Aje Field, Nigeria

The Aje gas and condensate field lies in Oil Mining Lease 113 (OML 113) in the Benin Basin, about 24km offshore of western Nigeria. The water depth in the region is 3,000ft.

Yinka Folawiyo Petroleum (YFP) is the operator of OML 113 with 60% interest. The remaining 40% is owned by a joint venture of Chevron Nigeria Deepwater, Vitol Exploration Nigeria, Panoro Energy, Energy Equity Resources and Jacka Resources.

Chevron was appointed as the technical advisor to the operator for the project and also assigned the responsibility to prepare a development plan for the field.

Providence Resources Oil and Gas earlier held a 2.667% interest in the OML 113. It was sold to Jacka in December 2011. During the same period, Chevron announced its plans to sell its interest to Energy Equity Resources.

The field is currently in the development planning stage, with first production is expected in 2014. The field is expected to reach a plateau production of 50,000-80,000 barrels of oil equivalent (boe) a day.

Location

The OML 113 licence covers an area of 960km2 and contains several prospects, including the Jubilee and Tweneboa fields.

OML 113 was originally known as Oil Operating License 309 and was awarded to YFP in 1991 to encourage the growth of Nigerian oil industry. Following the successful discovery of the Aje field, the licence was converted to OML 113 in 1998 with a term of 20 years.

Discovery

Aje was discovered by the Aje-1 well in 1996. The well encountered oil and gas over three zones of the Cretaceous Turonian age. It flowed at the rate of 60.2 million standard cubic feet of gas a day (mmscfd), 1,729 barrels of condensate a day (bcpd) and 2,389 barrels of oil a day (bpd).

Drilling and appraisal

In 1997 an appraisal well, Aje-2, was drilled 1km east of the Aje-1 well. It confirmed the presence of oil and gas in the Turonian reservoir as discovered by the Aje-1 well and encountered a deeper separate additional zone of the Cenomanian formation.

A third well, Aje-3, was drilled by Transocean's Sedco 709 semi-submersible rig in 2005. Although the reservoir quality was not optimum, the well encountered an oil and gas bearing column within the Turonian and Cenomanian reservoirs.

In the first quarter of 2008, another appraisal well called Aje-4 was drilled by the Transocean Deepwater Pathfinder drill-ship to carry out a complete appraisal of the field. Aje-4 well was drilled to assess the extent of the field and identify additional exploration targets. The well encountered hydrocarbon reserves in the main Turonian reservoir.

Drilling of the Aje-4 well confirmed the field contains a laterally extensive reservoir structure. The field was declared a commercial prospect in February 2009.

Appraisal of the field was based on 915km of 2D seismic data, 700km2 of 3D seismic data and an electromagnetic survey.

Geology and reserves

Aje is primarily a gas condensate field formed in a four-way dip closure trap. It contains gas and oil in the Turonian and Cenomanian reservoirs and an additional gas layer of the Albian formation.

Gross contingent resources of the Aje field are estimated at 380 million boe. Of this 28% is oil / condensate, 20% is LPG and 52% is gas.

Field development

The field is planned to be developed as a subsea tie back to a floating, production, storage and offloading (FPSO) vessel.

The Aje-1, Aje-2 and Aje-4 wells will be completed as producers.

A total of six producers are planned for the field. They will be connected to subsea wellheads and associated flowlines and manifolds in 320ft water depth. The flowlines will, in turn, be connected to the FPSO through risers.

Produced hydrocarbons will be processed by the FPSO and exported through the West African Gas pipeline or through a direct pipeline to connect to the Lagos gas infrastructure.