This paper presents the challenges and obstacles faced in the use of a new technology for the plugging and deoiling of sections of unpiggable flowlines before decommissioning. The solution used an ultralightweight, miniaturized coiled-tubing system that was deployable from the platform lower decks with minimal laydown area required. The system had the ability to traverse multiple bends, deoil the line, and deliver an expandable cement to plug the pipeline in a single operation.
First production in the Murchison field began in 1980, and the field has now reached the end of its life. As part of the decommissioning project, one of the subsea wells was seen to be still connected to the Murchison platform by two flowlines contained within a subsea bundle (PL123), with these flowlines having 4-in. outer diameters. These lines were installed to provide early production for the first year until all the infrastructure was put in place. The control lines and pressure-monitoring system had been disconnected at the platform sometime in the past (Fig. 1)....
Miniaturized Coiled-Tubing System Reduces Costs During Pipeline Decommissioning
05 December 2015