Sangomar Offshore Field

Sangomar offshore oil and gas field (formerly the SNE field) is located around 100km from Dakar, the capital city of Senegal.

Work on the initial Sangomar Field Development Phase 1 is underway. Once complete, it will become Senegal’s first offshore oil project.

The project is being developed by Rufisque Offshore, Sangomar Offshore and Sangomar Deep Offshore (RSSD) joint venture comprising Woodside and Societé des Petroles du Sénégal (Petrosen).

In the Sangomar exploitation area, Woodside (operator) and Petrosen hold 82% and 18% participating interests, respectively. Woodside has a 90% stake in the remaining RSSD evaluation area with Petrosen owning the remaining 10%.

The RSSD joint venture approved Sangomar Field Development Phase 1 (Sangomar Development) in January 2020 after all receiving government approvals and the execution of key contracts.

As of November 2022, the project is 70% complete. It is expected to commence production in 2023.

The first phase will target an estimated gross oil resource of 231 million barrels (MMbbl) of oil. Over the first phase of the development, it is expected to generate $2bn-$4bn of direct revenue for the Government of Senegal.

Location details

The Sangomar field is situated in the Rufisque, Sangomar and Sangomar Deep Blocks, which includes an area of 7,490km² within the Senegalese part of the Mauritania-Senegal-Guinea Bissau Basin.

Water depth in the region ranges from 700m to 1,400m.

Discovery

The Sangomar oil field was discovered by FAR in 2014 with the drilling of the SNE-1 exploration well.

The well, located in 1,100m water depth, encountered a 95m gross oil bearing column with net oil pay zone thickness of 36m in Albian aged sandstones. The SNE-1 well was drilled to a depth of 3,000m.

Another exploration well FAN-1, drilled to a total depth of 4,927m, encountered a 500m gross oil interval with a net pay of 29m of oil.

Project infrastructure

The Sangomar Field Development Phase 1 will include a stand-alone floating production storage and offloading (FPSO) facility, 23 subsea wells and supporting subsea infrastructure.

In November 2022, Woodside Energy announced the completion of the construction phase of the FPSO facility.

The facility is named after Senegal’s first president Leopold Sédar Senghor. It is designed to process 100,000 barrels of crude oil per day, 130 million standard cubic feet of gas per day and 145,000 barrels of water injection per day.

The FPSO will have storage capacity of 1.3 million barrels of crude oil. After processing, the oil will be exported using tankers.

Additionally, Leopold Sédar Senghor will be designed to enable integration of subsequent Sangomar development phases, including gas export to shore and potential future subsea tie-backs from other reservoirs and fields.

All the 23 wells will be connected by subsea units to enable safe flow of oil to the facility.

The vessel is slated to be delivered in 2023.

Once delivered, the FPSO will be permanently moored at a water depth of about 780m by an external turret mooring system.

Contractors involved

MODEC secured a Front End Engineering Design (FEED) contract for the FPSO in February 2019 and received the order to supply the vessel in January 2020.

COSCO Shipping Heavy Industry (Dalian) was responsible for the hull and marine works, external turret and topsides module installation and conversion work on the vessel.

The topsides modules of the FPSO were fabricated by COSCO and BOMESC Offshore Engineering Company.

The external turret mooring system is built by Penglai Jutal Offshore Engineering Heavy Industries (PJOE).

In December 2020, MODEC Group signed a contract with Woodside Energy for the operations and maintenance of the FPSO vessel. The external turret mooring system was supplied by SOFEC, a MODEC group company.

Modec contracted Hamworthy Pumps for a complete pump package for the FPSO project.

Keppel Offshore & Marine is responsible for the topsides integration and support during the pre-commissioning and commissioning activities for the FPSO.

After the FID was taken, Diamond Offshore was engaged for two well-based contracts for the drill rigs Ocean BlackRhino and Ocean BlackHawk.

Subsea Integration Alliance, a non-incorporated alliance between Subsea 7 and OneSubsea, received the contract for the construction and installation of the integrated subsea production systems and subsea umbilicals, risers and flowlines.