Blocks 1, 3 and 4 offshore Tanzania cover a 28,050 square kilometre area of the Mafia Deep Offshore Basin and northern portion of the Ruvuma Basin, located in water depths ranging from approximately 100m to greater than 3,000m.

Interest

On 28 October 2005, the Group was awarded a 100% interest in Block 1, offshore Tanzania. The Government of the United Republic of Tanzania has back-in rights of 12% in the event of a commercial discovery.  In 2006, the Group acquired a 100% interest in Blocks 3 and 4 which commenced on 19 June 2006. The Government has a back-in right of 15% in these two blocks.

Exploration and appraisal

n 2006, the Group completed a considerable amount of work to establish a stratigraphic framework for the whole of the southern Tanzanian offshore area in order to gain a better understanding of potential reservoir distribution and source potential. An infill 2D seismic survey was acquired and processed over Block 1 which was delivered for interpretation in Q2 2006 and a further 2D survey was acquired in Blocks 3 and 4 in 2007 and was delivered for interpretation in June 2007. Further 2D and 3D Seismic data for Blocks 1, 3 and 4 was acquired in 2008 with a view to maturing prospects in advance of a potential drilling campaign drillship in 2009 or 2010.

The Group has identified a number of very large prospective features which may contain reservoirs at more than one stratigraphic level. Preliminary evaluation of the seismic data suggests it might be possible, under certain circumstances, to identify changes in lithology and fluid content based upon changes in the attributes within the seismic data. It is sometimes possible to use these changes in seismic attributes to infer the presence of potential reservoir facies, and the interpretation of changes in fluid content can sometimes be used to infer a contact between hydrocarbons and water or indeed between different phases of hydrocarbons (oil and gas). This work is at an early stage; however it provides essential input that has been used to assess the exploration risk in the absence of any deepwater wells in the area.

The Group is optimistic that the petroleum system in the deepwater areas may be oil-prone but is also considering whether a gas-prone system may be commercially attractive as the structures mapped are substantial. The potential size of the accumulations means that, in the event of gas being discovered, a viable LNG programme is likely to exist.