Geoview_eLog

GEOVIEW & ELOG

For ONGC-SPIC, Mumbai, India 21-26th February 2011

Geoview and eLog Course Outline Introduction to Geoview User Interface Overview Loading Well Logs Deviated Wells Exercise 1: Data Loading and Checkshot Corrections Depth-time Tables Well Log Data Management Exercise 2: Well Log Editing Exercise 3: Well Log Data Management Exercise 4: Log Type Mapping Introduction to eLog Exercise 5: eLog Exercise 6: Log Classification Seismic Loading Exercise 7: Seismic Loading Moving Projects and Data Help 2

Introduction to Geoview Geoview is the toolbar from which all of the Hampson-Russell software products are launched. Geoview is also the main database for the storage of well data. The well database is managed through the Well Explorer program. Software Version Geoview, the Program Launcher:

Database Name

The Well Explorer:

3

The Geoview User Interface Under File > Settings: Paths: Allows you to set commonly used directories for the default path when opening well databases or projects or for importing for data. Preferences: Allows you to change the appearance of the interface, length of History list and “Most Recently Used” lists. Measurement System: Allows you to specify the measurement system defaults to either metric or imperial units.

Paths Menu

Preferences Menu

Measurement System Menu

4

The Well Explorer User Interface The Well Explorer program allows you to actively explore, view and manage the well database. < Table View Curve View >

< Map View Summary View >

5

Loading Well Logs Well log information can be loaded into a Geoview database by importing the information from ASCII files, by importing wells from OpenWorks or GeoFrame well log databases, or by copying wells from another Geoview well database.

Other information that can be imported are well locations (spots) and DXF drawing files containing culture information. Logs can be loaded in either time or depth domains. 6

Loading Wells From ASCII Files The supported well log ASCII formats are: LAS, GMA, GeoQuest IES, and general ASCII-format files. Loading ASCII-format Well Logs is a straight-forward procedure and requires the user to identify the data locations in the file. 1) Select the file(s)

2) Select the file format and data type

3) Identify the required file parameters

7

Loading Wells with the OpenWorks Well Exchange: To import well information from an OpenWorks well database: First, Start OpenWorks Well Exchange program

and then, in the Hampson-Russell Well Log Exchange program, select the File > Load OpenWorks Logs… option

8

Loading Wells with the OpenWorks Well Exchange: Select the wells, logs and tops that you want to import.

9

Loading Wells with the GeoFrame Well Exchange: The GeoFrame Well Exchange is an almost identical workflow. First, start the GeoFrame Well Log Exchange program

and the select the File > Load GeoFrame Logs… option

10

Loading Wells with the GeoFrame Well Exchange: And select the wells, logs and tops that you want to import.

11

Loading Well Logs by Typing in a Table For simple modeling exercises, you may find it convenient to enter logs by typing them in manually. This is done by first creating a well or opening up an existing well and then choosing to Create a new log in table from the list of Log Options.

You will then be provided with an empty log table that you can fill in by either typing in the values or pasting from the computer clipboard.

12

Deviated Wells

•

Files of well path deviation data are loaded into the Well Explorer in the same import menu as importing logs from files.

•

Deviations are measured in either absolute X & Y coordinates, relative X & Y coordinates (offsets) or dip and azimuth pairs.

•

If you are transferring log data from OpenWorks or GeoFrame, the deviation survey will automatically be picked up and transferred.

•

The deviation information will be used to correct the log to vertical (i.e., convert from MD (measured depth) to TVD (true vertical depth) ).

13

Loading Deviated Geometry Files Here is an example of a deviated geometry file. It is a simple ASCII file with a number of header lines followed by three columns of data: measured depth, X and Y.

< Header

In this case, the deviation is in terms of absolute X & Y coordinates. Relative coordinates (offsets) would also be acceptable as would dip and azimuth pairs.

14

Loading Deviated Geometry Files When loading the deviated geometry file, ensure that the Type of Data is marked as Deviated Geometry.

The file is read in by defining the parameters of the ASCII file such as the number of header lines and the column numbers of the data.

15

Log Types and Log Names
Every log within Geoview should have a ‘type’ and a ‘name’ associated with it.


P-wave, density, neutron porosity, gamma ray are examples of ‘log

types’. It is important that the log type is set correctly. The log type controls the parameters and functionality you can perform with that log, e.g. displaying different measurement units, relations and transforms etc…


The log names are used to distinguish logs of the same type from each

other by using a distinct name - for example, “P-wave_corr_1” and “Pwave_corr_2” are different names for logs of type P-wave.


