Disclosed are methods to counter buoyancy and install variable tension
risers using a weighted chain ballast line. An example of an apparatus
used in conjunction with the embodiments includes compliant variable
tension risers to connect deep-water subsea wellheads to a single
floating platform. The variable tension risers allow several subsea
wellheads, in water depths from 4,000 to 10,000 feet, at lateral offsets
from one-tenth to one-half of the depth, to tie back to a single floating
dry tree semi-submersible platform.