Hydraulic and earth engineering – Subterranean or submarine pipe or cable laying – retrieving,...
Reexamination Certificate
1998-02-06
2001-03-13
Lillis, Eileen D. (Department: 3673)
Hydraulic and earth engineering
Subterranean or submarine pipe or cable laying, retrieving,...
C137S015010, C137S317000, C015S104061, C134S022120, C134S16700R, C134S16800C, C134S16800C, C134S16700R
Reexamination Certificate
active
06200068
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to subsea pipeline hot tapping operations, and more particularly relates to subsea pipeline fluid blasting operations conducted through a pipeline hot tap.
2. Description of the Related Art
Subsea crude oil pipelines are often plugged by localized accumulations of paraffin, hydrate and other deposits. A paraffin blockage is caused by the paraffin precipitating out of the crude oil and packing in the pipe. The paraffin is very waxy and can clog or plug the pipeline. Plugging of pipelines is a well known problem. Pipeline operators attempt to prevent this problem by requiring regular pigging of the pipeline or through the injection of solvents or chemicals in the pipeline to prevent paraffin build-up.
Nonetheless, plugging of pipelines does occur. Typically, the paraffin blockage is removed from a subsea pipeline by raising the pipeline to the surface and severing the pipeline. The pipeline can then be mechanically cleaned or the plugged section replaced. With the plug removed, the pipeline is reconnected and lowered back down to the sea floor.
It is desirable to have an apparatus and method of using the apparatus for removing any blockage in a subsea pipeline due to paraffin or hydrates or other materials that may percipitate from crude oil, and more generally to blockages of any sort that can be removed by fluid blasting or chemical decomposition. It is also desirable to be able to remove a plug in a subsea pipeline without retrieval of the pipeline to the surface. It is also desirable to be able to remove a plug in a subsea pipeline without severing the pipeline. It is also desirable to be able to remove the plug with the pipeline under pressure while protecting the environment from oil spills.
SUMMARY OF THE INVENTION
The present invention provides a method for removal of pipeline blockages in a subsea pipeline without retrieval of the pipeline to the surface and an apparatus that can be used to implement this method. The plug is removed underwater with either divers or a remotely operated vehicle. The method and apparatus of the present invention provides for the removal of the plug with the pipeline under pressure and includes provisions to prevent the escape of pipeline fluid, thus protecting the environment.
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Bath William R.
Clark Timothy
Hettinger Fredric L.
Noce Roberto
Akin Gump Strauss Hauer & Feld L.L.P.
Lillis Eileen D.
Singh Sunil
Sonsub Inc.
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