Pre-Stack ProGetting started guide
Version 4.4
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• New Features- Synthetic modelling
- 1D Model Builder
- Processing algorithms Dip Filter
Tau-P Deconvolution
Velocity Converter
- New Attributes
- Cultural Data and Coordinate Reference System
- Multi-azimuth data support
- Utilities
• Improvements of existing features- Well Log Viewer
- Wavelet Tool
- Data Comparator
- 2D SEG-Y loading
Contents
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SYNTHETIC MODELLING
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1D synthetic modelling
Interpretation-Processing > Generate synthetic gather ...
Define logs and wavelet
for synthetic
Define geometry for output.
Can be copied from an
existing dataset in the
volume pool.
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1D synthetic modelling
Modelling options
Zoeppritz, Aki-Richards, etc
Can make synthetic with no NMO
correction for offset synthetics (but not
for angle synthetics)
If a T-D table exists in the well it can
be used. In that case the Fit Accuracy
parameter controls how closely the T-
D table is honoured.
If there is no T-D table or it is not
desired to use it, a single time-depth
pair can be entered manually and the
T-D curve is obtained from that point
and the integrated sonic log.
A simple overburden model can be typed in to define
what happens above the start of the logs. This is
important when creating offset synthetics, as it
affects the angle-to-offset relationship considerably.
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1D synthetic modelling
Log preconditioning
Logs can be de-spiked and
blocked if desired.
Spikes are identified by looking for
deviation from a moving window
average (the min amplitude) and a
maximum width (in depth). They are
replaced by interpolated values.
Blocking is based on identifying jumps
in the logs by comparing moving
window statistics. A block boundary is
defined if a jump exceeds a fraction of
the local value.
The maximum block thickness is also
specified to ensure that detail is not
lost in the blocking process.
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1D MODEL BUILDER
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Introduction
• New feature in version 4.4: 1D Model Builder
• Creates 3 synthetic logs at any well, Vp, Vs and density
( logs called .SynthModel_Vp, _Vs and _Rho )
• These logs are made from at least 3 user defined layers.
( Top, Target and Bottom layers + any added inbetween)
• The Target layer has a fixed top MD, from which the model is built
• All the layers have a thickness to define their top / base from this
• Layer properties can be defined as follows -
• : Vp, Vs, Rho by manual entry of values,
• : Vs, Rho by Castagna and Gardner equations
• : Vp, Vs, Rho by well facies or zone, averages
• : Vp, Vs, Rho by «Reservoir» Castagna fluid substitution
• : Vp, Vs, Rho by «Reservoir» Gassmann fluid substitution
• A Synthetic gather is created using ‘Start Synthetic Gather Algo..’
• Any model input log update, forces a redraw of this synthetic
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• Interpretation Processing 1D Model Builder
Introduction
• New feature in version 4.4:
• Creates 3 synthetic logs at any well - Density, Vp and Vs
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Model setup
Select Well for log use/save
Enter Target layer top depth ( MD )
( 2000 = model reference datum )
Choose which layers will be ‘reservoir’ and have fluid
substitution options
Enter layer thickness in m
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• Vs, Density coefficient selection
Layer properties definition
Shale coeffs
Sandstone coeffs
Select Preset lithology or enter
values into coefficient boxes
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Layer properties definition
Shale zone Vp, Vs Rho averages
• Vp, Vs, Density facies/zone averages 1
Zones created in Well Log Viewer, can be used to
calculate an average Vp, Vs, Rho - in this case for
Shale
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• Vp, Vs, Density facies/zone averages 2
Layer properties definition
Shale zone Vp, Vs Rho averages
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• Vp, Vs, Rho, from fluid substitution – reservoir layers only
Layer properties definition
Castagna equation – consolidated sands
Gassmann equation – soft sands
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• Example from Fred Hilterman’s 2001 SEG DISC book :
Seismic amplitude interpretation - 9000ft GOM AVO
Final 5 layer model
Brine filled Sand
Gas filled Sand
Calculated by Gassmann fluid sub, = 25%
Shale Vp = 2600 m/s, Sst (Brine) Vp = 3000 m/s, Vs & Rho from equations
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• Angle gather - with bpass wavelet 5-15-45-55
Calculate synthetic gather
Click on «Start Synthetic Gather algo» takes the model logs and
creates a gather synthetic.
