1 map showing the Acreage Release Title W15-2 in the area of Overlapping Jurisdiction in the Perth Treaty. Requested by RET August 2014. LOSAMBA register 707

1 map showing the Acreage Release Title W15-3 in the area of Overlapping Jurisdiction in the Perth Treaty. Requested by RET August 2014. LOSAMBA register 707

This presentation will provide an overview of geological storage projects and research in Australia.

Interpretative report from the GA0340/SOL5754 marine survey of the Leveque Shelf

The Early Cretaceous Gage Sandstone and South Perth Shale are a prospective reservoir-seal pair in the Warnbro Group of offshore Vlaming Sub-basin, Western Australia. Gage Sandstone reservoir plays include post-breakup pinch-outs against the Valanginian Unconformity, and 4-way dip closures with the South Perth Shale forming the top seal. Deposited as a lowstand component of the deltaic South Perth Supersequence, the Gage Lowstand Fan (previously referred to as the Gage Sandstone) infilled palaeotopographic lows of the Valanginian breakup unconformity. Sequence stratigraphic analysis was used to characterise the reservoir-seal pair by integrating 2D seismic interpretation, well log analysis and new biostratigraphic data. Palaeogeographic mapping of the South Perth Supersequence reveal a series of regressions and transgressions that lead to the infilling of the central palaeodepression. The Gage reservoir is a sand-rich submarine fan system and ranges from canyon-confined inner fan deposits to middle fan deposits on a basin plain. Major sediment contributions were from north-south trending canyons adjacent to the Mandurah Terrace. More detailed seismic facies mapping and well log analysis of the Gage Lowstand Fan determined that the sand sheets in the distal middle fan and stacked channelized sands in the inner fan may provide an extensive reservoir of good to excellent quality. Seal quality varies greatly and may explain the lack of exploration success at some structural closures. A re-evaluation of the regional seal determined the extent of the pro-delta shale facies within the South Perth Supersequence that provides an effective seal for the underlying Gage reservoir. 3D geological modelling confirms that the Gage reservoir exhibits properties suitable for hydrocarbon entrapment and CO2 storage. Migration path analysis identified the presence of multiple structural and stratigraphic closures at the top of the Gage reservoir, with the most favourable located in the Rottnest Trough. Previous petroleum systems modelling concluded that the maturity of some source rocks in the sub-basin likely occurred after the deposition of the effective seal. Deep-seated faults, penetrating the syn-rift section, are in direct contact with the Gage reservoir and it could be actively receiving hydrocarbon charge.

1 map showing the Acreage Release Title W15-3 in the area of Overlapping Jurisdiction in the Perth Treaty. Requested by RET August 2014. LOSAMBA register 707

The Coompana Province is one of the most poorly understood pieces of crystalline basement geology in the Australian continent. It lies entirely concealed beneath a variable thickness of Neoproterozoic to Cenozoic sedimentary rocks, and is situated between the Gawler Craton to the east, the Musgrave Province to the north, and the Madura and Albany-Fraser Provinces to the west. A recently-acquired reflection seismic transect (13GA-EG1) provides an east-west cross-section through the southern part of the Coompana Province, and yields new insights into the thickness, seismic character and gross structural geometry within the Coompana Province. To assist geological interpretation of the 13GA-EG1 seismic line, new SHRIMP U-Pb zircon ages have been acquired from samples from the limited drill-holes that intersect the Coompana Province. New results from several granitic and gneissic rocks from the Coompana Province yield magmatic and/or high-grade metamorphic ages in the interval 1100 1200 Ma. Magmatic or high-grade metamorphic ages in this interval have not been identified in the Gawler Craton, in which the last major magmatic and metamorphic event took place at ~1590 1570 Ma. The Gawler Craton was largely unaffected by ~1100 1200 Ma events, as evidenced by the preservation of pre-1400 Ma 40Ar/39Ar cooling ages. In contrast, magmatic and metamorphic ages of 1100 1200 Ma are characteristic of the Musgrave Province (Pitjantjatjara Supersuite) and Madura Province (Moodini Supersuite). The new results from the Coompana Province have also yielded magmatic or inherited zircon ages at ~1500 Ma and ~1640 Ma. Once again, these ages are not characteristic of the Gawler Craton and no pre-1700 Ma inherited zircon has been identified in Coompana Province magmatic rocks, as might be expected if the province was underlain by older, Gawler Craton-like crust. The emerging picture from this study and recent work from the Madura Province and the Forrest Zone of the western Coompana Province is that the Coompana Province has a geological history that is quite distinct from, and generally younger than, the Gawler Craton to its east, but that is very similar to the Musgrave and Madura Provinces to the north and west. The contact between the Coompana Province and the Gawler Craton is interpreted in the 13GA-EG1 seismic line as a prominent west-dipping crustal-scale structure, termed the Jindarnga Shear Zone. The nature and timing of this boundary remain relatively poorly constrained, but the seismic and geochronological evidence suggests that it represents the western edge of the Gawler Craton, marking the western limit of an older, more isotopically evolved and multiply re-worked craton to the east, from a younger, more isotopically primitive crust that separates the South Australian Craton from the West Australian Craton.

