Origin Spuds Gas Appraisal Well Onshore Perth Basin

Operations at the gas appraisal well Beharra Springs 4, operated by Origin Energy and located in the onshore Perth Basin Production License L11, commenced at 5:30 p.m. WST on Wednesday using the Century 18 drilling rig. The operation at 6 a.m. WST Thursday was drilling ahead at 230 meters in a 311-millimeter (12-1/4 inch) hole.

Beharra Springs 4 is located 30 kilometers southeast of the township of Dongara and 2 kilometers north of the Beharra Springs Gas Plant. The primary target is the Late Permian Wagina Sandstone, the main producing reservoir in the Beharra Springs, Beharra Springs North and Tarantula gas fields.

Beharra Springs 4 is designed to appraise the Wagina Sandstone in a compartment interpreted as being separated from the main Beharra Springs gas field.

Surface co-ordinates for the Beharra Springs 4 drilling location are as follows:

--Latitude: 29 degrees 26' 41.00" S
--Longitude: 115 degrees 09' 01.94" E

The Century 18 drilling rig is being used to drill Beharra Springs 4 vertically to an intermediate casing depth at approximately 3,240 meters measured depth in the lower Kockatea Shale. The well will be suspended after intermediate casing is set and the Century 18 rig will be released. The production section of Beharra Springs 4 will be drilled underbalanced using a Coil Tubing Unit (CTU) in May 2007 to a planned final total depth at approximately 3,374 meters measured depth. Total anticipated aggregate time to drill and case the intermediate hole is 28 days.

Participants in L11 and Beharra Springs 4 are:

--Origin Energy Developments Pty Ltd* (Operator) 67.0%
--Arc (Beharra Springs) Pty Ltd** 33.0%