Vessel Handling System

Overview

Geoprober has designed a handling system for vessels of around 100m that would significantly increase the range of activities that it can perform. These include:

- Deepwater exploration drilling

- Well intervention

- Subsea tree installation

- Riser and umbilical installation

Challenge

One of the main limitations for small multipurpose vessels to successfully carry out deepwater operations lies with the Safe Working Load of its handling system. The handling systems on most vessels suspend the loads at significant height creating stability problems and greatly reducing the operability envelope and capability of such systems. Vessel stability is a complicated aspect of naval architecture which may be simply defined as the tendency of a floating vessel to return to its original upright position of equilibrium after being tipped by the forces of wind and sea.

Solution

Geoprober’s subsea reverse derrick greatly improves the stability of the vessel because the heavy loads are suspended and handled below the keel, lowering its centre of gravity. The complete system consists of two structures coupled by means of an eight fall rope system with an intermediate keel moonpool rope management system. The Tension Frame lowers and raises the loads that can also be suspended at the drill floor while the Tension Frame freely travels up or down around the pipe.

The reverse derrick is supported by cables from a tensioning system that enables active heave compensation. Loads can be held between the drill floor and the reverse derrick which has a safe working load of 375 tonnes.

When combined with Geoprober’s drill-in wellhead and subsea-shut-off system, an equipped vessel would be capable of drilling either a top-hole for a production well or a complete slim-hole exploration well. The high load capacity would also enable intervention with a riser and a much greater range of downhole operations.