Pioneer Enjoys More Success Offshore Gabon

Pioneer Natural Resources Company has drilled a fourth successful well on its Olowi block in the shallow waters offshore Gabon. The Gnadi Marin-1 well was drilled approximately five kilometers and nine kilometers north-northeast of Pioneer's previously announced Olowi Marin-1 and Olowi Marin-2 wells, respectively. The other successful well, the Awena Marin-1, was drilled earlier this year on another section of the block approximately 13 kilometers southeast of the current well location. Pioneer holds a 100% working interest in the block.

The Gnadi Marin-1 well was drilled to a total depth of 1,056 meters and found the same Lower Gamba sandstone reservoir present in the other wells. The top of the Lower Gamba reservoir was found within three meters of the pre-drill prediction and was full to base with oil. The reservoir was tested and flowed at rates between 1,600 and 2,000 barrels of oil per day on various choke sizes from a 14 meter perforation interval.

The four wells drilled to date by Pioneer have established the presence of a continuous oil rim along the edge of a large geologic structure. Seismic processing and interpretation continue on other areas of the structure where Pioneer plans to drill additional extension wells in 2003. The current interpretation of the structure indicates that the oil rim could extend around an area that is 27 kilometers long and 12 kilometers wide. Pioneer expects to complete plans for potential initial development by year-end.

In southern Tunisia, the Adam-1 well is currently drilling to test the Silurian Acacus sandstone play on the 1.2 million-acre Borj El Khadra (BEK) permit. Pioneer has a 40% working interest, subject to government participation, in the well operated by AGIP Tunisia BV. Results of the well should be known by late August. At least two additional wells are planned for later this year on two of Pioneer's four other concessions in southern Tunisia. These wells will target both the Silurian Acacus and the TAGI sandstone plays.

Appraisal sidetrack operations have been completed on the Ozona Deep discovery drilled in 2001 where Pioneer owns 32% working interest. The first appraisal sidetrack was drilled east of the initial discovery well in Garden Banks block 515 to test the upside potential of the field. The sidetrack encountered salt at the proposed reservoir location and was abandoned. The second sidetrack, drilled southeast of the original discovery, was a successful appraisal of the reservoir established by the discovery well. However, the well results indicate the reservoir is more complex and contains fewer recoverable reserves than previously estimated. Pioneer and the operator, Marathon Oil Company (68% WI), are currently evaluating these results and considering options for development of the field. The field is in the Auger mini-basin in the Gulf of Mexico in approximately 3,300 feet of water.