The British firm said it has had success in Uganda's Lake Albert Rift Basin with the Ngege-1 exploration well and has found both oil and gas.
The well is the second in a continuous exploration campaign in the Butiaba region of Blocks 1 and 2.
"We are very pleased with the efficient progress we are making with the Butiaba campaign in Uganda. This is the 11th well in the basin to encounter hydrocarbons," said Aidan Heavey, chief executive of Tullow.
Tullow is a leading independent oil and gas exploration and production group, with interests in more than 100 exploration and production licenses in 23 countries and focuses on four core areas in Europe, Africa, South Asia and South America.
Tullow's interests are primarily focused on gas in the United Kingdom's southern North Sea where it has significant interests, and the company also has interests off the shore of the Netherlands and Portugal.
In Africa, Tullow has exploration and production in Gabon, Ivory Coast, Mauritania and Equatorial Guinea and two large appraisal and development programs in Ghana and Uganda. Tullow also has exploration interests in Mauritania, Senegal, Congo, Tanzania, Madagascar, Namibia and Angola. In South Asia, Tullow has exploration and production in Pakistan and Bangladesh and high-impact exploration activities in India, and in South America, Tullow has interests in Trinidad and Tobago, French Guiana and Suriname.
Oil prices rise again on Nigerian tensions.
Supply disruptions in Nigeria and escalating tensions between Israel and Iran pushed oil prices up again, despite Saudi Arabia's promise to increase its output.
A recent cease-fire by rebels responsible for attacks on facilities in the Niger Delta did little to ease the increase, and there were two new attacks that knocked out additional output. About 340,000 barrels per day of Nigerian output were stopped by militant attacks last week.
Further threats and a limited strike by Nigeria's senior oil workers union at Chevron also affected prices, though the strike has yet to affect production.
A meeting of top energy leaders in Jeddah, Saudi Arabia, over the weekend did little to alter the rising trend of oil prices, analysts said.
Saudi Arabia said it will lift production for a second time to 9.7 million barrels per day in July, its highest level of production in more than 30 years, but the Gulf Times reported the tensions far outweighed the output increases in speculators' minds.
OPEC warns oil prices will not come down.
The president of the Organization of Petroleum Exporting Countries, Chakib Khelil, said oil prices "will not come down."
He said the cartel had done all it could to ease prices, and some analysts said his comments pushed up crude, The Telegraph reported.
European Union Energy Commissioner Andris Piebalgs said he was "not convinced" speculators are to blame and repeated his call for the OPEC to pump more oil.
"The market is currently hijacked by speculators," including hedge funds. "There is no shortage of supply, as I said before," said OPEC Secretary-General Abdalla el-Badri.
OPEC members, aside from Saudi Arabia, have no intention of raising output to bring down near-record prices, he said.
Rep. John Dingell, D-Mich., chairman of the congressional House Energy and Commerce Committee, said the growth in speculating on oil prices "raises troubling concerns about whether the oil future prices have become de-linked from underlying supply-and-demand fundamentals and whether the commodities markets have become a casino for unscrupulous speculators who profit at the expense of the American people."
Closing oil prices, June 24, 3 p.m., London
Brent crude oil: $135.77
West Texas Intermediate crude oil: $137.32