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Legacy product - no abstract available

No product available. Removed from website 25/01/2019

Legacy product - no abstract available

No product available. Removed from website 25/01/2019

Legacy product - no abstract available

Legacy product - no abstract available

During March to May 1992, the Australian Bureau of Mineral Resources (BMR)and the Philippine Office of Energy Affairs (OEA) conducted a joint marineseismic and sniffer survey in four Philippine offshore sedimentary basins. Theproject was funded by the Australian International Development AssistanceBureau (AIDAB), and the survey was conducted using the Australiangovernment's geoscience research vessel Rig Seismic. A total of 2750 km of192-channel seismic data, plus geochemical sniffer, gravity, magnetic andbathymetric data was obtained jointly. This comprised 580 km in the NEPalawan Shelf, 730 km over the Cuyo Platform, 490 km in Tayabas Bay, and950 km in Ragay Gulf. Because of the extensive fishing activities at night time,particularly in Ragay Gulf, acquisition of seismic data after dark was abandonedin the latter part of the survey. During these hours the geochemical sniffer program was continued over identified anomalies, and an additional 900 km of sniffer, gravity and bathymetry data were recorded. Although not a lot can be deduced before the seismic data are processed, theship-board seismic monitors show plenty of structuring, and deep depocentreswith up to 4 seconds of stratified section. Because the weather during thesurvey period was very calm and therefore conducive to the collecting of low-noise data, the quality of the processed sections is expected to be excellent. Geochemical anomalies were recognised in the NE Palawan Shelf and in RagayGulf. These were particularly significant in Ragay Gulf and were related to: (1)previously identified prospects (ie R-1 and R-2 in the 0EA-World Bank Report,and the Alibijaban prospect identified by Far East Resources); (2) faults; and (3)deep diapir structures. They fall into two distinct anomaly types: type 1 is characterised by high methane, ethane and propane with traces of butane andpentane, indicating dry to wet thermogenic gas; type two has high methane andtraces of C2+, indicating very dry gas. In order to better understand the flux rate of hydrocarbon release and thecomponent fractionation and magnitude of the source of the seep, Ragay Gulfwas revisited after the seismic shooting was completed. Here, eightgeochemical vertical profiles were recorded and 28 gas samples collected forisotope analysis. In one example, hydrocarbons were concentrated under thethermocline at about 140 m water depth. The newly acquired data will be processed in BMR, integrated with existing seismicand well data from previous industry sources, interpreted and analysed for petroleumpotential. The final analysis, together with basic data, will then be presented to theexploration industry, initially in the Philippines and Australia, and laterinternationally, in order to promote further exploration.

The measurement of the concentrations and molecular compositions of light hydrocarbon gases within the water column overlying offshore sedimentary basins can provide, under suitable circumstances, significant information on hydrocarbon source rock maturity and/or type, and the most likely locations for petroleum accumulation within basins. These measurements are usually made using a hydrocarbon 'sniffer', which comprises a submersible fish which is towed near the seafloor, and from which water is pumped to the surface and continuously analysed via gas chromatography. Compared with overseas, relatively few 'sniffer' surveys have been carried out around Australia, and hence the applicability and usefullness of this technique to the Australian situation is as yet undetermined. As a continuation of its geochemical research program, the Division of Marine Geosciences and Petroleum Geology (Australian Bureau of Mineral Resources) will conduct a co-operative geochemical research survey withTransglobal Exploration and Geoscience (TEG) of Leucadia, California, USA, in southeastern Australia between February 1 and March 2, 1989. The cruise will be of 30 days duration and will involve work in the Gippsland, Bass, Otway and Stansbury Basins and the Torquay Sub-basin. A detailed proprietary program will be carried out in the Bass and Stansbury Basins in co-operation with Amoco Production Company. Two regional lines will be run from the Torquay Sub-basin, across the Cape Otway-King Island High, to the Crayfish Platform in the west of the Otway Basin (see Fig. 2). Regional lines will also be run in the Gippsland Basin, with an additional detailed program over several known oil and/or gas accumulations. In addition to the water column geochemistry, a limited sampling program will investigate the light hydrocarbon geochemistry of sediments over known oil and gas fieldsin the Gippsland Basin.