To make your project work easier, take the time to set the log types (and log units) correctly in Geoview before you start working on a project.

16

Log Types and Log Names Well Explorer Table View display of the logs for one well. Log Name

Log Type

17

Log Type Mapping Hampson-Russell log types may not match other software log types. You can define a table of log aliases to match imported log types to Hampson-Russell log types. For example, you may already have a database with compressional velocity logs mapped as type “SONIC”. HRS does not recognize logs of type “SONIC” but it does recognize “P-wave”. Log Type Mapping will match the “SONIC” log type to the HRS “P-wave” log type. An ASCII file of commonly used aliases can be created and imported into other HRS well databases. 18

Depth-Time Logs Some logs are automatically and internally computed – such as depth-time logs. We usually want to know where our logs (measured in depth) correspond to in the seismic (measured in time). The depth-time log controls the conversion of depth measurements to time measurements for each well. A depth-time table is usually computed automatically from the sonic velocity log. Check shots and manual correlations to the seismic can be used to modify the depthtime table. We will discuss this in further detail after the next exercise.

19

Exercise 1: Data Loading and Check Shot Corrections In this exercise, we will read in a real set of well logs from an LAS file and by typing in a table. Next, we will explore the software interface, set the datum and perform a simple checkshot correction. After the exercise, we will discuss the depth-time curves, check shot corrections and the datum. First, we will set the paths for the default starting locations for data, project and database locations. Start Geoview. (this will be either a Desktop icon or under the Start > Programs > HRS Applications menu) We will not open or create a database yet. Click Cancel on the first menu. 20

Click on File > Settings > Paths… in the Geoview menu bar.

The Paths Preferences menu allows you to set the default starting path locations when opening data (logs, horizons, seismic), opening projects or opening databases. Set the Default Data Directory path location as shown. Click OK. 21

Now select Database > New.

Create a new well database called: geoview_database.

On the Well Explorer, select Import Data > Logs,….

22

Find the file geoview_logs.las. Select the file and click Add >> In this case, the software has correctly identified this data to be in LAS format. Click Next > Accept the destination well name of Well 1 and click Next >

23

Now specify the Well Type to GAS WELL. You can also define X and Y locations and the elevation properties, as well as the units:

In this case, the KB and surface elevations are contained within the file headers and have automatically been read. 24

Click on Next > to get the final log table:

Click on View File Contents. 25

This will open a Window that shows you the log names and units. In this case, the parameters look correct. Scroll down and you will also see that log tops are also included. Close this window and click on OK on the log loading window to complete the log loading process. Warning windows will appear: click Yes to complete the loading. These messages refers to the recorded Density and Gamma Ray values found between the KB and the surface elevations (i.e., data not in the ground) 26

The Measurement System window will appear. Click OK to accept that the default measurements will be using the Metric system.

For projects with a mixture of measurement, the specific measurement units can be individually changed.

27

Now that all the logs have been inserted into the database, select Well 1 under the well name column and click Display Well.

This will make the Log Display Window appear, showing the logs and tops in Well 1.

28

In the Log Display window, click on View > Display Options. A menu appears that allows you to change the display parameters. It has a number of tab pages as follows:

LAYOUT The log display is organized as a series of tracks, allowing multiple logs to be plotted on top of each other. If you wish to overlay logs, simply tick both logs in the same track column. In this example, we will not overlay any logs. 29

Click on Active Logs…. Active logs are the logs that will be used in any operation, such as: • the P-wave and density logs used to compute the internal impedance (the internal impedance log is used to create the zero-offset synthetic) • the P-wave and S-wave logs used to compute the internal Poisson’s Ratio On the right side of the menu, there is a list of Log Types and, beside each log type, is the selected Active Log. Currently, in this well, there is only one log of each type, so there is no choice.

Click Cancel to close this menu. 30

The Curves menu allows you to change the ranges of the log amplitude tracks and the color of the logs. We will test this in a later exercise.

31

Click on the Scale & Details tab and set the scale as shown below:

32

Click OK to see the following display:

33

Now, in the Well Explorer, click once on the blue arrow to the left of Well 1 to list the logs in the well

Click on the arrow next to Tops The tops can be edited from here > Click the back arrow to return to the previous window.

