Dry tree subsea well communications apparatus and method using variable tension large offset risers

摘要

Disclosed are compliant variable tension risers ( 106 ) to connect deep-water subsea wellheads ( 102 ) to a single floating platform ( 104 ). The variable tension risers ( 106 ) allow several subsea well-heads ( 102 ), 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 ( 104 ). Also disclosed are methods to counter buoyancy and install variable tension risers using a weighted chain ballast line ( 228, 230 ).