Imaging below seafloor canyons and other rugose features
Dominic Fell A C , Kiran Dyal A , Tony Hallam B and Sebastian Nixon BA WesternGeco, Level 5, 256 St Georges Terrace, Perth, WA 6000, Australia.
B Origin, Level 5, 135 Coronation Drive, Milton, Qld 4064, Australia.
C Corresponding author. Email: fell0@slb.com
The APPEA Journal 57(2) 728-732 https://doi.org/10.1071/AJ16062
Accepted: 21 March 2017 Published: 29 May 2017
Abstract
Rugose seabed and near seafloor features in marine seismic datasets such as canyons, mass transport deposits and paleo-channels, present a major imaging challenge that can be overcome by a rigorous and careful approach in the earth model building process. To obtain an accurate image of the deeper target levels, a modelling and data driven update of the distinctive velocity characteristics of the overburden features are necessary. Without adequately addressing the complexity of the shallow velocity field, the final depth image of the target intervals can be poorly focussed and contaminated with non-geologic structural distortions. Inadequate corrections ultimately have an adverse impact upon the interpretation of the dataset.
This paper presents a successful earth modelling approach used to obtain an accurate depth image for a marine dataset located on the shelf break in the Otway Basin. The case study area includes extensive seafloor canyons and associated paleo-channels, requiring the strategic use of several geologically constrained model updating technologies in order to obtain a final imaged section free of velocity related structural distortions.
Keywords: depth imaging, depth migration, earth model building, seafloor topography, tomography.
Dominic Fell is a Depth Imaging Area Geophysicist for WesternGeco based in Perth, Australia. Dominic joined WesternGeco in 1996, moving to Perth in 2009. Dominic has experience in a wide range of imaging projects from across the world, with a particular focus in recent years on offshore Australia and New Zealand. |
Kiran Dyal is a Geophysicist for WesternGeco based in Perth, Australia. Kiran joined WesternGeco in 2006 where she worked on land and marine depth imaging projects based in Calgary before moving to Perth in 2010. Kiran has extensive experience with depth imaging throughout offshore Australia and New Zealand. |
Tony Hallam has been a Geophysicist with Origin Energy for six years. Starting in a functional team, he gained exposure to many of Origin’s assets including conventional and coal seam gas. The last three years have been spent working with Origin’s offshore conventional assets on the southern margin. |
Sebastian Nixon is a Geophysicist in the Conventional Exploration team with Origin Energy based in Brisbane. Sebastian joined Origin Energy in 2010 after nine memorable years with various New Ventures, Exploration and Quality Improvement teams at Santos and AWE. Sebastian is currently focussed on conventional exploration/appraisal opportunities across the southern margin of Australia. |
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