This section describes how to select the input seismic trace data for use in the Spectral Blueing operator design. Spectral Blueing requires that you select a predetermined number of seismic traces from the full 3D survey area or sub-area, determined by the user. Trace is random within the area. Our aim is to select a set of traces which is representative of the 3D Survey Area for which we are trying to derive a SsbQt operator. With the data selected it will normally be necessary to constrain it in some manner. The sub-section below describes how you can select and constrain the trace data.
This section provides a button which will allow you to pop-up a seismic selector dialog. This section also allows you to specify the 3D Survey Area to be used to retrieve trace data for Spectral Blueing analysis.
| Select Input Data dialog (Input Seismic tab) | Description |
|---|---|
 | The picture to the left shows the top portion of the Input Seismic tab, where seismic data volume have been selected. This is the standard way of selecting seismic data volume when using the software with Landmark's SeisWorks or Schlumberger's GeoFrame data repositories. |
The type of select dialog that is displayed will depend on the data repository that the Spectral Blueing application is connecting to. The Selector dialog displayed will configure itself automatically. With the seismic data selected it is usually desirable to define a sub-area. This is achieved by clicking the button from the 3D Survey Area radio button group. Following this the user would select sub-area using the Start In-line, End In-line, Start X-line and End X-line edit boxes. Finally, the number of traces is specified and the button is clicked.
With the seismic data volume selected you can now load a set of traces to be analysed. Here you can optionally choose to select traces from the full 3D survey area or sub 3D survey area. This is achieved using the radio button group as follows:
for the complete area
and setting the In-line and X-line Start and End values for a sub-area
Typically you would select a single sub-area. Specifying a sub-area in this manner enables you to include an area of the survey where the trace data is known to be of good quality and is representative of the survey area as a whole. With sub-area selected it is simply a case of specifying the number of traces to load (default 40) via the Num. Traces spinbox widget. This is then followed by you clicking the button to load a random set of traces. A list of the randomly loaded traces is then displayed beneath the button. The software also enables you to select trace data from multiple sub-areas. This is achieved by specifying another In-line/X-line Start and End range and clicking the button again. The goal is to generate seismic trace spectra which is good representation of the area as a whole. If you attempt to specify an area which is outside of the available area then a warning message will be issued when you attempt to load seismic traces by clicking the button. You will also get an error message if you set an area which would not allow enough unique traces for the Num. Traces requested.
| Loading and Clearing Data | Description |
|---|---|
  | The image to the top left shows the SsbQt Main Window with Select Input Data Dialog superimposed. The Raw Seismic spectra resulting from clicking the button on the "Select Input Data Dialog" (above left) with Num. Traces set to 40 and a 3D Survey Area is defined by: In-line: 1400 - 1800 X-line: 4300 - 5400 By default, all loaded traces are used in the spectra calculation and contribute to the Seismic Mean Spectrum. However, you can remove a given trace from the SsbQt analysis by deselecting it via the Input list. Deselection of a trace is simply achieved by unchecking the tick box. If you want to completely remove the deselected trace you click the button. Alongside each trace on the Input list, are various properties associated with the trace. These include Trace Id (or trace label), In-line, X-line, RMS Amp, RMS Err, Horz Time. The RMS Amp property is derived from the input seismic trace, whereas the RMS Err property is derived from the trace spectrum. The latter can be considered as a "goodness of fix" parameter as it compares trace spectrum with the smooth mean trace spectrum. So for RMS Err, the smaller the number the better the fit. Loaded traces, by default, are sorted by Trace Id. However, you can sort the list of traces using one of the other properties. This is easily achieved by clicking the column header on the Input list. So, for example, if you want to sort by RMS Amp in ascending order, you click the RMS Amp header label. To sort in descending order you click the RMS Amp header label again. You can also change the position of the property columns. This is simply achieved by clicking and holding on a property header, then dragging the property header to its new position. The top LH image shows the result of clicking the push button. Here 40 traces have been randomly loaded and immediately displayed in the "Raw Seismic" chart within the SsbQt Main Window. Also visible is a portion of the "Select Input Data Dialog" showing the trace list on the "Input" tab sorted by ascending RMS Amplitude values. The bottom LH image shows the result of clicking the push button. Clear list removes all traces previously loaded to memory and has the immediate effect of removing this data from the "Raw Seismic" chart within the SsbQt Main Window. |
Specifying the time range (gate) is an important step. Ideally, you should choose a time gate in the range of 500 - 1000 msec which should be over the zone of interest. You can set the Time Range mode in one of three ways via the "Range" radio button.
