Multi-component Steps

 

This section documents the processing steps available in the Multi-
Component category.

 

The multi-component processing steps currently available are:                                                                                   

 

 

Note on Multi-component trace header values

 

Receiver types and Receiver component trace header values

Receiver Type

Receiver component trace-header value

Hydrophone or pressure sensor

11

Vertical-component receiver

12

Crossline-component receiver

13

Inline component receiver

14

Rotated vertical-component receiver

15

Rotated transverse-component receiver

16

Rotated radial-component receiver

17

Summed vertical component receiver

28

 

Source types and Source component trace header values

Source Type

Source component trace-header value

Vertical-component source

22

Crossline-component source

23

Inline component source

24

Rotated vertical-component source

25

Rotated transverse-component source

26

Rotated radial-component source

27

 

Apply PS Non-hyperbolic Moveout

 

Usage:

The Apply PS Non-hyperbolic Moveout step uses the combination of P-wave stacking velocities and Gamma functions to correct for non-hyperbolic moveout. Converted wave travel-times are not a hyperbolic function of offset.  The total moveout of a converted wave reflection can be described accurately with the double square root (DSR) equation.  This equation gives the complete travel time correction as a function of offset, bounce point and gamma, where gamma is defined as the ratio of compressional-wave to shear-wave velocity. 

 

Input Links:

1.       Seismic data in any sort order (mandatory).

2.       PS Nhmo Gamma Function card data file containing gamma pics (optional).

3.       Velocity Function card data file containing P-wave velocity pics (optional).

 

 

Output Links:

1) Seismic data in any sort order (mandatory).

 

Reference:

Yilmaz, 2001, ‘Seismic Data Analysis’, 2nd Ed. p.1946-1959.

 

Example Flowchart:

 

 

Step Parameter Dialog:

 

 

 

Parameter Description:

 

Gamma field definition: Specify gamma field description for PS nonhyperbolic moveout.

 

Use gamma functions from data file — If checked, an auxiliary card data file with the gamma field description will be automatically linked into the process.

 

Use gamma field from seismic file — If checked, an auxiliary seismic file with the gamma field description will be automatically linked into the process.

 

Use constant gamma — If checked, a constant gamma value will be used for the moveout correction.

 

Constant gamma — Enter the constant gamma value to be used for the moveout correction.

 

Scale input gamma values by (%) — Enter a value to be used to scale the input gamma field.

 

P-wave velocity field definition: Specify P-wave velocity field description for PS nonhyperbolic moveout.

 

Use velocity functions from data file — If checked, an auxiliary card data file with the P-wave velocity field description will be automatically linked into the process.

 

Use velocity field from seismic file — If checked, an auxiliary seismic file with the P-wave velocity field description will be automatically linked into the process.

 

Use constant gamma — If checked, a constant P-wave velocity value will be used for the moveout correction.

 

Constant gamma — Enter the constant P-wave velocity value to be used for the moveout correction.

 

Scale input gamma values by (%) — Enter a value to be used to scale the input P-wave velocity field.

 

Mute control: Specify stretch mute parameters.

 

Apply stretch mute — If checked, apply a strectch mute after the moveout correction.

 

Percentage — Enter the percentage of strecht mute to be applied.

 

Taper length (samples) — Enter the taper length for the stretch mute in number of samples.

 

Interpolation Type Selection: Specify the interpolation type (linear or quadratic). The moveout function causes trace data samples to be moved in time to new locations. Since these new time locations of the data sample values are not usually exactly at the sample interval of the data, the data is interpolated to be evenly sampled at the correct sample interval.

 

Linear — If selected, uses a linear interpolation following the equation of a line (y = mx + b) to interpolate data values between or beyond existing data.

 

Quadratic — If selected, uses a quadratic interpolation following the equation of a quadratic (y = ax^2 + bx + c) to interpolate data values between or beyond existing data.

 

 

CCP Binning - Asymptotic

 

Usage: The Common-Conversion Point (CCP) Binning – Asymptotic processing step will split a converted wave (P-S) trace into pieces and place each piece into the correct 2D or 3D bin location. The Gamma value (normally about 2.0) is used to calculate the curve defining the conversion P to S wave points.

