Hydraulic and earth engineering – Diving – Remote control
Patent
1998-11-04
2000-05-30
Bagnell, David
Hydraulic and earth engineering
Diving
Remote control
405188, 405190, 166345, 166351, 166365, B63C 1110, E21B 712
Patent
active
060684275
DESCRIPTION:
BRIEF SUMMARY
The present invention relates generally to systems and methods for remotely controlled handling, manipulating and replacement of components on sea bottom based installations. Such equipment is usually mounted on a so-called template or bottom frame installed on the sea bottom, and comprises equipment such as valves, couplings, controls, piping, instrumentation etc.
Bottom based installations of this kind is in increasing degree designed such that service components can be operated and replaced preferably by means of tools mounted on a so-called ROV, i.e. remotely controlled movable underwater vessels, equipped with tooling in order to carry out the necessary work.
A problem in connection with the use of remotely controlled sub-sea vessels, hereinafter called ROV, is that the weight or buoyancy of the ROV with everything attached thereto, usually will vary during the work in connection with the replacement, because, when a component for instance is released from the installation and is supported by the tool on the ROV, the weight of the ROV will increase equal to the component weight. And on the contrary, when the ROV is submerged down from the sea surface with a component to be mounted on the installation, the weight of the ROV will be reduced accordingly. Such weight variations create problems, and in order to manoeuvre the ROV under full steering control, the ROV must usually be provided with adjustable buoyancy or be cable suspended during submersion with supported equipment, so that the ROV subsequent to release of the equipment is attaining neutral buoyancy. A usual way to solve these problems is to utilise larger and more costly ROVs, which however is followed by increased costs. Replacement of equipment and the like will still be rather time consuming due to the need for buoyancy variations, and which again leads to expensive operations.
A main object for the present invention is to arrive at a new solution of this problem, such that the ROV can preserve substantially neutral buoyancy during replacement operations. Thereby, one can utilise a smaller and less expensive ROV, at the same time as the necessary operations can be carried out in less time.
SUMMARY OF THE INVENTION
The present invention is based on the known principle of utilising various kinds of counterweights in order to compensate varying loads on the ROV in order to obtain an approximate neutral equilibrium buoyant state in the ROV, including equipment attached thereto during the operations. Known systems are, however, hampered with complexity, require use of complicated handling equipment and some also require the use of cables leading to the sea bottom for buoyancy adjustment and/or cable up to a surface vessel.
As illustrative for the known art, one can refer to Norwegian patent 165487 and U.S. Pat. Nos. 4,721,055 and 5,046,895.
The system in accordance with the invention for diverless replacement of a functional component installed on a service unit on a bottom based installation, concerns primarily components which may be fitted releasably into said service unit as inserts, and having an externally extending manoeuverable part, and where said replacement is carried out by a manipulating tool mounted on a remotely operated vehicle (ROV), and where ROV supported weight compensation means are used for compensating the weight of the component in order to maintain the ROV in substantially neutral buoyancy state during the operations, and the system is based on a weight compensation means comprising a separate adapter element having the same weight as the component to be replaced, said adapter element or adapter equipped to be releasably supported by the manipulating tool, said adapter having an upper end and a lower end and a central axis extending therethrough, and a centrally extending throughgoing opening having transverse dimensions larger than the largest transverse dimension of the component, the upper end of said adapter arranged to be releasably connected to said manipulating tool and said lower end of said adapter fitted to
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ABB Offshore Technology AS
Bagnell David
Lee Jong-Suk
LandOfFree
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