Calculating Surface Consistent Deconvolution

Theory

What is Surface Consistent? A Single Operator calculated for all traces that have the same surface point location in common. Why do we perform surface consistent? During the seismic acquisition survey design phase we design the survey parameters for a normal situation however when we acquire the data in different terrains the conditions will be quite different. Due to sub-surface nature, the data is recorded with many distortions due to various reasons like the survey design, acquisition instruments or the sub-surface change in properties.

Surface consistent deconvolution assumes that a seismic trace consists of the convolution of a number of components which go together to produce the seismic trace. For example, each shot, each receiver position, each CDP and each trace offset (or channel number) contributes its own spectral modification to the seismic trace.

Surface consistent deconvolution attempts to reverse this process by extracting the original log spectra (for each shot, each receiver) from all of the original input data. This is done by averaging the log spectra for each shot, each receiver, each CDP and each offset (Channel) and then using a Gauss-Seidel iterative technique to isolate the individual components. Using the Gauss-Seidel method, it computes the deconvolution filters for each frequency band to improve the resolution of the seismic wavelet.

Input data

Input DataItem

Input SEG-Y data handle

connect/reference to the input data that went through all the denoise procedures and statics.

Input trace headers

connect/reference to the output trace headers of the input seismic gather.

4D mute picking

Mute is useful if there is any data above the first arrivals. It is necessary to remove any noise the first breaks. Provide the input mute picks file if necessary.

Use trace vector on disk

This option is used when the input data size is big. By default, FALSE. If checked, the user should provide the Input traces data handle.

Input traces data handle

connect/reference to the Output traces data handle of the Open seismic traces module. This option isn't available for "Read seismic traces" or "Read SEG-Y traces" modules.

Fast solving & Gauss-Seidel TVOD size parameters are only applicable when we the user uses the option "Use trace vector on disk".

Parameters

Read Traces per chunk - Number of traces to read in for the calculation

Desired amplitude level

Set the desired amplitude level. By default, 1.

Domain for calculation { CS CR, CS CR Offset, CS CR Offset Bin }

Surface Consistent Deconvolution (SCDCN) will be performed in 3 different domains. There are many reasons to perform/calculate the SCDCN in different domains.

Common Source domain takes care of the distortions created by the source wavelet or seismic source like dynamite/vibroseis/air gun.

Common Receiver domain will look into the distortions recorded at the receives due to receiver sensitivity and noise levels recorded.

Common Offset domain handles all the amplitude variations caused by the offsets.

Common Bin takes care of any distortions spatially.

Mute taper

It is used to avoid any sharp boundaries. This option is required when the user used the input mute file.

Advance for Solver

This section deals with the solver parameters. For solving, we use Gauss-Seidel method to resolve all the distortions of the seismic wavelet and improves the spatial and temporal resolution of the seismic wavelet in an iterative method. We do the iteration until the parameters are stabilized (convergence). This is controlled by the threshold value where the difference between the successive iteration processes should be smaller and smaller as we proceed further.

Threshold Factor

specify the threshold value that should be considered for stopping the iteration process where the successive iteration values reaches the user defined threshold factor/value.

Solver iterations

specify total number of iterations to be performed for calculation.

Maximum offset

specify the maximum offset to be considered.

Minimum offset

specify the minimum offset to be considered.

Offset step

specify the offset step size

Use azimuth domain

In case the seismic distortions are caused due to azimuths (distortions due to the directional variations). By default, FALSE. If checked, the user has to be provide the number of azimuths to be considered in the calculation.

Number of azimuths

specify the number of azimuths considered for the calculation.

Restore

This sections deals with the restoration of the seismic reflection energy by performing the deconvolution in time or frequency domain.

Deconvolution Domain { Time (Predictive), Frequency }

choose the preferred domain from the drop down menu to perform the deconvolution. By default, Time (Predictive).

