Angola continues to develop; Ghana grows in importance
Gene Kliewer
Technology Editor, Subsea & Seismic
There are some parallels between West Africa and Latin America when it comes to oil and gas operations. West Africa has a hot area of success – off Angola, much like Brazil is in Latin America. West Africa has a traditional petroleum activity area of Nigeria in decline due to operations issues where Latin America has Venezuela.
There is another interesting area in which the two success examples of Angola and Brazil may have a common ground – geology. There are studies on both sides of the Atlantic Ocean investigating the prospects of the Brazilian producing strata stretching over to West Africa. The two areas were joined in Pangea, according to geologic logic, before they drifted apart with their respective tectonic plates. Angola, Equatorial Guinea, and some fledgling exploration areas are the targets of this theory.
AngolaAngola is set for significant expansion of offshore oil and gas developments in the short- and medium-term, according to a recent country briefing by the US Energy Information Administration (EIA). Membership in OPEC plays a role in the production volumes realized over time.
Angolan production capacity could peak at 2.5-3 MMb/d of oil by 2015 based on existing discoveries, the EIA says. In December 2009, Angolan officials said total country reserve numbers could be as high as 13.1 Bbbl. Other estimates put the reserves in the 9.5 Bbbl range.
Angola's membership in OPEC has kept the country's rate of growth in oil production below the rate of growth in oil production capacity, despite continued discoveries offshore and evident pressure to surpass OPEC limits.
Like its analog Brazil, Angola continues to have strong exploration and drilling results. Some of the most recent finds are as follows:
The Cabaça Norte-1 well, offshore Angola, has hit pay, according to operator Eni Angola. It is the second discovery in block 15/06. The well reached TD of 2,830 m (9,285 ft) and produced more than 6,500 b/d of oil during production tests limited by surface equipment.
After delineation, the well could become the largest discovery in the block to date, the company says. Eni and its partners plan further drilling in the vicinity to accelerate the development of a second production hub in the block (the Northeastern Hub). The company has drilled four exploration wells on the block, with three (Sangos, N'Goma, and Cabaça Norte) resulting in discoveries.
The Northwestern Hub, centered upon the Sangos and N'Goma discoveries, is currently in the pre-development phase -- ongoing studies and appraisal drilling are under way.
Eni has a 35% working interest and is the operator in block 15/06; Sonangol E&P is the concessionaire. Other partners include Sonangol Pesquisa e Produção (15%), SSI Fifteen (20%), Total (15%), Falcon Oil Holding Angola (5%), Petrobras International Braspetro (5%), and Statoil Angola Block 15/06 Award (5%).
The Gardenia-1 well in block 17/06 has hit pay, according to Total subsidiary TEPA (Block 17/06) Ltd. The Gardenia-1, the first on the offshore Angola block, discovered hydrocarbon reservoirs in the Miocene and the Oligocene. The well produced 4,000 b/d of 25° API oil during tests on the Miocene interval, the company reports.
Operator BP has hit oil with the Tebe discovery in ultra deepwater block 31. This is the nineteenth find in the block. The discovery is in the southern portion of block 31, southeast of the Hebe discovery. It was drilled in a water depth of 1,752 m (5,748 ft) and reached 3,325 m (10,909 ft) TVD below sea level. Well results confirmed the capacity of the reservoir to flow in excess of 5,000 b/d under production conditions, the company says.
NigeriaWhile unrest and logistics problems held back the pace of developments in Nigeria, there still were successes and new plays joining the action.
Afren, Oriental Energy Resources and Energy Equity Resources are teaming to explore and develop the OML 115 concession off southeast Nigeria. The permit is adjacent to the Ebok and Okwok development area where Afren and Oriental are already in partnership.
Under the terms of the farm-in agreement with EER, Afren will acquire a 32.5% interest in the license as technical advisor for an up-front cash cost of $6 million. Eventually, Afren's effective economic interest will be between 32.5 and 40.625% of field revenues. Afren will fund drilling of one exploration well on the license at an estimated cost of $30 million, which could spud in the second half of 2010.
OML 115 is in the prolific offshore eastern Niger Delta, also close to the Zafiro complex offshore Equatorial Guinea. The southern portion of the Okwok structure, Okwok South, extends into OML 115. Afren says further prospects are delineated within the channelized Qua Iboe system. It estimates a potential gross un-risked resource of 270 MMbbl.
Following recent appraisal drilling on the Ebok field, Afren has confirmed a 116 MMbbl development with upside to 182 MMbbl, rising to 304 MMbbl with Okwok included. Afren/Oriental also see potential for a production hub around a joint Ebok/Okwok/ OML115 development. This would offer cost synergies including joint storage and export operations and shared services.
Afren's latest appraisal well on the Ebok field exceeded expectations. Ebok-6, drilled by Transocean's jackupAdriatic IX on the Ebok D2 southern lobe, encountered a gross oil column of 107 ft (32.6 m).
The result has led Afren to upgrade volumes in the D2 structure to 135 MMbbl. Around 23 MMbbl is thought to be recoverable, lifting the total 2P Ebok recovery estimate to 116 MMbbl.