 

Input Links:

1)      Seismic file containing 3C or 4C data (mandatory)

 

Output Links:

1)      Seismic file containing 3C or 4C data with traces binned into common conversion points (mandatory).

 

Reference:

Yilmaz, 2001, ‘Seismic Data Analysis’, 2nd Ed.

 

Example Flowchart:

 

 

Step Parameter Dialog:

 

 

 

Parameter Description:

 

Line definition (for 2D): Define line parameters. These parameters are exclusive for 2D surveys.

 

Start of line easting (for 2D) — Enter the start of line easting.

 

Start of line northing (for 2D) — Enter the start of line northing.

 

End of line easting (for 2D) — Enter the end of the line easting.

 

End of line northing (for 2D) — Enter the end of the line northing.

 

Line number (for 2D) — Enter the line number.

 

Line azimuth (for 2D) — Enter the line azimuth.

 

First midpoint number (for 2D) — Enter the first midpoint number.

 

Common midpoint increment (for 2D) — Enter the common midpoint increment.

 

Common midpoint size (for 2D) — Enter the common midpoint size.

 

Grid definition (for 3D) — Define the 3D grid. These parameters are exclusive for 3D surveys.

 

Corner 1 – Easting (for 3D) — Enter the easting (x) coordinate of the first corner of your survey.

 

Corner 1 – Northing (for 3D) — Enter the northing (y) coordinate of the first corner of your survey.

 

Corner 2 – Easting (for 3D) — Enter the easting (x) coordinate of the second corner of your survey.

 

Corner 2 – Northing (for 3D) — Enter the northing (y) coordinate of the second corner of your survey.

 

Corner 3 – Easting (for 3D) — Enter the easting (x) coordinate of the third corner of your survey.

 

Corner 3 – Northing (for 3D) — Enter the northing (y) coordinate of the third corner of your survey.

 

Inline bin size (for 3D) — Enter the size in distance units of the in-line side (1 to 2) of each bin.

 

Crossline bin size (for 3D) — Enter the size in distance units of the cross-line side (1 to 3) of each bin.

 

First inline number (for 3D) — Enter the first inline number. This line number is assigned to all the bins along the side of the survey from corner 1 to corner 2.

 

Inline increment (for 3D) — Enter the increment in line numbers between adjacent CMP lines.

 

First crossline number (for 3D) — Enter the first crossline number. This location number is assigned to all the bins along the side of the survey from corner 1 to corner 3.

 

Crossline increment (for 3D) — Enter the increment in locations between adjacent CMP locations.

 

Coordinate definition: Specify whether the corner points define the bin centers or corners following the figure below.

 

 

Corner points define bin centers — If selected, specify that corner points define bin centers.

 

Corner points define bin corners — If selected, specify that corner points define bin corners.

 

Survey dimensions: Specify whether the dimensions of the survey are 2D or 3D.

 

2D — If selected, specify 2D line survey.

 

3D — If selected, specify a 3D grid survey.

 

Project updates: Specify project updates.

 

Update from project — Select to update from the project.

 

Gamma — Enter the gamma parameter value. Gamma is the ratio of Vp/Vs velocities. This parameter defines the curve of the conversion point.

 

CCP Binning - Dynamic

 

Usage:   The Common-Conversion Point (CCP) binning - Dynamic step assigns CCP numbers to mode-converted PS data as a function of the source-receiver offset and a constant or time-variable Vp/Vs ratio (gamma).

 

Input Links:

1)      Converted wave data volume in any sort order (mandatory).

2)      Nhmo gamma function card (optional).

 

Output Links:

1) Converted wave data volume in any sort order (mandatory).

 

Reference:

Yilmaz, 2001, ‘Seismic Data Analysis’, 2nd Ed.

 

Example Flowchart:

 

 

Step Parameter Dialog:

 

 

Parameter Description:

Corner 1 - Easting — Enter the easting (x) of the first corner of the bin grid (2D or 3D).

