Technical Library

  • Efficient reflectivity modelling for full wavefield FWI

    Author: Tony Martin, Yang Yang, Norman Daniel Whitmore, Nizar Chemingui, Tiago Alcantara, Eric Frugier
    First Break - 1 March 2021

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    The authors describe an efficient modeling of reflectivity to drive full wavefield full waveform inversion. Reformulating the variable density acoustic wave-equation in terms of vector-reflectivity, represents a step towards full automation, and enables a greater diversity of applications.

  • From a regional AVA screening to focused elastic attributes estimation: an integrated solution from seismic acquisition to reservoir characterization

    Author: Cyrille Reiser, Elena Polyaeva, Scott Opdyke
    SEG - 1 October 2020

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    Understanding the elastic properties of reservoirs in exploration can be very challenging - due mainly to the lack of well information, limited regional geological understanding, and the quality and reliability of seismic data available.

    This case study illustrates how this challenge can be addressed through an integrated solution from broadband seismic acquisition to elastic properties, applied recently to the underexplored deep-water Orphan Basin, offshore Eastern Canada.

    A multisensor seismic dataset covering close to 22,500 km2 was acquired over three seasons (from 2017 to 2019) and now constitutes a great platform for understanding the geology as well as extracting elastic properties. The understanding of the prospectivity was performed at the regional scale, then on more localized area using one of the very few wells present in the area. On this localized area the newest depth imaging technologies with Full Waveform Inversion (FWI) and Least-Squares Migration (LSM) were used. In addition, a three term Amplitude Versus Angle (AVA) inversion was performed and matched at the well without using the well actively in the process but by using the broadband seismic data only: velocity and amplitude.

    Turnaround time was also a key element in this regional project. To significantly reduce this, an integrated team of imaging and quantitative interpretation specialists was dedicated to the project from the start. Pre-stack AVO QC was performed iteratively during the processing to ensure that the final pre-stack data was fit for purpose and AVO/AVA compliant for further Quantitative Interpretation (QI) analysis.

  • High-resolution velocity model building and least-squares imaging offshore Canada: a deep-water Orphan basin example

    Author: Tiago Alcantara, Eric Frugier, and Bruno Virlouvet
    SEG - 1 October 2020

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    A 500km2 proof-of-concept project in deep-water Canada demonstrated the benefits of combining recently acquired multisensor streamer data and new imaging technologies to
    produce a detailed velocity model and a robust seismic image that can minimize uncertainties prior to drilling. We describe the full waveform inversion (FWI) and least-squares migration (LSM) workflow that not only resulted in high-resolution seismic sections, with improved fault definition and signal to noise (S/N) ratio in the Cretaceous and Jurassic sections, but also produced AVO-compliant image gathers that can benefit quantitative interpretation

  • Back-Propagating into the Future

    Author: Andrew Long
    Industry Insights - 23 September 2020

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    I discuss the important similarities and distinctions between RTM (Reverse Time Migration), LS-RTM and FWI, and also relate their fundamental reliance upon back-projection to Deep Neural Network training used in many machine learning pursuits. Hence, the title of this newsletter points to the powerful concept that is paving the ways forward for reducing uncertainty in seismic imaging and seismic characterization in coming years. This newsletter is also written to accompany the TechByte webinars on ‘Least-Squares Migration’ and ‘Illumination vs AVO’.

  • Orphan Basin, Canada | From Regional Prospect Screening to Reliable Reservoir Attributes Estimation

    Author: Scott Opdyke, Cyrille Reiser, Tiago Alcantara, Elena Polyaeva
    GeoExpro - 4 May 2020

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    A new, high quality regional dataset covering 22 469 sq. km is enabling the identification of important petroleum system elements in the underexplored Orphan Basin, offshore eastern Canada. Block evaluations for the upcoming license rounds can be performed with confidence with this multi-sensor broadband seismic data and its reliable pre-stack attributes. The most recently acquired part of this regional dataset is the North Tablelands survey, acquired in 2019 as an extension of the Tablelands and Long Range surveys, which were shot in 2017–2018 by PGS and TGS. Fast-track data was delivered just five weeks after the last shot of the North Tablelands survey. A full integrity volume is available now and provides a single, continuous high-resolution seismic dataset available for licensing early next year, encompassing the Long Range, Tablelands and North Tablelands surveys.

