Tortue

Location and Water Depth

The GTA project is located in ultra-deep waters, approximately 120 km offshore, at a water depth of about 2,850 meters (9,350 feet) on the maritime border of Mauritania and Senegal.

Project Overview

The Greater Tortue Ahmeyim project is an offshore liquefied natural gas (LNG) project, representing Africa's deepest offshore project to date. It involves the development of two main gas fields: Tortue and Ahmeyim, which are part of the C-8 block offshore Mauritania and the Saint-Louis Offshore Profond block offshore Senegal.

Ownership and Partners

The project is jointly developed by:

• BP (operator) - 60% in the Saint-Louis Offshore Profond block and 62% in the C-8 block
• Kosmos Energy - 30% in the Saint-Louis Offshore Profond block and 28% in the C-8 block
• Petrosen (Societe des Petroles du Senegal) - participating in the project
• SMHPM (Societe Mauritanienne des Hydrocarbures) - 10% in the C-8 block
• Petronas - 10% in the Saint-Louis Offshore Profond block.

Gas Reserves

The GTA field is estimated to contain approximately 15 trillion cubic feet (tcf) of recoverable gas reserves, spread over an area of about 33,000 km².

Discovery and Appraisal

• The Tortue field was discovered by the Tortue-1 exploration well in 2015, which encountered 117 meters of net gas pay.
• The Ahmeyim field was discovered by the Ahmeyim-2 well in 2016, which encountered 78 meters of net gas pay.
• The Greater Tortue Ahmeyim-1 (GTA-1) appraisal well, drilled in 2019, encountered 30 meters of net gas pay in a high-quality Albian reservoir.

Development Phases

The project is planned to be developed in phases:

• Phase 1: The initial phase involves an ultra-deepwater subsea system with four gas production wells tied back to a mid-water floating production, storage, and offloading (FPSO) vessel. The gas is processed on the FPSO, and then transported via a 100 km subsea pipeline to a nearshore floating LNG (FLNG) facility. This phase is expected to produce 2.3 million tonnes per annum (mtpa) of LNG. The final investment decision (FID) for Phase 1 was made in December 2018, and commercial production was initially scheduled for the first half of 2022 but has been updated to the last quarter of 2023.
• Phase 2: Announced in February 2023, this phase is expected to produce up to 3 mtpa of LNG upon commissioning. Production from Phase 2 is forecast to begin in 2027 and peak in 2028, with the project expected to continue until 2051.

Infrastructure

• FPSO: The FPSO vessel, set sail from the COSCO Qidong Shipyard in China in January 2023, will be moored 80 km offshore at a water depth of 120 meters. It is designed to process up to 500 million metric standard cubic feet per day (Mmscfd) of gas and will accommodate up to 140 personnel.
• FLNG: The FLNG facility, converted from a 125,000 m³ Gimi LNG carrier at Keppel Shipyard in Singapore, will be located approximately 10 km offshore in 30 meters deep waters. It will produce 2.3 mtpa of LNG under a 20-year lease and operation agreement with Gimi MS Corporation.

Contractors and Suppliers

Key contractors involved include:

• TechnipFMC: Front End Engineering Design (FEED) for the FPSO.
• KBR: FEED contract for Phase 1.
• McDermott: FEED for the subsea umbilicals, risers, and flowlines (SURF) scope.
• BHGE: FEED for the subsea production system (SPS) scope.

Production and Export

The processed gas will be liquefied at the FLNG facility and exported globally. BP Gas Marketing will off-take the entire LNG output from the project. Additionally, some gas will be supplied to the domestic markets of Mauritania and Senegal.

Regulatory and Cooperation Agreements

The governments of Mauritania and Senegal signed an inter-government co-operation agreement in February 2018 to develop the cross-border gas project, with each country sharing resources and revenues on a 50/50 basis. The project was granted the status of ‘National Project of Strategic Importance’ by the presidents of both countries in July 2021.

This project is a significant milestone in the energy sector for both Mauritania and Senegal, leveraging advanced technologies and international cooperation to tap into the region's substantial gas reserves.