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South Australia oil shale deposit indicated

Linc Energy Ltd., Brisbane, said it has discovered an oil shale deposit of more than 200 billion tonnes at 100 m thick in the Arckaringa basin in South Australia 450 miles northwest of Adelaide.

The company said the deposit lies in the Early Permian Stuart Range formation in PEL 122 and is projected to extend into PEL 121. The formation is 2,801 ft deep and covers 284,000 acres. Rock-Eval pyrolysis indicates potential oil yields of 25-45 l/tonne in upper and lower intervals, respectively.

The shale was intersected during completion of the company’s Arck-1 stratigraphic exploratory well and is near the oil show at its Maglia-1 exploratory well.

Linc Energy said its current studies indicate that the Stuart Range formation shale is expected to be in the oil generation window at depths over 700 m. The company has identified a large section of the Boorthanna trough some 93 by 12 km where the formation lies at depths in the oil generation window. The trough also has coalbed methane potential (OGJ Online, Mar. 28, 2008).

The Arck-1 well found the formation to be 124 m thick at 854-978 m. The most prospective sequence of black shale is 70 m thick at 899-970 m. The entire section has been wireline cored and logged. Total organic carbon averages 5.4% in the upper sequence and 7.7% in the lower interval. TOC was 10.44% at 954.5 m.

Permian coal intersected while drilling appears to be hosting fluorescence source oil in cleat and natural fractures similar to the results at Maglia-1.

After drilling Arck-1, the rig drilled the Wirrangulla Hill-1 well 10 km north. It encountered oil fluorescence in the upper geological sequences and Stuart Range formation shale thickness similar to Arck-1. Both well locations are in PEL 122 in the southern Boorthanna trough.

The company also drilled two dry holes and has completed shooting 1,153 line-km of 2D seismic in the basin in late August. Seismic interpretation is expected in the first quarter of 2012. Linc Energy said it is “piecing together the potential for a new hydrocarbon producing region.”

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