Method for changing connecting tubes in FPSO (floating production storage and offloading) single-point buoys

Abstract

The invention relates to the field of production of offshore oil, in particular to a method for changing connecting tubes in FPSO (floating production storage and offloading) single-point buoys. The method aims at realizing inward rotation tower type single-point mooring. The method comprising the steps of lowering worn connecting tubes by using a long bolt and a hydraulic jack; then mounting a wire rope sling; and changing the single-point worn connecting tubes one by one by using an auxiliary winch arranged on the upper portion of a rotation tower. By the method for changing the connecting tubes in the FPSO single-point buoys, single-point flexible vertical tubes can be remounted or heads of the single-point flexible vertical tubes can be fixed before typhoon, so that the time for whole construction is prolonged, and the worn connecting tubes can be changed in a single-point manner even during typhoon. Moreover, because the auxiliary winch is arranged on the upper portion of the single-point rotation tower, relative motion does not exist, strict ship limiting operation is not required when the worn connecting tubes are lowered and new connecting tubes are lifted, construction risks can be reduced, and the construction cost for a ship is saved.

Description

technical field [0001] The invention relates to the field of offshore oil production, in particular to a method for replacing an inner connecting pipe of an FPSO single point buoy for an inner turret type single point mooring system. Background technique [0002] FPSO is a floating production and storage device that integrates production, storage, and external transportation. It is fixed by an inner turret type single point mooring. The crude oil produced from the wellhead platform passes through the submarine pipeline to the underwater base plate. Point the flexible riser, buoy inner connection pipe and swivel head to reach the FPSO for processing. There are connecting pipes in the buoy to transport the oil, gas and water produced in the oil field. The oil and gas water contains corrosion products, which will corrode the connecting pipe, or for other reasons, the connecting pipe needs to be replaced. The connecting pipe is usually prefabricated in the single point buoy ...

AI Technical Summary

Problems solved by technology

Its shortcomings are as follows: First, this plan is considered in combination with the initial design of the single point. Although it is safe, there are many things to disassemble. Sections, etc., the workload is relatively large

Secondly, when using a 300t crane to hoist and lower the connecting pipe, since the 300t winch is on the rotating FPSO and rotates relative to the turret, it is necessary to restrict the operation of the ship, and the operation of the ship is relatively strict, and the FPSO is not allowed during the hoisting process. There is rotation, therefore, this scheme requires two three-purpose workboats for ship-limited operations

Furthermore, if it is a typhoon season, if this method is used, when a typhoon is encountered during the replacement, because the rotating head has been removed, the two flexible risers need to be fixed and restored. It is very difficult to do this, so Conventional methods can only be replaced in non-typhoon seasons and from March to May when the weather is relatively good, and the time window for replacing single-point connecting pipes is very narrow

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