EGU2020-3598
https://doi.org/10.5194/egusphere-egu2020-3598
EGU General Assembly 2020
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

2D to 3D high-resolution seismic data conversion: imaging a shallow water metal bearing mine tailings deposit in Portmán Bay, Spain

Emma Soldevila1, Ramon Carbonell2, David Amblas1, and Miquel Canals1
Emma Soldevila et al.
  • 1Universitat de Barcelona, Faculty of Earth Science, Department of Earth and Ocean Dynamics, Spain (emma.soldevila@ub.edu) (damblas@ub.edu) (miquelcanals@ub.edu)
  • 2Spanish national Research Council (CSIC), Institute of Earth Sciences Jaume Almera (ICTJA), Spain (ramon.carbonell@csic.es)

High-resolution (HR) 3D seismic acquisition is expensive and often not available due to a variety of reasons. This work builds an optimized workflow to convert a dense 2D HR seismic grid into a 3D seismic volume. The task has been developed within a broader project, NUREIEVA, which aims at characterizing a metal-rich onshore and shallow marine mine tailings deposit in Portmán Bay, Murcia, Spain, which developed from 1957 to 1990. Hence, in the framework of the NUREIEVA project a very dense set of 2D HR seismic lines was acquired. The geophysical equipment used to capture the submarine extent, thickness and internal structure of the mine tailings deposit was a hull-mounted Kongsberg TOPAS PS18 single-channel parametric source. The seismic grid thus acquired consisted of 1309 2D lines, with an approximate distance between lines of 10 m, covering an area of 7.45 km2. The parametric source yielded a vertical resolution of 15 cm, which is very high if compared with conventional seismic reflection data.

 

In order to visualize the internal architecture of the mine tailings deposit in all directions, it is desirable to convert the dense 2D network of lines into a full 3D data volume. Such a data volume is intended to assist reaching faster deposit delimitation and more accurate volumetric calculations. For this purpose, a new optimized 2D to 3D conversion processing flow including a 3D interpolation scheme has been designed. Given the specific characteristics of the input data, a number of challenges had to be addressed, namely: (i) a very high vertical resolution that differs by at least two orders of magnitude from the horizontal resolution; (ii) a large data volume (2 TB), which involves extensive computing time; (iii) the heterogeneity in the acquisition parameters. Because of this, the lines had to be processed previously to the 3D interpolation to homogenize the imaging characteristics and signal content. This new methodology can be now applied for obtaining a 3D volume to any case where a single channel dense 2D seismic grid is available. Furthermore, the new methodology, duly adapted to each particular scenario, represents a low cost alternative to conventional HR 3D seismic and could prevent further seismic shooting in areas when 2D data is already available.

How to cite: Soldevila, E., Carbonell, R., Amblas, D., and Canals, M.: 2D to 3D high-resolution seismic data conversion: imaging a shallow water metal bearing mine tailings deposit in Portmán Bay, Spain, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3598, https://doi.org/10.5194/egusphere-egu2020-3598, 2020.

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  • CC1: Comment on EGU2020-3598, Alba Gil de la Iglesia, 06 May 2020

    Hello Emma,

    Very nice presentation. I have two questions:

    1. You recommended for future workflows, to planning a 2D seismic grid, more regular during the acquisition. That does imply that you recommend a new semi-3D marine seismic cube? 
    2. if you recommend a 2D seismic line, then how are you going to deal with out-of-the-plane features, that are move visible in a 3D cube, or for a more accurate location of a reflection after applying DMO?

     

    Thank you

    • AC1: Reply to CC1, Emma Soldevila, 08 May 2020

      Hi Alba!

      Thanks so much for looking into our research. I may answer your questions.

      1. We have been able to put some best practices when acquring 2D seismic data and willing to convert it to a 3D block. Those include planning a 2D seismic grid as much regular as possible during acquisition. Shooting a fine and regular 2D grid will lower the uncertanty when interpolating into 3D. The workflow can be applied to irregular grids as well, but if the 2D seismic still needs to be acquired, we recommend planning .

      2. Alba, good point. We Actually managed to obtain 2D seismic in many different directions, so it would be difficult to miss any out-of-plane strucutres. Looking at your work and comparing it to ours, we worked in recent sediments with interesting internal structures, but not complex deformed deep geology like your case study. Our wokflow works very well for recent sediments or mild structures. You would probably need to add a geological model constrain to run a similar workflow in the Zinkgruvan mining area. I know of study in Brazil that applied a geological model constraing before converting old 2D seismic into 3D.