Drilling Vessel

drilling

Drilling Vessel

Drilling vessels have always been at the forefront of the developments in the offshore industry, whether it concerns mono hull or semi-submersible vessels. And with operational conditions ranging from drilling to sailing, the optimisation of the performance of this type of vessels is a complex task. In the past drilling vessel were positioned at the field using a mooring system, but as a result of the ever increasing requirements for working water depth most drilling vessels are nowadays equiped with a DP system.

 

 

As the name already suggests, this type of vessels are at sea for a special purpose. Their primary task is drilling for oil, laying cables, creating artificial islands, laying cables, installing wind turbines, an so on. These ships should be able to sail the sea as efficient and safe as possible, but should also be able to be keep position or to follow a certain track while on the job. The typical full hull form of these type of vessels, the use of thrusters and nozzled propellers and the requirements on dynamic positioning and workability require a special approach with respect to design, calculations and model tests. Issues which are usually addressed are flow separation, dynamic positioning capability, thruster-thruster and thruster-hull interaction, moonpool oscillations, loads on legs of jack-up vessels, seakeeping behaviour at transit and zero speed and dynamic tracking.

 

 

The Offshore Department has been involved in many drilling vessel model tests and numerical simulations, assessing the motions, mooring loads, DP performance and green water loads.

The Seakeeping Department has been involved in studies investigating the motions of the water inside the moonpool, when the vessel is sailing or during drilling operations.

The Ships Powering Department has been involved in projects where the lay-out of the moonpool was optimised in terms of ship resistance and propulsion.

The Trials & Monitoring Department can be involved in full-scale measurements of motions and loads of these vessels.

Dynamic Positioning (DP) and Dynamic Tracking (DT) are methodologies to keep a vessel at a certain position (DP) or track (DT) using thrusters instead of mooring lines. By measuring its position (and heading) and comparing it to the required position, the DP system on board can determine its position error. The control system reacts on that by determining what thruster action is needed to bring the vessel as close as possible to the required position. DP systems can nowadays be found on many types of vessels: drilling vessels, installation vessels, heavy lift vessels, cable and pipelaying vessels.