Method for replacing upper anchor cable of mooring anchor legs

Abstract

Disclosed is a method for replacing an upper anchor cable of mooring anchor legs. The method includes 1), arranging a plurality of limiting tugs on the stem of a floating production storage and offloading oil tanker; 2), mounting protractors on the mooring anchor legs; 3), descending a tensioner to the sea floor and then tightening an anchor chain; 4), cutting a loosened anchor chain ring; 5), demounting the tensioner; 6), regulating heading of the oil tanker to be perpendicular to the anchor legs; 7), uplifting the upper anchor cable; 8), demounting an old upper anchor cable section head; 9), pulling a new upper anchor cable section head to the bottom of a single point; 10), mounting the new upper anchor cable section head; 11), connecting the new upper anchor cable section head with one section of the anchor chain to form a complete anchor leg; 12), releasing an underwater hydraulic tensioner steel strand to a natural state and demounting the same; 13), remeasuring water entry angle of the anchor legs and water depth and position of an lower anchor cable section head of the anchor legs. By the application of the method, all construction work like recycling the old anchor cable and mounting the new anchor cable are realized under the condition of not releasing the floating production storage and offloading oil tanker; therefore, production efficiency and reliability are improved.

Description

technical field [0001] The invention relates to a method for replacing an anchor cable, in particular to a method for replacing an anchor cable on a mooring anchor leg. It belongs to the field of offshore oil engineering. Background technique [0002] At present, the internal turret single point mooring system is a single point mooring system widely used in floating production storage and offloading (FPSO). After the oilfield facilities are put into use, after years of operation, the single point mooring anchor legs are prone to damage. Among the various components of the mooring anchor leg, the upper anchor cable is in a state of repeated contraction and stretching for a long time, and its probability of damage is very high. Broken wires and loose strands are frequent damages to the upper anchor cable. When the damage reaches a certain level, the maximum safe load value that the upper anchor cable can bear will be lower than the safe load value required for the design of ...

AI Technical Summary

Problems solved by technology

However, this anchor leg tensioning method is not easy to control the mechanical tensioning process and tension degree, and has high requirements on the performance of the operating ship, so the ship needs to be equipped with a large crane or winch (generally more than 150T)

Therefore, the selection of operating ship resources is relatively limited, the cost of ships is high, and this method is greatly affected by weather factors (generally, the combined wave height is 1.5m or below before lifting can be carried out), and the construction progress is difficult to control

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