Image: The Greater Tortue Ahmeyim LNG project is located on the maritime border of Mauritania and Senegal, West Africa. Image courtesy of BP p.l.c.
The Middle East trails North America for projected LNG capacity additions over the next four years
The Greater Tortue Ahmeyim LNG project is expected to commence production in 2022. Image courtesy of Eiffage.

Greater Tortue Ahmeyim is an offshore liquefied natural gas (LNG) project based on upstream gas production in 2km-deep waters on the maritime border of Mauritania and Senegal. It is the deepest offshore project in Africa till date.

The LNG project is being jointly developed by BP, Kosmos Energy, Societe des Petroles du Senegal (Petrosen), and Societe Mauritanienne des Hydrocarbures (SMHPM) with BP as the operator.

Planned to be developed in phases, the Greater Tortue Ahmeyim LNG project will produce up to 10 million tonnes of LNG a year (Mtpa).

A new well named Greater Tortue Ahmeyim-1 was drilled to a total depth of 4,884m in the eastern portion of the Greater Tortue area, which encountered 30m of net gas pay in high-quality Albian reservoir in July 2019. The new discovery indicates the potential to expand the capacity of the LNG project beyond 10Mtpa in future.

The project will produce 2.5Mtpa of LNG in its first phase of development for which the final investment decision (FID) was taken in December 2018.

Construction on the offshore LNG project is expected to be started in the second half of 2019, with the start of commercial production is scheduled for 2022.

Greater Tortue Ahmeyim discovery and development background

The Greater Tortue Ahmeyim project is based on the development of two offshore gas fields namely Tortue and Ahmeyim.

The Tortue field, located in the C-8 block in Mauritania offshore waters, was discovered by the Tortue 1 discovery well, which was drilled up to a depth of 2.7km in 2015.

The Ahmeyim field, located in Saint Louis Offshore Profond block of Senegal, was discovered by the Ahmeyim-2 discovery well, which was drilled up to 5.2km depth in 2016.

The Tortue 1 discovery well encountered 117m of net gas pay, while the Ahmeyim-2 encountered 78m of net gas pay.

BP entered into an agreement with Kosmos Energy for co-developing the gas fields in December 2016.

The governments of Mauritania and Senegal signed an inter-government co-operation agreement to develop the cross-border Greater Tortue Ahmeyim offshore gas field in February 2018. Greater Tortue Ahmeyim ownership details

The Saint-Louis Offshore Profond block offshore Senegal is owned by BP (60%), Kosmos Energy (30%), and Petronas (10%).

The C-8 block offshore Mauritania is owned by BP (62%), Kosmos Energy (28%), and SMHPM (10%).

Greater Tortue Ahmeyim gas reserves

Spread over 33,000km², the Greater Tortue Ahmeyim field is estimated to contain approximately 15 trillion cubic feet (tcf) of recoverable gas reserves.

Infrastructure facilities for Greater Tortue Ahmeyim phase one development

The Greater Tortue Ahmeyim field will be initially developed with a deepwater subsea production system comprising four gas production wells tied-back to a floating production, storage and offloading (FPSO) unit.

The gas will be processed for the removal of heavier hydrocarbon components on the FPSO. The processed gas will be further sent via a 100km-subsea pipeline to a near-shore floating LNG (FLNG) vessel named Gimi.

The Gimi FLNG will be capable of producing 2.5Mtpa of LNG a year for global export. The remaining gas will be sent through pipelines to Mauritania and Senegal gas markets, for domestic consumption.

BP Gas Marketing will off-take the entire LNG output from the Greater Tortue Ahmeyim phase one development project.

Gimi FLNG details

BP signed a 20-year lease and operate agreement (LOA) for the Greater Tortue Ahmeyim FLNG unit with Gimi MS Corporation in February 2019.

Estimated to cost £1.02bn ($1.3bn), the FLNG development involves the conversion of LNG carrier Gimi at Keppel Shipyard in Singapore.

GIMI MS will construct and operate the FLNG unit and invest 70% of its total development cost, while First FLNG, a subsidiary of Keppel Capital, provides for the remaining 30% of the project cost.

Contractors involved in Greater Tortue Ahmeyim LNG project

TechnipFMC was contracted for the engineering, procurement, construction, installation, and commissioning (EPCIC) of the FPSO unit for the project in March 2019. It followed a front-end engineering and design (FEED) contract for the FPSO awarded to the same company in April 2018.

Golar LNG is responsible for the construction and operation of the Gimi FLNG, while Keppel is engaged for the conversion works associated with the project.

Black & Veatch will provide the PRICO® liquefaction process for the Gimi FLNG.

KBR was awarded the engineering, procurement, and construction management (EPCM) contract for the facilities integration as well as for the terminal quarters and utilities management for the near-shore terminal of the project in May 2019. It followed a FEED contract awarded in October 2018.

KBR was also awarded the pre-FEED contract for the second and third phase development of the Greater Tortue Ahmeyim offshore project in April 2019.

CH2M HILL was sub-contracted by KBR for the civil and marine engineering services of the Greater Tortue Ahmeyim LNG project in October 2017.Eiffage Génie Civil Marine in a consortium with Saipem was awarded the EPCI  contract for the near-shore terminal of the project in February 2019, followed by a FEED contract awarded  in April 2018.