Invest News DetailReuters - U.S. oil major Exxon Mobil and Türkiye's state-owned petroleum firm TPAO will invest between $400-450 million in the first stage of oil exploration in the Black Sea, TPAO chief executive Mehmet Uysal said on Wednesday. He was speaking at a ceremony where the two sides signed an agreement to explore for oil in the sea, which lies to the north of Türkiye. Drilling is expected to begin by the end of 2009 or the start of 2010 if oil is found in the Black Sea, where officials estimate the volume of reserves at 10 billion barrels.