Dynamic positioning (DP) is a computer-controlled system to automatically maintain a vessel's position and heading by using its own propellers and thrusters. Position reference sensors, combined with wind sensors, motion sensors and gyrocompasses, provide information to the computer pertaining to the vessel's position and the magnitude and direction of environmental forces affecting its position. Examples of vessel types that employ DP include ships and semi-submersible mobile offshore drilling units (MODU), oceanographic research vessels, cable layer ships and cruise ships.
Offshore support vessel Toisa Perseus with, in the background, the fifth-generation deepwater drillship Discoverer Enterprise, over the Thunder Horse Oil Field. Both are equipped with DP systems.
SBX underway
GPS satellite in orbit
Light taut wire on the HOS Achiever
Offshore drilling is a mechanical process where a wellbore is drilled below the seabed. It is typically carried out in order to explore for and subsequently extract petroleum that lies in rock formations beneath the seabed. Most commonly, the term is used to describe drilling activities on the continental shelf, though the term can also be applied to drilling in lakes, inshore waters and inland seas.
An oil drilling platform off the coast of Santa Barbara, California – 6 December 2011