Avouma oil field is located 17km south-east of the Etame field offshore Gabon in West Africa. It is part of the Etame Marin block, which covers an exploration area of 307,360ha off the coast of Gabon, with water depth starting at 200m.
The field came on-stream in January 2007. It is expected to produce until 2015.
Vaalco Energy is the operator with 28.07% working interest. Partners include Pan-Ocean (31.36%), Sasol Petroleum International (27.75%), Tullow Oil (7.5%)Sojitz Etame (2.98%) and PetroEnergy Resources (2.34%). The field’s development has required an investment of $100m to date.
The field was discovered in July 2004 by the EAVOM 1 well which struck a net oil pay of 11m. The well tested 6,600bopd of oil on a 40/64in choke.
Based on the analysis of the discovery well, the Avouma field was declared commercial.
Geology and reserves
The high quality Avouma field reservoir is made of the Gamba sandstone formations. Proved undeveloped reserves contained at the field are estimated at 1.4m barrels.
In 2005 an exploration well was drilled south of the Avouma field by GlobalSantaFe’s semisub, Aleutian Key. The well did not encounter any hydrocarbons and was later plugged and abandoned.
The Government of Gabon approved the development of Avouma field in May 2005. The field has been developed as a satellite to the Etame field. The development plan included drilling of two horizontal production wells.
The first production well was drilled and tested in 2006. It flowed at a rate of 5,500bopd. The second well was also drilled subsequently and both the wells were placed on production in 2007.
The Avouma platform was installed in 2006. It features four piles, a 650t steel jacket and a 650t deck.
Petróleo Nautipa FPSO
Oil recovered by the Avouma platform is sent to the Petróleo Nautipa FPSO through a 19km insulated pipeline of 8in diameter. The FPSO was constructed in 1975 at the Nippon Kokan Yard in Japan. It was converted from a suezmax tanker and has a dead weight of 141,330t. It has a storage capacity of 1.1m barrels and features an eight-point spread mooring system.
Vaalco contracted the FPSO from Fred.Olsen Production in 2002 and installed it at the Etame field in 2006. The contract has been extended over the years and the current contract is until September 2015 with an option of an extra year.
In 2005, Gulf Island Fabricators was awarded the contract for building the Avouma platform. Global Industries was contracted to transport and install the platform and the pipeline that connects it to the FPSO. The installation was carried out between July 2006 and August 2006 using pipelay barge Cheyenne. Global Industries also installed a flex pipe tie-in skid and in-line piggable Y skid.
Fugro Seacore was subcontracted by Global Industries to provide drilling and grouting services to install the piles of the Avouma platform. Fugro used its B5 pile top drill to carry out the drilling activities.
Placing the horizontal sections on both the production wells was a challenge for Vaalco. To address this problem, Schlumberger’s PeriScope Bed Boundary Mapping technology was used.
The technology enabled the horizontal section of the first well to be placed within 0.6m of the reservoir roof and the second well to be placed 0.5m above the reservoir roof.
Schlumberger provided its PowerDrive (a rotary steerable system), TeleScope (telemetry while drilling service) and geoVISON675 (resistivity imaging) technologies for the field drilling.