The Tortue/Ahmeyim gas project is located along the maritime border of Mauritania and Senegal. Image courtesy of CH2M.
The Tortue/Ahmeyim gas project is expected to commence production in 2021. Image courtesy of Carey Akin.

The Tortue/Ahmeyim gas project is located off the coast of Mauritania and Senegal, along the maritime border, in 2,700m of water.

The project is jointly owned by BP (60%, operator), KOSMOS Energy (30%), and Societe Mauritanienne Des Hydrocarbures et de Patrimoine Minier (10%).

An Inter-Government Cooperation Agreement was signed by the Mauritania and Senegal governments in February 2018, enabling the development of the project. The two governments have agreed upon a 50-50 share of the resources and profits from the gas field development.

The final investment decision on the project is expected by the end of 2018 and first production is expected in 2021.

Tortue/Ahmeyim gas project location and reserves

The Tortue/Ahmeyim gas project straddles two blocks including the C-8 and Saint-Louis Profound blocks along the maritime border of Mauritania and Senegal. It covers an area of 33,000km² in the two blocks, which are part of the Greater Tortue area.

The Greater Tortue area is estimated to contain 25 trillion cubic feet of gas, while the Tortue/Ahmeyim gas project is estimated to contain 15 trillion cubic feet of gas.

Discovery details of Tortue/Ahmeyim gas fields

The Tortue field was discovered by the Tortue-1 exploration well drilled in mid-2015. The well encountered approximately 117m of net hydrocarbon pay in high-quality reservoir sands in the Albian and Cenomanian intervals.

An appraisal well named Ahmeyim-2 was drilled up to 5,200m depth. The well penetrated the seismic-inferred gas-water contacts, which resulted in the expansion of the productive field area from 50km² to 90km². The well encountered 78m of net gas pay in two high-quality reservoirs of the Lower Cenomanian and Albian formation.

Tortue/Ahmeyim gas project development plan

The development plan entails the drilling of four wells, which will be tied-back to a floating production storage and offloading (FPSO) vessel through production pipelines. The produced gas will be processed to separate the liquids and transported onto a floating liquid natural gas terminal (FLNG) through 100km of flowlines for liquefaction.

“The Tortue field was discovered by the Tortue-1 exploration well drilled in mid-2015.”

The liquefied gas will transported to a proposed onshore hub terminal through a transmission pipeline with domestic gas connection points. The hub terminal is proposed to feature breakwater-protected berths.

Contractors involved

The preliminary front-end engineering design (pre-FEED) and project support contract was awarded to KBR in August 2017. The pre-FEED activities are expected to be completed by the end of 2019.

CH2M, a sustainable energy company, was sub-contracted by KBR to provide civil and marine engineering support in October 2017. The company will play a central role in decision-making on the location, layout, construction of the onshore hub, and planning of marine operations and project execution.

The FEED contract for the field development was awarded to McDermott International and BHGE in March 2018. McDermott will be responsible for defining the subsea umbilicals, risers and flowlines to be used for the project, while BHGE will focus on defining the subsea production system.

BP awarded Technip FMC the contract for the FEED for the FPSO unit of the project in April 2018. The contract facilitates the transition to an engineering, procurement, construction and installation (EPCI) contract during the later phases of the project.