dears, How can I estimation the signal/noise ratio of seismic data by using petrel?
thanks
Dear Mohamed, I recommend the following workflow. I hope it is helpful.
1) Go to the Quantitative interpretation-tab.
2) Pick the S/N estimation (at the right side of this window).
3) New window will pop up, you can choose three options:
a) A 3D seismic volume, partial or whole volume.
b) A 2D line from the 3D volume, or
c) A 2D seismic survey.
4) Define your zone of interest boundaries, such as:
a) From a 3D seismic volume, the whole or partial volume.
b) From a 3D seismic volume, select a 2D line such as inline or crossline.
c) From a 2D seismic file, a partial or a whole line.
d) The vertical interval, as a TWT constant time (above/below) or by horizons interpretation (above/below).
5) Select parameters of the window length analysis, e.g., 250 ms is the default option.
6) On the output tab, you can choose three kinds of wavelets:
a) Signal wavelet.
b) Noise wavelet.
c) SNR (signal/noise ratio) wavelet.
7) Click Ok
8) A new wavelet/s will be generated in the corresponding new output tab folder created in the above step.
9) Go to the new output tab folder and make right-click.
10) Go and pick the Open spectral analysis tool.
11) New Analysis window will pop up, click on Add row icon to add 2 other rows.
12) Drop Noise in the first row, then S/N in the last row.
13) Color them based on your best analytical colors and click on the view check box to view them.
14) SNR is low (high noise level) for example if you choose:
a) The whole volume including the edges.
b) A shallow target.
c) A deep target such as below the basement (chaotic imaging).
d) A fault / structural fault zone, such as a fold and thrust belt.
e) A seismic with a poor fold or coverage (number of traces by CDP/CMP).
f) Unmigrated seismic file.
g) A land survey versus a marine survey.
h) The Fresnel zones as a function of offset and velocity gradient.
15) To avoid an SNR low, I recommend that you to selecting or focus on your specific zone.
16) You can view the S/N to see the level of noises at each frequency level, or you can see the noises are high from the shallow part (high frequency), to the deep (low frequency)
17) New VOI is introduced at this time, to check the outcome.
18) Following the same workflow, you can see the signal enhanced slightly at lower frequencies, while it still has the same base signal to noise at medium frequencies.
19) you can zoom in using the magnify mode for better analysis too.
20) It is recommended to analyze the frequency before analyzing the S/N to make sure the right window is used.
Please, let me know any questions. Best regards, Mario E. Sigismondi
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