34

This well, in the foothills of the Rocky Mountains in Alberta, ties to a seismic volume that was processed with a seismic reference datum (SRD) of 2700 m.a.s.l. This means that time 0 of the seismic corresponds to 2700 m elevation. In the Well Explorer, click on the SRD button to specify the Seismic Reference Datum. Set the Seismic Reference Datum elevation to 2700 m and set the Replacement Velocity to 1900 m/s. Click Next >>.

35

Right now, this well only has one depth-time curve that was computed automatically. Check Recalculate option and select the Change option and then click OK at the bottom of the menu. Click OK to acknowledge the change in the message window.

36

Scroll up in the Log Display Window to the top of the log. The red horizontal line represents the SRD and the location of time 0.

SRD = Time 0

37

Now we will apply a check shot correction to this well. A check shot is a log with a series of depths and travel-time pairs created by generating a seismic wave at the surface and measuring the wave travel time with geophones in the borehole. In this example, we will type in the check shot values. On the Well Explorer window, click on Log Options > Create a new log in table and select Check Shot for the log type.

38

A 7th log will appear with the log name of Check Shot 1.

Click on Help > Windows Explorer… in the Geoview program launcher to open the file explorer.

39

In the HRS_DATA\geoview_data directory, find the file called Well1_Checkshot and open it.

With your mouse, select the last three rows containing the data, rightclick with the mouse to Copy it to the computer clipboard. Note that in this file, the depths are column 1 and the checkshot times are in column 2. 40

Now, in the Well Explorer, click on the arrow to the left of the Checkshot log to access the data table. In the Table View, select both columns as shown using the mouse:

Make sure the cells light up as blue

Then select Log Data Options > Paste from clipboard to selected.

41

If done correctly, the table will be filled in with the values from the file. Click Update* to save the new data.

Click on the back arrow icon to move back to the Well Log Table View.

42

The new log is now listed in the Well Explorer. However, we have incorrectly told the software that the log is relative to the KB when in fact it is relative to surface. Correct the Measured From reference for the Check Shot log to Surface and click Update* and then Yes when prompted. Now view the Log Display Window.

43

Even though the check shot log has been added, the check shot does not modify the travel time correction until we choose to apply it. This is because choices still need to be made about how to modify the original depth-time curve to honor the check shot depth-time data.

44

To apply the check shot correction, click on Option > Check Shot Correction:

The Check Shot Parameters menu appears. This allows you to select different calculation and interpolation parameters for applying the check shot correction. Clicking the Apply button will let you see how these choices are applied in the correction.

45

Also, the Check Shot Analysis window will be displayed:

You will only see these 2 curves if you choose to Apply Relative Changes or Apply All Changes, if you decide to change the sonic log.

The smooth curves on the left are the depth-time tables before (black) and after (red) the check shot correction. The curves on the right of the display show the sonic log before (black) and after (red) the check shot correction. The middle track, the “drift curve” is the difference between the two depthtime curves.

46

There are a number of modifications which could be made to the automatic calculation: 1.

Data points from the checkshot survey can be deleted. Simply highlight the value to remove and use Edit > Delete Point to remove it. We will not do this here as we only have two points. Deleted points can be easily restored.

47

2.

Change the “Type of Interpolation” option. Try different types and click Apply to see how they affect the time depth curve correction. A smoother may also be applied to the interpolation type.

48

3.

Change the “Sonic Log Changes” option and test different methods. This options controls whether or not the log velocities will be altered by the check shot application.

Apply relative changes and Apply all changes both modify the log velocities.

Change depth-time curve only leaves the velocities untouched.

49

When you have finished testing all the parameters, we will save the check shot corrected log. Ensure that you have selected “Change depth-time curve only” and “Spline” interpolation without a smoother.

Click Ok on the Check Shot Analysis window.

50

This menu now appears:

Click Ok on the menu. This will create a new check shot corrected sonic log, with the name P-wave_chk.

-- End of Exercise 1 -51

Depth-Time Logs The depth-time logs control the depth-to-time conversion of each well. The depth-time log is usually automatically calculated from the sonic log velocities by integrating the quotients of the depth interval by the interval velocity. Multiplying by two yields the two-way travel time. This is expressed in the following equation: where: ti = time down to layer i i

dj ti = 2* ∑ j =1 Vj

dj = thickness of layer j Vj = velocity of layer j

Note: The time to an event depends on all the velocities above that layer, including the first velocity to the surface, V1. That velocity is unknown and is usually approximated by extrapolating the first measured velocity back to the surface. 52

Depth-Time Logs A P-wave log must always be associated with a Depth-Time log. In the example below, there are two P-wave logs and two associated Depth-Time logs.

