Intervention AUV
Encyclopedia
Intervention AUV or I-AUV is a type of Autonomous Underwater Vehicle
Autonomous Underwater Vehicle
An autonomous underwater vehicle is a robot which travels underwater without requiring input from an operator. AUVs constitute part of a larger group of undersea systems known as unmanned underwater vehicles, a classification that includes non-autonomous remotely operated underwater vehicles...

. Its characteristic feature is that it is capable of autonomous interventions
Well intervention
A well intervention, or 'well work', is any operation carried out on an oil or gas well during, or at the end of its productive life, that alters the state of the well and or well geometry, provides well diagnostics or manages the production of the well....

 on the subsea installations, a task usually carried out by ROV
Rov
Rov is a Talmudic concept which means the majority.It is based on the passage in Exodus 23;2: "after the majority to wrest" , which in Rabbinic interpretation means, that you shall accept things as the majority....

s or human divers.

Before I-AUVs

Basic maintenance as well as repairs were traditionally done by human divers equipped with the appropriate pressure-resistant suits. Such operations were burdened with a high dependency on weather and involved direct hazards on humans. Due to slow exhaustion of the shallow oil sources, the oil wells were installed in deeper water (>500m of depth). This made diver operation less feasible due to heavy suits and higher associated risks. Beginning in the 80's, those duties were gradually taken over by ROV
Rov
Rov is a Talmudic concept which means the majority.It is based on the passage in Exodus 23;2: "after the majority to wrest" , which in Rabbinic interpretation means, that you shall accept things as the majority....

s which were reaching a status of a proven tool.

Both methods of intervention require mobilization of surface support vessel which is necessary either to supply and retrieve the divers or to deploy and control the ROV at work. The costs of maintaining such vessels or hiring them to complete an intervention are high (in the order of hundreds of thousands USD for a day of operation) and contribute significantly towards the operational expenses connected to running the field.

Beginnings of the concept

After AUVs reached the stage of development allowing commercial application, hydrographic, fishing and oil exploration businesses quickly adapted them for several tasks like bottom mapping or water column measurements. Most of the application, however, involved survey AUVs for data collection.

Progress in computational power and techniques, development of underwater navigation systems (like Ultra-short baseline
Ultra-short baseline
USBL is a method of underwater acoustic positioning. A complete USBL system consists of a transceiver, which is mounted on a pole under a ship, and a transponder/responder on the seafloor, a towfish, or on a ROV...

 or Sonar
Sonar
Sonar is a technique that uses sound propagation to navigate, communicate with or detect other vessels...

), acoustic modems and cameras made it possible to build vehicles which could be controlled precisely enough to execute an intervention mission requiring precise positioning & control and a level of reasoning about the environment. Such missions might include manipulating valves on an oilfield Christmas tree
Christmas tree (oil well)
In petroleum and natural gas extraction, a Christmas tree, or "tree", is an assembly of valves, spools, and fittings used for an oil well, gas well, water injection well, water disposal well, gas injection well, condensate well and other types of wells...

 or, at a more advanced stage, retrieving a biological specimen from the seafloor for scientific study. Further research will probably extend the list of possible operations of I-AUVs.

Examples


External links

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