The wavelet applied comes from the project wavelet list.
Use the «Tie log depth» modelling option to ensure the synthetic Target layer top is at the right
TWT.
( MD = TVDss = 2000m = 2.0secs )
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View results in Data Comparator
Data Comparator allows wiggle trace display
Also amplitude extractions can be made for the brine and gas
cases and visually compared in the plots above the gathers.
( blue = brine, red = gas )
The first gather is with a 50m gas reservoir thickness
The 2nd with only 10m
The thinning of the layer has dimmed the AVO response but
it stays opposite in polarity
Brine Sand
Gas Sand
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PROCESSING
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Dip Filter
• Processing Dip Filter
• Attenuate given dips on pre-stack volume in the offset class domain or post-stack
Section size and overlap. Recommends large section and overlap
of 50% in all axis
Definition of dip to remove
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Tau-P deconvolution
• Processing Tau-P deconvolution
• Predictive gaped deconvolution in Tau-P domain. Targets short period multiples. Input is non NMO corrected gathers
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Tau-P deconvolution
Definition of both design and application windows
Graphical gap design. Shift + Mouse left button
to move the line.
Tau-P transform parameters and operator length parameters.
NB: Operator length correspond to the active part of the operator.
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• Processing Velocity converter
• Input a velocity volume and convert to Interval/RMS on the fly.
Velocity converter
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NEW ATTRIBUTES
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Dip-Steered Semblance
Stack with dipping events and its inline slope attribute
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• Go to Attributes -> Dip-steered semblance
• The algorithm takes as input a seismic volume and its inline and crossline slopes computed per offset classes.
• Semblance is a measure of the coherence of seismic data and is equal to the energy of a stacked trace divided by the energy of all the traces that make up the stack. The stencil within which the semblance is computed will use the inline and crossline slopes to follow dipping events, resulting in a better estimation of the signal coherency for structures with large dips than with conventional vertical moving windows.
Dip-Steered Semblance
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• Slopes can be calculated with Attributes -> Structural Dip
• For time domain data the slopes will be measured in slowness along the inline and crossline direction
• This attributes are derived from the second-moment matrix of the seismic that involves the computation of the gradient in a stencil
Dip-Steered Semblance
Dipping event
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• The user has to specify 2 parameters for slope calculation
• Noise scale: defines the resolution of the filter.
• Integration scale: gives a trade of between edge-enhancing diffusion and coherency enhancing diffusion behavior
Dip-Steered Semblance
Positive slope
associated to the
dipping event
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Signal to Noise Ratio
Signal to Noise Ratio extracted at top reservoir
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• Go to Attributes -> Signal to Noise Ratio
• S2N is defined as the ratio between the signal power to the noise power. Two methods have been implemented to estimate this measure. A correlation method based on the assumption that the form and phase of the signal is consistent across neighbor traces and that the noise is spatially incoherent and uncorrelated to the signal. The stack method makes the assumption that the seismic wavelet is stable in a given spatial window and that the noise is white.
Signal to Noise Ratio
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Signal to Noise Ratio
• Correlation method
• The user specifies the size of the stencil (in space and time) and the maximum time shift which corresponds to the half-length of the correlation window
• Xc = average correlation coefficient between central and neighbors traces
• Ac = auto-correlation coefficient of the central trace
• S2N = Xc/(Ac-Xc)
Region with high signal
to noise ratio
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Signal to Noise Ratio
• Stack method
• The user specifies the size of the stencil (in space and time)
• Since the noise is assumed to be white its spatial average value inside the stencil is zero
• Therefore the energy of the signal is the spatial some of the square of the stacked trace and the energy of the noise is the total energy minus the energy of the signal
Region with low signal to
noise ratio
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• Go to Attributes -> Geometric Properties
• Input has to be an horizon or a stack volume (in this case the computation will be done for every time slices)
• Curvature attributes are calculated by locally fitting (in a least-square sense) a second order 2D polynomial to the input horizon
• Outputs will be the maximum and minimum curvature as well as the maximum dip angle and azimuth
Geometric Properties
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Geometric Properties
Maximum dip angle computed on a synthetic checkerboard
Horizontal dip (0 degree) at the top of the anticline
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Examples
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Examples
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Example
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Examples
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COORDINATE REFERENCE SYSTEMS (CRS) AND CULTURAL DATA
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• Project CRS is defined in Project->Edit Project Geometry in the tab Project CRS
Project Coordinate Reference System (CRS)
Green: Currently chosen Project CRS
Blue: Cursor marked CRS
Complete definition of Project CRS –
in Well-Known Text (WKT) format
Name of CRS
Number in the IOGP’s EPSG Geodetic Parameter
Dataset. IOGP : International Association of Oil &
Gas Producers. EPSG : European Petroleum
Survey Group. www.epsg.org
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• Open Project CRS tab in Project->Edit Project Geometry
• Choose a new CRS from the predefined list
• Double click on the new CRS (turns green), and Save
Choosing a new CRS
Filter used to reduce the number of
possible CRS’s. Only CRS’s that fit
the filter will be visible. Use wildcard *
between text strings.
