The Oyo deepwater oilfield is located 75km off the shore of Nigeria in OML blocks 120 and 121. Its oil resources lie at a water depth of 410m (1,345ft).
Discovered in 1995, Oyo is one of the first oilfields to be discovered off the coast of Nigeria. The Federal Republic of Nigeria leased OML 120 block for oil mining in 2002. The appraisal wells were drilled between 2006 and 2007. Initial production from two wells began in December 2009. The associated gas from the wells is reinjected through a third well to increase oil recovery and reduce flaring.
The Oyo field is operated by Nigeria Agip Exploration, a subsidiary of Eni. The operator holds a 40% stake in the project. The remaining 60% interest was held by Allied Petroleum, which was acquired by CAMAC Energy in April 2010. The acquisition was completed in February 2011.
Oyo oil reserves
Early seismic data estimated the probable and proved recoverable reserves at the Oyo field to be 45 million barrels of light crude oil. The drilling of appraisal wells began in 2006 and six appraisal wells were drilled in total.
The proven resources were later revised to 50 million barrels.
In April 2011, Netherland, Sewell & Associates produced an independent engineering report with the latest estimated reserves at the OML 120 and 121 blocks. The field is estimated to have 1.9 billion barrels of crude with a high of 6.3 billion barrels of oil-in-place. The associated recoverable and prospective oil resources are 626 million barrels with a high of 2.2 billion barrels.
Eni has been the operator of the field since April 2010. The field started production at a rate of 25,000bopd.
Oyo field details
The OML 120 block occupies 917km2. Hydrocarbon resources lie at water depths ranging from 150m to 1,000m. The OML 121 block lies south of block 120, in an 887km2. The resources lie at depths of 150m to 1,000m.
Development of the Oyo field was approved in 2008. The field consists of two production wells, one water injection well and a gas injection well. The two subsea production wells are tied back to the Armada Perdana FPSO.
Armada Perdana FPSO
The 308.7m long, 46m wide and 22.6m-deep Armada Perdana FPSO has a 156,483t deadweight.
Armada Perdana was originally an oil tanker built in 1984. It was converted into an FPSO at the Keppel Shipyard in Singapore between 2008 and 2009.
The scope of works included the fabrication, installation and integration of a 12-point spread mooring system, topside facilities, a riser balcony, accommodation upgrades and installation of auxiliary support systems.
The single hull FPSO has side impact protection. It is also equipped with gas treatment and re-injection facilities. It arrived and was moored on OML 120 block of the Oyo field in August 2009.
The Armada Perdana FPSO has a crude oil treatment and production capacity of 40,000bopd. It can store up to 1.1 million barrels of crude oil and is equipped with associated gas treatment and reinjection facilities. Its gas compression capacity is 66mmscf per day.
Contracts for the Oyo oilfield
Aker Solutions was contracted in 2008 to supply four subsea trees and associated control systems, wellheads, dynamic and static steel tube umbilicals, a work-over system, tie-in connection systems and system engineering.
Technip was awarded a $119m turnkey contract for the development of the field. The scope of works included engineering, fabrication and installation of risers, gas and water injection flowlines, gas injection, 20km of flexible production and 15km of umbilicals. The subwells are connected to the Armada Perdana FPSO.
NGL Tech was the process design consultant for the FPSO conversion. Exion Asia was a key supplier. Excel Marco provided integrated control and safety system. Tranter International provided the heat transfer equipment.
Century Energy Services was involved in the logistics and support, spare parts procurement, and training personnel for FPSO operations. Separation internals of horizontal separators were supplied by Zeta-pdm.
The Armada Perdana FPSO is owned and operated by Bumi Armada. The company was selected to provide five-year fixed time charter services (extendable by another five years) in June 2008.
The FPSO conversion received a five-year loan of $190m in September 2009 from seven lead arrangers: the structuring bank SMBC, Banca UBAE, ABN AMRO Bank, Australian and New Zealand Banking Group, Standard Chartered Bank, Malayan Banking and WestLB.
SACE acted as the mandated lead arrangers coordinator. Watson, Farley & Williams was the legal advisor for Bumi Armada in the fundraising.