Agbami Oil Field, Niger Delta, Nigeria

The $3.5bn Agbami oil field project is Nigeria's largest deepwater development and lies in OPL Blocks 216 and 217, approximately 220 miles south-east of Lagos and 70 miles offshore of Nigeria, in the central Niger Delta.

In late 1996, Texaco and Nigerian independent oil company Famfa were granted exploration rights to the 617,000-acre block 216. Agbami was proven in this block by Texaco during 1998 and, two years later, Statoil's Ekoli-1 well confirmed that the discovery extended into block 217.

Development of the field has been unitised between these two blocks – ChevronTexaco is the operator, with a 68.15% interest; Statoil has an 18.85% interest (which it took in 2004) and Petrobras holds the other 13%.

The field is owned by the terms of a deepwater production-sharing contract (PSC) between Texaco and Famfa.

DRILLING

The discovery well Agbami-1, completed in January 1999, encountered 420 net feet of pay, in multiple oil zones from 8,200ft to the total depth of 12,400ft. The well penetrated stacked reservoir sands saturated with oil, ranging in overall column thickness from 400ft to over 1,000ft. The quality of the oil from these zones is 35°-45° API gravity, with a very low sulphur content.

The well spudded on 15 July 1999 in 4,700ft of water, making it the deepest water-depth well in Nigeria. It reached the total depth in late November 1999 and was temporarily suspended to allow for flow testing and possible production at a later date.

WELL APPRAISAL

In January 2000, Texaco drilled the Agbami-2 appraisal well with the drillship Glomar Explorer. This confirmed the size of the Agbami structure.

The Agbami-2 appraisal well was drilled in 4,800ft of water, to a total depth of 15,683ft. The well encountered 534ft of pay in five separate oil-bearing zones, one of which flowed at a maximum rate of 10,000bpd with a well-head pressure of 2,200lb/in² (psi). Surface equipment limitations prevented the achievement of a higher flow rate.

Oil from the reservoir is light, sweet crude (45° API gravity) with very low levels of contaminants such as vanadium, nickel and iron.

OIL RESERVES

Total field reserves are estimated at around one billion oil-equivalent barrels.

AGBAMI FIELD DEVELOPMENT

Agbami is being developed with a subsea production system tied back to a floating production, production, storage and offloading (FPSO) ship.

When it comes on stream, expected to be by the third quarter of 2008, loading will be accomplished via a single-buoy mooring located 1.2 miles from the Agbami FPSO vessel.

THE FPSO

The vessel was built by South Korea's Daewoo Shipbuilding & Marine Engineering. In 2005, it awarded the contract for engineering design and procurement services for the topsides to KBR and the class contract to ABS.

With an overall storage capacity of 2.15 million barrels of crude oil the Agbami FPSO, which arrived amid some secrecy at the field at the end of 2007, is one of the largest facilities of this type ever built.

It has 13 topside modules, which contain the main process and utility systems. Weighing about 30,000t, the vessel topsides generate 75MW of power and have living quarters for 100 personnel. It cost $1.2bn.

The FPSO is being moored in about 4,700ft of water, and at least 40 subsea wells will most likely be necessary to fully exploit the field. It will be designed to handle 250,000bpd, 450 million cubic feet of gas production and 450,000 barrels of injected water a day – rates that should be reached at peak production in 2010. About 415 million cubic feet of gas a day will be reinjected.

Designed to store about 2.2 million barrels of oil, the vessel is set to be on location for more than 20 years.

Agbami is expected to be of value to less-complex refiners, especially those with no vacuum residuum conversion, limited hydrotreating / sulphur recovery and limited cracking capacity.