ATP Oil & Gas (ATPG)

Oil and gas revenue increased 26% in 2005 compared to 2004 primarily as a result of increased commodity prices. Our realized sales price per Mcfe in 2005 was 41% higher as compared to 2004. The increase was partially offset by an 11% decrease in production.

Oil and gas revenue increased 43% in 2004 compared to 2003 as the result of 12 properties brought on line during 2004, including our Helvellyn property, located in the U.K. Sector—North Sea. Another component of the increase was a 9% increase in our sales price per Mcfe in 2004 as compared to 2003. Due to the shut down of Helvellyn in September 2004 as a result of maintenance at the receiving terminal and the interruption of Gulf of Mexico production due to the hurricanes experienced during the third quarter of 2004, approximately 1.1 Bcfe of production was deferred into future periods.

Lease Operating

Lease operating expenses include costs incurred to operate and maintain wells and related equipment and facilities. These costs include, among others, workover expenses, operator fees, processing fees, insurance and transportation. Lease operating expense for the years ended December 31, 2005, 2004 and 2003 was as follows ($ in thousands):

The 37% increase per Mcfe in 2005 compared to 2004 was primarily attributable to costs incurred in the Gulf of Mexico for uninsured costs incurred as a result of the tropical storm activity during 2005, and certain fixed costs relative to our lower production volumes in 2005.

The 13% decrease per Mcfe in 2004 compared to 2003 was primarily attributable to the aforementioned increase in production. Additionally, workover activities in 2004 were significantly lower than in 2003.

Exploration

During 2005, exploration expense includes one exploratory, step-out well at our producing Eugene Island 30/71 complex. This well found non-commercial quantities of hydrocarbons, resulting in exploration and dry hole expense of approximately $5.3 million.