Reduced J-tube pull force

DETAILED DESCRIPTION What is claimed is: 1.
A method for reducing the force required to move a pipe through a J-tube attached to an offshore platform and for reducing corrosion at the interface between air and salt water in the J-tube comprising: introducing a mixture of fluorocarbon polymer and a hydrocarbon carrier into the J-tube, the mixture having a lower specific gravity than water; and moving the pipe through the J-tube.
2.
The method of claim 1 wherein the fluorocarbon polymer is polytetrafluoroethylene and the carrier is a hydrocarbon.
3.
A method for reducing the force required to move a pipe through a J-tube attached to an offshore platform and for reducing corrosion at the interface between air and salt water in the J-tube comprising: introducing a mixture of fluorocarbon copolymer and a hydrocarbon carrier into the J-tube, the mixture having a lower specific gravity than water; and moving the pipe through the J-tube.




Description:
BACKGROUND OF THE INVENTION This invention pertains to the use of J-tubes on offshore platforms for installing pipelines extending upwardly from the seafloor.
In offshore petroleum operations, a platform frequently serves as an operational base and a production terminal for oil and gas wells.
A problem common to all such offshore platforms is providing a connection from an above-water facility to a pipeline which lies on the seafloor.
A typical method of providing the connection is the use of a J-tube guide member which is a continuous tubular structure having the shape of a J and through which a riser pipeline is pulled from the seafloor to the above-water facility.
This J-tube runs down along the length of the platform, bends near the seafloor and thus runs generally parallel to the seafloor a short distance.
The lower end of the J-tube frequently includes a flared portion referred to as a bell mouth.
The upwardly pulled pipeline, i.
e.
the riser, provides a fluid flow path from the above-water facility to the pipeline on the seafloor