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Congo (Brazzaville): Deep-water start-up marks an upturn

FIRST OIL in late April from the country's deepest-water field, Total's Moho-Bilondo, should mark an upturn in oil prospects. The new field will lift the country's production – 260,000 barrels a day (b/d) in 2006, but less last year – by 90,000 b/d in 2010, and there should be further increases as other new developments move ahead.

Total developed Moho-Bilondo, in water 540-730 metres deep, with nine producing wells and five water-injectors, tied back to a floating production unit moored at a depth of 600 metres. Oil is landed through an 80 km, 16 inch pipeline to the firm's Djéno terminal. Wellheads, the two manifolds and other subsea facilities were supplied by FMC, the floater was built by Hyundai Heavy Industries and the pipeline was laid by Acergy.

Total says Moho-Bilondo was brought on stream only 33 months after construction contracts were signed – but 10 years had passed between the original Moho discovery, in 1995, and the development decision, indicating a series of economic and engineering challenges. Disappointments at the firm's Nkossa field, about 15 km away in water 150-300 metres deep, had confirmed the area's difficult geology and led to caution. Nkossa, brought on stream in 1996, was planned to produce 120,000 b/d, but the target was never achieved and capacity now is nearly 60,000 b/d.

The Moho discovery was viewed as too small for a stand-alone development, and a tie-back to Nkossa was considered. The nearby Bilondo discovery, made in 1998, helped to trip Moho into commerciality as a joint development – but, according to a geophysicist close to the project, the plan was reconsidered at the end of 2003 when costs had increased to the point at which the required project rate-of-return would not be achieved.

With the licence about to expire, Total and its largest partner, Chevron – which has its own experience of the area's geology as operator of Block 14, off Cabinda – "made a desperate endeavour to revive the project", according to the geophysicist. Long-offset seismic, depth-converted seismic, modelling and other studies were reviewed in the hope of identifying satellite reserves.

The outcome was a make-or-break decision in June 2004 to drill a prospect adjacent to the Moho-Bilondo core area. The well, Mobim-1, came in as "a resounding success", lifting the base-case assessment of project reserves by 70% and leading to the go-ahead decision for the development. Total's present estimate of recoverable reserves for Moho-Bilondo is "close to 230m barrels".

There are also prospects for a development in the northern part of the Moho-Bilondo licence. Two exploration wells drilled last year, Moho Marine Nord-1 and -2, "revealed significant additional resources of good-quality oil", the operator said. Development studies have started and an appraisal well is scheduled for this year. Interests in the Moho-Bilondo licence are Total, 53.5%, Chevron, 31.5%, and the state-owned oil company, Société Nationale des Pétroles du Congo, 15%.

Further offshore, in the ultra-deep-water Mer Très Profonde Sud licence, Total is studying the development of five discoveries made between 2000 and last year. Andromède, Aurige and Pégase are in the southeast part of the block and Cassiopée Est and Persée Nord Est lie to the north and west. Water-depths are around 2,000 metres. Total has 40% of the licence, with Eni and ExxonMobil each holding 30%.

Total is the largest producer in the country, normally lifting nearly 100,000 b/d of equity oil. But the firm's – and the country's – production was badly affected last year by an accident involving a cargo hose at the Nkossa field, in which two people were killed. Production was shut down for 11 weeks and resumed at a low rate. With a new cargo hose fitted, Nkossa's production has increased to 45,000 b/d. Fitting of another new hose, planned for the third quarter of this year, should allow production to regain its full capacity of nearly 60,000 b/d.

 

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