Thursday, 25 July 2013

Frequency Decomposition: Standard vs. HD

GeoTeric enables you to be able to tailor Frequency Decomposition to your project objectives.  This is primarily done through the different methods available as well as the ability to interactively adapt the decomposition to the data’s’ spectrum.
The three methods available in GeoTeric constitute two categories; standard and high definition.  The standard methods are conventional decomposition with a sliding window, to include, Constant Bandwidth and Constant Q methods.  HDFD, on the other hand, utilises an algorithm that enables high definition frequency decomposition, essentially retaining the resolution of your original seismic.
It does this by determining an analytic wavelet representation of the seismic trace and minimizing loss of the resolution in the time domain.  Time domain resolution is gained at the expense of frequency domain resolution, as all time-frequency transforms must trade off frequency and temporal resolution.
However, the HDFD adaptively manages the resolution trade off in a way that preserves the scale characteristics of the seismic trace at every point, avoiding the “windowing effects” that are inherent in other approaches to frequency decomposition, such as Continuous Wavelet Transform, CWT.

In contrast, standard FD is not adaptive but instead uses specific Gabor Wavelets to pinpoint frequencies of interest with a great deal of flexibility. i.e. it produces a small part of that analytic wavelet representation within the HDFD.
As a result applying standard FD can reduce vertical resolution as with other direct wavelet based techniques such as CWT.


Our work on standard FD and HDFD has revealed that they are in fact complimentary in many Geological Expression workflows. However, the high vertical resolution provided by the HDFD is very important for interpretative objectives at reservoir scale.
If you have a common practice within GeoTeric that you think others could benefit from or have particular success story you wish to share, why not get in contact share it amongst the GeoTeric community?


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