Synthetic Generation

January 2011

Seismic Micro-Technology, Inc.

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SynPAK

Synthetic Generation

Version 8.6

Trademarks and CopyrightThis manual was produced by Seismic Micro-Technology, Inc.Version 8.6January 2011

Seismic Micro-Technology, Inc.8584 Katy Freeway, Suite 400

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Tel: (713) 464-6188Fax: (713) 464-6440

Internet Address: www.seismicmicro.comE-Mail Address: [email protected]

Marketing: [email protected] Support: [email protected]

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protected by the laws of the United States and other countries. Additionally, if publication occurs, the following notice shall apply: Copyright ©RDSP I, L.P., All Rights reserved.Microsoft is a registered trademark of Microsoft Corporation. Windows® 2000, Windows XP, and Windows XP x64, Windows Vista, Windows 7 operating systems, MS-DOS and SQL Server are trademarks of Microsoft Corporation. Oracle® Databases are registered trademarks of Oracle Corporation. OpenWorks, SeisWorks, Interpret 2000 and Interpret 2003 are registered trademarks of Landmark Graphics Corporation.SMT incorporates BMC® AppSight™ Black Box Technology in its software. BMC Software, BMC Software logos and all other BMC Software product and service names are registered trademarks or trademarks of BMC Software Inc. © 2009 BMC Software, Inc. All rights reserved.All other trademarks are the property of their respective holders.©2009 - 2011 Seismic Micro-Technology, Inc. All Rights Reserved WorldwideKINGDOM and this manual are both copyrighted and intended for use by a single user or a single computer whose model is authorized by Seismic Micro-Technology, Inc. You are entitled to electronically transcribe KINGDOM DVD to the hard disk of an authorized computer so long as KINGDOM and related software packages are operated on only one computer at a time. You are further entitled to electronically transcribe the DVD to other DVD(s) for archival storage only. Physical duplication of the KINGDOM software and SENTINEL is expressly forbidden. No portion of KINGDOM software may be incorporated into any other program. No other usage or transcription in any form is allowed without the express written permission of Seismic Micro-Technology, Inc.No portion of this manual may be reproduced, transmitted, transcribed or stored on any information retrieval system, or translated into any foreign language or any computer language in any form and by any means whatsoever without the express written permission of Seismic Micro-Technology, Inc.This document contains confidential information and trade secrets proprietary to Seismic Micro-Technology, Inc.

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Synthetic Generation

Introduction

This tutorial guides you through the creation of a synthetic seismogram. The examples shown here are from the Sooner Project included in Demo Data Sets on the KINGDOM 8.6 DVD, which is usually loaded to C:\The Kingdom Demo Projects\.

The objectives of this tutorial are to show you how to:

• Select parameters needed to generate a synthetic seismogram

• Generate a wavelet to convolve with the Reflection Coefficient log

• Display a synthetic seismogram in SynPAK.

Before you start the tutorial:

1. Start KINGDOM by double-clicking on the The KINGDOM software 8.6 icon on your desktop.

2. Open the Sooner project (sooner3D.tks in the directory: C:\Kingdom Demo Projects\SOONER\) by selecting Project > Open. Select SMT as the author.

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Entering the SynPAK Parameters

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To open a SynPAK window:

1. Either select Wells > Generate Synthetic Seismogram, or Project > SynPAK from the main menu to open the Select Well and Borehole dialog box.

Figure 1 — Select Well and Borehole dialog box

In this dialog box:

2. Select SOONER UNIT:21-5-9 (a well in the Sooner data set) as Well Name and the default Untitled1 as Borehole. Make sure that All Wells are turned on in the Project Tree.

3. Turn ON the option to Create New to create a new synthetic. Turn ON Use Default Template.

If the Select Existing option is turned on, a list can be pulled down and a previously created synthetic can be selected.

4. Click OK to open the Select Synthetic Seismogram Parameters dialog box.

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T-D Chart tab

Figure 2 — Select Synthetic Seismogram Parameters dialog box (T-D Chart tab)

1. On the left side of the dialog box, check the well name to confirm your selection for the well.

2. Check the information on the well to ensure all the information is correct before proceeding. (It should agree with the information in the figure above).

If you need to make changes, click Cancel to close this dialog box and select Wells > Edit > Wells from the main menu bar to open the Edit Well Data dialog box, where you can make any changes.

