What is an offshore drilling rig?
An offshore drilling rig is a platform designed for use in relatively shallow water to serve as a base from which to drill for oil or natural gas. Offshore structures are often erroneously referred to as drilling platforms, but in reality these are usually production platforms. A drilling rig consists of a drilling tower mounted on a pontoon. The rig sometimes floats (this is usually known as a semi-submersible) or it can have legs which can be lowered to the seabed in order to raise the entire structure by tens of metres. The latter type of construction is known as a self-elevating platform; if cylinders are used to provide the upward movement then it is referred to as a jack-up rig. Drill ships or semi-submersibles are used for drilling in deeper waters. These can be fixed in place with anchors or by using dynamic positioning. A drilling rig serves as a base from which to carry out exploratory drilling for oil or natural gas. When a drillable amount of oil or gas is located, the rig
