Norwegian oil company Hydro announced on Monday a promising oil discovery under the oil and natural gas fields already producing at the enormous Troll field in the North Sea. The Oslo-based petroleum and light metals group said prospects for developing the find in the deeper rock structures were promising because the oil is so close to an existing offshore field. Hydro said further tests and drilling will be needed to determine the amount of additional oil that could be produced. Troll is Europe's largest natural gas field currently in operation, and also produces 260,000 barrels of oil per day from...