Longitude Brings Barging into Play
Longitude Engineering, to prepare contractors for the decommissioning of smaller rigs in a cost-effective manner, has developed an innovative decommissioning barge concept to safely remove small oil and gas platforms for Thailand’s PTT Exploration and Production.
The barge concept uses reverse float-over and onboard lifting methods to remove the topside and substructure utilizing the same vessel. For the primary float-off lifting system, Longitude partnered with German-based hydraulics specialist Bosch Rexroth to develop a heave compensated, hydraulic lifting and skidding system.
The resulting vessel design can accommodate the removal of different types of topsides and jackets without modifying the barge; from removal preparation stages, lifting, topside skidding and securing to underwater disposal for the substructure and load in to a disposal yard for the topside. It also has the ability to accommodate 60 operational and marine crew for a period of up to 40 days. Some project cargo contractors have already shown interest in this concept.
“By developing this time and cost-saving solution, we hope to create a wider awareness among contractors within the region in order that they may adopt similar methods in the removal of multi-platform fields,” said Jean-Baptiste Meier, Longitude’s lead engineer. “The Southeast Asian fields present many similar small platforms where innovative thinking can be used to make an economy of scale in the removal operations.”
In 2017 Boskalis decided to convert one of its semi-submersible heavy-lift vessels into a self-propelled crane vessel, including a 3,000-ton revolving crane. The available deck space of 165 meters by 43 meters is unique in its class. Among other things, the Bokalift will be used for decommissioning obsolete oil and gas platforms. Due to its DP-2 capabilities there is no loss time for anchor spread deployment. The vessel can accommodate 150 persons and will have a helicopter deck available for offshore transfers. Delivery is expected in 2018.
A firm decision on the conversion of another Boskalis heavy-lift vessel into a crane vessel is expected to take place in the course of 2018.
Photo credit: Longitude
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