 

Corner 1 - Northing — Enter the northing (y) of the first corner of the bin grid (2D or 3D).

 

Corner 2 - Easting — Enter the easting (x) of the second corner of the bin grid (2D or 3D).

 

Corner 2 - Northing — Enter the northing (y) of the second corner of the bin grid (2D or 3D).

 

Corner 3 - Easting — Enter the easting (x) of the third corner of the bin grid (3D).

 

Corner 3 - Northing — Enter the northing (y) of the third corner of the bin grid (3D).

 

Inline bin size — Enter the size of a bin in the inline direction in meters or feet (2D or 3D).

 

Crossline bin size — Enter the size of a bin in the crossline direction in meters or feet (3D).

 

Line number — Enter the line number (2D).

 

First inline number — Enter the first inline number (3D).

 

Inline increment — Enter the inline increment (3D).

 

First CMP number — Enter the first CMP number (2D).

 

First crossline number — Enter the first crossline number (3D).

 

CMP increment — Enter the CMP increment (2D).

 

Crossline increment — Enter the crossline increment (3D).

 

Offset bin size – Enter the offset bin size (2D or 3D).

 

Corner points define bin centers — If selected, specify that corner points define bin centers.

 

Corner points define bin corners — If selected, specify that corner points define bin corners.

 

Survey dimensions: Specify whether the dimensions of the survey are 2D or 3D.

 

2D — If selected, specify 2D line survey.

 

3D — If selected, specify a 3D grid survey.

 

Constant Gamma Stacks

Usage:

The Constant Gamma Stack step generates a file of constant gamma stack traces, where gamma is defined as the Vp/Vs ratio. A P-wave stacking velocity field must be supplied, and you choose the number of gammas with which to stack your data, the first gamma to apply, and the last gamma to apply. You have the option to apply a stretch mute, if you so desire. With the series of constant gamma stack traces, you page through these stacked panels in Display and interactively pick gamma functions that result in the most coherent stacked sections.

 

Input Links:

1.       Seismic data pre-stack, in CMP sort order (mandatory).

2.       Velocity card data file containing p-wave stacking velocity functions (mandatory).

 

Output Links:

1.       Seismic data pre-stack, in CMP sort order (mandatory).

 

Example Flowchart:

 

 

 

Step Parameter Dialog:

 

 

 

Parameter Description:

Gamma range: Specify the range of gammas to use in the analysis. A stacked section is calculated for each gamma linearly interpolated between the starting and ending input gamma.  The gamma increment will be: Ginc = (last gamma – first gamma)/(Number of gammas-1).

 

First gamma — Enter the starting gamma for the analysis. This gamma will be used for non-hyperbolic NMO on the first output stack. {>0.0}

 

Last gamma — Enter the ending gamma for the analysis. This gamma will be used for non-hyperbolic NMO on the last output stack. {>0.0}

 

Gamma increment — Enter the number of velocities to use in the analysis.  A stacked section is calculated for each velocity linearly interpolated between the starting and ending input velocities.  The velocity increment will be: inc = (last velocity - first velocity)/(Number of velocities-1).

 

P-wave velocity field definition: Define the P-wave velocity field.

 

Use velocity functions from data file — If checked, velocity functions will be applied from a data file.

 

Use velocity field from seismic file — If checked, a velocity field will be applied from a seismic file.

 

Use constant velocity — If checked, a constant velocity will be applied to the data.

 

Constant velocity — Enter the NMO velocity. This constant velocity will be used if a set of velocity function cards is NOT linked to the NMO correction step.

 

Scale input velocities by (%) — Enter the amount by which the input velocities are scaled up or down. A value of 1.0 does not alter the velocity field.

 

Line range: Specify the line range.

 

First line to analyze — Enter the first CMP line number to analyze.

 

Last line to analyze — Enter the last CMP line number to analyze.

 

Line increment — Enter the CMP line increment between lines to analyze.

 

Location range: Specify the location range.

 

First location to analyze — Enter the first CMP location to analyze.