  • The music of marine seismic: A marine vibrator system based on folded surfaces

    Author: Okwudili Orji, Mattias Oscarsson-Nagel, Walter Söllner, Endrias Asgedom, Øystein Trætten, Rune Voldsbekk
    The Leading Edge - 1 April 2020

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    Marine vibrators have bespoke geophysical benefits that are yet to be harnessed because of robustness and efficiency issues. We have developed a new marine vibrator source technology that is efficient and stable. The source technology overcomes the historical problems of inefficiency and robustness by using folded surface technology and resonance frequency tuning. We show measured output examples that demonstrate that the folded surface concept combined with small displacements can provide the required output levels. Our source system consists of a low-frequency module covering 1–10 Hz and a high-frequency module covering 10–125 Hz. The source control system has shown high stability and precision and can handle harmonic distortion. With the aid of synthetic data examples, we demonstrate that seismic data acquired using marine vibrators in either intermittent or continuous mode can be processed. Finally, we demonstrate the environmental friendliness of the source in comparison to air gun-based sources.

  • Rejuvenated Seismic Data Available to Boost Exploration in the Flex Trend

    Author: PGS
    E&P Daily News - 18 September 2019

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    Dataset improves knowledge in GoM subsalt.

  • Marine vibrator source: Modular projector system

    Author: Okwudili Orji, Mattias Oscarsson, Walter Söllner, ØysteinTrætten
    SEG - 15 September 2019

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    There is a desire by the marine geophysical industry for a seismic source with a low environmental footprint. Received sound pressure level (SPL) and sound exposure level (SEL) can restrict how seismic surveys can be conducted in sensitive areas.
    To address this desire, we have developed a broadband nonimpulsive source based on the concept of modular transducer elements. The source has a controlled output that can emit
    arbitrary signals, enables flexible source geometries, and can produce ultra-low frequency content that facilitates robust full waveform inversion.
    Sea trials and testing indicate that the developed source will meet the challenging output demands and exhibit the necessary robustness to be a viable seismic source for the
    future. Large scale testing is planned in 2019.

  • Marine vibrator source: Modular projector system

    Author: Okwudili Orji, Mattias Oscarsson, Walter Söllner
    SEG - 15 September 2019

    View summary

    There is a desire by the marine geophysical industry for a seismic source with a low environmental footprint. Received sound pressure level (SPL) and sound exposure level (SEL) can restrict how seismic surveys can be conducted in sensitive areas.
    To address this desire, we have developed a broadband nonimpulsive source based on the concept of modular transducer elements. The source has a controlled output that can emit
    arbitrary signals, enables flexible source geometries, and can produce ultra-low frequency content that facilitates robust full waveform inversion.
    Sea trials and testing indicate that the developed source will meet the challenging output demands and exhibit the necessary robustness to be a viable seismic source for the
    future. Large scale testing is planned in 2019.

  • Marine Vibrator Source: Modular System with Folded Oscillating Surface

    Author: Mattias Oscarsson-Nagel, Walter Söllner, Øystein Trætten, B. Armstrong, D. Nams, P. Yeatman
    EAGE - 3 June 2019

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    There is a desire by the marine geophysical industry for a seismic source with a low environmental footprint.
    Received sound pressure level (SPL) and sound exposure level (SEL) can restrict how seismic surveys can be conducted in sensitive areas.
    To address this desire, we have developed a broadband non-impulsive source based on the concept of modular transducer elements. The source has a controlled output that can emit arbitrary signals, enables flexible source geometries, and can produce ultra-low frequency content that facilitates robust full waveform inversion.
    Sea trials and testing indicate that the developed source will meet the challenging output demands and exhibit the necessary robustness to be a viable seismic source for the future. Large scale testing is planned in 2019.