MILAN, Italy -- Eni has agreed to take a 35% operating interest in the Keta block offshore Ghana from current operator Afren. The farm down is subject to approvals from Ghana’s government and the other partners, GNPC and Mitsui.

Afren will retain a 35% participating interest. In exchange, Eni will carry Afren’s share of costs associated with drilling one exploration well during the current exploration period. Afren also will receive non-drilling back costs and a carry through a 3D seismic acquisition program required for the next phase of the license phase.

Eni already has a presence in Ghana and has a drilling rig available that could spud an exploration well on the Keta block this summer.

The acreage is in the Volta River basin off eastern Ghana, next to the maritime boundary with Benin. Afren says the block has Tertiary and Cretaceous prospectivity, with the exploration focusing on the Cretaceous Albian to Campanian sections. There are a variety of trapping and depositional settings, some of which show potential for significant stratigraphic trapping and giant fields.

Last year the partners pursued subsurface studies that led to identification of several large-scale prospects in the same Turonian intervals that have proven to be prolific hydrocarbon reservoirs in Ghana’s eastern offshore zones. As a result, gross unrisked prospective resources on the block have been upgraded to 1,412 MMboe.

Off neighboring Cote d’Ivoire, Afren operates the CI-01 block, which contains a proven petroleum system in multiple reservoirs within the Cretaceous. Oil and gas has been found and tested in the Ibex and Kudu fields, and gas in the Eland field.

The block is adjacent to the Jubilee and Tweneboa oil and gas discoveries. Afren has applied the latest understanding of the Cretaceous depositional systems to the existing well and seismic dataset to redefine the distribution of oil and gas in Kudu and Ibex, and other accumulations on the block. The company now thinks these discoveries could be significantly larger than originally mapped.

Afren is performing detailed subsurface work and aims to establish a well site to test the new Cretaceous interpretation. It also is considering acquiring more 3D seismic over the block, and evaluating other techniques such as electromagnetic surveying to aid its understanding of these complex depositional systems.

To speed appraisal and development of the block, the partners are investigating joint development opportunities with operators of adjacent acreage

To the east in Nigeria-Sao Tome & Principe JDZ block 1, Total has taken Chevron’s 45.9% operating interest (Afren has a 4.4% interest). The block covers an area of around 700 sq km (270 sq mi) in water depths ranging from 1,600-1,800 m (5,249-5,905 ft).

A discovery resulted from Obo-1, the sole exploration well to date in the block in 2006, which encountered 150 ft (45.7 m) of net pay and proved a working hydrocarbon system in the JDZ.

Total plans to reprocess the existing seismic data and has proposed drilling this year one appraisal well on Obo and one exploration well.

Afren also has a 25% interest in block 2B offshore South Africa, operated by Thombo. This concession is in the Orange River basin, a shallow water area between the Ibhubesi gas field and the Namaqualand coast. It covers around 5,000 sq km (1,930 sq mi), with water depths ranging from the shore line out to 250 m (820 ft).

The main reservoir objectives are the fluvial and lacustrine sands of the Lower Cretaceous AJ graben, which occur in three sequences. The A-J1 exploration well, drilled in 1989, encountered oil in these sequences, and tested 36° API oil.

Reprocessing of 2D seismic data has since defined other Lower Cretaceous rift graben prospects, genetically analogous to the Lake Albert play in Uganda. And further prospectivity has been identified within a fractured basement play (analogous to Yemen), which could form a secondary exploration play.

In the near term, the partners will acquire 350 sq km (135 sq mi) of new 3D seismic data, reprocess existing 2D seismic, and continue seismic inversion and regional biostratigraphy studies ahead of exploration drilling in 2012. Operatorship will transfer to Afren on completion of the seismic acquisition.

03/29/2011