Getting it right the first time in the Ceduna Sub-basin: regional and target depth imaging in a frontier setting
Weidi KohPetroleum Geo-Services, 1060 Hay Street, West Perth, WA 6005, Australia. Email: weidi.koh@pgs.com
The APPEA Journal 57(2) 767-771 https://doi.org/10.1071/AJ16180
Accepted: 3 April 2017 Published: 29 May 2017
Abstract
The acquisition and depth imaging of almost 20 400 km2 of broadband seismic data in the Great Australian Bight has created an excellent dataset fit for quantitative interpretation. This new dataset was derived from a merge of 12 400 km2 of 2011 vintage conventional streamer data in an almost seamless manner with 8000 km2 of 2014 vintage dual-sensor streamer data.
The Ceduna Sub-basin is the main depocentre of the Bight Basin. It lies adjacent to the continental shelf and slope and is covered by two broad bathymetric terraces in water depths ranging from <200 to >4000 m. A potentially prospective Late Jurassic syn-rift to Late Cretaceous post-rift sedimentary succession (fluvial to paralic sediments) >15 km thick is imaged with remarkable quality and resolution. Features of particular interest include large stacked fan and channel systems, as well as simple, structurally closed formations.
Careful survey design and execution optimised efficiency, enabling each survey to be acquired in less than one season. Particular attention was given to amplitude versus offset and phase compliance, including customised flows to overcome a paucity of well control in this frontier area. Optimised preprocessing, velocity model building and survey merging were applied to ensure structural and depth integrity in the final images. Regional and targeted mapping and quantitative interpretation results testify to the value of the multifaceted geophysical and geological disciplines used in the overall project execution.
Keywords: amplitude versus offset (AVO), depth imaging, dual sensor, frontier basin, Great Australian Bight, prestack depth migration (PSDM), prestack time migration (PSTM), quantitative interpretation (QI), springboard.
Weidi Koh has a BSc in physics and is currently a project leader at PGS. He has 8 years extensive experience in processing marine 3D seismic dataset and velocity model building for depth imaging. He has completed projects in various basins in areas such as the North West Shelf, Australia, the Great Australia Bight, offshore Myanmar and offshore Ireland. He is adept with industry standard and proprietary algorithms, such as full waveform inversion, prestack depth Kirchhoff migration, wavefield extrapolation migration and PGS beam migration. |
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