2.1.1 Fault Likelihood (FL)

Fault Likelihood is the unthinned version of our Thinned Fault Likelihood volume, which is used as an input to the Fault Extractor and Thinned Fault Likelihood.

Workflow

To process the Fault Likelihood volume, click on this icon and select Fault Likelihood under Attributes.

Parameters

Input Volume: Normally the standard poststack seismic volume is a good default input for computing TFL. In case the seismic is extremely noisy, we suggest to first filter the raw seismic using our structurally oriented median filter, and then use the filtered seismic as input for TFL. Furthermore, if you have a color inverted seismic or spectraly blued seismic volume, then using that as input is recommended over the standard seismic volume.

Volume subselection: this is useful if you the user want to speed the process, a subselection area can be set.

Advanced settings

Filter Size (inl/crl/sample): Smaller step-outs used in FL dip computation, e.g. 1-1-16 or 2-2-32, capture small scale features. However, bigger FL dip computation step-outs e.g. 4-4-100, significantly improve the characterization of the bigger fault lineaments by improving their connectivity.

Fault likelihood scan setting: The algorithm will scan for the fault dips and strikes within a given range of the dips to maximize the fault likelihood. The input parameters here depend on how flat/steep the seismic data is. If you are dealing with a layer cake data set, small angle range would be reasonable. Nr Steps is how many scans should be done. Initially the full strike (0 - 360 degrees) and a large dip range (25 - 65 degrees) should be tested. Afterwards, better (more realistic) results can be achieved by constraining the strike/dip range. As a rule of thumb, it is always recommended to use wider dips and strikes to extract more information from the data.

Velocity (m/s) Velocity needs to be used in time surveys to convert angles. Use an average value for your data set, it will not affect the results much.

Apply thinning: The user should select yes in order to output the Thinned Fault Likelihood.