INTRODUCTION: TYPES OF RIGS

The rig building sector in the marine industry has seen unprecedented growth in the last few years. Singapore, now the rig building centre of the world, commands a majority percentage of the world rig building order book. More importantly, the rigs built here are premium Singapore products. This has been a great success story especially when not too long ago, the marine industry as a whole was labelled a sunset industry.

First, we shall describe and define the various structures used in the oil exploration and drilling industry.

An oil platform is a large structure used to house workers and machinery needed to drill and then produce oil and natural gas in the ocean.

Jack-up platforms, as the name suggests, are platforms that can be jacked up above the sea with legs than can be lowered like jacks. These platforms, used in depths of up to 500 ft (about 150 metres) of water, are designed to move from place to place, and then anchor themselves by deploying the jack-like legs.

Semi-submersible platforms have pontoons of sufficient buoyancy to cause the structure to float, but of weight sufficient to keep the structure upright. Semi-submersible rigs can be moved from place to place, and can be lowered into or raised by altering the amount of flooding in buoyancy tanks. They are generally anchored by cable anchors during drilling operations, though they can also be kept in place by the use of dynamically positioned thrusters. Semi-submersibles can be used in depths from 600 to 6,000 feet (180 to 1,800 metres).

Drillships are maritime vessels that have been fitted with drilling apparatus. They are most often used for exploratory drilling of new oil or gas wells in deep water but can also be used for scientific drilling. It is often built on a modified tanker hull and outfitted with a dynamic positioning system to maintain its position over the well.