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ROVworld Subsea Information FAQ (Frequently Asked Questions)



Category: Main -> About ROV

Question
•  What is an ROV?
•  What is an AUV?
•  What can ROV's do?
•  Where are they working?
•  How deep do they work?
•  Where can I get information on designing an ROV?
•  How big are ROV’s?
•  How many people are in an ROV crew?
•  How does remote technology compare with diving?
•  What other areas can ROV / remote technology be used?
•  How are ROV's operated/controlled?

Answer
•  What is an ROV?
A Remotely Operated Vehicle (ROV) is essentially an underwater robot that allows the vehicle's operator to remain in a comfortable environment while the ROV works in the hazardous environment below. The total ROV system is comprised of the vehicle, which is connected to the control van and the operators on the surface by an umbilical cable, a handling system to control the cable dynamics, a launch system and associated power supplies. The umbilical carries the power and the command and control signals to the vehicle and the status and sensory data back to the operators topside. In many cases, the umbilical includes additional strength members to allow recovery of heavy devices or wreckage.

ROVs can vary in size from small vehicles with TVs for simple observation up to complex work systems, which can have several dexterous manipulators, TV's, video cameras, tools and other equipment. The range of ROV sizes is shown in the photo below, where several classes of Perry Tritech's vehicles are displayed along with a top hat handling system. The mechanism of the top hat handling system, which contains deployable neutrally buoyant cable for local excursions. Such handling techniques allow the heavy umbilical to remain vertical in the water column while the ROV maneuvers with the smaller cable, free of the surface dynamics, which in many cases, can pull the ROV from its work station.

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•  What is an AUV?
Today, advanced technology is allowing many ROVs to shed their cable, and thus become free to roam the ocean with out such physical constraints. These emerging systems, which are battery operated, are called autonomous underwater vehicles (AUVs) and are used for Survey, Ocean search and oceanographic research.

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•  What can ROV's do?
There was a day that the operator was glad just to get his ROV back, regardless of what it was able to do. But those days are long gone and ROVs today have become a highly reliable part of both offshore and inshore operations by commercial, government, military and academic users. Far from the early "flying eyeballs" such as the RCV 225, modern ROVs cover tasks from inspecting the hazardous inside of nuclear power plants to repairing complex deepwater production systems offshore in the oil and gas industry. In general, ROVs are used to perform the following:

Diver Observation–act as a dive buddy to ensure diver safety and provide assistance.
Platform Inspection–from visual inspection to using instruments to monitor the effects of corrosion, fouling, locating cracks, estimating biologic fouling, etc.
Pipeline Inspection–follow underwater pipelines to check for leaks, determine overall health of the pipeline and insure the installation is acceptable.
Surveys–both visual and acoustic surveys are necessary prior to installing pipelines, cables and most offshore installations.
Drilling Support–everything from visual inspection, monitoring installation, operational support and repair when necessary using multiple manipulators.
Construction Support–a natural follow-on to drilling support. The tasks here can become more complex with the use of manipulators and powered tools and cutters.
Debris Removal–offshore platforms can become a "trash dump" underwater. ROVs provide a cost effective method of keeping the area clean and safe.
Call Out Work–support in many of the previous areas, however, the tasks are usually for one or several days for systems not permanently assigned to offshore platforms or drill ships.
Platform Cleaning–one of the most sophisticated tasks using manipulators and suction cups for positioning and 100-horsepower systems driving brushes, water jets and other abrasive devices.
Subsea Installations–as capability has increased, vehicles have begun to support the construction, operation, inspection, maintenance and repair of subsea installations, especially in deep water.
Telecommunications Support — Inspection, Burial or Repair–from towed plows that bury cables for protection from trawlers and anchors to sophisticated vehicles that can locate, follow, retrieve and rebury subsea telecommunication cables.
Object Location and Recovery–ROVs may have received their highest level of recognition from tragedies such as passenger jet crashes and the space shuttle disaster. Search, location, and recovery of lost objects has become routine.

