Allseas takes over BP pipelay work

British Petroleum (BP) has awarded a contract to a Swiss-based offshore contractor Allseas to complete the subsea pipelay work on the Greater Tortue Ahmeyim (GTA) project. BP is one of the world’s largest integrated oil and gas companies. BP is involved in almost every step of the oil and natural gas supply chain, from exploration to the sale and marketing of energy products.

Allseas specialises in offshore pipeline installation, heavy lift, deep-ocean polymetallic nodule collection, and river waste collection. GTA is an offshore Liquefied Natural Gas (LNG) project on the maritime border of Mauritania and Senegal, involving one of the deepest subsea developments in Africa. Allseas will deploy its Pioneering Spirit construction vessel, for the contract work to begin in early December 2023.

The Pioneering Spirit is not only the largest and most capable heavy-lift construction vessel but also the world’s largest pipelay vessel, with an impressive S-lay tension capacity of 2,000 tonnes. Allseas will also use its Oceanic vessel to support installation work. The wells on the GTA project are around 80 km from the Floating Production Storage and Offloading (FPSO).

The installation of the pipelines and subsea structures is a highly complex task that requires meticulous planning and execution.

McDermott had begun working on the project earlier this year but pulled out after being unable to perform. McDermott announced a restructuring agreement in September, amending and extending debts and bringing in $250 million of new capital. McDermott had deployed its Amazon pipelay vessel to carry out the work but ran into problems and is now in Las Palmas.

Under the contract, Allseas will be responsible for the installation of about 75 kilometres outstanding on the two 16-inch links export pipelines with Field Termination Assemblies (FTAs) in water depths ranging between 1,500 and 2,800 metres. Allseas will also install four 16-inch Corrosion Resistant Alloy (CRA) infield lines with FTAs up to 2 kilometres long in 2,800 metres of water. The agreement demonstrates both BP’s and Allseas’ willingness and ability to take on highly complex pipelay projects with fast-track planning and execution scopes.

Allseas is excited to work with BP on this project, this opportunity re-establishes the partnership between the two companies and creates a platform on which to grow and strengthen future collaboration between BP and Allseas. The commercial and engineering teams from BP and Allseas have worked to evaluate the technical feasibility of installing the pipelines and subsea structures, originally designed for a J-lay solution. It was not clear when Allseas is expected to complete the pipelay, but it aimed to finish installing infield flowlines and subsea structures in the first quarter of 2024.

Allseas’ Pioneering Spirit is well-suited for the installation of mixed-diameter pipelines and subsea structures in ultra-deepwater.

With a remarkable 2,000-tonne tension holding capacity, the Pioneering Spirit vessel will be equipped with a special 1,000-tonne J-mode installation frame, designed in-house and built at Allseas’ yard in Heijningen, the Netherlands, to install the 10 FTAs. The GTA FPSO is currently offshore South Africa’s east coast, while the Gimi LNG vessel is moored in Singapore. Golar LNG is building the Gimi LNG vessel to liquefy the gas.

BP’s partners for the GTA project include Societe des Petroles du Senegal (Petrosen), Societe Mauritanienne des Hydrocarbures (SMH), and Kosmos Energy. The BP-operated project will have a total capacity of up to 3 million Tonnes Per Year (TPY) of liquid natural gas. Spread across the C-8 block off the shore of Mauritania and the Saint-Louis Profond offshore block in Senegal, the field is estimated to hold up to 15 trillion cubic feet of recoverable gas resources.

The Gimi LNG vessel would leave Singapore in September. As pioneers of dynamically positioned S-lay technology, characterized by its fast installation speeds in all water depths, Allseas has successfully installed over 27,500 kilometres of pipeline worldwide.