Technical Library

  • EAGE 2022 Highlights

    Author: Andrew Long
    Industry Insights - 28 June 2022

    View summary

    The 83rd EAGE conference was held in Madrid on 6-9 June, in a welcome return to in-person attendance. I briefly review the key technical themes and profile 12 technical presentations given my PGS authors. Topics cover Full Waveform Inversion (FWI), simultaneous inversion of velocity and reflectivity (PGS Ultima), developments in marine seismic acquisition, the inversion of reservoir properties from multi-azimuth (MAZ) seismic data, automated subsurface characterization, an integrated workflow for identifying Carbon Capture & Storage (CCS) sites, applications of deep learning to seismic data processing, and water velocity static corrections in deep water areas for 4D reservoir monitoring.

  • Accurate reservoir attributed delivered with GeoStreamer X in the South Viking Graben, Norway

    Author: Cyrille Reiser, Roberto Ruiz, Eric Mueller, Julien Oukili
    GeoExpro - 15 June 2022

    View summary

    Following a very successful 2019 GeoStreamer X survey in the South Viking Graben, Norway, an additional multi-azimuth survey was acquired further north covering the Utsira High and the Vana Sub-basin. This case study will review the main imaging benefits of various stratigraphic intervals such as the Tertiary and the deeper Jurassic. The implemented technologies and methodologies have enabled the accurate estimation of reservoir properties as well as highlighting the underexplored Vana Sub-basin and near-field opportunities on the Utsira High.

    A combination of innovative acquisition, quantitative interpretation, and seismic morphology interpretation delivers enhanced understanding of the main prospective stratigraphic intervals (Tertiary–Jurassic) and an improved assessment of the volumetry of exploration targets.

  • Combining wide-tow multi-sources with a non-uniform streamer configuration: A case study from the Sarawak Basin

    Author: Martin Widmaier, Carine Roalkvam, Okwudili Orji, Ashish Misra
    EAGE - 25 May 2022

    View summary

    New survey design solutions for marine towed streamer acquisition were recently introduced by Widmaier et al. (2019). One of the key technical elements was the concept of wide-tow multi-sources, i.e., the distribution of multiple sources along the front of a streamer spread. All the wide-tow source case studies acquired in recent years have made use of uniform multi-source and multi-streamer spreads (i.e., regular streamer and source separations), thus following the same industry standards as in marine seismic surveys with narrow source configurations. However, uniform configurations may not always be feasible or optimal due to operational or geophysical constraints. In this article, we revisit the basics of the wide-tow multi-source method and make the step from a uniform to a non-uniform design. The first seismic survey using this novel method is currently being acquired in a challenging area offshore Malaysia.

     

     

     

  • Simultaneous dual sensor wavefield separation and seismic data compression using parabolic dictionary learning.

    Author: Mohammed Ouhmane Faouzi Zizi, PGS / University of Oslo (UiO), Pierre Turquais, Anthony Day, Morten W. Pedersen
    EAGE - 25 May 2022

    View summary

    Areas covered by seismic exploration surveys are continuously increasing and the data recorded are becoming of very large size. In addition, conventional seismic processing and imaging is a long

    meticulous workflow which is time consuming and very expensive in terms of human and computational resources. Consequently, allowing seismic processing steps in a compressed domain can play a key role in the marine seismic industry as it would be a faster and cheaper alternative to the standard seismic processing sequence and would save cost on storage and data transfer. Parabolic dictionary learning has the ability to compress the seismic data by transforming them into an appropriate sparse domain, and also to extract local parameters which relate to the kinematics of the wavefield. In this paper, we use these kinematic parameters to correct for the geophone obliquity problem and thus enable the dualsensor wavefield separation processing step in the compressed domain. Without the need for data interpolation, our method succeeds in reconstructing aliased events and shows comparable results to an industry-standard FK based algorithm in terms of up- and down-going pressure fields reconstruction. It also comes with the advantage of compressing the data by a factor higher than 10.

  • Combined burial and rock physics modelling to determine complex velocity and avo depth trends offshore Canada

    Author: Per Avseth, Cyrille Reiser, Ivan Lehocki, Tore Hansen, Kristian Angard, Dig Science; and Laurent Feuilleaubois, Mitigrate (Formerly PGS)
    EAGE - 25 May 2022

    View summary

    A comprehensive rock physics and AVO feasibility study, where we combine burial and rock physics modelling, has been conducted for the Tablelands and North Tablelands area, offshore Newfoundland. The burial history was assessed in 3D from seismic velocity information, calibrated to selected wells in the area.There is a natural ambiguity between the temperature and burial histories. We therefore introduce the term “pseudo-uplift” referring to deviations from normal compaction for a given temperature gradient. The “pseudo-uplift” cube can be used to constrain 3D rock physics and AVO feasibilities away from the selected wells within a selected area of interest. We model different scenarios, including a “pessimistic” one (P90) with respect to reservoir quality and fluid sensitivity, an “optimistic” one (P10), and an “expected” one (P50). These AVO scenario-cubes could be used to screen, rank and derisk leads and prospects in the area from real AVO data.

