ATP starts production at Wenlock

ATP Oil & Gas Corporation announces first production from its Wenlock W1 well in Block 49/12a of the Southern Gas Basin of the U.K. North Sea. The company’s wholly-owned subsidiary, ATP Oil & Gas (U.K.) Limited, is the operator and owns a 100% working interest. The well tested at a rate of 58 MMcf/d, the limit of the test equipment, in July 2007. Based on initial flows the well has the capacity to exceed this level during normal operations.

The Wenlock W1 well was completed in the Rotliegend Leman sandstone in two fault blocks. One fault block contained the targeted proved undeveloped reserves included in ATP’s year-end 2006 reserve report. The second fault block contained additional natural gas reserves which were not included in ATP’s 2006 reserve report as proved reserves.

ATP believes a portion of the reserves in the second fault block will be classified as proved in ATP’s 2007 reserve report. Located in 75 feet of water, the Wenlock W1 well is the first phase of the company’s development plan in this hub area. Significant upside exists at the Wenlock hub with two additional drilling opportunities currently being evaluated.