A dramatic shot of an oil rig in operation as the sun sets. There are six types of oil rig in use around the world. Most favour the submersible structures as they are nearly motionless once flooded with water, providing a stable base for deep sea oil exploration. Normal oil rigs not only drill for oil but are able to refine and process it. Jack-up rigs are another common type of oil rig structure but this relies on long legs standing on the sea floor and means they are limited by the depth of the water.