end of the pipe would not be nable to be handled correctly,that is the root cause of error in its derivation process.