Product no longer exists, please refer to GeoCat #30413 for the data

Contained in: Proceedings of papers presented at an industry workshop held in Perth, 20 June 2002. Edited by K.F. Cassidy (See link)

Contained in: Proceedings of papers presented at an industry workshop held in Perth, 20 June 2002. Edited by K.F. Cassidy (See link)

Contained in: Proceedings of papers presented at an industry workshop held in Perth, 20 June 2002. Edited by K.F. Cassidy (See link)

Contained in: Proceedings of papers presented at an industry workshop held in Perth, 20 June 2002. Edited by K.F. Cassidy (See link)

Contained in: Proceedings of papers presented at an industry workshop held in Perth, 20 June 2002. Edited by K.F. Cassidy (See link)

Contained in: Proceedings of papers presented at an industry workshop held in Perth, 20 June 2002. Edited by K.F. Cassidy (See link)

EXECUTIVE SUMMARY The estuarine process study of Wallis Lake (Webb, McKeown and Associates) identified: nutrient and animal faecal pollution; and human faecal pollution and other urban runoff pollutants from the Forster-Tuncurry area as the principal source of pollutants in the estuary. The major findings of this study are listed below. Rural and Urban Inputs The sediments at each site contained a unique miospore signature (pollen and spore) characteristic of catchment sources (although no specifically urban signature was found). The majors rivers (Sites 1 and 5) are characterised by specific biomarkers derived from terrestrial plants and by very high concentrations of dry sclerophyll (Eucalyptus Gummifera type) pollen and sclerophyll swamp (Allocasuarina/Casuarina) pollen respectively. The major river sites have strong signals related to herbivore faecal contamination, most probably from cattle. There was little input of pollen or biomarkers from the rural catchments to the shallow lagoon that constitutes the southern portion of Wallis Lake. No specifically urban signature was detected. Urban sources, such as human sewage and petroleum products were not found at Site 2 (urban catchment end-member) or any of the other sites. No specifically urban pollen was found at Site 2, although this site did have the highest concentration of exotic pollen Organic Matter in the Sediments The organic matter present at each site consists of a mixture of terrestrial and algal material; however, it is the algal material that decomposes most rapidly. Dinoflagellate indicators (microfossils and biomarkers) were present in low concentrations The occurrence of distinctive suites of miospores and biomarkers for rural catchments and the association of high concentrations of faecal (herbivore) biomarkers with rural inputs indicates that the input of organic material from these catchments can be mapped throughout the lake.

Results from an audit of 32 petroleum exploration wells in the Bass Basin have shown that approximately half of the wells in the basin were invalid tests due to off-structure drilling or mis-interpretation. Of the remaining wells, primary reasons for failure were lack of effective seal, timing, trap validity, lack of access to mature source rocks or reservoir problems. In parts of the basin the regional seal (Demons Bluff Shale) has undergone a period of structural inversion during the late Tertiary resulting in seal breach. Anticlinal closures of Eocene age were particularly affected, while structures located on fault-bounded basement highs were less affected, and provide the only fields within the basin. In the Yolla and White Ibis fields, access to mature source rocks was provided by large-displacement, non-sealing faults, that linked the upper EVG reservoirs with deeper source rocks. Traps without this conduit have as yet been unsuccessful. Sandy units within the Eastern View Group in the Pelican Trough are tight reservoirs that have good porosity but poor permeability. This is due to diagenetic effects that prohibited the creation of secondary porosity and permeability. Although identified risks within the basin can be minimised, the key to successful exploration will be finding traps that were in-place prior to the generation of hydrocarbons, but did not undergo significant Tertiary inversion.

10-12 July, 2002.