Mozambique plans future in big-league gas


Mozambique seems set to become an exporter of liquefied natural gas (LNG), following a third large deepwater discovery at the end of November.

The US company Anadarko said its Lagosta well, drilled off the northern part of the coast, found multiple reservoirs holding 168 m of gas zones. The well followed two previous discoveries with the Windjammer and Barquentine wells, both drilled about 25 km to the north of Lagosta.

After the latest well, Anadarko said the finds “exceed the resource size-threshold necessary to support an LNG development”, and said it will start studies on commercialisation options. LNG could provide “tremendous economic value for the people of Mozambique, the government and the partnership”, the company said.

The discoveries lie about 40 kilometres off the coast, a distance which could allow them to be developed as subsea-to-beach tie-backs. Water-depths are substantial - 1,548 m at Lagosta, 1,585 m at Barquentine and 1,464 m at Windjammer. The Windjammer and Barquentine wells showed, respectively, 146 m and 127 m of gas zones, with indications that the lower reservoirs are connected. None of the finds has been tested, but Anadarko is scheduling at least one test for the Belford Dolphin drillship, which drilled all three discovery wells, in 2011.

Because Mozambique’s deepwater offshore is barely explored, there is a good probability of more discoveries in the numerous structures shown by seismic surveys. Anadarko’s next well will be into the Tubarão structure, southwest of Lagosta.

The discoveries lie in Area 1, where the interests are: Anadarko, 36.5 per cent, Japan’s Mitsui, 20.0 per cent, Indian companies BPRL Ventures and Videocon, 10.0 per cent each, the UK’s Cove Energy, 8.5 per cent and Mozambique’s state company, Empresa Nacional de Hidrocarbonetos, 15.0 per cent (carried).


Second oil discovery for Sierra Leone

A second deepwater oil discovery has raised hopes for the new oil area spanning the waters of Sierra Leone, Liberia, Ivory Coast and Ghana. US company Anadarko said in November that a well into the Mercury prospect - only the second deepwater well drilled in Sierra Leone - found over 41 m of oil zones. The well was drilled in 1,600 m of water about 65 km southeast of the first discovery, Venus, of September 2009.

The Venus discovery caused a stir in the industry because the oil was held in a stratigraphic trap - the same type of trap as in Ghana’s Jubilee field, over 1,000 km to the east. Geologists speculated that many similar discoveries might be made in the intervening area. Stratigraphic traps, in which oil is held in place by changes in the porosity and permeability of overlying rocks, have been overlooked in the past because they do not show up well in seismic surveys.

Anadarko said: “The Mercury well demonstrates that the stratigraphic trapping systems we have identified are working and that the petroleum system is generating high-quality oil”. The well, drilled by Transocean’s Deepwater Millennium drillship, found nearly 35 metres of zones holding light 34°-42° API crude and over 6 m holding heavier 24° API crude. The well was suspended for possible testing or sidetracking. Interests in the licence, SL-07B-10, are Anadarko, 65 per cent, Repsol, 25 per cent and Tullow 10 per cent.

Anadarko plans to accelerate exploration and appraisal of the area in 2011. The firm said 3-D seismic surveys over its five contiguous licences off eastern Sierra Leone and western Liberia have shown 17 prospects or leads. However, the Deepwater Millennium is committed to move to Ghana next , to carry out appraisal drilling at the Owo and Tweneboa fields, to the west of Jubilee.


Ghana’s Jubilee ready for start-up

At presstime, the Jubilee oilfield - the first worldscale field in Ghana - was being readied for first oil on 15 December. Tullow, the UK-Irish company which operates the development, said it produced some crude at the end of November and was using it to commission the processing equipment on the floating production, storage and offloading (FPSO) vessel.

Jubilee will start flowing only three and a half years after its discovery, by the US firm Kosmos, in June 2007 -- an extremely fast development time for the first field in a new oil province. Initial production will be about 55,000 bpd. The flow will rise over three to six months, as additional wells are connected-in, to the plateau rate for the first-phase development of 120,000 bpd.


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