Author(s)

I. Politopoulos & E. De Langre

Abstract

Dynamic analysis of an impacting vertical drillstring I. Politopoulos, E. De Langre Departement de Mecanique et de Technologic, Commissariat a I'Energie Atomique, Centre d'Etudes de Saclay, 91191 Gif-Sur-Yvette, France ABSTRACT The mode superposition method is applied to problems which are present in the dynamic behavior of drillstrings. Phenomena which are discussed are mainly axial load effects on the stiffness of the structure, and impact forces including Coulomb friction forces. Some examples of numerical simulation of phenomena, using the proposed method are presented, showing its efficiency. INTRODUCTION Drilling is a very complicated process. Among others, one can meet phenomena such as bit-rock interaction, fracture of the rock, stability of the wellbore, fluid- formation interaction, fluid-drillstring interaction, buckling of the drillstring, impacts of the drillstring on the well, friction, parametric vibrations of the suspension cables, mud circu

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