(ShareCast News) - FTSE 250 oil and gas exploration group Tullow Oil said its Cheptuket-1 well in Northern Kenya has encountered good oil shows.Cheptuket-1, which is in Block 12A, is the first well to test the Kerio Valley Basin and was drilled to a final depth of 3,083 metres.The objective of the well was to establish a working petroleum system and test a structural closure in the south-western part of the basin.Tullow said the strong oil shows encountered in Cheptuket-1 indicate the presence of an active petroleum system with significant oil generation. Post-well analysis is in progress ahead of defining the future exploration programme in the basin.The company said further exploration activities are now being evaluated following the encouraging Cheptuket-1 and successful Etom-2 results.Exploration director Angus McCoss said: "This is the most significant well result to date in Kenya outside the South Lokichar basin. Encountering strong oil shows across such a large interval is very encouraging indeed."I am delighted by this wildcat well result and the team are already working on our follow-up exploration plans for the Kerio Valley Basin."Tullow operates Block 12A with 40% equity and is partnered by Delonex Energy with 40% and Africa Oil Corporation with 20%.