Computational modeling of shock-wave loading by the detonation of a cylindrical explosive charge in a drill pipe

To develop a technology of fracturing a drill pipe with its subsequent extraction from a well at a depth of more than 5000 m, we performed a numerical study of the shock-wave loading of the inner surface of the pipe by the detonation of a special cylindrical charge. Two cases of detonation of the cylindrical charge explosive are considered: plane front detonation and diverging spherical detonation. The computational model is a layered structure which consists of a cylindrical explosive charge in a copper casing, a steel pipe, and drilling mud. The shock-wave impact on the drill pipe is calculated in a three-dimensional formulation using the Eulerian multi-component approach. The calculations confirmed the possibility of fracturing the drill pipe in the region of the lock joint. It is shown that shock-wave impact by plane front detonation far exceeds in pipe damage the impact by diverging spherical detonation. The minimum charge length sufficient for fracturing the drill pipe was determined from the results of additional calculations.