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use of Variance as Seismic Attribute 
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Joined: Fri Oct 01, 2010 10:15 pm
Posts: 8
Post use of Variance as Seismic Attribute
Hi everybody,
Similar to my question about the Root Mean Square... What is Variance and how can I use it to visualise sedimentary bodies, like channels? thanks!


Thu Mar 24, 2011 7:45 am

Joined: Wed Sep 01, 2010 10:06 pm
Posts: 102
Post Re: use of Variance as Seismic Attribute
Vikesh,

The variance (the opposite of coherency) attribute is calculated in three dimensions and represent the trace-to-trace variability over a particular sample interval and therefore produces interpretable lateral changes in acoustic impedance. Similar traces produce low variance coefficients, while discontinuities have high coefficients. Because faults and channels may cause discontinuities in the neighboring lithologies and subsequently in the trace-to-trace variability they become detectable in 3D seismic volumes. Variance can thus be seen as the lateral counterpart of RMS as the later indicates vertical variations.

Deos that answer your question?


Thu Mar 24, 2011 8:29 am

Joined: Fri Oct 01, 2010 10:15 pm
Posts: 8
Post Re: use of Variance as Seismic Attribute
Thank you petrel_user. that is the answer I was looking for!


Thu Mar 24, 2011 1:51 pm

Joined: Wed Mar 07, 2012 6:36 pm
Posts: 1
Post Re: use of Variance as Seismic Attribute
Hi Petrel user,
Could you please make it clear what you mean my 'calculated', what is to be calculated, is the acoustic impedance or amplitude,..?
And also as it is calculated in 3D so the results are expected to see the changes in acoustic impedance laterally and vertically?
Thanks much

Petrel_user wrote:
Vikesh,

The variance (the opposite of coherency) attribute is calculated in three dimensions and represent the trace-to-trace variability over a particular sample interval and therefore produces interpretable lateral changes in acoustic impedance. Similar traces produce low variance coefficients, while discontinuities have high coefficients. Because faults and channels may cause discontinuities in the neighboring lithologies and subsequently in the trace-to-trace variability they become detectable in 3D seismic volumes. Variance can thus be seen as the lateral counterpart of RMS as the later indicates vertical variations.

Deos that answer your question?


Wed Mar 07, 2012 7:11 pm

Joined: Wed Sep 01, 2010 10:06 pm
Posts: 102
Post Re: use of Variance as Seismic Attribute
Actually variance only highluights vertical variations in accoustic impedence. It compares traces next to each other at each sample position. If there's a differnece it's probably due to a fault or a channel (amongst noise of course)


Wed Mar 07, 2012 9:40 pm
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