‘Low-cost’ barge suited to platform removals in the Gulf of Thailand

Offshore staff

SINGAPORE – Longitude Engineering has developed a decommissioning barge concept for safe removal of small oil and gas platforms for the Thai state oil company PTTEP.

According to Longitude, part of the London Offshore Consultants Group, the aim was to develop a viable and cost-effective alternative to conventional ‘reverse installation’ through the use of heavy-lift crane barges, for the removal of the topsides and jackets.

PTTEP has 90-100 minimum facilities platforms in the Gulf of Thailand with topsides weighing up to 800 metric tons (882 tons) and with jacket dry weights of up to 1,000 metric tons (1,102 tons).

Longitude’s contract involved conceptual naval, structural, mechanical, and electrical engineering, along with outline operational procedures, schedule, and capex and opex estimates for the new removal concept.

The barge concept employs reverse float-over and onboard lifting methods to remove both the topsides and substructure, using the same vessel.

For the primary float-off lifting system, the company teamed up with hydraulics specialist,Bosch Rexroth, to develop a heave-compensated hydraulic lifting and skidding system.

The resultant vessel design is said to allow removal of different types of topsides and jackets, without the need for modifying the barge, from the removal preparation stages, through lifting, topsides skidding and securing to underwater disposal for the substructure and delivery of the topsides to a disposal yard.

It can accommodate a crew of 60 for a period of up to 40 days.

Engineering undertake comprised the naval design, definition of the operational weather windows, development of associated vessel layouts, the structural, marine and mechanical systems design, and the electrical systems definition.

In addition, Longitude devised preliminary operational procedures for lifting operations, transport, load-in and associated operational schedules and capex/opex.

Currently PTTEP is in discussions with Thailand’s Department of Mineral Fuels (DMF), the government body regulating offshore oil and gas operations, on sanctioning the decommissioning program, with removals set to get under way in the next few years.

As the new decommissioning regulations are implemented, all concessionaires will have to submit their decommissioning plan and cost estimates to DMF for financial security placement at the first stage.

Longitude’s lead engineer Jean-Baptiste Meier said: “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.

“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.”

04/16/2018