 

Last location to analyze — Enter the last CMP location to analyze.

 

Location increment — Enter the CMP location increment between groups of CMP locations to analyze.

 

Locations per analysis — Enter the number of CMP locations in each analysis panel.  At each CMP location a range of constant velocity stacks will be generated from the first velocity to the last velocity in increments of Vinc.

 

Mute Control: Specify the parameters for the stretch mute definition.

 

Apply mute from data file — If checked, a mute will be applied to the NHMO corrected data from a data file.

 

Apply stretch mute — If checked, a stretch mute will be applied to the NHMO corrected data.  Stretch muting restricts the stretching of the data due to the NMO correction. If not checked, the stretch mute must be supplied by an Early Mute card linked to the Constant Gamma Stack step.

 

Percentage — Enter the percent stretch mute. The smaller the percent the more severe the mute function.

 

Taper length (samples) — Enter the mute taper length in samples. Longer taper lengths result in a smoother transition from the mute zone to the data zone.

 

Interpolation Type Selection: Specify the interpolation type (linear or quadratic). The moveout function causes trace data samples to be moved in time to new locations. Since these new time locations of the data sample values are not exactly at the sample interval of the data, the data is interpolated to the correct sample interval.

 

Linear — Linear interpolation uses the equation of a line (y = mx + b) to interpolate data samples between or beyond existing data.

 

Quadratic — Quadratic interpolation uses the equation of a quadratic (y = ax^2 + bx + c) to interpolate data samples between or beyond existing data.

 

Trace Amplitude Definition: Specify the trace amplitude definition.

 

Use relative amplitude traces — Relative amplitude traces will be summed in the stacking process.  Relative amplitude traces are scaled independently of one another.

 

Use true amplitude traces — Selects the use of true amplitude scaled traces in the analysis.  True amplitude traces are scaled by one common factor per record.

 

Converted Wave Receiver Statics

 

Usage:

The Converted Wave Receiver Statics step uses a cross correlation and least squares fitting to calculate receiver statics for converted wave traces (P=S).

 

Input Links:

 

1)      Seismic file containing converted wave data traces sorted in receiver order (mandatory).

 

Output Links:

1)      Seismic file containing converted wave data traces sorted in receiver order (mandatory).

2)      Receiver statics file containing the calculated receiver statics (mandatory).

 

Reference:

 

Example Flowchart:

 

 

Step Parameter Dialog:

 

 

Parameter Description:

 

Window start time (ms) — Enter the start time for the analysis.

 

Window end time (ms) — Enter the end time for the analysis.

 

Number of traces in analysis window — Enter the minimum number of traces considered for the converted waver receiver statics.

 

Inversion stability factor — Enter a small value used to stabilize the matrix inversion and prevent inverting zeros which causes instatility

 

Maximum allowable static — Enter the maximum amount of static correction.

 

Crooked Line Asymptotic CCP Binning

Usage:

The Crooked Line Asymptotic Common-Conversion Point (CCP) Binning step will split a converted wave (P-S) trace into pieces and place each piece into the correct crooked line bin location. The Gamma value (normally about 2.0) is used to calculate the curve defining the conversion P to S wave points.

 

Input Links:

1)      Seismic file containing 3C or 4C data (mandatory)

2)      Line Definition File containing the crooked line fit information (mandatory)

 

Output Links:

1)      Seismic file containing 3C or 4C data with traces binned into common conversion points (mandatory)

 

Reference:

-

 

Example Flowchart:

 

 

Step Parameter Dialog:

 

 

Parameter Description:

 

Number of first midpoint — Enter the first midpoint to be considered for the Asymptotic CCP binning.

Inline bin dimension — Enter the bin dimension in the inline direction.

Line width — Enter the line width to be considered for the asymptotic CCP.

Gamma — Enter a value for gamma parameter as defined by Vp/Vs ratio.

Source and receiver binning: Define bin for sources and/or receiver locations.

Bin source locations — If checked, bin source locations.

Bin receiver locations — If checked, bin receiver locations.

