Tullow Oil in the first half drilled nine exploration wells and 11 appraisal wells across the portfolio with a 60 per cent overall success ratio, according to a trading update on Wednesday.During the first six months of the year, the explorer made strong progress in Kenya with a new oil discovery at Etuko-1 and a significant upgrade to Ngamia and Twiga-South oil resources. Tests of the Ngamia-1 and Twiga South-1 wells revealed a doubling of previous estimates of net oil pay to 200 metres and 75 metres, respectively, an optimised flow rate potential of around 5,000 barrels of oil per day (bopd) for each well and significantly increased discovered volumes.In Ghana, the group received government approval for its planned development of the TEN project, its second offshore prospect in the country. In Uganda, the company expects to sign a memorandum of understanding for the development of the Lake Albert Basin project following talks with partners and the government. "We also continue to have an industry-leading exploration and appraisal programme with results from key frontier wells in Kenya, Ethiopia, French Guiana, Norway and Mauritania all expected in the second half of the year," said Chief Executive, Aidan Heavey."With high-quality production continuing to underpin our financial position, we are well placed for the remainder of this year and into 2014." RD