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An Efficient PSDM with Geological Constrained Velocity Model Building Case Study in the UK Northern North SeaNormal access

Authors: X. Lu, R. Woods, A. Menari, C. Tyagi, L. Ward, S. Joseph, A. Mitra, A. Karagul and A. Benassi
Event name: 77th EAGE Conference and Exhibition 2015
Session: Seismic Imaging - Case Histories I
Publication date: 01 June 2015
DOI: 10.3997/2214-4609.201412776
Organisations: EAGE
Language: English
Info: Extended abstract, PDF ( 3.3Mb )
Price: € 20

Summary:
With the current global uncertainty in the hydrocarbon exploration environment, it is becoming ever more important to ensure that the maximum value is extracted from existing seismic datasets. Advances in data-processing technology mean that improvements in image accuracy, resolution, signal-to-noise ratio and amplitude fidelity can be made even on conventional datasets acquired and processed within the last few years. Following the this strategy, we recently finished a 3D PSDM re-processing project in the UK North Sea. The survey area comprises 6 different legacy surveys from 3 vendors. To make this project efficient in terms of timing and cost, we used the archived partially pre-processed gathers after denoise and demultiple processing as a starting point for the re-processing. The datasets were carefully matched, merged and regularized to provide a single seamless final product. Ray-based tomography has been very successful in building sub-surface velocity. However, as many other geophysical inversion problems, tomography suffers from non-uniqueness in the solution. To reduce the uncertainty in the velocity model, numerous extra constraints were introduced in tomography to constrain the inversion result. Here we also show how the velocity model was updated by following the local geological constraints and consequently achieve a much improved final imaging.


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