A MODEL BASED APPROACH TO DESIGN OF PASSIVE AND ACTIVE HEAVE COMPENSATION OF CROWN MOUNTED DRILLING EQUIPMENT

摘要

The current work is on passive and active heave compensation of offshore drilling equipment. The main purpose of heave compensation while drilling from vessels or semisubmersible platforms is to maintain the drilling operation unaffected by the wave induced motion. Specifically, this paper deals with the problem of bit-liftoff, i.e., the situation where the drillbit looses contact with the formation. The investigated system is of an existing crown mounted compensator and the passive heave compensation scheme is described including the usefulness of force equalizing cylinders. Also, an approach to the design of a controller for the active heave compensation system is put forward that is based on the sensor signals available. A detailed model of the crown mounted compensator is developed that includes mechanics, hydraulics and pneumatics. It is developed in the commercial modeling environment of SimulationX™ and used together with a worst case scenario as evaluation tool for the proposed control scheme.