Drilling riser
Encyclopedia
A drilling riser is a conduit that provides a temporary extension of a subsea
oil well
to a surface drilling facility. Drilling risers are categorised into two types: marine drilling risers used with subsea blowout preventer
(BOP) and generally used by floating drilling vessels; and tie-back drilling risers used with a surface BOP and generally deployed from fixed platforms
or very stable floating platforms like a spar
or tension leg platform (TLP).
(BOP), and usually power and control lines for the BOP.
The design and operation of marine drilling risers is complex, and the requirement for high reliability means an extensive amount of engineering analysis is required.
When used in water depths greater than about 20 meters, the marine drilling riser has to be tensioned to maintain stability. A marine riser tensioner located on the drilling platform provides a near constant tension force adequate to maintain the stability of the riser in the offshore environment. The level of tension required is related to the weight of the riser equipment, the buoyancy of the riser, the forces from waves and currents, the weight of the internal fluids, and an adequate allowance for equipment failures.
To reduce the amount of tension required to maintain stability of the riser, buoyancy modules are added to the riser joints to make them close to neutrally buoyant when submerged.
The international standard ISO 13624-1:2009 covers the design, selection, operation and maintenance of marine riser systems for floating drilling operations. Its purpose is to serve as a reference for designers, for those who select system components, and for those who use and maintain this equipment. It relies on basic engineering principles and the accumulated experience of offshore operators, contractors, and manufacturers.
Subsea
Subsea is a general term frequently used to refer to equipment, technology, and methods employed in marine biology, undersea geology, offshore oil and gas developments, underwater mining, and offshore wind power industries.- Oil and gas :...
oil well
Oil well
An oil well is a general term for any boring through the earth's surface that is designed to find and acquire petroleum oil hydrocarbons. Usually some natural gas is produced along with the oil. A well that is designed to produce mainly or only gas may be termed a gas well.-History:The earliest...
to a surface drilling facility. Drilling risers are categorised into two types: marine drilling risers used with subsea blowout preventer
Blowout preventer
A blowout preventer is a large, specialized valve used to seal, control and monitor oil and gas wells. Blowout preventers were developed to cope with extreme erratic pressures and uncontrolled flow emanating from a well reservoir during drilling. Kicks can lead to a potentially catastrophic...
(BOP) and generally used by floating drilling vessels; and tie-back drilling risers used with a surface BOP and generally deployed from fixed platforms
Fixed Platform
A fixed platform is a type of offshore platform used for the production of oil or gas. These platforms are built on concrete and/or steel legs anchored directly onto the seabed, supporting a deck with space for drilling rigs, production facilities and crew quarters. Such platforms are, by virtue of...
or very stable floating platforms like a spar
SPAR (platform)
A spar, named for logs used as buoys in shipping and moored in place vertically, is a type of floating oil platform typically used in very deep waters. Spar production platforms have been developed as an alternative to conventional platforms...
or tension leg platform (TLP).
Marine drilling riser
A marine drilling riser has a large diameter, low pressure main tube with external auxiliary lines that include high pressure choke and kill lines for circulating fluids to the subsea blowout preventerBlowout preventer
A blowout preventer is a large, specialized valve used to seal, control and monitor oil and gas wells. Blowout preventers were developed to cope with extreme erratic pressures and uncontrolled flow emanating from a well reservoir during drilling. Kicks can lead to a potentially catastrophic...
(BOP), and usually power and control lines for the BOP.
The design and operation of marine drilling risers is complex, and the requirement for high reliability means an extensive amount of engineering analysis is required.
When used in water depths greater than about 20 meters, the marine drilling riser has to be tensioned to maintain stability. A marine riser tensioner located on the drilling platform provides a near constant tension force adequate to maintain the stability of the riser in the offshore environment. The level of tension required is related to the weight of the riser equipment, the buoyancy of the riser, the forces from waves and currents, the weight of the internal fluids, and an adequate allowance for equipment failures.
To reduce the amount of tension required to maintain stability of the riser, buoyancy modules are added to the riser joints to make them close to neutrally buoyant when submerged.
The international standard ISO 13624-1:2009 covers the design, selection, operation and maintenance of marine riser systems for floating drilling operations. Its purpose is to serve as a reference for designers, for those who select system components, and for those who use and maintain this equipment. It relies on basic engineering principles and the accumulated experience of offshore operators, contractors, and manufacturers.