ATP Begins Production from its Helvellyn Field

ATP Oil & Gas has commenced first production from its Helvellyn field located in the Southern Gas Basin of the North Sea. The Helvellyn sidetrack well located in Block 47/10 reached a total measured depth of 13,850'. Utilizing a 2400' horizontal section drilled through the Rotliegend sand, the well flowed at a test-equipment-limited rate of 65 million cubic feet per day (MMCF/D) during January, 2004. Initial delivery rates are expected to be greater than 50 MMCF/D. The Company's wholly-owned subsidiary, ATP Oil & Gas (UK) Limited, is the operator and owns a 50% working interest. Natural gas was initially discovered on this block in 1985 with the drilling by BP Petroleum Development Limited of the 47/10-1 vertical well which tested at 29.4 MMCF/D.

"Production from Helvellyn validates ATP's international development strategy," said T. Paul Bulmahn, ATP's Chairman and President. "ATP achieved first production within 18 months of approval by the UK government of the field development plan and we are enthusiastic about continuing to develop ATP's high quality inventory of projects with proved reserves in the North Sea."