Method for replacing mooring anchor leg through lifting and pulling by double ships

Abstract

The invention relates to a method for replacing a mooring anchor leg through lifting and pulling by double ships. The method for replacing the mooring anchor leg through lifting and pulling by the double ships comprises the steps of adjusting floating production storage and offloading (FPSO) heading; loosening the anchor leg; respectively connecting an auxiliary lifting and pulling ship and an anchor mooring treatment ship to a first preset position and a second preset position on a balance weight chain; using the auxiliary lifting and pulling ship for recycling a winch belt and lifting the winch belt to the designated depth, and synchronously moving the ship along an FPSO reverse direction; using the anchor mooring treatment ship for recycling the balance weight chain and an old lying buried cable until recycling all damaged sections of the old lying buried cable on a deck, and meanwhile, using the auxiliary lifting and pulling ship for cooperatively moving the ship; cutting and recycling the damaged sections of the old lying buried cable; manufacturing a new upper cable joint of rest sections of the old lying buried cable, connecting with a lower cable joint of a new lying buriedcable, and lowering into water; through the cooperation of the anchor mooring treatment ship and the auxiliary lifting and pulling ship, moving the ship and paving along an original design route; andtensioning the anchor leg. According to the method for replacing the mooring anchor leg through lifting and pulling by the double ships provided by the invention, the laying buried cables can be replaced under the circumstance that FPSO is in place without stopping production, and only part of the lying buried cable and the balance weight chain need to be recycled and paved, so that the workloadis greatly reduced, the construction operation risk and the operation time are reduced, and the yield loss of an oil filed is reduced.

Description

technical field [0001] The invention relates to a mooring system, and more specifically, relates to a method for replacing mooring anchor legs by pulling two ships. Background technique [0002] The internal turret single point mooring system (STP, Submerged Turret Production) is a single point mooring system widely used in floating production storage and offloading tankers (FPSO, Floating Production Storage and Offloading). The FPSO single point mooring system will have great differences in the structure and installation method of the entire mooring system according to the difference in water depth, design manufacturer and whether it can be released. The single point mooring system usually includes 6-12 anchor legs with the same structure, each anchor leg is composed of ACT chain (adjustment chain), upper anchor cable, mid-water buoy, connecting plate (triangular plate or quadrangular plate, etc.), It is composed of lower anchor cable, counterweight chain, ground cable, an...

AI Technical Summary

Problems solved by technology

[0006] Second, the construction time increases

In order to repair the ground cable, the entire anchor leg needs to be recovered and re-laid, which requires more offshore operation time

[0007] Third, the construction cost increases

When replacing mooring anchor legs in shallow water, it is necessary to use saturated divers for auxiliary operations, which increases the construction cost

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