Total's Owowo South B-1 exploratory well earlier this year off Nigeria was an oil discovery, partner Nexen has confirmed. The well was drilled in the southern portion of Oil Prospecting License (OPL) 223, in a water depth of 670 m (2,198 ft), 20 km (12.4 mi) northeast of the Usan field. The well reached a total depth of 2,227 m (7,306 ft) and encountered several oil-bearing reservoirs containing light oil, according to logs and other analysis.
GhanaGhana is fast becoming one of the E&P bright spots for offshore Africa.
An appraisal well on the deepwater Tweneboa discovery found a large hydrocarbon column, according to operator Tullow Oil. Tweneboa -2 was drilled by the semisub Atwood Hunter in the Deepwater Tano block to an interim subsurface depth of 3,860 m (12,664 ft), in a water depth of 1,321 m (4,334 ft). The location is around 6 km (3.7 mi) southeast of the Tweneboa-1 discovery. Analysis of drilling, wireline logs, and reservoir fluids confirm this is a major oil and gas-condensate field, Tullow says.
The well encountered a gross reservoir interval of 153 m (502 ft) containing 32 m (105 ft) of net hydrocarbon pay in stacked reservoir sandstones: this comprised a 17-m (56-ft) oil bearing zone below a 15-m (49-ft) gas-condensate bearing zone.
Tullow adds that a combined hydrocarbon column of at least 350 m (1,148 ft) has been established between the lowest known oil in Tweneboa-2 and the top of the gas-condensate at Tweneboa-1, proving a highly prospective and extensive turbidite fan system which will need to be evaluated through further wells.
Following completion of logging operations, Tweneboa-2 will be deepened to test added exploration potential beneath the Tweneboa structure.
The rig will next mobilize to drill an exploration well in the nearby West Cape Three Points block, east of the Jubilee field. Tullow (49.95%) operates the Deepwater Tano license, in partnership with Kosmos Energy (18%), Anadarko Petroleum (18%), Sabre Oil & Gas (4.05%), and the Ghana National Petroleum Corp. (GNPC) (10% carried interest).
The Mahogany Deep-2 appraisal well offshore Ghana has confirmed the down-dip extent of the main Jubilee reservoirs and intersected two new light oil accumulations, Kosmos Energy says. Mahogany Deep-2, drilled 3 km (1.86 mi) from Mahogany-3, is the furthest down-dip Jubilee well in the West Cape Three Points license. The company reports that results of drilling, wireline logging, and samples of reservoir fluid indicate that the well encountered good quality hydrocarbon-bearing reservoir sandstones in three zones.
An interval of 12 m (39 ft) net pay has proved an extension of the main Jubilee reservoirs. In addition, a new shallower accumulation with 2 m (7 ft) net pay was encountered and supports exploration prospects in undrilled areas to the south and east.
In total, the well intersected 53 m (174 ft) of net reservoir sandstones, 20 m (66 ft) of which were in the Mahogany Deep section. These were found to be water bearing, but are not connected to the Mahogany Deep accumulation at Mahogany-3.
The well also encountered a new reservoir in a deeper stratigraphic level beneath the Mahogany Deep section. An oil sample was recovered from a 1-m (3-ft) zone, which has not been encountered in any other wells in the license to date.
Kosmos Energy plans to evaluate the new accumulations discovered by the well using recently reprocessed high resolution 3D seismic data. The company expects to drill further potential extensions of the Jubilee field and associated prospectivity in early 2010.
The Odum-2 appraisal well has confirmed the 2008 Odum oil discovery on the West Cape Three Points block, according to operator Kosmos Energy. Results of drilling, wireline logs, and reservoir fluid samples show the Odum-2 well penetrated net hydrocarbon-bearing pay of 20 m (66 ft) in high-quality stacked sandstone reservoirs over a gross interval of 182 m (597 ft), the company reports. The well is northeast of the Odum-1 well and east of Kosmos' Mahogany-1 exploration well and the Jubilee oil field.
Odum-2 encountered oil pay in two intervals that appear to be in static pressure communication with the Odum-1 well, the company says. The Odum-2 well encountered an oil/water contact 58 m (190 ft) below the lowest-known oil in the Odum-1 well, extending the known oil column beyond the deepest oil seen in the Odum-1. Reservoir fluid samples recovered indicate an oil gravity of approximately 18-19° API.
The Atwood Hunter drilled Odum-2 to TD of 2,506 m (8,222 ft) in 816 m (2,677 ft) of water. Following the drilling of the well, the rig will moved to the adjacent Deepwater Tano block where it will drill the Tweneboa-2 well.
The deepwater Jubilee field development offshore Ghana is on track to deliver first oil late in 2010, according to partner Tullow Oil.
CameroonA subsidiary of Bowleven has awarded Plexus Holdings a contract for the supply of POS-GRIP wellhead systems and drilling services, offshore Cameroon.
Bowleven has a rig to drill its Etinde permit offshore Cameroon. Once a contract is final, the program should start as planned in April/May with the IE field appraisal well (IE3).
Bowleven has determined locations for both IE-3 and the MLHP-5 exploratory wells. The location and timing of the IF-2 well will depend on a review of additional seismic acquisition over MLHP-7.
Currently, existing 3D seismic over the permit is being re-processed, and tendering is under way for the acquisition of new seismic data.
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