  • Stepping towards automated Multisensor noise attenuation guided by deep learning

    Author: Bagher Fermani, Yash Pal, Morten W. Pedersen, Edwin Hodge
    EAGE - 25 May 2022

    View summary

    Despite technological advancements in marine seismic multisensor acquisition and processing, noise attenuation remains a fundamental step in the early processes for producing high-quality upgoing pressure wavefield data. If we assume the main shortcoming of traditional methods is in the noise detection step, deep learning can be used in only the detection step and the selected noise attenuation engine can be automatically guided by the deep learning noise classification. We have created different deep learning models to detect a variety of noise types present in both marine hydrophone and geophone records. These models are used to automatically classify the samples in the noise attenuation workflows and pass the samples to the appropriate noise attenuation steps. Targeted noise detection lets us perform a better targeted noise attenuation with appropriate levels of harshness without undue concern over possible signal loss. Models can also be used at any step of the processing to classify the samples in both hydrophone and geophone records. The improvement in noise attenuation and its impact on the PUP generation is presented for a real dataset. The advantages to turnaround and quality that arise from the use of these workflows are discussed.

  • The Acoustic wavefield generated by a vessel sailing on top of a streamer spread

    Author: Stian Hegna
    EAGE - 25 May 2022

    View summary

    During the acquisition of a source-over-cable survey in the Barents Sea, part of one sail line was repeated without triggering the airgun arrays. The acoustic signals associated with the vessel sailing on

    top of the streamer spread were recorded continuously by the streamers. This acquisition configuration offers an almost complete measurement of the wavefield generated by the vessel covering a large range of emission angles and frequencies. The acoustic wavefield generated by this vessel has been characterized from the measured direct arrivals. The image obtained after deconvolving this wavefield from the received wavefield will be presented and compared to the image obtained from an airgun source.

  • Data-driven reservoir properties estimation using MAZ towed multisensor streamer seismic: A Norwegian case study

    Author: Cyrille Reiser, Roberto Ruiz
    EAGE - 25 May 2022

    View summary

    This paper will focus on a data driven approach for reservoir properties estimation of a recently acquired and processed multi-azimuth multisensor survey in the prolific South Viking Graben, Norway. The implemented technologies and methodologies will be performed without the need of building a low frequency model necessary to achieve absolute reservoir properties and applied on the under-explored Vana sub-basin in the Upper Jurassic interval. This case study will highlight that a combination of an innovative acquisition, quantitative interpretation, and seismic morphology interpretation delivered enhanced imaging and understanding of the Jurassic interval.

  • A new look at autoregressive low frequency reconstruction of seismic data

    Author: Maiza Bekara, Ramzi Djebbi, Nizar Chemingui
    EAGE - 25 May 2022

    View summary

    This abstract proposes a novel, easy to deploy and computationally fast solution to reconstruct the low frequency content of seismic data for FWI application. This solution is needed when the SNR is very poor or when denoise fails to enhance sufficiently the low frequency content of the data. The method follows a signal processing approach and does not need to train an offline model on auxiliary data, as is the case for solutions based on machine learning. The reconstruction is done from the higher frequencies using a recursion filter which is estimated from the data itself. The novelty of the proposed method is that it transforms the data locally from the time-space domain to the time-slowness domain where the reconstruction is performed. This transformation enforces the time domain sparsity needed to justify the use of recursion modeling in the frequency domain and exploits the spatial coherency in the data. The method also implicitly uses the signal cone limits of the seismic wavefield to provide a physically constrained solution. The proposed method was tested on many datasets to condition it for FWI and proved to be successful to help the inversion to mitigate cycle skipping and to improve the final model.

  • Integrating FWI and reflection tomography to rejuvenate legacy seismic data: an example from the Faroes-Shetland Basin

    Author: Antonio Castiello, Gareth Venfield, Jens Beenfeldt, Eric Mueller, Jamshade Khan
    EAGE - 25 May 2022

    View summary

    We present a robust depth imaging workflow that incorporates high-resolution Full Waveform Inversion (FWI) and reflection tomography constrained by geological interpretation. This approach has allowed us to both update the long wavelength and the fine details of the velocity model by a simultaneous combination of eight vintage streamer surveys characterized by a wide range of acquisition parameters. We demonstrate the benefits of this integrated scheme by presenting the results from the West of Shetland area, offshore UK.