SNE Deepwater Oil Field, Senegal

SNE Deepwater Oil Field

The world's largest oilfield discovered since 2014, the SNE Deepwater Oil Field is located in the Rufisque, Sangomar and Sangomar Deep Blocks, which cover a combined area of 7,490km² within the Senegalese portion of the Mauritania-Senegal-Guinea Bissau Basin.

Cairn Energy is the operator, with a 40% interest in the three blocks, while the other partners include ConocoPhillips (35%), FAR (15%) and PETROSEN (10%). Woodside Petroleum has signed an agreement with ConocoPhillips to acquire the latter's stake in the blocks, which is expected to be realised in late-2016.

"Production from the field is expected to peak at 140,000 barrels of oil per day (bopd)."

The commercial viability of the project was announced in September 2016, and the project is currently in the pre-front end engineering design (Pre-FEED) stage. First oil from the project is anticipated to flow in 2022.

Production from the field is expected to peak at 140,000 barrels of oil per day (bopd).

SNE Deepwater Oil Field discovery and appraisal

The SNE deepwater oilfield was discovered in November 2014 with the drilling of the SNE-1 exploration well to a water depth of approximately 1,100m and a total depth of 3,000m. The well encountered a 95m gross oil-bearing column within upper Albian sandstones.

The oil field was further evaluated by drilling the SNE-2, SNE-3, SNE-4 and BEL-1 appraisal wells from November 2015 through May 2016.

The drilling and evaluation of the SNE-2 well was completed in January 2016. The well was drilled at a water depth of 1,200m and to a total depth of 2,800m within the Sangomar Block. Oil from the well flew at 8,000bopd from the lower reservoir unit and at 1,000bopd from the shallower heterolithic reservoir unit during drill-stem testing (DST).

The drilling of the SNE-3 well was completed in March 2016. Oil from the well flowed at a maximum rate of 5,200bopd and main flow rate of 4,500bopd over a six-hour period during DST.

Completed in April 2016, the BEL-2 well was encountered an oil column of 100m and confirmed the extension of reservoirs in the northern area of the oilfield.

The SNE-4 was drilled at a water depth of 942m and to a total depth of 2,944m within the Sangomar Block in May 2016. It encountered a gross oil column of 100m in the upper reservoir and confirmed the extension of reservoirs in the eastern extent of the oilfield.

Reserves at the West African oil field

As of August 2016, the contingent recoverable resources from the field were estimated to be 1C, 2C and 3C of 348 million metric barrels (MMbbls), 641MMbbls, and 1,128MMbbls respectively.

SNE oilfield development details

The initial development plan for the project proposes the use of either a new floating production, storage and offloading (FPSO) vessel or a converted FPSO.

The standalone facility will be designed with topside expansion options to accommodate the extra capacity from future development phases and satellite tie-backs.

The initial phase of the project will involve the development of 20 to 25 wells, whereas between 70 and 80 wells are expected to be developed during the field life.

Drilling rigs

The exploration wells were drilled deploying Transocean's fifth-generation, dynamically-positioned, semi-submersible deepwater drilling rig named Cajun Express.

The appraisal wells were drilled deploying the seventh-generation dual-activity drillship named Ocean Rig Athena.

Key players involved

AMOG performed the pre-engineering studies for the West African oilfield.