53

Depth-Time Logs If you load: a log of type P-wave, a Depth-Time curve is automatically created by integrating the velocity values. a log of type Depth-Time, you can either (1) create a new P-wave log or (2) tie the Depth-Time log with an existing P-wave log.

If you delete: • a Depth-Time log from Geoview, it is automatically recalculated.

• a P-wave log, the corresponding Depth-Time log will also be deleted. 54

Depth-Time Logs Another option in the Well Explorer is to Copy the Depth-Time curve from another well and replace an existing Depth-Time curve.

55

Check Shot Corrections Applying Check Shot Corrections to a sonic log is a standard process used to ensure that the sonic log (measured in the depth domain) is placed at the correct time sample in the seismic section. Seismic shots are detonated at the surface and receivers down the borehole record the one-way travel times for a particular depth. This data is used to modify the existing depth-time table. The check shot correction can be applied from any number of log display locations: •Well Explorer

•eLog

•AVO Modeling 56

Applying Check Shot Corrections The Check Shot Analysis menu allows you to determine the method by which you will update the depth-time table. Since the Depth-Time table is tied to the P-wave velocity log, you will have to make decisions about if and how to change the sonic log velocities and how to interpolate the depth-time corrections between the check shot data pairs.

57

Applying Check Shot Corrections The interpolation of points on the drift curve uses one of three options:

Linear: Honors the points exactly with straight line segments between. Spline: Honors the points exactly with smooth curves between. Polynomial: Fits a smooth curve using least-squares optimization.

58

Types of Check Shot Corrections Changing the depth-time table implies a possible change in the original sonic log velocities. There are three options: 1. Apply all changes. This option changes all the velocities in the log in such a way that the new log will integrate to exactly the desired times. Note: This involves a ramped velocity above the first measured depth to handle the bulk time shift and to minimize the effect of spurious reflections on the synthetic.

59

Types of Check Shot Corrections 2. Apply relative changes This option changes the velocities for layers between the first and last check shot depth only. No ramp is added above the first measured depth. The resulting log will integrate to the desired times except for a bulk time shift.

60

Types of Check Shot Corrections 3. Change depth-time curve only This option does not change the velocities in the sonic log. The resulting log will not integrate to the desired times, but GEOVIEW will use the new depth-time table. This option has the effect of maintaining the original reflection coefficients for synthetic calculations.

61

Types of Check Shot Corrections The choice of which of these check shot options to use depends on what the user is trying to achieve.

Use of either option 1 or 2 above can result in significant changes in the measured sonic log velocities of the well. Therefore, in all cases where the actual measured velocity values are going to be used, the user should use the final option (Change depth-time curve only).

If you are going to use the velocity logs to build a velocity function for time-to-depth conversion later on, the first option (Apply All Changes), will guarantee that the velocity function will correctly tie the seismic times to the log depths.

62

Well Log Data Management The Well Explorer Table View will list all of the wells in the database and provides information for each well: X & Y surface location, Kelly Bushing (KB) elevation, Surface elevation, Measurements units, Well Type, etc…

A vertical line indicates a vertical well A wiggly line indicates a deviated well

63

Well Log Data Management The well log database can be explored by using the arrow keys to move into the wells, logs, tops and deviated geometry files.

Clicking on these arrows will access the stored digital log data.

64

Manual Editing of Log Data

Log data can be edited manually using the Log Data Options button. As well, the data can be quickly copied to and from the computer clipboard. 65

Log Tops (Markers)

Log Tops can be entered and modified easily in the Well Explorer.

66

Deviated Geometry In the Log Table View, click on the Deviated Geometry arrow to view the well path deviation surveys.

Deleting the Deviated Geometry is also possible in the Table View.

The Deviation Survey Data can also be edited if required.

67

Deviated Geometry by Dip/Azimuth If the deviated geometry is specified in terms of Dip and Azimuth there are two calculation methods for interpreting the well path: Minimum Curvature and Tangential. These can be changed in the Well Explorer Table View of the Deviated Geometry. The default method is Minimum Curvature and accounts for the bending of the well bore between measurement points. The Tangential Method uses straightlines to interpolate between points.

