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Summary of Proposal MTH0092

TitleDevelopment of methods for detecting offshore natural hydrocarbon seeps, pollution and onshore subsidence in petroleum provinces of Australia using X-band SAR
Investigator Thankappan, Medhavy - Geoscience Australia, Geospatial and Earth Monitoring Division
Team Members
Dr Jones, Andrew - Geoscience Australia, Petroleum & Marine Division
Dr Logan, Graham - Geoscience Australia, Petroleum & Marine Division
Wettle, Magnus - Geoscience Australia, Petroleum & Marine Division
Reddy, Shanti - Geoscience Australia, Geospatial & Earth Monitoring Division
SummaryObjective: Australia’s NWS has significant petroleum exploration potential with several large commercial oil and gas fields. The NWS covers macro-tidal environments with intense current flows generating low backscatter features on SAR that are similar to slicks from natural hydrocarbon seepage. The study will enable the examination of X-band SAR data in the context of oceanography, geology and biology that will lead to better understanding of seepage slicks and false positives on SAR enabling classification of seepage slicks with a higher confidence. This study will contribute to the definition of a methodology framework for offshore natural hydrocarbon seep detection in Australian petroleum provinces in the NWS & Gippsland Basin and also develop techniques to detect coastal subsidence associated with anthropogenic activities in the Gippsland region.

Methods: The study will use data from a number of sources including space borne SAR, optical and other ancillary data plus data collected from marine surveys. A minimum of three coverages of satellite data will be requested to aid in the multi-temporal characterisation of slicks. Request for systematic programming of new satellite data will be done to ensure that it is collected during optimal weather conditions and tidal cycles. Limited data acquisition requests may also be made at times following a major seismic event like an earthquake, which may trigger hydrocarbon release from the sea-bed. Request for acquisition of interferometric data would be made to study coastal subsidence in the Gippsland Basin.

A decision tree approach will be followed in categorising the slicks observed in the SAR data using ancillary information (wind, wave and bathymetry information). A GIS will be used to record seepage slicks identified on the SAR images. Seepage slicks will also be ranked according to the confidence level. The slicks that repeat in successive coverages would be potential seep candidates for further investigation. Data from the marine survey will be used to exclude slick features that may be the result of currents or bathymetry. The marine survey is expected to identify areas of active seeps providing the opportunity to sample hydrocarbons in the water column and in sea-floor related features, enabling seepage location to be typed with its hydrocarbon source. We intend to use the repeat-pass interferometry capability of TerraSAR-X to detect millimetre scale deformations related to coastal subsidence in the Gippsland study area.

Deliverables: A report describing techniques used and results of analysis of TerraSAR-X data for characterisation of natural seeps in a macro-tidal environment and the use of repeat-pass interferometry to detect coastal subsidence. Publication of scientific results in appropriate journals/scientific forums.

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