Force Variations on Heave Compensating System for Ultra-Deepwater Drilling Risers

This paper discusses modeling aspects related to dynamic analysis of deep water drilling risers. These risers must have a heave compensator that maintains a near constant tension in the riser independent on platform motions. Traditional riser analysis will apply constant top tension or a simple parametric model that may give approximate tension variation. The present paper describes an alternative analysis procedure that consists of the following step: • Global riser analysis including calculation of dynamic stroke of the heave compensator from platform motions and riser dynamics. A “pipe-in-pipe” approach is used to represent the hydraulic cylinders. • Calculation of dynamic tension variat…