By Moses Aremu
West Africa remains the top deepwater exploration and production destination on the planet. In the sixteen years since the contest for deepwater spoils was established, this corner of the south Atlantic has led the two other contestants: Brazil and the US Gulf Of Mexico, in attracting investment dollars.
In spite of the recent boost in activity of the US Gulf of Mexico and the discoveries of huge reservoirs below the salt cover in deepwater Brazil, the early lead that West Africa had taken in the mid nineties has turned its waters into a vast, busy parking yard for FPSOs, with such decade old fields as Zafiro, Girassol and Dalia each doing in excess of 150KBOPD on average, even as reservoir maintenance work sets in; relatively newer fields are gushing oil at world class rates and a queue of field development projects are lined up from Equatorial Guinea to Angola.
- Take a look at fields that coming on stream in the next two to four years:
Pazflor. TOTAL’s Pazlor project in Block 17, will develop production from the Perpetua, Acacia, Zinia and Hortensia discoveries. First oil is expected in 2011 at the initial rate of 220,000 BOPD. The four fields are scattered over an area of 600 square kilometers, six times the size of Paris, at a water depth of about 1,200metres. Acacia contains light oil, whereas the other three are Miocene characterized by heavy, viscous oil. TOTAL plans to use subsea oil-water separators for the Heavy Oil reservoir. The separated oil and water will be pumped to the FPSO using Electrical Submersible Pumps(ESPs). TOTAL has built an FPSO capable of processing 220,000 BPD of oil and with storage capacity of 1.9 million barrels, The produced water will be re-injected into the reservoirs. The two subsea production systems encompass 49 wells (25 producers, 22 water injectors and two gas injectors) and three subsea separation units connected to six ESPs. The topsides control system is designed to accommodate 21 additional wells and a fourth Subsea separation unit.
CLOV, also in Block 17, will involve gathering hydrocarbon fluids from tour fields: Cravo, Lirio, Orchidea and Violet (CLOV). TOTAL has received approval from its partners to begin drilling in 2012 so as to achieve first oil in 2014. The subsea development will consist of 34 wells tied back to an FPSO with a processing capacity of 160,000 BPD at plateau and storage capacity of 1.78 million Bbls. The FPSO will be able to process two types of crude oil, light oil from Oligocene reservoirs and heavier oil from Miocene reservoirs. Both oil streams would be combined aboard the FPSO in a single train prior to storage.
Aseng: First production from the Aseng field is estimated to commence by mid-year 2012 at 50,000 barrels of oil per day gross (16,500 barrels per day net). Equatorial Guinea’s authorities approved the field development plan for this Noble Energy operated field in July 2009. Located in Block I, it represents the first oil development in the country’s part of the Douala Basin. Initial development of the field will include five subsea wells flowing to a floating production, storage, and off loading vessel (FPSO) where the production stream will be separated. The oil will be stored on the vessel until sold, while the natural gas and water will be injected back into the reservoir to maintain pressure and maximize oil recoveries. The FPSO, to be located in approximately 945metres(3,100feet) of water, will be designed with capacity to handle 120,000 barrels of liquids per day, including 80,000 barrels of oil per day. In addition, the vessel will be capable of re-injecting 170 million cubic feet per day of natural gas. Storage on the vessel will be approximately 1.5 million barrels of oil and condensate. Total cost of development, excluding the cost of the FPSO, which will be leased, is estimated at $1.3 billion ($530 million net). The majority of this capital is to be invested in 2010 and 2011. Over the life of the project, the company expects to recover gross hydrocarbon liquids of approximately 100 to 120 million barrels, with initial reserve bookings beginning in 2009. In addition, there is an estimated 450 to 550 billion cubic feet of gas resources at Aseng that will be produced as part of an integrated gas monetization project once the pressure maintenance phase is completed.
AlenFirst production at Alen field, in deep- water Equatorial Guinea, is estimated to commence by the end of 2013 at 37,500 Bbl/d gross (18,750 barrels per day net). The country’s Ministry of Mines, Industry, and Energy approved the field development plan in December 2010. Initial field development will include three production wells and three subsea natural gas injection wells tied to a processing platform. Produced condensate will be separated and piped to the Aseng floating production, storage, and offloading vessel on Block “l’ 24km to the south, where it will be held until sold. Associated natural gas will be re-injected back into the reservoir to maintain pressure and maximize liquid recoveries. The Alen processing facility will be located in approximately 240 feet of water and is designed to handle 440 million cubic feet per day (Mmcf/d) of natural gas and 40,000 barrels per day (BCPD) of condensate. Natural gas reinjectiori is estimated to be 380 Mmcf/d during gas-recycling. The total cost of development is estimated at $1.6 billion ($735 million net).
Usan Production startup is projected for this TOTAL operated oilfield, in 2012. Maximum total production of 180,000 BOPD is expected by 2013. Located in 900metres of water, Usan Field was discovered in 2002 and began development in 2008. Development drilling commenced in June 2009. There will be 23 production wells as well as 19 water and gas injection wells. Hyundai Heavy Industries will deliver the FPSO in late 2011. Cameron was awarded the contract for the 44-well subsea development.
2. And those that may come on stream in the next four to seven years…
Egina: Front-end engineering design of TOTAL’s deepwater Engina development was nearing completion as of July 2010. The French major awarded the subsea FEED to Nigerian company Dover Engineering in July 2009, with Wood Group companies J P Kenny and MCS Kenny assigned to support the project’s delivery. Egina, discovered in 2003, is in 0ML130, in water depths up to 1,750 m. The Greater Egina development will take in the Egina Main, Egina South, and Preowei fields, although the current programme only covers the Egina Main field — the other two fields are probable future tiebacks. The subsea work scope of work included design studies and engineering assessments; development of specifications; and documentation and technology studies, all relating to the design of the umbilicals, flowlines, risers, and the subsea production systems.
Uge: Negotiations with government and partners for field development is moving slowly along for this 2006 discovery. Uge-1 encountered 100 meters net oil in 1,263 meters of water in OPL 214. The discovery well was drilled a total depth of 5,260metres.
Bosi: Sanction for ExxonMobil operated Bosi field development has been much slower than would have ordinarily been expected of this 1996 discovery. Since a Final Investment Decision(FID) hasn’t happened, all figures are mere estimates. One such is that production will be around 135,000 BOPD optimum, and the crude will be stored in a refurbished FPSO.
Aparo and Bonga SW.
These two fields share a common geologic structure and will be developed simultaneously. The structure is located in 1,344m water depth. The project was delayed in 2009 to secure agreement among the stakeholders on the scope and commercial terms of the project.
Nsiko: Chevron’s next Deepwater project is Nsiko Field, located 144km offshore the western Niger Delta at 1,812m water depth. Subsurface evaluations and field development planning were completed in 2008. Development activities and FEED will begin upon negotiation of the commercial terms.
3. And still in the smithy…
West Africa’s New deepwater discoveries:
This is what Tullow Oil, the UK listed independent, says: “In March 2009, the Tweneboa-1 exploration well discovered a highly pressured light hydrocarbon accumulation. This was followed up by the successful Tweneboa-2 well in January 2010, which encountered oil and gas-condensate 6km south of the original discovery. In July, the Owo-1 oil discovery continued the extraordinary success of Tullow’s West African Equatorial Atlantic campaign, intersecting 53 metres of net oil pay, establishing Owo as a major new oil field. Further appraisal of both fields will form a major part of the 2011 programme with additional prospects already identified.”