Tangential Method

Minimum Curvature Method

68

Exercise 2: Editing data in Geoview In this exercise, we will edit an erroneous data point in the density log. From the Well Explorer window, access the density log data. With this data window open, look at the Density log in the Log Display Window. On the Density log you will see a very low log value at about 686.2 m vertical depth. This data point has to be removed from the log values.

69

In the Well Explorer, try and find this low density value from the log listing and delete it.

70

Can’t find the density value to delete? Notice that the log window is displaying the Depths from Surface – the input log values are relative to Kelly Bushing. The difference between the Kelly Bushing and the Surface is 7.89 m.

Therefore, to find the data point, add 7.89 m to the depth being read from the log display. The erroneous point is actually at 694.2 m measured from the KB.

71

The depth datum can be changed in the Log Display window easily. Click on the eyeball menu, select the Scale & Details tab and change the Uniform Scale Datum to Kelly Bushing. Click Ok to apply the changes. Now the Log Display window shows the depth values relative to KB.

72

Another method to find values in the logs is to use the Curve View display. Click on the Curve View and zoom in until the bad data point is clearly visible. Click on the Highlight icon.

73

Using the cursor, highlight the area around the spike (start from the top and drag down). The zone will be highlighted in yellow. Now, go into the Density table view…

74

The area that was highlighted in the Curve View is now highlighted in the Log table view. (If this doesn’t work, start a new Well Explorer window and try again).

75

Select the row with the bad data point by clicking somewhere in the row.

Use Log Data Options > Delete Selected rows from table to remove it. Click Update and Yes to apply the edit.

Now go back to the Curve View. The data point has now been removed.

76

In the Log Display Window, the edited data point may still be visible in gray.

If the edit is not visible, or if you want to turn it off, you can change this in the View > Display Options menu and toggle on/off Previous Log Curves in the Layout tab. 77

Click on the History tab of the Well Explorer to view the history of the log.

You can add your own comments to the History file if you want to have more details. Click File > Save to save your comments.

-- End of Exercise 2 --

78

Exercise 3: Well Log Data Management We will now load a new Geoview database – one that contains multiple wells – and look at more data management tools.

On Geoview, click Database > Open and select the blackfoot.wdb well database. Click OK. It will take a few seconds to load.

79

This database has 23 wells already loaded; these are a mixture of vertical and deviated wells. Geoview has the ability to filter the well list. This allows the user to list all the wells within the database that contain a particular log type.

80

For example, to find all the wells that start with 1 and contain a Gamma Ray, enter 1* in the Well name field, select Gamma Ray as the Log type and “apply to wells and logs”. Click Apply Filter

81

The result will be a list of the 8 wells that satisfy the Well name and Log type conditions.

82

Click on the Summary Report , change the data analysis range and then Generate Report. This will produce a report of all the statistics for the Gamma Ray logs in wells that start with 1* between the DINOSAUR PARK and MISSISSIPPIAN log tops. After, click Clear to remove the well and log filter. The full well list will appear.

83

Now, on the Log Type drop down menu, select Check Shot , “apply to wells only”and click Apply Filter.

Once the filter has been applied, only the wells that contain a Check Shot log are listed in the Table View. In this case, there are 3 wells in the database with a Check Shot.

Click on Curve View to graphically view the logs in the wells. 84

Click on the [+] in front of each well to expand and display all of the logs within the three wells.

Using the Ctrl key, select one of the DT logs in each of the three wells…

85

1 2

In the Curve View Menu, (1) select the view Profile Mode and (2) click on the Plot button…

86

1

Now, in the Well Data List, (1) using the Ctrl key, select the three Depth-Time curves for each of the three DT logs… 2 3

In the Curve View, (2) change the View Mode to Overlap Mode and (3) click the Plot icon. Two of the Depth-Time curves look similar but the generic31 log in well 03-21 does not look correct. It is actually a check shot log that has been incorrectly mapped as a depth-time table. 87

2

3

Let us remove the last track. (1) Look at the bottom of the display. The track with the Depth-Time curves is listed as Track 4. (2) Select Track 4 from the selection list and (3) click on the single red x.

1 88

1

2

We can also view the logs relative to a selected Log Top. (1) Select Flatten On Top as the Datum and (2) Select the BASAL BELLY RIVER from the list of tops.

