A new multipurpose vessel will play a key role on Shell’s Malampaya project offshore Malaysia. Pieter van Hekken explains.
In the Q1 this year , Boskalis Offshore will start one of the most challenging projects in its history. Boskalis Offshore, a subsidiary of Netherlands-based Royal Boskalis Westminster N.V., is responsible for the seabed work—excavation and rock placement—as well as for the Transport & Installation (T&I) of a new offshore platform at the Malampaya gas field, off the island of Palawan, under a contract with Shell Philippines Exploration.
|The Malampaya depletion compression platform|
Malampaya’s production, at about 380MM scf/d natural gas and 15,000 bbl/d condensate, currently supplies fuel to three natural gas-fired power generation plants in the Batangas area. At the moment, it is the country’s only major source of natural gas supply. Shell estimates Malampaya powers about 30% of the Philippines’ electricity requirements.
The Malampaya Deep Water Gas-to-Power Project is a joint venture involving the Philippine National Oil Company (10% WI), Chevron (45% WI), and Shell Philippines Exploration (45% WI and operator). Operations began in 2001.
The Malampaya reservoir, in the deepwater Palawan basin, is produced via a 10-slot subsea manifold in 820m water depth tied back to a platform 30km away in 43m water depth. A Phase 2 of the project saw two more subsea production wells drilled on the field, using the ENSCO 8504. Phase 3, the current project, is part of the optimization of the field.
To maintain the gas pressure in the field, an offshore depletion compression platform (DCP), currently under construction in Keppel Subic Shipyard Inc.’s fabrication yard in Subic Bay, on the west coast of the island of Luzon in Zambales, Philippines, will be installed alongside the existing production platform. The DCP’s two gas turbine-driven compressors will maintain the gas at reservoir pressure. Condensate is removed on the platform and the dry gas transported via a 504km-long (313mi) 24in. export pipeline to Batangas port for further processing.
The project is one of the first in which the expertise of Boskalis and SMIT, acquired by Royal Boskalis in 2010, have been brought together in an integrated package.
Boskalis was awarded the contract in April 2013. Boskalis Offshore opened a project office in Manila, next to Shell, as part of the preparation work. One of two new, multipurpose vessels, the Ndeavor, delivered in November, was also designed with the project in mind.
The first phase of seabed preparation begins in Q1, this year, and the T&I phase in Q4. Timing and proper planning for this project are crucial. The power plants in Batangas port area are responsible for the electricity supply to some 40% of the people of Philippines. It is vital that the gas flow isn’t interrupted. When the DCP platform is hooked up to existing platform, Shell will have to take the existing facilities offline, so the whole procedure has to be planned years in advance. Preparation work has involved sourcing rock to create rock pads for the platform procured from local quarries. A further 10,000 tonnes of iron ore is needed for ballasting, with Boskalis’ Rock Department is providing assistance to test if the rock meets the specifications.
The project also involves the use of two new multi-functional cable-laying/ offshore services vessels, the Ndeavor, and the Ndurance. Both vessels are 99m-long, 30m-wide, have a 4.7m draught, and weigh 7500 DWT. They have 62 cabins, for 104 people, Both vessels were built by Samsung C&T Corporation and Shanghai Zhenhua Heavy Industries Co., Ltd. and classified by Lloyd’s Register.
Ndeavor, which underwent sea trials in November, also has a 100-tonne, active heave compensated crane, with a 15m reach, and a helideck. It will be used for the excavation and rock-placement work. It will also be the command vessel during installation of the platform, placing ballast in the footings, and during the positioning of a bridge between the two platforms.
|Boskalis Offshore's new multipurpose vessels, the Ndeavor|
Ndeavor’s sister vessel, Ndurance, is the designated cable layer, and is being fitted with a 5000-tonne turntable.
These vessels had to be as versatile as possible to fulfill the requirements of the client. Ndeavor had to have DP2 capability and we felt the best solution was to fit the vessel with both excavation and rock installation equipment.
The first phase of the work offshore will be preparing the seabed for the installation of the DCP, which will involve excavating down to various depths.
Ndeavor can handle the entire scope in the first phase. The vessel will remove the top layer of carbonate sand, and, after excavation, use engineered rock to back fill to an elevation of -42.73m Lowest Astronomical Tide (LAT). The removed sand will be taken to a designated location alongside the platform.
A trial seabed preparation pad will then be constructed and validated south of the proposed DCP location before construction of four seabed preparation pads on the backfilled surface, to a target LAT -41.73m.
Surveys of each phase of the work, including pre-excavation, post-excavation, pre-backfill, post-backfill, pre-pad installation, post-pad installation surveys and progress surveys during the execution of each phase.
The next phase of work will see Boskalis Offshore take the DCP to the location, position it and install it using 3-4 100/200-tonne anchor handling tugs. Temporary equipment will be installed on the DCP. Installation will involve coordinating involved subcontractors, to perform the grouting operation, and constant surveying the platform’s position to ensure installation.
To stabilize the platform, dense iron ore gravel ballast is put into all four footings as soon as the installation has been completed. Rock, for scour protection, and sourced from local quarries, will then be placed around the four footings.
Ndeavor will take command during the positioning of the new platform, and transportation of the iron ore ballast. Then, a permanent bridge, linking the gas production platform to the new compressor platform, will be installed between the two platforms. A second bridge will be installed giving temporary access from the bay to the platform.
To install the permanent bridge, a Barge Master motion-compensated platform lifting system will be fitted on the aft of Ndeavor. It will then sail out to location. Once on site, the bridge will be held still by the Barge Master so it can be lifted off safely by two temporarily installed lifting arrangements.
This bridge, which is around 220-250 tonnes, can be lifted safely from the moving vessel by the Barge Master system, which provides a very stable platform. The use of the Barge Master is a world first, using largely proven technology but in an innovative way.
The integrated approach has many benefits for the client. We can handle all of the work in-house: rock installation, earth moving, tow out, installation of the new platform, ballasting of the legs, install the iron ore to give stability and the bridge between the new and existing platforms.
Our client does not have to deal with interface issues. Usually the seabed work would be completed, then we would hand over to the client, and then the client hands over to a second contractor for the rock installation. Also, because one multipurpose vessel is doing many tasks, the client has to approve only this vessel. Shell accepted Boskalis’ own safety program No Injuries, No Accidents (NINA), on the project.
The Malampaya project is the second assignment in a row that Boskalis Offshore is executing in the Far East for Shell.
On the Bukom project in Singapore, Boskalis Offshore completed trenching, pre-lay and post-lay rock placement. In addition, all diving activities related to the pipelaying for an import pipeline and installing an SBM buoy were carried out by divers from Boskalis Offshore Subsea Services.
Images courtesy of Boskalis Offshore
Pieter van Hekken is regional manager for Boskalis Offshore Subsea Contracting in the Far East and Australia. He holds a BSc in Civil Engineering from the University of Applied Sciences in Utrecht, the Netherlands, and an MSc in Civil Engineering, Management and Geo-Technology from the Southbank University in London. Before assuming his current position in 2007, he worked in various project management roles for Boskalis worldwide for more than seven years.