Full - this range would cover the full trace length. It is rarely used
Sub - here you additionally need to specify Absolute Start Time and Absolute End Time. This Time Range mode is the default.
Horizon - here you additionally need to specify the Relative Start Time and Relative End Time. You also need to specify the horizon to be used.
Of the three options the Horizon Range mode is the preferred mode since it allows the gate to follow the geology and should, with a well interpreted horizon in the target zone, give in theory, trace spectra which are more closely matched.
| Modifying Time Range | Description |
|---|---|
 | The image to the left shows the SsbQt Main Window with Select Input Data Dialog superimposed. Here "Full" (full trace range) has been selected for the radio button. This mode is rarely used since our goal is to design a Spectral Blueing operator over the zone of interest. This will optimise the process over that zone. However, it does allow you, although insensitive, to see the start and end times of the entire trace. |
 | The image to the left shows the SsbQt Main Window with Select Input Data Dialog superimposed. Here "Sub" (sub trace range) has been selected for the radio button. In this mode the Absolute Start time and the Absolute End time Line Edit fields will be sensitised. This allows you to specify a time gate for the zone of interest. Typically you would specify a time gate which has a time range between 500msec and 1000msec. |
 | The image to the left shows the SsbQt Main Window with Select Input Data Dialog superimposed. Here "Horizon" (horizon relative trace range) has been selected for the radio button. In this mode the Relative Start time and the Relative End time Line Edit fields will be sensitised. This allows you to specify a time gate for the zone of interest. Typically you would specify a time gate which would give you a time range between 500msec and 1000msec. Specifying the Start and End times here are relative to a geologic horizon. A negative number represents time above the horizon whereas a positive number is a time below the horizon. The time gate can be either above, below or span the horizon. The image below shows the Horizon Input Dialog which can be popped up by clicking the push button.
|
Occasionally, it is necessary to remove one or more poor spectral traces which contribute to the generation of the mean spectra. This is easily achieved by identifying problem spectral traces from the chart and deselecting these traces from within the Select Input Data Dialog.
| Removal of anomalous data | Description |
|---|---|
  | The Main Window with Select Input Data Dialog superimposed (top left) shows the Raw Seismic spectra resulting from clicking the button on the "Select Input Data Dialog" (above left) with Num. Traces set to 5 and a 3D Survey Area defined by: In-line: 1400 - 1800 X-line: 4300 - 5400 By default, all loaded traces are used in the spectra calculation and contribute to the Seismic Mean Spectrum. If one or more seismic trace spectra displayed on the Raw Seismic plot were anomalous then it is possible to remove those traces from the Seismic Mean Spectrum calculation. Let us consider the blue trace (which appears to have a particularly low amp (dB) at around 60Hz). Now, if we wish to exclude this trace from the mean calculation, we must first identify it. This is achieved by pointing close to one of the vertexes of this spectrum and clicking on it. We need to be within few pixels of the vertexes to be able to identify it. If we are within range when we click, then the spectra named, together with the Frequency and Amplitude of the vertex, is displayed in the Status Area of the Main Window. In this case, the raw seismic spectra is identified as "TRACE_003". We can now to go to the Input Trace list and click checkbox to the left of entry "TRACE_003". This causes the trace to be flagged as not currently selected and the Raw Seismic plot on the Main Window is updated accordingly. The Seismic Mean spectrum (black) on both displays changes as a consequence. An alternative method, which works well in this case, is to look at the RMS Err property. You will note that the RMS Err of TRACE_003 is significantly larger than that of the RMS Err values of the other trace spectra. So if you sort by RMS Err, you will easily be able to identify any trace spectra with abnormally large RMS Err value. You should note that once you toggled off a trace, it may loose its RMS Err value as the spectrum is not calculated. |
The Select Volume dialog provides you with a 3D seismic volume selector. From here simply select the seismic volume you require for your SsbQt analysis and operator design. A Volume filter is provided to reduce the list to a manageable size for projects with many volumes.
| Select Volume dialog | Description | ||
|---|---|---|---|
| The images to the left show examples of the "Select Volume" dialog for selection of a seismic volume. The LH image shows a seismic volume list without a seismic volume filter. The RH image shows the use of a filter to create a shorter list. As can be seen, the wild card character (*) can be used in the Filter field. |
The Horizon Input Dialog provides you with a horizon selector. From the Horizon Data tab, simply select the horizon you require for your SsbQt analysis and operator design. A Horizon filter is provided to reduce the list to a manageable size for projects with many horizons.