DeconvolDomain - Frequency

In case the deconvolution domain is frequency, the deconvolution calculation happens in the frequency domain where the data is transformed from time domain to frequency domain by using Fourier transform. In that case, the user needs to provide the phase domain parameters.

Phase Domain { Minimum Phase, Zero Phase }

Naturally, Deconvolution expects the data in minimum phase where it is easier to distinguish between the signal and noise (seismic energy is concentrated at the very beginning) unlike the zero phase wavelet where the energy is distributed symmetrically with a slight delay of time.

DeconvolDomain - Time (Predictive)

Deconvolution will be performed in time domain.

Predictive interval

specify the predictive interval value

Noise

specify the percentage white noise added to the deconvolution process to stabilizes the result.

Auto correlation length

specify the auto-correlation length. This helps in better parametrization of the deconvolution.

Smoothing Filter

smoothing filter value is used to smoothing of the spectra.

Fast solving

By default, TRUE (Checked). This will helps in solving the Gauss-Seidel method much faster. This parameter is applicable only when the user reads the data from "Open seismic traces" ONLY.

Minimum frequency to restore

specify the minimum frequency to be restored. By default, -1 which means all frequencies.

Maximum frequency to restore

specify the maximum frequency to be restored. By default, -1 which means all frequencies.

Gauss-seidel TVOD bulk size

Default value is good to start with. This is valid when the Fast solving option is checked.

Settings

Auto-connection

By default, TRUE(Checked).It will automatically connects to the next module. To avoid auto-connect, the user should uncheck this option.

Execute on { CPU, GPU }

select which type of processor will be used for calculations: CPU or GPU.

Distributed execution

if enabled: calculation is on coalition server (distribution mode/parallel calculations).

Bulk size

chunk size is RAM in megabytes that is required for each machine on the server (find this information in the Information, also need to click on action menu button for getting this statistics):

Limit number of threads on nodes

limit numbers of of threads on nodes for performing calculations.

Job suffix

add a job suffix.

Set custom affinity

SetCustomAffinity - true

an axillary option to set user defined affinity if necessary.

Affinity

add your affinity to recognize you workflow in the server QC interface.

Number of threads

limit number of threads on main machine.

Run scripts

it is possible to use user's scripts for execution any additional commands before and after workflow execution:

Script before run

path to ssh file and its name that will be executed before workflow calculation. For example, it can be a script that switch on and switch off remote server nodes (on Cloud).

Script after run

path to ssh file and its name that will be executed before workflow calculation.

Skip

By default, FALSE(Unchecked). This option helps to bypass the module from the workflow.

Output data

Output DataItem

Generates the Output data item with all the trace headers information.

Average amplitude level

Outputs the average amplitude level

Output gather CS

Output common shot gather after SC Deconvolution

Output gather CR

Output common receiver gather after SC Deconvolution

Input gather CS

Input common shot gather before SC Deconvolution

Input gather CR

Input common receiver gather before SC Deconvolution

FrequencyResponseSpectrumItem

Outputs the frequency response spectrum as an item.

Information

Number of sources

total number of sources

Number of receivers

total number of receivers

Number of bins

total number of bins

Number of frequencies

total number of frequency bands

Frequencies step

frequency step size

Examples

In this example workflow, we are reading an input data set which had undergone denoise and statics procedures.

Connect/reference the Input Dataitem to Output Dataitem of "Read seismic traces"

Execute the workflow and generate the vista items. We'll see the common shot and common receiver gathers before and after application of the SC deconvolution, convergence of solver for each frequency band, source and receiver amplitude map for each frequency band.

Actions

Load from file

This action item allows the user to load the previously saved SC deconvolution calculation file ".scdecon".

Save to file

This action item allows the user to save the calculated surface consistent deconvolution values into a file. Click on this option and new pop-up window opens. Provide the file name and click Save. It will save the file with an extension of ".scdecon".

Video lesson

YouTube video lesson, click here to open [VIDEO IN PROCESS...]

Related articles

Yilmaz. O., 1987, Seismic data processing: Society of Exploration Geophysicist

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