After double clicking on a given CRS,
it will be chosen as the Project CRS. Notice that whenever the user marks a CRS by
clicking on it, it will turn blue. When choosing a new
CRS by double clicking on it, the new CRS will look
blue. If the user moves the cursor to another CRS and
marks it by clicking once – this CRS will turn blue,
while the chosen Project CRS will be visible as green.
The CRS Definition will be updated
when choosing a new Project CRS.Save the new Project CRS
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• Project Import Import Cultural Data...
• Input a file or directory with cultural data in shapefile format.
Cultural data - import
Shapefile format
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Cultural data – in File Manager
Imported cultural data visible in File Manager
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Cultural data – in Map Viewer
Turn visualization on/off, and change color.
Example from the Norwegian
Continental Shelf: Block data
and discoveries.
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• The shapefile contains information about the UTM zone for the imported cultural data.
• PSPRO will convert or transform the imported cultural data to the project defined coordinate reference system.
• There is no coordinate conversion or transformation for project data (seismic, horizons, well locations etc.).
• It is still the user’s responsibility to import project data in a consistent way, i e. that the coordinates for all project data are imported with the same UTM zone.
Cultural data and coordinate reference system
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UTILITIES
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Unit conversion
• Utilities Unit converter
In any viewer, click on the read out value to change
the units.
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• Utilities Trace header interpolation
• Workflow for interpolating a stack and using the header for SEG-Y output
- Interpolate the stack volume
- Interpolate the original headers to the same geometry
- In SEG-Y output, used the interpolated header to copy the X/Y locations
Trace header interpolation
Same grid as the volume you want to output Tick off to create a new header
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SUPPORT OF MULTI AZIMUTH DATA
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Import of Irregular files
• Pre-Stack Pro currently do not handle the import of 5D irregular SEGY files.
• For this you will need the tool Seismic Data Certification developed by Fraunhofer ITWM.
• Please contact directly Dr. Norman Ettrich to request the binary and user manual: [email protected]
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2D Viewers
COV gathers displayed in the prestack viewer
Switch between the first fold axis and the second fold axis
Browse through first/second fold classes
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2D Viewers
• Supported input data are:
-COV (common offset vectors)
-COCA (common offset common azimuth)
-CICA (common incidence angle common azimuth)
COCA/CICA gather = polar binning - COV gather= Cartesian binning
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2D Viewers
Look at your COCA/CICA gather along the offset/angle direction for constant azimuth
sectors
Look at your COCA/CICA gather along azimuth direction for constant offset/angle slices
Look at your COV gather along the Offset X direction
Look at your COV gather along the Offset Y direction
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Algorithms
• Most algorithms have been extended to handle 5D data.
• However, the following ones can’t currently have multi-azimuth gathers as input:
-EPS 3D - Structural Dip
-Q Models & Filters - Multi Well Scalar
-Tau-p decon - AVO Scaling
-Semblance Optimization - RMO
-Continuous Velocity Analysis – Offset Interpolation
-Dip Filter
-PCube
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Algorithms
• In addition, some algorithms will only allow COCA or CICA gathers (mostly for Geophysical reasons):
-Offset to Angle (and reciprocal)
-Radon
-2D ECED
- AVA attributes
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Algorithms
Linear Radon muting on COCA gathers
Change the preview for different
second fold (azimuth/Offset Y)
values
Create a 5D mute (one mute per
azimuth sector) by right clicking
on a control point
Gather displayed along
the first fold
(offset/angle/offset X)
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5D Horizon Tracking
Parameters for 5D extension are
the same as for the classic 4D
extension.
