Block 10 BB and 13T

Drilling began in Block 10BB in January 2012 at Ngamia-1. On 26 March 2012 Tullow Oil and Africa Oil announced their discovery in Block 10BB, and a second followed in November 2012 in Block 13T at Twiga South-1. These finds exceeded expectations. Further drilling in Block 10BB was conducted in May 2013 on the Etuko prospect, yielding further oil findings, though of a lower quality. In September 2013, a fourth consecutive discovery was made at Ekales. This is significant as Ekales lies directly between Ngamia-1 and Twiga South-1, which bodes well for further oil discoveries. Since 2012 the drilling has yielded a 100 percent success rate, earning the area the name "the string of pearls". Tullow and Africa Oil will drill a further 12 wells over the next year, beginning with the Bahasa and Sala wells, thought to contain 700 million barrels of oil.

It is thought that Blocks 10BB and 13T contain 280 million barrels (MMbbl) and 87 MMbbl of gross contingent oil resources respectively. The estimate for gross gross unrisked prospective resources is 2364 MMbbl for Block 10BB, and 2174 MMbbl for Block 13T. In its half yearly results, Tullow said the test results are a big step towards establishing the commercial viability of Blocks 10BB and 13T.