| Select Dialog (Input Seismic tab) with button to pop up horizon input dialog | Description | ||
|---|---|---|---|
| The images to the left show examples of the "Select Horizon" dialog for selection of a seismic horizon. The LH image shows a seismic horizon list without a horizon list filter. The RH image showa the use of a filter to create a shorter list. As can be seen, the wild card character (*) can be used in the Filter field. |
This section describes how to select the input well log Acoustic Impedance data for use in the Spectral Blueing operator design. Spectral Blueing requires that you select one or more Acoustic Impedance logs from those available for the project. These Accoustic Impedance logs are then used to generate Reflectivity. We use the reflection coefficient curves to generate spectra Ideally we would like to generate Reflectivity spectra from multiple well logs as this should help to retrieve a better global spectrum to curve fit. However, data from the different wells might be of variable quality so it is up to you to decide which wells to use. The figure below shows the Input Well Log tab on the Select Input Data Dialog.
In the above dialog, the large central area is to display and control the selection of Well Log Acoustic Impedance data. It consists of twelve fields: Field/Well/Logs, Top, Base, Common Well Nm, UWI, Remark, In-line, X-line, Horz Time and Horz Src. These fields can be moved by grabbing (click and hold) the field header and dragging to a new position. Clicking on the field headers sorts the list according to data in that field. The Field/Wells/Logs provides a facility to expand and contract the entire list. Additionally this field allows Acoustic Impedance data to be selected and deselected.
The sub-section below describes how you can select and constrain the data.
Loading Acoustic Impedance data from ASCII is straightforward. Simply click on the push button to pop up a file selector. Within the File Selector you can traverse the file system to locate Acoustic Impedance data in ASCII format. The File Selector allows one or more ASCII files to be open at once. Use the <Shift> key modifier to select consecutive files and the <Ctrl> key modifier to select non-consecutive files from within the File Selector dialog. You can also MB1 and drag the mouse over a number of ASCII files.
| ASCII Well Log Selection | Description |
|---|---|
 | The picture to the left shows the top portion of the Input Well Log tab, where well log data has been loaded. In this case, the well log data was loaded from ASCII files. The central list area shows four impedance curves have been loaded. One each for four wells. Normally well log ASCII data files do not contain inline, xline or horizon data. So, in such cases, it is not possible to select a time range relative to an interpreted horizon. However, SsbQt recognises certain XML style meta tags, which can be used by you to provide additional data. Below are the five XML style meta tags recognised by SsbQt. <inline>inline data here</inline> <xline>xline data here</xline> <horztime>horizon time data here</horztime> <xcoord>x coordinate here</xcoord> <ycoord>y coordinate here</ycoord> These XML meta tags are normally inserted on one line within the ASCII file. For example, in Landmark style ASCII files these would normally be placed on the second line (which is blank). It is not necessary to include all the meta tags. Normally only the <inline> and <xline> meta tags are supplied as there is then sufficient information for horizon data to be extracted from the supplied horizon. In this example, the horizon information for well_4.dat, well_3.dat and well_3.dat can be obtained from the supplied horizon (Horz Scr = horz) using the In-line and X-line data supplied via the meta tags <inline> and <xline>. For well_1.dat however, the horizon information comes from the <horztime> meta tag (Horz Scr = well) since no In-line or X-line data has been supplied. |
This section describes how you can define the format for ASCII file reading of well Reflectivity log data. Clicking the push button will pop up the "Define ASCII File Format" dialog.
| Define ASCII File Format dialog | Description |
|---|---|
 | The picture to the left shows the "Define ASCII File Format" dialog. This dialog has three groups: Select ASCII Format, Record and Column Information and File Time Column Units. Select ASCII Format: This group contains a radio button with two options and . In mode (default) the other two groups are desensitised. In mode you will need to additional supply information in the other two groups. Although no explicit LAS input facility is provided, you can normally read LAS files in mode. Record and Column Information: If your ASCII has header records before the wireline curve data, you should skip these by specifying a value in the input field. You should also specify which column the time data and the impedance data can be found. By default these are set to 1 and 2 respectively. File Time Column Units: This radio button item allows you to specify whether the time data is in s for . |
Loading acoustic impedance data from OpenWorks database is straightforward. GeoFrame database access is not currently supported in this release (see Load ASCII Wells...). The details of loading Reflectivity data from OpenWorks are explained in the table beneath.