Bin coordinates: Define bin coordinates. Bin coordinates can be either defined as line of midpoins.

Line coordinates — If selected, bin coordinates are line coordinates.

Midpoint coordinates — If selected, bin coordinates are midpoint coordinates.

 

Crooked Line Dynamic CCP Binning

 

Usage: The Crooked Common-Conversion Point (CCP) binning - Dynamic step assigns CCP numbers to mode-converted PS data as a function of the source-receiver offset and a constant or time-variable Vp/Vs ratio (gamma) for 2D crooked lines.

 

Input Links:

1)    Converted wave data volume in any sort order (mandatory).

2)    Line definition file (mandatory).

3)    Auxiliary gamma card data file (optional).

4)    Auxiliary P-wave velocity card data file (optional).

 

Output Links:

1)      Seismic file (mandatory).

 

Reference:

-

 

Example Flowchart:

 

Step Parameter Dialog:

 

 

Parameter Description:

Number of first midpoint — Enter the number of the first midpoint to be binned.

Inline bin dimension — Enter the bin dimension in the inline direction.

Line width — Enter the line width for the binning.

Offset bin size — Enter the ofsset bin size.

Gamma: Define parameters related with the gamma parameter. Gamma is defined as the Vp/Vs ratio.

Use gamma field from data file — If checked, use gamma field from an auxiliary data file.

Use constant gamma — If checked, use a constant gamma value.

Constant gamma — Enter contant gamma value.             

Compressional-wave velocity: Define parameters related with the P-wave velocity.

Use velocity field from data file — If cheked, use a velocity P-wave file.

Use constant velocity — If cheked, use a constant P-wave velocity for the entire survey.

Constant velocity — Enter the value for the constant P-wave velocity.

Source and receiver binning: Define bin for sources and/or receiver locations.

Bin source locations — If checked, bin source locations.

Bin receiver locations — If checked, bin receiver locations.

Bin coordinates: Define bin coordinates. Bin coordinates can be either defined as line of midpoins.

Line coordinates — If selected, bin coordinates are line coordinates.

Midpoint coordinates — If selected, bin coordinates are midpoint coordinates.

 

Horizontal Component Rotations

 

Usage:

The Horizontal Component Rotations step rotates the horizontal components of a multi-component data volume through rotation angles determined by the Two Component Horizontal Rotation step.  The rotation angles are read from a Rotation Card file.  In the case of 2D data acquisition with field oriented 3C receivers, an option exists to limit the rotation angle to a user-specified range.

 

Input Links:

1)      Seismic data in common receiver order (mandatory).  The trace header must be updated with source-receiver azimuth and source- and receiver-component types.  The common-receiver gathers should be sorted by (1) receiver number; (2) source-receiver offset; (3) receiver component.

2)      Rotation Card file containing the estimated rotation angles (optional).

 

Output Links:

1)      Seismic data in common receiver order (mandatory). 

 

Example Flowchart:

 

Step Parameter Dialog:

 

 

Parameter Description:

 

Input type: Define the type of multicomponent data.

 

Three components — If selected, the input multi-component seismic data is three components.

 

Two horizontal components — If selected, the input multi-componend seismic data is considered two horizontal components.

 

 

Orientation type: Define the type or orientation.

 

Fixed orientation — If selected, entire data has a fixed orientation.

 

Orientation defined in header— If selected, the orientation of the data varies and must be defined in the header.

 

Orientation angles: Define the orientation angles.

 

Orientation of inline component (deg.) — If fixed orientation, enter the orientation (azimuth) of the inline component in degrees.

 

Orientation of crossline component (deg.) — If fixed orientation, enter the orientation (azimuth) of the crossline component in degress.

 

Orientation trace header — If orientation defined in header, select the location of the header key word with the orientation (azimuth) value.

 

Orientation units — If orientation defined in header, select the units for orientation (azimuth) (degrees or radians)

 

Component labels: Define the components labels.

 

Vertical component value — Enter the label value corresponding to the vertical component.

 

Inline component value — Enter the label value corresponding to the inline component.