Tullow Oil's Ngiri-2 appraisal well in the Butiaba region of Uganda Block 1 has encountered over 40 metres of net oil bearing reservoir, the thickest oil pay so far encountered in the Butiaba area.The well, 1.7 km north of the Ngiri-1 discovery well, was drilled down to 892 metres where reservoir quality is said to be "excellent", akin to the Kasamene field in Block 2, where a production rate of 3,500 barrels of oil per day (bopd) was achieved during testing last year.Ngiri-2 well is the first of a multi-well appraisal programme planned to further evaluate the extent and recovery potential of the Ngiri field. Appraisal wells Ngiri-3 and Ngiri-4 are planned for the fourth quarter of 2010."Our exploration and appraisal campaign in Uganda has now discovered over 950 million barrels of oil (P50)," exploration director, Angus McCoss, said. "In addition to this, our estimate of the yet to find prospective resource remains unchanged at 1.5 billion barrels of oil (P50).""This continued success supports our planning for the accelerated basin-wide development with our future new partners Total and CNOOC."Tullow operates its 100% interests in three licences, Blocks 1, 2 and 3A, in the Lake Albert Rift Basin in Uganda.