5D gathers
3D horizon
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5D Horizon Tracking
Extend your horizons to prestack both in the offset and azimuth
direction
Horizon extend along the offset direction
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5D Horizon Tracking
Extend your horizons to prestack both in the offset and azimuth
direction
Horizon extend along the azimuth direction
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COCA Sectorization
Rebin your data from COV (Cartesian) to COCA (polar)
Stack together all the traces falling in
the same bin or select the trace that is
the closest to its center
Select the desired number
of azimuth sectors
Choose an appropriate number of
Offsets
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WELL LOG VIEWER
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Well Log Editor Custom edits
1. Create a temporary copy for editing
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Well Log Editor Custom edits
2. Combine logs and choose
Custom merge
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Well Log Editor Custom edits
3. Choose 2nd log and use Custom
Equation to create a new log.
In this example we are creating a Vp/Vs ratio
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Manage Wells T/D Tables
Several T/D tables can be associated to one well
One must be active and applied to the wellpath for the stretch
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Well Log Set
1. Manage Log Set
2. Create a set and move logs to it.
Log set can then be manipulated as a group
of objects.
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WAVELET TOOL
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New Features
• Setting the default sample interval
• Reorganised menus
• Automatic zero-phasing on load
• Creating spectra from well logs
• Coloured inversion workflow
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Set the default sample interval
• This value is used as the default sample interval for any new wavelets
created in the wavelet tool.
• Wavelets loaded from the project keep their original sample interval.
• If it is changed during a session, any wavelets already in the tool are
not resampled, they keep their original sample interval. Any wavelets
created after the change will have the new default sample interval.
• This is just the default value for the sample interval. The individual
GUIs for adding wavelets still allow you to change the sample interval
for individual wavelets.
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Reorganised function menus
• The tabs have been
replaced by a drop-
down menu list.
• There is an item for
coloured inversion
to clarify the
workflow.
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Zero-phasing on load from project
• Since the first step in many workflows is to zero-phase
the extracted spectra, an option has been added to
“Load from project” to perform this automatically.
• It is On by default, so don’t forget to switch it off if you
need the phase information too.
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Creating spectra from well logs
Choose a t-d table
from drop-down list
Start and end depths (in MD) for the spectral
analysis can be typed in or defined by tops.
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Coloured inversion
• The key steps in the
coloured inversion
workflow are collected in
the CI Function group to
clarify the workflow.
• The tools have been
modified to include
spectral smoothing,
tapering, and filtering
where necessary instead
of having to use
separate functions.
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DATA COMPARATOR NEW FEATURES
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Attributes computation
1. Select input volume
2. Select attribute
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Amplitude extraction
1. Right click and select
«Extract amplitude on all panels»
2. Parameters window opens
3. The amplitude extraction is done
on all visible panels
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Use of points set
Points Set are Seed points put a different locations.
It allows you to cycle through all locations on all panels.
1. Activate it by clicking on the flag icon
2. Choose the SeedPoints set and go trough each
location.
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New icons and other features
• 1. Set the width of all panels
• 2. Toggle on/off the read out extraction for all panels
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• A horizon that has been snapped on one panel can be used for Amplitude Extraction on another panel, when dragging the horizon on the panel there is now a small pop-up that asks whether the horizon should just be displayed on the panel or used for an extraction.
• The Datapanels can now be reordered using Drag & Drop in the tree and resized manually via the context menu or all at once via a toolbar button.
• The y− axes of the amplitude plots are now synchronized by default if the Data panel display data from the same domain. This can be disabled in the Control Tab.
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2D SEG-Y LINES
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2D SEG-Y lines import
Necessary keys are:
- Line number
- CDP number
- World X and Y coordinates
- Fold
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2D SEG-Y lines import
A path representing the line position will be created
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• It is possible to import several lines as a batch
• The lines position can be displayed on a map using the corresponding arbitrary paths
2D SEG-Y lines import