Dynamic behaviour of deepwater drilling column under collisions with drillship moonpool

Abstract

The paper presents a theoretical and numerical approach to the dynamic behaviour of drilling column (DC) in deep water under various exciting forces, due to seawater motion and drillship displacement allowing for possible collisions between DC-to-moonpool walls. The solutions of motion equations for each section of DC (the first section being located in the moonpool, whereas the second section is submersed in the sea), are presented individually and compared afterwards. For the step-by-step integration of DC equations the implicit Newmark's method is applied. The first section solution is determined by means of quadratures. The second section solution is determined by means of the asymptotic Tupchiev's method and the method of pass. The determination of DC-to-moonpool wall contact points is done iterationally. A computer program of DC dynamic behaviour simulation has been developed. Examples of the simulation have been presented. The program can be used for the analysis of deepwater DC stresses at design stage.