| Database Well Log Loading | Description |
|---|---|
  | The two images to the left show the top portion of the Input Well Log tab, used to load OpenWorks well log Reflectivity data. The top image shows the state when the "Input Well Logs" tab is first selected by you following display of the "Select Input Data" dialog. Here you click the push button to pop up "Select Wellset" dialog (see Section Wellset dialog below). If no well data has been previously selected then clicking the will also pop up the "Select Wellset" dialog. From the "Select Wellset" dialog highlight the Wellset you require and click the push button. This will cause all Reflectivity data logs which have the specified naming convention to be automatically loaded but not selected for the OpenWorks Wellset. You can then select from the list the Reflectivity data logs you wish to use in the analysis. It is assumed that acoustic impedance logs will have the characters "Imp" (upper or lower case) somewhere within the log curve name or in the remark field. If, for a given well, there are no such Reflectivity log curves or the log curve doesn't meet the assumed naming convention, then the user can still load Reflectivity log curves manually. The bottom image to the left shows, in the central area, that three Reflectivity log curves, two for the ALB-HT-X1 well and one for the ALB-HT-X2 well, have been automatically loaded. Here we have selected one the Reflectivity curve from each well. We can also manually select Reflectivity well log. This is achieved by right clicking on well name which will pop-up a menu with Selecting this item will pop-up the "Select Database Logs" dialog which lists the available logs allowing you to choose an Reflectivity log curve however it is named. The push buttons and are self explanatory. Note the push button will change to a push button after the initial automatic selection. |
The Select Wellset dialog provides you with a well set selector. From here simply select the well set you require for your SsbQt analysis and operator design. A well set filter is provided to reduce the list to a manageable size for projects with many well sets.
| Select Wellset dialog | Description | |
|---|---|---|
| The image to the left show an example of the "Select Wellset" dialog for selection of an OpenWorks well set. |
The Select Database Logs dialog provides you with an Acoustic Impedance log selector. Here you can select any database log in time irrespective of how it is named. An acoustic impedance log filter is provided to reduce the list to a manageable size should there be many logs for the well.
| Select Wellset dialog | Description | |
|---|---|---|
| The image to the left show example of the "Select Database log" dialog for selection of OpenWorks impedance logs in time. Note only one Reflectivity log can be selected at a time. |
Specifying the time range (gate) is an important step. Ideally, you should choose a time gate in the range of 500 - 1000 msec which should be over the zone of interest. You can set the Time Range mode in one of three ways via the "Range" radio button.
Full - this range would cover the full trace length. It is rarely used
Sub - here you additionally need to specify Absolute Start Time and Absolute End Time. This Time Range mode is the default.
Horizon - here you additionally need to specify the Relative Start Time and Relative End Time. You also need to specify the horizon to be used.
Of the three options the Horizon Range mode is the preferred mode since it allows the gate to follow the geology.
| Modifying Time Range | Description |
|---|---|
 | The image to the left shows the SsbQt Main Window with Select Input Data Dialog superimposed. Here "Full" (full trace range) has been selected for the radio button. This mode is rarely used since our goal is to design a Spectral Blueing operator over the zone of interest. This will optimise the process over that zone. However, it does allow you, although insensitive, to see the start and end times of the entire trace. |
 | The image to the left shows the SsbQt Main Window with Select Input Data Dialog superimposed. Here "Sub" (sub trace range) has been selected for the radio button. In this mode the Absolute Start time and the Absolute End time Line Edit fields will be sensitised. This allows you to specify a time gate for the zone of interest. Typically you would specify a time gate which has a time range between 500msec and 1000msec. |
 | The image to the left shows the SsbQt Main Window with Select Input Data Dialog superimposed. Here "Horizon" (horizon relative trace range) has been selected for the radio button. In this mode the Relative Start time and the Relative End time Line Edit fields will be sensitised. This allows you to specify a time gate for the zone of interest. Typically you would specify a time gate which would give you a time range between 500msec and 1000msec. Specifying the Start and End times here are relative to a geologic horizon. A negative number represents time above the horizon whereas a positive number is a time below the horizon. The time gate can be either above, below or span the horizon. Clicking the push button will pop up the Horizon Input Dialog. |