Now we can either apply an existing T-D chart to the log data, or we can create a new T-D curve by integrating a sonic or pseudo-sonic log. There is an active T-D chart, 1-28 Dix Shifted Stretched 21-5-9, for this well.

3. Accept the active T-D chart.

If <None> appears in Active T-D Chart or you need to apply a different T-D chart, click the Select or Edit button under Active T-D Chart to select a different chart.

The Time-Depth Charts dialog box opens. Select the name and click OK. The message, “Time Depth data has been changed. Do you want to apply these changes?” opens. Click Yes.

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Velocity tab

1. Click the Velocity tab.

Figure 3 — Select Synthetic Seismogram Parameters dialog box (Velocity Tab)

2. Select the DT (sonic) log to be used to compute a velocity log.

Note: The resistivity or density logs can also be used in case there is no sonic.

Warning: Do not click OK yet!

Density tab

1. Click the Density tab.

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Figure 4 — Select Synthetic Seismogram Parameters dialog box (Density Tab)

2. Remove the checkmark in the Use Constant Density selection box to activate the list of logs.

3. In this list, click the density log, RHOB, to highlight it.

Note: If a log other than a density is selected, a pseudo-density log is automatically calculated.

Ref(erence) Log tab

1. Click the Ref. Log tab (or Reference Log).

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Figure 5 — Select Synthetic Seismogram Parameters dialog box (Ref. Log Tab)

Use this tab to show logs in separate panels to be used as a reference in the zone of inter-est. Typically an SP or Gamma log is used as a reference log.

2. In the Panel column, select Ref. log(9) if it is not already selected.

3. In the RefLog Name column, click the empty text box to open a pull-down menu. (The down arrow does not appear until you click in the RefLog Name column.)

4. From the pull-down menu, select GR.

Wavelet tab

1. Click the Wavelet tab.

Use this tab for selecting or creating a wavelet to be convolved with the Reflection Coef-ficients.

This does notappear untilyou click theblank text box.

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Figure 6 — Select Synthetic Seismogram Parameters dialog box (Wavelet Tab)

2. Click Generate Wavelet to open the Wavelet Wizard dialog box.

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Figure 7 — Wavelet Wizard - Step 1 dialog box

In the Wavelet Wizard dialog box, the methods that SynPAK uses to generate a wavelet are shown.

• Compute a theoretical wavelet — to generate a wavelet using Ormsby, Ricker, Klauder, Minimum, Butterworth, Gaussian, and O’Brien wavelets.

• Extract from seismic traces [Frequency Matching] — to extract a zero phase seismic wavelet from 2D or 3D seismic data.

• Extract from seismic traces [Walden-White Method] — This will be grayed out initially. It computes a wavelet that when applied to the reflection coefficient series acts as a matching filter between the extracted seismic trace and the reflection coefficient series.

• Extract from seismic traces [Wiener-Levinson] — This cannot be activated until the reflection coefficients are computed and an extracted seismic trace is selected. It computes a wavelet that, when convolved with the reflection coefficients, will most closely reproduce the extracted seismic trace. It can also compute a filter that, when convolved with the extracted seismic trace, will most closely reproduce the reflection coefficients.

• Import from a disk file — to import a wavelet from a disk file.

3. Turn ON the second option, Extract from seismic traces [Frequency Matching].

4. Click Next to open the Extract a Wavelet - Step 2 dialog box.

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Figure 8 — Wavelet Wizard - Step 2 dialog box

SynPAK provides three methods to select seismic traces for the computation of a wavelet.

• Traces within a set distance from a borehole - this automatically selects all the traces within a specified radius around the borehole.

• All traces within a polygon on a map view - this allows you to specify seismic traces to be extracted from a survey by drawing an irregular polygon on a map.

• Samples within a rectangle on a vertical seismic display - this allows you to select seismic time samples from a seismic section by drawing a rectangle on the seismic section.

5. Turn ON the Traces within a set distance from a borehole option and click Next to open the Extract Wavelet at Well Borehole dialog box.

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Figure 9 — Extract Wavelet at Borehole dialog box

6. Select SOONER UNIT: 21-5-9 and the borehole, and for the seismic survey, select Sooner 3D, and for the Seismic Type, select Amplitudes.

