Velocity model building and depth imaging for complex areas with shallow and deep velocity anomalies: Papua Province (Indonesia) examples, Mogoi 2D land PSDM project

2003 ◽  
Author(s):  
Howard Crook ◽  
Sergey Birdus
Keyword(s):  
Model Building ◽  
Velocity Model ◽  
Depth Imaging ◽  
Velocity Model Building ◽  
Velocity Anomalies

Velocity model building for tilted orthorhombic depth imaging

2012 ◽  
Author(s):  
Yunfeng Li ◽  
Weishan Han ◽  
Chuen-song Chen ◽  
Tony Huang
Keyword(s):  
Model Building ◽  
Velocity Model ◽  
Depth Imaging ◽  
Velocity Model Building

Resolving near-seabed velocity anomalies: Deep water offshore eastern India

Geophysics ◽  
2008 ◽  
Vol 73 (5) ◽  
pp. VE235-VE241 ◽  
Author(s):  
Juergen Fruehn ◽  
Ian F. Jones ◽  
Victoria Valler ◽  
Pranaya Sangvai ◽  
Ajoy Biswal ◽  
...  
Keyword(s):  
Velocity Field ◽  
Deep Water ◽  
Model Building ◽  
Velocity Model ◽  
Narrow Channel ◽  
Small Scale ◽  
Low Velocity ◽  
Near Surface ◽  
Velocity Model Building ◽  
Velocity Anomalies

Imaging in deep-water environments poses a specific set of challenges, both in data preconditioning and velocity model building. These challenges include scattered, complex 3D multiples, aliased noise, and low-velocity shallow anomalies associated with channel fills and gas hydrates. We describe an approach to tackling such problems for data from deep water off the east coast of India, concentrating our attention on iterative velocity model building, and more specifically the resolution of near-surface and other velocity anomalies. In the region under investigation, the velocity field is complicated by narrow buried canyons ([Formula: see text] wide) filled with low-velocity sediments, which give rise to severe pull-down effects; possible free-gas accumulation below an extensive gas-hydrate cap, causing dimming of the image below (perhaps as a result of absorption); and thin-channel bodies with low-velocity fill. Hybrid gridded tomography using a conjugate gradient solver (with [Formula: see text] vertical cell size) was applied to resolve small-scale velocity anomalies (with thicknesses of about [Formula: see text]). Manual picking of narrow-channel features was used to define bodies too small for the tomography to resolve. Prestack depth migration, using a velocity model built with a combination of these techniques, could resolve pull-down and other image distortion effects in the final image. The resulting velocity field shows high-resolution detail useful in identifying anomalous geobodies of potential exploration interest.

Getting it right the first time in the Ceduna Sub-basin: regional and target depth imaging in a frontier setting

2017 ◽  
Vol 57 (2) ◽  
pp. 767
Author(s):  
Weidi Koh
Keyword(s):  
Model Building ◽  
Survey Design ◽  
Velocity Model ◽  
Quantitative Interpretation ◽  
Depth Imaging ◽  
Velocity Model Building ◽  
Amplitude Versus Offset ◽  
Dual Sensor ◽  
Streamer Data ◽  
Great Australian Bight

The acquisition and depth imaging of almost 20400 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 12400 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.

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