Longitude Engineering reportedly has developed a cost effective decommissioning barge concept for the removal of small oil and gas platforms for the PTT Exploration and Production (PTTEP), a subsidiary of the Thai state owned oil company. 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. The focus being the removal of 90-100 of PTTEP’s minimum facilities platform assets in the Gulf of Thailand, which have topside weights up to 800 tonnes and jacket dry weight up to 1000 tonnes.
“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.
Longitude’s contract was to deliver the conceptual naval, structural, mechanical and electrical engineering, along with outline operational procedures, schedule and CAPEX & OPEX costing for the new removal concept.
The solution is a barge concept that uses reverse float-over and on-board lifting methods to remove both the topside and substructure using the same vessel. For the development of the primary float-off lifting system, Longitude partnered with 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.
PTTEP is currently in discussion with Thailand’s Department of Mineral Fuels (DMF), the government body regulating offshore oil and gas operations, which will sanction the decommissioning work, for the start of their removal program which is due to commence in the coming years.
With the implementation of new decommissioning regulations, all concessionaires must submit the decommissioning plan with cost estimation to DMF for financial security placement at the first stage.