Operations
Uganda project
Drilling programme
Overall, the full results of seismic and field work identified at least two structures, each having 100 million barrel potential and a number of other leads and prospects which required further data and/or interpretation to fully define. The first two well locations, Iti-1 and Sambia-1 were selected based on a combination of seismic, gravity and oil micro-seep data. They are both adjacent to the deepest part of the basin where geochemical results indicated that significant volumes of hydrocarbon could have been generated. The structural features of both locations were similar to those evaluated successfully in Licence EA1 – clearly defined large, adjacent fault traps in a central basin position.
The Iti-1 well was drilled in June 2009 and results were disappointing. The well developed, high quality fluvial reservoir sands encountered in the shallow discoveries in EA1 and northern EA2 were absent in the Iti-1 well, substantially reducing the reserve potential of the prospect. On the basis of the Iti-1 result, Sambia-1 was not drilled. Detailed analysis of the well data after completion of the well did, however, point to the presence of oil in a 35 metre-thick reservoir sand just above basement although production testing would have been required to assess productive potential. Although the result of Iti-1 remains ambiguous and is disappointing in the context of clearly discovering commercial hydrocarbons, the presence of oil in the basin and migration potential were confirmed. The results have also led to a much greater understanding of the basin model and distribution of sediments.
On the basis of the Iti-1 well result and subsequent data interpretation, the second exploration well, Avivi-1 was relocated near Rhino Camp town where the presence of thicker, better quality reservoir was thought to be more likely. The well did not encounter oil and tested water with only small traces of oil from a wireline fluid sampler. Electric logging confirmed the absence of hydrocarbons. Although the well failed to encounter hydrocarbons, valuable and encouraging information was gained, which, together with the information from Iti-1, will allow a much greater understanding of the Licence.
Having integrated the information from the first two exploration wells on EA5, it was concluded that considerable exploration potential still exists in the Licence. Avivi-1 encountered thick sequences of organic rich sediments which are likely to represent good mature source rocks in the deeper areas of the basin. These thick clays would also provide very effective trap sealing properties.
Wireline logs and water samples clearly demonstrated that the Avivi structure is water bearing but mid-mature oil was entrained in the sampled water confirming that oil has been generated in the Licence and is currently migrating. The composition of this oil is similar to that of oil recovered from Iti-1 and surface oil samples. Pressure data from Avivi-1, when combined with pressure data from Iti-1, is consistent with a possible oil accumulation at Iti-1 in low permeability reservoir sand. The uncertainty related to generation and migration of oil in the Rhino Camp Basin had, therefore, been significantly de-risked. The results of the GGI have confirmed these conclusions by identifying an oil generation kitchen and a large structurally high area where reservoir properties are likely to be of acceptable quality. A 100 million barrel discovery is still feasible.
Global Petroleum Limited funded most of the cost of Iti-1, thereby earning an option to take a 25% EA5 Licence Interest, and maintained that option by funding 25% of the cost of Avivi-1. Their future intentions are still under review.