These tasks only touch the surface. Military applications such as mine countermeasures are critical to the Navy. Inshore operations use smaller ROVs for many tasks from inspection to body recovery. And, the use of ROVs by academia is increasing rapidly, including the development and application of autonomous systems.

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•  Where are they working?
There are several spots around the world where the majority of ROV operations occur. They are primarily tied, of course, to the production of oil and gas. It is estimated that nearly 400 work class ROVs are in operation at this time servicing the oil and gas industry. The following paragraphs discuss the level of ROV activity around the world.

Europe - The North Sea has always been an area of high ROV activity with systems being operated in both the UK and Norwegian Sectors. One of the largest concentrations of ROVs is in this region with over 100 systems in operation. The majority of operations in the North Sea are in water depths of 492 ft (150 m) or less. Recently, there has been a move to West of Shetlands, designated a "frontier" area where the water is much deeper—1,148 to 3,281 ft (350 to 1,000 m)—and wind and current conditions more severe. Norway has drilled its deepest well in 4,180 ft (1,274 m) of water and they have discovered gas at 12,795 ft (3,900 m) in the Voring basin.

Asia - Much activity stretches from Western Australia (Asia Pacific) to Malaysia and the South China Sea. Mobil and Texaco are conducting seismic studies in the Gorgon field of Western Australia in 2,953 to 5,249 ft (900 to 1,600 m) depths in search of additional natural gas reserves. Expenditures in this region in 1999 may reach 22 percent of the world’s total being spent on offshore oil and gas developments.

South America - The majority of ROV operations in South America are occurring off Brazil, mainly in the oil rich Campos Basin. Petrobras continues the race to deeper water in the Campos Basin in depths up to 6,562 ft (2,000 m). Petrobras' Marlim South development currently holds the record for the deepest onstream well at 5,732 ft (1,747 m) and has another waiting at a depth of 6,020 ft (1,835 m).

North America - Reports indicate 104 deepwater prospects in water deeper than 9,843 ft (3,000 m) and 31 rigs simultaneously drilling in these deepwater regions. As much as 35 percent of the production in the Gulf in the year 2000 may be in deep water, up from a mere 4 percent in 1995. Between 1987 and 1997, the number of operators in the Gulf has increased from 77 to 157. Over 100 ROVs support work in the Gulf.

Arctic - Russia is opening up, with major developments offshore about to be exploited. Some of these prospects will be in water depths of 1,312 ft (400 m) and in the icy Barents Sea and Kara Sea, where the largest gas reserves in the world may be located.

Africa - West Africa is a major hot spot with new leases available in water to 8,383 ft (2,555 m). For example, Exxon is drilling off Nigeria in 4,836 ft (1,474 m) in the Gulf of Guinea and is exploring in depths to 6,601 ft (2,012 m) offshore of the Congo.

Other - Other areas where ROVs are required are off Newfoundland, Alaska, the Caspian Sea off Azerbaijan, Trinidad, the West Coast of California, off Australia in the Indian Ocean, the Bass Strait in the Tasman Sea and the Mediterranean Sea off Egypt.

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•  How deep do they work?
Tasks for ROVs in support of oil exploration and development, deepwater pipelines, and many other areas, continues to increase in both depth and complexity. As shown in the figures below, the exploration water depths in the Gulf of Mexico have more than doubled during the last two decades, increasing from depths of 3,500 ft (1,067 m) in 1976 to 7,600 ft (2,316 m) in 1996. Drilling in the Gulf of Mexico and off Brazil in depths beyond 3000 ft (914 m) accounted for over 90 percent of the worldwide effort between 1985 and 1997. And this trend is not expected to decrease in the future.

1976 3,500 Feet (1070 m)
1978 4,500 Feet (1370 m)
1987 7,500 Feet (2290 m)
1996 7,600 Feet (2320 m)
2001 Depths far in excess of the above are common place now.

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•  Where can I get information on designing an ROV?
We’ve been asked many times for information on ROV design, so we hope this section will be useful. The following are good references on ROV and/or undersea vehicle design.

