TDW Offshore Services (TDW) announced completion of two key pipeline interventions offshore Australia for a major operator. The two operations were carried out using the SmartPlug pressure isolation tool for distinctly different purposes. The technology makes it possible to isolate pipeline pressure in a designated section of pipeline for hours - or months - to create a safe environment during construction works or while repairs are made.
First use of isolation technology to protect line from falling objects
The first intervention, which took place during installation of a substructure on part of a major construction project, was carried out to protect a live gas infield flow line from falling objects. The line runs between two platforms offshore Australia. During construction, piles can be dropped and topple over onto a pipeline, causing damage that could result in a catastrophic event. To limit the negative consequences that could flow from a dropped object, TDW isolated the operating facility from the surrounding impact zone. It was the first time that TDW used its SmartPlug system to mitigate the risk of damage to a pipeline during a construction operation.
TDW isolated the pressure in a 30-inch subsea flow line. First, a dual-module SmartPlug isolation tool was launched from the platform and pigged to the set location, and set. The pressure was then bled off from that point back to the platform. For the next six months, the SmartPlug tool remained in the line while construction activities took place. During this period, TDW used its remotely-operated SmartTrack tracking and pressure-monitoring system to continuously monitor the location of the SmartPlug tool and pressure in the line.
As a result of the intervention, it was only necessary to bleed down the affected section of the pipeline, which extends approximately 330m from the platform, as opposed to the entire system, said Rolf Gunnar Lie, Regional Business Development Manager Asia Pacific for TDW. It also meant that they were able to install the new structure, while taking precautionary steps to reduce the potential impact of a dropped object. The benefits that this operator realized as a result of the intervention are considerable, he added.
Isolating pipeline pressure onshore
The second pipeline intervention took place on a section of a 40-inch gas export pipeline (trunkline) that extends from an offshore platform to an onshore terminal. The intervention was required to complete a hydrotest on a 40-inch trunk line terminal refurbishment project involving multiple valve replacements. After a beach valve and pig receiver valves were replaced, a hydrostatic strength test was required. To ensure that this test was safely executed, the affected line was isolated by TDW with the SmartPlug tool. The tool was then pigged from the receiver to the set location using water. After the hydrotest was completed, the plug was pigged efficiently back to the launcher using nitrogen within the scheduled timeframe.
By using the SmartPlug tool, we were able to provide this valued customer with a fast, efficient isolation so that the hydrostatic strength test could be carried out safely, said Lie. In addition to the enhanced safety benefits, associated maintenance costs were reduced because the pipeline was isolated without reducing pipeline pressure or displacing pipeline inventory, he added.