The London-based firm however says it encountered a tight fractured rock section with hydrocarbon shows of 796 metres deep and more tests needed to be done to ascertain the extent of the fractures and establish if the oil can actually flow through.
In a statement, Tullow Oil said Twiga South-1 has been drilled to a total depth of 3,250 metres and has been successfully logged and sampled.
Three sandstone reservoir zones, similar to Ngamia-1, have been encountered and moveable oil, with a density (API rating) greater than 30 degrees, has been recovered to surface.
The Twiga South structure is the second prospect to be tested in the Lokichar Basin as part of a multi-well drilling campaign in Kenya and Ethiopia and is the first oil discovery in Block 13T.
It is located 22km to the north of the Ngamia-1A discovery and further de-risks a number of other similar features on the western margin of the basin.
Tullow said a series of flow tests will now be conducted on the well over the next four to eight weeks. Following completion of the testing programme, the rig will move back to flow test the Ngamia-1 well.
Elsewhere in Tullow’s East African Rift basin acreage, a result from the Paipai-1 well in Block 10A in Kenya is expected by the end of the year and the Sabisa-1 well in the South Omo Block in Ethiopia is expected to commence drilling by the end of December.
Tullow has a 50 percent operated interest in the Twiga South-1 well with Africa Oil holding the remaining 50 percent interest.