7. Enter 1000 (feet) in the Enter a radius (of capture) text box.

8. Click OK to open the Trace Information dialog box.

9. In Starting Time, enter 0.5; in Ending Time, enter 2.5 (second) from which the wavelet is extracted.

Note: It is best to select a time gate where the synthetic can be calculated. Start below the mute zone and end above the low frequency data at depth. Note that the number of traces to be used is provided in this dialog box.

To change the number of traces, click Cancel and change the radius.

10. Click OK to close the Trace Information dialog box.

A progress bar shows that the traces are being read in from the data set and a wavelet is being extracted.

When the extraction process finishes, the next step of the Wavelet Wizard is opened.

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Figure 10 —Wavelet Wizard - Extract

In this portion of the wizard, you can change the phase of the wavelet, display the com-puted frequency spectrum, or print out the wavelet.

11. For this tutorial, just click Next to go to the Wavelet Wizard - Save dialog box of the wizard.

12. Enter Ext_wave_1000ft_21-5-9 in the text field below Save as.

Note: If you use spaces instead of underscores ( _ ) to break the words in the names of wavelets, synthetics and T-D Charts, a long name will be wrapped into multiple lines in a panel title display in the SynPAK window.

Note: You could also export the wavelet as either a text or SEG Y file by clicking on the appropriate button.

13. For this tutorial, click Finish.

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Figure 11 — Select Synthetic Seismogram Parameters dialog box (Wavelet Tab)

14. Click the down arrow in the Wavelet Name option and select Ext_wave_1000_ft_21-5-9 from the pull-down list.

Note: The next tab, Trace, is used to select a set of seismic traces for comparison with the synthetic. This is explained in Seismic Matching, the second SynPAK tutorial.

Note: We will discuss the Imported Synthetic Tab later in this tutorial.

Update tab

1. Click the Update tab.

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Figure 12 — Select Synthetic Seismogram Parameters dialog box (Update Tab)

If you turn ON the first option, Interactively show SynPAK changes in 2d/3dPAK seis-mic display while editing, shown in the right panel of the above figure, the synthetic of this well shown on a seismic line will be instantaneously updated when you edit the syn-thetic.

The second option, Do not show SynPAK changes in 2d/3dPAK seismic display until Synthetic is saved, will not update the synthetic while editing.

Select the first option.

2. Click OK.

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Main SynPAK Window

Figure 13 — SynPAK Window

The main SynPAK window includes the selected logs, wavelets, and both polarities of the synthetic. Also displayed are the Acoustic Impedance (AI) and the Reflection Coefficients (RC).

1. Click the Set Scales icon to open the Scales/Settings dialog box.

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Figure 14 — Scales/Settings dialog box

2. Click the Vertical tab.

3. In Inches per second, enter 20 to change the vertical scale. Also note the other display parameters available in this dialog box.

4. Click OK.

5. To save the synthetic you have just generated, from the main menu bar, select Synthetic > Save As to open the Save Synthetic as dialog box.

6. In this dialog box, enter Sooner_21-5-9_Ext_Wave_1000_ft and select a color for the synthetic.

7. Click OK to close the dialog box.

The new synthetic and the extracted wavelet are saved in the project.

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Figure 15 — SynPAK Window (with Synthetic and Wavelet)

8. Click the Project Tree window and scroll down to the 21-5-9 well under the Well List folder of the Wells folder.

9. Expand the Sooner Unit (21-5-9) well folder by clicking on the + sign in the box to the left of the well number.

You can see the Log Curves, Synthetics and T-D Charts folders under the Sooner Unit (21-5-9) well. You may need to click the + signs in the boxes to the left of the folder symbols to see the items in those folders.

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Figure 16 — Project Tree (showing Synthetics)

Imported Synthetic tab

This panel displays the imported synthetics to compare with the generated synthetics and the extracted seismic traces. You can import seismograms from a processed VSP survey, and synthetic seismograms generated by other applications, etc.

Since we do not have any imported synthetics in this project, we will export the Sooner_21-5-9 _Ext_Wave_1000_ft synthetic we have just saved and then import it into this panel.

To export the synthetic, we do the following:

1. With the SynPAK window activated, select Synthetic > Export Synthetic Trace > SEG Y from the main menu to open the Select Synthetic dialog box.

2. Select the well name by clicking on the down arrow of the Well Name text field and select SOONER UNIT: 21-5-9.

3. Select the synthetic by clicking on the down arrow of the Synthetic: text field and select the Sooner_21-5-9_Ext_Wave_1000_ft synthetic. Click OK to open the Export as SEG Y file dialog box.

