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.