Origin Energy Updates Perth Basin Drilling Program

Xyris 1 - Initial cleanup flows gas at rates up to 15.5 mmscfd

Origin Energy Limited advises that since the last report the exploration well Xyris 1 operated by ARC Energy and located in the onshore Perth Basin Production License L1 has been cased and completed and the drilling rig has been released to the EP 413 Joint Venture.

Following release of the rig the well has been perforated over a 24-meter interval at the top of the Dongara Sandstone reservoir and a clean up flow has been undertaken. This flow has occurred without a separator and hence flow rates are approximate. The test has however allowed optimum design of the production test which will be undertaken to obtain reserves information and provide more accurate confirmation of the initial results once a suitable separator is available.

The clean up flow was conducted using a series of choke sizes up to a maximum of 36/64 inch at which a flow rate of 15.5 million cubic feet per day was estimated. The well head flowing pressure at this choke size was 1993 psi. Field gas composition measurements indicate the gas to be of good quality and low in carbon dioxide.

The well has now been shut-in pending the commencement of the production test.

Participants in L1 and L2 (excluding the Dongara, Mondarra and Yardarino fields) and Xyris 1 are ARC Energy as operator with 50% and Origin Energy with the remaining 50%.

Jingemia 4 – Well Commences
Origin Energy Limited advises that the drilling of the oil development/appraisal well Jingemia 4 located in the onshore Perth Basin Exploration Permit 413, commenced on April 23, 2004 using the Century 11 drilling rig. Currently, 9-5/8 inch surface casing has been run to 501 meters and the well is waiting on cement prior to drilling ahead.

The Jingemia 4 well is being drilled from a surface location approximately 350 meters east northeast of the Jingemia Production Facility and has been located to intersect the Dongara Sandstone oil reservoir at a near crestal location. The aim of the well is to provide a second production offtake point at the Dongara Sandstone level and to appraise the reservoir potential of the immediately underlying Wagina Formation, which is interpreted to be above the field oil water contact at the Jingemia 4 location. Drilling to the top of the reservoir zone is expected to take approximately 10 days.

Coring of the Dongara Sandstone and Wagina Formation reservoirs is planned to provide information which will enable the field development plan to be optimized.

Participants in EP 413 and Jingemia 4 are Origin Energy Developments Pty Limited (Operator) 49.189%; Hardman Oil and Gas Pty Ltd 22.376%; ARC Energy Limited 15.495%; Voyager (PB) Limited 6.270%; Victoria Petroleum Offshore Pty Ltd 5.000% Norwest Energy NL 1.278%; Roc Oil (WA) Pty Limited 0.250%; John Kevin Geary 0.142%

ARC, Hardman and Voyager have entered into a number of Agreements that will ultimately result in ARC and Voyager's participating interest being 33.141% and 11.0% respectively.