Vanco has signed a petroleum agreement with Oranto Petroleum to acquire a 21% interest in the SL-5-11 offshore block in Sierra Leone.

The SL-5-11 block, which covers a 4,022km² area, has water depths in the range of 100m to 300m, and 2D and 3D seismic data have revealed the presence of several prospective exploration prospects.

Under the terms of the petroleum agreement, the company is required to drill one exploration well on the block before 2013.

SL-5-11 is owned by Lukoil, Oranto and Vanco, with each holding 40%, 30% and 21% interests, respectively.