The Early Ordovician (late Tremadoc to Arenig) Prices Creek Group outcrops only on the northern margin of the Canning Basin in a small area centred on Prices Creek, 60 km southeast of Fitzroy Crossing. Recent hydrocarbon and mineral exploration has shown that the Prices Creek Group, previously defined as consisting of a lower Emanuel Formation and an upper Gap Creek Formation can now be subdivided into four formations. The new formations comprise a basal transgressive sandstone unit, here named the Kunian Sandstone, which is overlain by a dolomitic carbonate-dominated unit, here named the Kudata Dolomite. The Kunian Sandstone does not outcrop, but the Kudata Dolomite, which was formerly included in the Emanuel Formation, is exposed at the base of the type section of that unit along Emanuel Creek. The Kudata Dolomite is conformably overlain by the revised Emanuel Formation. The Gap Creek Formation is informally divided into a lower fossil-rich dolomitic unit and an upper fossil poor unit that shows evidence of a hypersaline depositional regime near the top. The Poulton Formation is recognised in outcrop, paraconformably above the Gap Creek Formation and unconformably below the Pillara Formation. The sandstone-dolomite-shale sequence of the lower Prices Creek Group has some economic potential, both for hydrocarbons and minerals. Oil shows are common in shallow wells drilled into the Emanuel Formation and both live oil and bitumen have been found in cores from the Kudata Dolomite. The oil is probably sourced from the Emanuel Formation which also serves as an effective regional seal. Traces of lead and zinc have been found in the Kudata Dolomite, but the depth of the unit below the surface may reduce the economic value of any significant mineralisation that might be found.

A groundwater contamination plume with peak concentrations of the herbicides 2,4-D and 2,4,5-T of up to 180 mg/ L and 60 mg/L, respectively, occurs in the Kwinana industrial area near Perth, Western Australia. Drilling and sampling in 1989 and 1990 have indicated that contamination is largely restricted to a shallow sand aquifer, and that the underlying limestone aquifer is mostly unaffected. Contaminants may be undergoing microbial degradation at the margins of the contamination plume in the sand aquifer. This groundwater contamination incident occurred before the current Western Australian Environmental Act came into force, and responsibility for investigating and managing such contamination is vested in several Western Australian State Government agencies. There is currently no centralised resource pool in Western Australia to carry out investigations of groundwater contamination .

In this paper, petroleum hydrocarbon contamination at two field sites is characterised extensively to provide data for risk assessment, and remediation design and monitoring. A dissolved hydrocarbon plume in groundwater, emanating from a leaking underground storage tank, has been characterised in detail. The spatial and temporal variations of dissolved BTEX (benzene, toluene, ethylbenzene, xylene) compounds and naphthalene within the plume have been mapped. The plume extends greater than 420 m down hydraulic gradient from the site, is less than 3 m thick, and less than 40 m wide. Seasonal inundation of the residual non-aqueous phase liquid (NAPL) gasoline in the soil profile near the point of leakage, apparently provides an ongoing source for dissolved BTEX compounds in groundwater. Remediation would need to target the residual NAPL. Residual NAPL contents in the near-water table zone of a diesel/kerosene fuel spill also have been quantified. The NAPL contents of recovered cores have been correlated with soil particle size distributions, water table fluctuations and saturation-pressure (S-P) relations of soil cores. Cored profiles typically show residual NAPL contents over 0.5 to 1 m depth intervals with peak NAPL contents up to 26 % by weight, at or immediately above the water table. The mobility of the NAPL in these soil materials has been investigated. Such data have been essential for the planning, implementation and effective monitoring of a remediation strategy that targets this thin NAPL zone.