Dussafu, performance beyond expectation
The Dussafu license is situated within the Ruche Exclusive Exploitation Area (Ruche EEA), which covers 850 km2 and includes six discovered oil fields and numerous leads and prospects. The average water depth is 116 metres. The Production Sharing Contract allows for production of hydrocarbons from the Ruche EEA for up to 20 years from first production, which was achieved in September 2018.
Fields on the Dussafu block produce to the BW Adolo FPSO adjacent to the Tortue Field. Phase 1 of the Dussafu development included two subsea horizontal production wells at the Tortue Field. Production is aided by gas lift as the artificial lift mechanism. Tortue Phase 2 introduced four additional subsea production wells at Tortue Field as part of continued Dussafu development. The Hibiscus / Ruche development project in the Hibiscus and Ruche Fields is planned to initially drill up to six horizontal production wells, all targeting the Gamba reservoir.
In 2021, Tortue Field averaged a gross rate of approximately 11,300 barrels per day. Over 4.1 million barrels gross were produced during the year and the field uptime was 88%, including scheduled downtime. Gas lift capacity limitations deferred production in 2021 and will continue to constrain production until a second gas lift compressor is installed in the second half of 2022. Once commissioned, the wells at Tortue are expected to reach full potential.
After a pause in Tortue Phase 2 development due to COVID-19, drilling resumed in April 2021. DTM-6H, which was completed but not tied-in in 2020, and DTM-7H were brought online in October 2021.
The gross investment for Phase 2 was approximately USD 230 million, USD 45 million below the original budget of USD 275 million.
Recommencement of the Tortue Phase 2 drilling campaign in 2021 began with drilling the DHIBM-2 appraisal well, to further evaluate the Hibiscus field, and completed with DHBNM-1, to evaluate the Hibiscus North prospect. While DHIBM-2 did not encounter hydrocarbons, DHBNM-1 discovered oil in both Gamba and Dentale formations. Oil-in-place estimates were below expectation, so Hibiscus North is a likely candidate for a future subsea tieback option to Hibiscus Alpha rather than a standalone project.
BW Energy is currently executing the Hibiscus / Ruche development project, targeting the Hibiscus and Ruche Fields, approximately 20 kilometres northwest of the Tortue Field. The initial phase of this project involves the drilling of up to six horizontal production wells in a 12-well phased program, which will be connected to a production facility. Of these initial six wells, four wells will target the Hibiscus Field while the remaining two wells will target the Ruche Field. These initial wells will exploit the prolific Gamba reservoir.
BW Adolo FPSO will continue to serve as the hub for production in the Dussafu license. First oil from Hibiscus / Ruche development project is expected in late 2022, adding up to 30,000 bopd to gross production from the Ruche EEA in the second half of 2023. The development is expected to recover gross reserves of approximately 47.9 million barrels based on third party estimates. Gross investments for the Hibiscus / Ruche development project are currently estimated at approximately USD 393 million, which is expected to be funded largely from operating cash flow generated from production at Tortue.
BW Energy Gabon SA's operated ownership interest in the Dussafu license is 73.5%, Panoro Energy ownership is 17.5% and Gabon Oil Company’s ownership interest is 9%.
Tullow Oil completed the sale of its 10% ownership interest in the Dussafu Marin permit to Panoro Energy ASA in June 2021.