arckaringa basin

http://www.pir.sa.gov.au/__data/assets/pdf_file/0008/33659/prospectivity_arckaringabasin.pdf

Includes:

Exploration history
Petroleum exploration commenced in the 1960s with Delhi’s Oodnadatta aeromagnetic survey and was followed by gravity surveys (BMR, Dalhousie; and two by the department). Limited reflection and refraction seismic was also recorded in this period (Fig. 1). These surveys delineated the deep Boorthanna Trough. The first wildcat wells were Cootanoorina 1 (1967, Department of Mines) and Weedina 1 (1970, Pexa Oil). There were no indications of hydrocarbons in the Permian section, but trace gas and bituminous material were recorded from the Cootanoorina
Formation.
In 1969 the department commenced a seismic and seven well stratigraphic drilling program aimed at evaluating the basin outside PELs 5 and 6 area (Boorthanna Trough). At the same time surveys continued in the Boorthanna Trough (seismic and one wildcat — Weedina 1) commissioned by Pexa as part of a farmin commitment. No significant hydrocarbons were recorded.
The next phase of exploration was by Delhi in the mid 1980s and included seismic and two wells. Hanns Knob 1
terminated in Cootanoorina Formation and Birribiana 1 in Proterozoic dolerite. Traces of ditch gas were recorded in the latter. The Arckaringa Block was relinquished by Santos and Delhi in 1989.
PEL 24 covering the Phillipson Trough was granted to CRA in 1984. Exploration included seismic and one well.
Arkeeta 1, drilled in 1986 near the SE margin of the trough, intersected a thick Permian sequence overlying
Neoproterozoic redbeds and older metasediments.
Attempts so far to drill a diapir have been unsuccessful or inconclusive. The department’s drillholes Toondina 1 and 2 did not penetrate beneath the Permian sequence. Roebuck Resources’ mineral exploration drillholes, Todmorden 1 and 2, drilled into Cootanoorina Formation.
Currently, interest is being focused on the coal seam methane potential of the Arckaringa Basin.

Source rocks
Basal Stuart Range Formation and Boorthanna Formation range from immature to mature. Boorthanna Formation TOC is generally <0.5% although one sample from Weedina 1 measured 1.8%. The Mount Toondina Formation and much of the Stuart Range Formation while immature, have high TOC values indicating good oil-prone source potential at depth. TOC ranges from 0.45 to 2.7% in Stuart Range Formation, and is as high as 5.95% in Mount Toondina Formation.
In many areas depth of burial has not been sufficient for generation of hydrocarbons. Permian sediments are most likely to be thermally mature in southern deep parts of the Boorthanna Trough. In the Phillipson Trough a higher heat flow event 150 million years ago may have boosted maturity of the Permian sequence.
Reservoirs and seals Sandstone in the Mount Toondina Formation generally exhibits low porosity (6–9%). The Boorthanna Formation contains several thick units of porous and permeable sandstone (log porosity up to 13.5%).
Secondary vugular porosity and minor open parting along stylolites are observed in Cootanoorina Formation
carbonate. Stuart Range Formation and Bulldog Shale (Eromanga Basin) provide regional seals. Intraformational shale and siltstone in the Boorthanna and Mount Toondina Formations may locally provide seals.

Traps
Traps range from simple domes and faulted anticlines to potential diapiric traps. Diapirs delineated on the 1986
Ingomar Seismic Survey over the Phillipson Trough deserve further investigation.

Coal deposits
Seven deposits of lignite A/sub-bituminous C rank coal (American Society for Testing and Materials classification) aggregating more than 20 Gt of measured, indicated and inferred resource have been identified in the upper part of the Mount Toondina Formation (Fig. 5). These are multi-seam deposits with individual seams ranging up to 10 m, with a cumulative thickness of up to 30 m