Pipeline Intervention From a Dynamically Positioned Mono-Hull Vessel via a Flexible Riser

摘要

After a subsea mudslide near the mouth of the MississippirnRiver Delta, several sections of production or export pipelinesrnwere severed. The pipelines could not be retrieved to surfacernbecause they were buried deeply in the mud. Coiled tubingrnwas successfully used to clean and abandon these pipelines insiturnunder 200-feet of water. The coiled tubing was conveyedrnthrough a flexible riser from a Dynamic Positioning mono-hullrnvessel. The lengths of the four sections of pipeline cleanedrnwere 2400-feet, 1200-feet and 1800-feet with diameters of 8-rn10 inches.