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|Author||Topic: statics||3448 Views|
12 December 2018 at 3:28am
We're currently testing out Globe claritas for our activities. For the first breaks picking, we're wondering if there is a method similar with the Neural Network of Promax or the autopicking in GeoTrust? This means we could pick, say 10 shot gathers for example, and then propagates the picking to all the gathers based on this? We thought this could have been done via the correlation with a library of existing picks but we haven't managed to apply it. Once we've defined it, we pick a few manual first breaks (they appear in red and we see them in the areal dynamic display) but then when we launch the autopicking from library all the first breaks end at 0ms. Could you clarify if it is the right way to do the "seeded" auto-correlation and if yes, how to do so?
12 December 2018 at 2:52pm
The option to autopick first breaks from a library shouldn't actually be available in SV.
The SV application was designed to replace the older sqc viewing application. sqc included a 'Library' button and allowed the secondary or main pick method to be set to correlation with a library of existing picks. This method worked fairly well for a few shots, but the library would soon become out-of-date. As such this method was not moved across to the SV application when it was created as a replacement for sqc. If you wish to have a play with the option of auotpicking first breaks from a library and see how that goes for you, you can still access the sqc application by typing the command 'sqc' into a terminal window. The sqc application only views seg-y files so hdf5 input can't be viewed with this older application.
In SV a variety of automatic picking algorithms are available and these algorithms are grouped into three tiers: primary, secondary and tertiary. The primary picking algorithms are used for the initial, approximate position of the pick, and essentially provide a seed for the main picking algorithms. The secondary picking algorithms provide the main pick, and the tertiary algorithms allow this main pick to be further refined by snapping to a peak, trough, zero crossing, or inflection. Any of the categories may be bypassed by selecting (none) as the method for that category. The resulting picks may be passed through a simple quality check that ensures that the ratio of RMS amplitudes above and below the pick is less than a specified amount. The 'Overwrite existing picks?' parameter on the autopicking parameter form specifies what to do when you run the autopicker on traces that have already been picked: You can answer No (in which case already picked traces are never re-picked), Yes (in which case they are always re-picked), or 'Automatic', in which case automatic picks can be overwritten, but manual picks cannot. The default is 'Automatic'. When you have the automatic picking parameters set so that they’re giving you the best result, you can set SV to autopick all the shots in the input datafile, by choosing the 'Autopick ALL shots' option from the 'Utils' item in the SV toolbar menu.
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