Rick Wilkinson
OGJ Correspondent
MELBOURNE, Sept. 21 -- Sydney-based Mosaic Oil NL has reported its Rockhampton-1 well in permit ATP709P, onshore southeastern Queensland, found oil and gas.
Electric logs indicated an 11.5 m interval of wet gas in the Permian-age Tinowon sandstone over a 2,394-2,405.5 m interval as well as the possibility of a 12 m thick section of oil reservoir in the overlying Triassic-age Rewan formation at 2,316-2,328 m.
Unstable formation conditions preclude open-hole testing, so a workover rig must be brought in to run drill stem tests through casing to confirm the find. Meanwhile the well reached 2,527.5 m TD.
The Rockhampton-1 wildcat, 20 km northwest of Mosaic's Waggamba oil and gas field and 45 km south of Churchie field, was drilled outside any conventional structure. The result points to a completely new Permian stratigraphic fairway that may be extensive. It lies 5 km from production and pipeline facilities at Tinker field.
During the last 3 years Mosaic reignited interest in the southern Bowen basin region with a series of discoveries in the Permian Tinowon sands. This formation was previously dismissed as tight and unproductive. It also contains clay minerals that react with water-based drilling fluids.
However, using a coiled tubing unit rather than conventional rigs and drilling with the inert fluid nitrogen, Mosaic has reentered and brought on stream several discoveries, such as Waggamba and Tinker fields, previously abandoned as uneconomic. The company has also made new discoveries, such as Churchie field. All the finds are near existing production and pipeline infrastructure.
Mosaic plans to follow up production testing on this week's find with a program of 3D seismic in mid-2005 to delineate other drilling targets.
