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COLOP - Operator design for colored inversion, spectral blueing and spectral whitening

Colored inversion is a robust seismic reservoir characterisation tool, which provides band limited impedance data from seismic reflectivities (Lancaster and Whitcombe, 2000). 

The main part of the process is the color operator design. This simple utility can do this task using amplitude spectrums exported from OpendTect.

The workflow is simple:

  • Load seismic amplitude spectrum exported from OD
  • Load well based impedance spectrum exported from OD
  • Define tresholds graphically (amplitude treshold, well spectrum regression limits, operator length)
  • Define polarity and taper parameters
  • Export the final operator, and load it into OD

 

The application is coded in Lazarus using FPC and FFT code of Alglib, and the used icons were modified from FatCow Farm Fresh  Icons. Source files of COLOP project are available for download to build the app on other platforms like OSX or Linux.

Concept and prototype can be found as an IPython Notebook in the filelist, or here.

Attachments:
FileDescriptionFile sizeLast modified
Download this file (COLOP in python.ipynb)COLOP concept and prototypeIPython Notebook144 kB2015-05-25 09:39
Download this file (COLOP_src.7z)COLOP SourcesLazarus Source files of COLOP project104 kB2015-05-25 09:37
Download this file (F2 COLOP DEMO.7z)Demo dataSample spectrums from F3 dataset7 kB2015-05-25 09:37
Download this file (COLOP.exe)COLOPwin32/win64 executable3065 kB2016-04-10 16:52
Download this file (COLOP.7z)COLOP.exe zipped with 7-zipwin32/win64 executable zipped to solve download problem787 kB2016-04-10 16:53

COLOP NEW 500px

The idea of color inversion is simple and straightforward. The Earth's impedance spectrum seems to be fractal, which means that the spectrum follows a power law function, so it is predictable:

The aim of this technique is to find an operator which can transform the seismic amplitude spectrum to match the Earth's impedance spectrum.

The main part of the process is the color operator design. COLOP can do this task using amplitude spectrums exported from OpendTect.

 

COLOP can work in three modes. Colored inversion mode (CI), spectral blueing mode (SB), and spectral whitening (SW) mode.

In the case of CI mode, operator has -90 degree phase spectrum.

In the case of SB mode, operator is calculated from AR(f), which can be defined by following equation: AR(f)=cfß; ß=alfa+1; and the operator has zero phase spectrum. In SW mode flat (white) target spectrum is the basic assumption.

 

References:

Lancaster, S. and D. Whitcombe, 2000, Fast-track ‘coloured’ inversion: SEG Expanded Abstracts, 19, 1298-1301.

Blache-Fraser, G., and J. Neep, 2004, Increasing seismic resolution using spectral blueing and colored inversion: Cannonball field, Trinidad: SEG Expanded Abstracts, 23, 1794-1797.

Neep, J. P., 2007, Time variant coloured inversion and spectral blueing: 69th EAGE Annual Meeting, Extended Abstracts, B009. 

COLOP Tutorial

This tutorial demonstrate a workflow based on the public F3 dataset which can be downloaded from the Open Seismic Repository.

Tutorial Workflow:

  • Start OpendTect, Open F3 demo project
  • Visualize F02-1 well on your scene
  • Generate P-Impedance log amplitude spectrum and export it.
  • Visualize seismic data using volume rendering at the neighbourhood of the well.
  • Generate amplitude spectrum of visualized seismic, export it.
  • Start COLOP, load seismic and well spectrums.
  • Click on Refresh to calculate raw operator
  • Tune your parameters to get the best operator:
    • Seismic amplitude spectrum treshold
    • Log frequency range for least squared linear regression
    • Operator length and taper length, polarity
  • Check your operator efficiency using QC button
QC2
  • Export your operator form COLOP, and import it into OpendTect
  • Convolve your seismic with the operator to get the band limited impedances
  • Apply your attribute on your volume, and enjoy your meal:)