4. Select an appropriate directory, enter Sooner_21-5-9_Ext_Wave_1000_ft as the file name and click Save to complete the export process.

To import the synthetic, we do the following:

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1. With the SynPAK window activated, select Synthetic > Import Synthetic Trace > SEG Y from the main menu to open the Import as SEG Y file dialog box.

2. Go to the appropriate directory, select the Sooner_21-5-9_Ext_Wave_1000_ft segy file we have just exported and click Open to open the Import Synthetic Trace From SEG Y File dialog box.

3. With Well Name SOONER UNIT: 21-5-9 selected, in the Synthetic/Synthetic Trace field, select or enter Imported_Sooner_21-5-9_Ext_Wave_1000_ft, select a color and click Import to complete the import process.

Now, return to the SynPAK window to display the imported synthetic.

4. Click the Select icon in the SynPAK window to open the Select Synthetic Seismogram Parameters dialog box and click the Imported Synthetic tab.

Figure 17 — Select Synthetic Seismogram Parameters dialog box (Import Synthetic Tab)

5. Click Add Panel and select Imported_Sooner_21-5-9_Ext_Wave_1000_ft in the Imported Synthetic Name column. (The correct synthetic shows up in this case because it is the only imported synthetic at this time). Then click OK.

The imported synthetic panel is appended to the previously generated panels as shown. It is identical to the synthetic in the Synthetic(+) panel. It can be moved to another position as needed for trace to trace comparison.

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Figure 18 — SynPAK window with Imported Synthetic

Wavelet OverlayThis SynPAK feature allows you to select one or more reflection coefficients on the RC panel by clicking on them and displays their convolution with the wavelet as an overlay on the synthetic trace. It provides you with the tool to investigate how the reflection coefficient(s) may affect the shape of the synthetic trace. It gives you a quick and dirty method to evaluate whether the impedance change in your interested geological feature may produce an observable change on the synthetic. It can also be used to estimate the minimum length of sonic log required to minimize the distortion of the synthetic over the zone of interest caused by data drop-off at the ends of the sonic log.

When you place the cursor within the RC panel, it turns into a crosshair with a W on its upper right corner (Figure 17).

1. Arrange your SynPAK window to show the panels as shown in figure below.

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Figure 19 — SynPAK window with Wavelet Overlay (5 traces)

2. Click the first reflection coefficient (at about 1.292 second) in the RC panel. The How to Use Wavelet Overlay help opens in the lower right corner.

3. Then hold down the Shift key and click the last reflection coefficient (at about 1.486 second).

Note: When the entire reflection coefficient series is selected, the resulting wavelet overlay should be identical to the synthetic. However, because the Wavelet Overlay Scale Factor has not been properly adjusted, the wavelet overlay is not identical to the synthetic. See the next two steps for applying the adjustment.

4. Right-click the Synthetic(+) panel and select Panel Properties to open the Panel Properties dialog box.

5. Adjust the # Traces to 1 and change the Wavelet Overlay Scale Factor to 2.5. Then, click OK to return to the SynPAK window as shown in figure below. The amplitude of wavelet overlay is adjusted to overlay exactly on the left trace of the synthetic for close examination.

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Note: A different Wavelet Overlay Scale Factor may be needed to exactly match the amplitude of the synthetic seismogram.

Figure 20 — SynPAK window with Wavelet Overlay (2 traces)

6. Now, click the 5 large reflection coefficients (1.330 - 1.340 seconds) to deselect them.

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Figure 21 — SynPAK window with Wavelet Overlay (5 RC un-selected)

The resulting wavelet overlay trace shows that the large peak at 1.337 second of the synthetic disappeared indicating the velocity and density values around that time are the main contributors for that peak event.

You may want to try selecting and deselecting more reflection coefficients to observe their effects.

You can deselect all the reflection coefficients simultaneously by right-clicking on the RC panel and select Disable Wavelet Overlay on the pop-up menu.

The next step is to correlate the synthetic to real seismic data. You can shift, stretch or squeeze the synthetic seismogram to achieve a better tie to the extracted seismic data. To do that, you can go to the Seismic Matching tutorial.

You have successfully completed the Synthetic Generation part of the SynPAK tutorials.

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Synthetic Generation