A drilling rig that is used exclusively to drill offshore exploration and development wells and that floats upon the surface of the water when being moved from one drill site to another. it may or may not float once drilling begins. two basic types of mobile offshore drilling units are used to drill most offshore [...]

A type of mobile offshore drilling unit that floats and is not secured to the seafloor (except for anchors). floating units include inland barge rigs, drill ships and ship-shaped barges, and semisubmersibles. see mobile offshore drilling unit.

A type of mobile offshore drilling unit that has a part of its structure in contact with the seafloor when it is on site and drilling a well. the remainder of the rig is supported above the water. the rig can float, however, allowing it to be moved from one drill site to another. bottom-supported [...]

1. for ships, water taken onboard into specific tanks to permit proper angle of repose of the vessel in the water, and to assure structural stability. 2. for mobile offshore drilling rigs, weight added to make the rig more seaworthy, increase its draft, or sink it to the seafloor. seawater is usually used for ballast, [...]

A device used to blend slurries or gels, usually mobile equipment.

A mobile submersible drilling structure consisting of a barge hull that rests on bottom, steel posts that rise from the top of the barge hull, and a deck that is built on top of the posts, well above the waterline. it is used to drill wells in water no deeper than about 30-35 feet (9-10.7m). [...]

The placement of compressors, pumps, cooling systems, treating systems, and so forth, in a series with another unit or units of like design to improve operating efficiency and results.

The speed at which drilling fluid or cement moves in the annulus. it is important to monitor annular velocity to ensure that the hole is being properly cleaned of cuttings, cavings and other debris while avoiding erosion of the borehole wall.
the annular velocity is commonly expressed in units of feet per minute or, less commonly, meters per [...]

The turning force that is applied to a shaft or other rotary mechanism to cause it to rotate or tend to do so. torque is measured in units of length and force (footpounds, newton-meters).

1. the area of the formation that is damaged because of the invasion of foreign substances into the exposed section of the formation adjacent to the wellbore during drilling and completion.
2. the pressure drop from the outer limits of drainage to the wellbore caused by the relatively thin veneer (or skin) of the affected [...]

Usually a single well drilled offshore by a mobile offshore drilling unit to produce hydrocarbons from the outer fringes of a reservoir that cannot be produced by primary development wells drilled from a permanent drilling structure (as a platform rig). sometimes, several satellite wells will be drilled to exploit marginal reservoirs and avoid the enormous [...]

Extensions of the producing string with seals to travel within a packer bore and/or extensions.

A substance that consists of large molecules formed from smaller molecules in repeating structural units (monomers). in oilfield operations, various types of polymers are used to thicken drilling mud, fracturing fluid, acid, water, and other liquids. see micellar-polymer flooding, polymer mud. in petroleum refining, heat and pressure are used to polymerize light hydrocarbons into larger [...]

Drilling for oil or gas in an ocean, gulf, or sea, usually on the outer continental shelf. a drilling unit for offshore operations may be a mobile floating vessel with a ship or barge hull, a semisubmersible or submersible base, a self-propelled or towed structure with jacking legs (jackup drilling rig), or a permanent structure [...]

Abbreviation: mobile offshore drilling unit.