Submersible Vehicle Systems Design. 1990. Editor: Eugene Allmendinger. Published by the Society of Naval Architects and Marine Engineers, 601 Pavonia Avenue, Jersey City, N.J. 07306, 1990. ISBN 0-939773-06-6

Design Aspects of Underwater Intervention Systems. 1996. By Hawley, Nuckols, Reader and Potter. Published by Kendall/Hunt Publishing Company, 4050 Westmark Drive, Dubuque, Iowa 52002. ISBN 0-7872-1510-4

Exploring the Deep. General Reference. 1994. Michael Welham. Published by Haynes Publishing, Sparkford, Nr. Yeovil, Somerset BA22 7JJ. ISBN 1-85260-471-9

The International Marine Contractors Association (IMCA) has recently published the "Code of Practice for the Safe and Efficient Operation of Remotely Operated Vehicles. For information call +44-181-547-1566

Sound Underwater Images: A Guide to The Generation and Interpretation of Side Scan Sonar Data. By John P. Fish and H. Arnold Carr. Available from American Underwater Search and Survey Ltd., Box 768, Cataumet, Massachusetts, USA 02534. ISBN 0-936972-14-9

The following can be obtained from the Marine Technology Society at 1828 L. Street, Suite 906, Washington, DC. Email MTSPubs@aol.com or try http://www.MTSociety.org. MTS Publications include:

The Operational Effectiveness of Unmanned Underwater Systems (CD ROM) (Released — 2/99)

Operational Guidelines for ROVs (1984)
Proceedings from ROV ‘83-’92
Proceedings from UI ‘93-’99

Several books on ROV Operations, along with a variety of other publications, are available through Ocean News and Technology magazine. Write to Technology Systems Corp., P.O. Box 2174, Palm City, FL. 34991-7174 for a listing or check their site at http://www.ocean-news.com.

Publications include:
Handbook for ROV Pilots/Technicians
Remotely Operated Vehicles of the World
An Introduction to ROV Operations
The Competent ROV Pilot/Technician
Competence with High Voltage AC Power

Distribution for ROV Personnel

Handbook for ROV Supervisors
Build your Own Underwater Robot

Or click on our Amazon link on the left bar of this webpage.

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•  How big are ROV’s?
Small inspection only ROV’s can be as small as a football whilst some of the heavier work class Vehicles are as large as a small car. Some of the specialised cable burial ROV’s are similar in size, shape and weight as a bulldozer and can weigh up to 18 tons on deck!
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•  How many people are in an ROV crew?
One supervisor and one Pilot/Technician are required to operate the smaller inspection only ROV’s per 12 hour period whereas a Supervisor and two Pilot/Technicians are required to operate the larger vehicle systems each 12 hours.
Larger crews may be required depending on the work programme and hours of operation required by the client.
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•  How does remote technology compare with diving?
Remote technology in water depths shallower than about 30 meters is generally not cost effective. In increasing water depths it becomes more cost effective to about 300 meters after which diving is no longer an option. It is generally slower to complete work using remote technology for work underwater or in other hazardous locations such as mine sites or sewers but the added time penalty is more often than not offset by smaller crew size and less complex and costly surface support equipment. Of course it is much safer than diving as man is not exposed to the risks associated with working underwater.
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•  What other areas can ROV / remote technology be used?
The use of remote technology in other areas of industry is only limited by ones imagination and ability to pay for it. Some applications where this or similar technology is used are:

• Bomb disposal

• Sewer inspection and remediation

• Potable water pipeline inspection and remediation

• Cable burial

• Manufacturing

With the rapid advancement in computer and control technology there is virtually no limit to what can be achieved with remote technology
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•  How are ROV's operated/controlled?
The operator (pilot) on the surface can see the task site via underwater television cameras and / or sonar devices and other sensors on the ROV. Various manual and hydraulic tools can be deployed by the manipulator to the site to perform tasks. In some cases special tools are designed and built to perform specific tasks. Very complex tasks can be carried out using remote technology whether it be by use of a generic ROV or specially designed equipment for doing specific work.
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