The proof that crude oil can be mined in commercial quantities in Kenya has been shown by the results of drill stem tests in the Twiga South 1, one of the two onshore oil discoveries in the country in 2012.
Operator Tullow Oil recorded a cumulative rate of 2,812 BOPD in three separate sands in the Auwerwer formation in the well, after carrying out five flow tests between January and late February, 2013.
One test (DST 3)flowed at a maximum natural flow rate of 1,860 BOPD of 37°API oil, another (DST 4A) flowed at a rate of 491 BOPD while the third (DST 5)flowed 461BOPD, using a Progressive Cavity Pump (PCP). The company says that surface equipment acted as flow constraints. “With optimised equipment these flow rates would increase to a cumulative rate of around 5,200 BOPD”, Tullow claims in a statement. “37 degree API waxy sweet crude was flowed from all three zones in the Auwerwer formation with good quality reservoir sands encountered and the well has been suspended as a potential future production well”, the statement explains. “As with DST 4A, a Progressive Cavity Pump (PCP) was used to artificially lift at DST 5, whilst DST 3 flowed naturally”. Two deeper tests were also completed on the tight reservoir rock at the bottom of the well and, as anticipated, both produced at sub-commercial flow rates and reconfirmed the presence of moveable oil.
Tullow’s partner, Africa Oil Corporation reports that “the reservoir quality of the Auwerwer sands appears to be significantly better than predicted which was also supported by recent core analysis data with several values over 1 darcy permeability”. These tests provide the first potentially commercial flow rates achieved in Kenya and provide real encouragement for the forthcoming DST programme at the Ngamia discovery, located approximately 22 kilometres to the south of Twiga South-1. With the conclusion of the Twiga South-1 testing programme, the Weatherford-804 rig will move to Ngamia-1A to re-enter the well and perform at least four flow tests.