Malampaya topsides installedNews // April 5, 2001
The topside facility was set on its concrete base as a complete integrated deck in the South China Sea on 17 March, 14 days ahead of schedule. At an installation weight of 11,500 tonnes, the Malampaya topsides is the largest integrated deck ever installed in Asia Pacific and is currently the largest offshore installation in the world using the float over method.
This method, pioneered by KBR, allows a complete integrated deck to be installed as one unit thereby maximising the fabrication and testing work that can be completed onshore.
KBR's scope of work is to engineer, procure, fabricate, install and commission an offshore gas processing facility for its client, Shell Philippines Exploration BV. KBR was awarded this scope in August 1998.
The topsides set sail from its fabrication site in Singapore on 01 March and arrived at its destination 50km northwest of Palawan Island, the Philippines on 10 March having covered 1,134 nautical miles. The average speed of the tow was five knots with the route passing the north coast of Borneo.
The tow was performed by three ocean going tugs with a combined power of 39,000bhp, generating a bollard pull of up to 300 tonnes. Sea states experienced during the tow were generally calm with swells of up to 2m.
The Malampaya topsides were transported on a newly constructed barge, theH-541 owned by Heerema Marine Contractors Nederland BV who held asub-contract from Kellogg Brown & Root to transport and install the topsides.
The H-541 is 165m long, 42m wide and during the transportation maintained a draught of 5.7m. The topsides were supported 22m above the deck of this barge on a transportation truss weighing 1,500 tonnes.
This truss, together with the barge freeboard enabled the legs of the topsidesto pass over the tops of the Concrete Gravity Sub-structure (CGS) shafts during the initial installation phase.The H-541 barge and its three tow tugs rendezvoused with the Rockwater 2,a Halliburton owned vessel, a manoeuvring tug and a further ocean going tug atthe location of the CGS offshore Palawan Island in the Philippines on 10 March2001. The Rockwater 2 is capable of dynamic position holding without usinganchors and was to act as the construction support vessel over theinstallation period.
During the initial two days after arrival of the installation spread, final preparations for the topsides installation were made on the CGS and H-541 barge. On the 14 March a second manoeuvring tug joined the installation spread and with all eight vessels and equipment checked and ready the vessels waited for the sea states to reduce such that installation could commence.
On the morning of 16 March the swell at the CGS location had reduced to 0.5m and the forecast for the next 72 hours was good. At 06.00 hours on 16 March one tow and one docking tug commenced manoeuvring the H-541 barge to the CGS location.
Two pre-laid anchors and four docking lines attached to the CGS shafts were connected to winches on the H-541 barge and the H-541 was then manoeuvred between the legs of the CGS.
At 03.10 hours on 17 March 2001 the H-541 barge was connected to the first of the four-inch diameter steel wire mating lines and by 07.45 hours all mating lines had been connected and environmental conditions were confirmed as within limits for the installation to proceed.
Ballasting operations then commenced with 36 pumps combining to transfer seawater at more than 21,000 tonnes per hour into the H-541. At 15.20 hours first contact was made between the CGS leg mating units and the deck leg supports of the topside facility. Rubber columns in the deck legs and on the transportation frame allowed a progressive transfer of weight to the CGS.
Fifty seven minutes later the topsides weight had been fully transferred to the CGS and nine hours later the H-541 barge was clear of the platform. Sand jacks on each of the four CGS leg mating units were then simultaneously released allowing the topsideto be lowered in a controlled manner into its final position. The contact points are now being welded together to form the one permanent structure of the Malampaya Platform.
Kellogg Brown & Root will use the Rockwater 2 as its Construction Support Vessel during the offshore commissioning phase that is now just starting. The target is to complete commissioning such that the platform can export treated gas by 01 August 2001 through a 504km pipeline to shore.
This will allow the onshore gas plant at Batangas on Luzon Island, the Philippines to start its commissioning on schedule. Following onshore gas plantcommissioning the Malampaya platform will be ready to supply gas to powerplants in the Philippines by 01 October 2001.