89

Click on the eyeball menu to show the Curve View Display Parameters menu. Choose Tops on the sidebar and then select the “Label tops on all tracks”. This will let us see all the names of the tops.

Click OK.

90

Well 03-21 is missing several log markers. We can graphically add them using the Curve View display.

Missing 2 tops in this well.

First, click on the “Pick Tops” icon…

Then select Well 03-21 and enter the Top name as OLDMAN FM. (This top name is the same as in the other two wells).

91

This is just an exercise, but choose the depth location where you think the OLDMAN FM top is present in the 03-21 well.

1

(1) Click on the log track with the cursor, (2) Click Apply to create the top (3) Click Close to close the menu.

2

92

The new top will now be displayed in all three wells. If it is not shown, click on the View > Display Parameters and Show All Tops. Now click on the Base Map tab…

93

Use the Shift key to select all three wells in the Well Data List. The selected wells are now highlighted in red in the Base Map.

Remove the log filtering by clicking on the Clear button. Now all 23 wells are displayed in the Well Data List.

94

The default map is not to scale. Click Map Scale = 1: 50000 to display to scale.

Well locations are marked with the appropriate symbol for the well status. For deviated wells, the top hole locations are marked X. 95

We can also load culture information from DXF drawing files. Click Import Data > Load Culture Data Add All >> the DXF files in the DXF directory and Start Read. Then click OK.

96

The DXF files are now displayed as a map overlay.

Click on the eyeball menu and select Culture Data > Layer Selection on the sidebar. Select Show Culture Data and deselect the Pipeline Annotation.

In the Culture Appearance tab, change the Pipeline Thickness to 2. Click OK.

97

Now click on the cube icon to display the 3D well path viewer.

98

These options allow the user to display the well path cube from above or from either of the cube’s sides. The default is to display in perspective view. This mini-cube allows you to change the orientation of the display. Click & drag within this window. The cube will rotate accordingly.

99

Click View > Navigation Tools and switch the Orientation Controls option on. The Depth Scalar allows the user to set the vertical display scale. As you rotate the cube, the Rotation Angles will track the changes made. Using these controls and the View Location option, you can define the display precisely. This allows for consistency between displays. The Annotations allow you to chose whether or not to display the well names, tops etc. Further alterations to these annotations can be made under View > Well Annotations. When you have finished, close the window and return the Well Explorer window back to Table View.

100

Exercise 4: Log Type Mapping All logs within Geoview should be assigned a type. More than 60 types have been set up within Geoview, although it is possible to add more. These include: P-wave S-wave SP Temperature Saturation Gamma Ray Elastic impedance Caliper Density Porosity Resistivity … 101

From the Table View, access the log listing for Well 12-16. The log named DTS has no log type associated with it. One option is to select the log type from the selection menu. However, this requires that we do the same for every well in the database. We will use the mapping options to apply this change to all the wells.

102

On the Well Explorer menu, select Options > Log Type Override….

This menu will appear. Fill it out as shown here and click Apply. Click Yes to the confirmation request and Yes to reload the data.

103

The DTS log is now defined as type S-wave.

This process was applied to all the wells in the database that had a log named DTS. The messages in the menu show which wells were affected.

Now, let’s confirm that the S-wave logs look reasonable and have the correct units by showing them as a log profile in the Curve View. 104

Click on the Filters selection list and select Curve View Filter.

Then select the Advanced selections… button.

105

In the Advanced selections menu, Add All the wells to the Selected Wells list, and choose to plot the S-wave log with a fixed start and end range of 1000 m/s to 3500 m/s. Click Next > , Apply and Cancel.

106

The Curve View now shows all the Shear-wave logs plotted at the same scale.

-- End of Geoview Exercises --

107

Introduction to eLog eLog is the well log editing and interpretation software. eLog is run either as a stand-alone program or it is embedded within programs such as AVO, Strata, Pro4D and ProMC. Functionality available within eLog includes: • Well-to-seismic correlations. • Fluid Replacement Modelling (FRM) - this is used to model saturated

log responses for AVO analysis. • Log cross-plotting. • Log generation from mathematical operations or applying standard

geophysical relationships. • Wavelet generation and extraction.

108

Log Editing Some log editing facilities are available on the Edit Logs sidebar button. Here are the options:

109

Log Blocking Blocking is used to block and simplify log responses. The blocking tool allows multiple logs to be blocked simultaneously. The interfaces between blocks are called boundaries. Here are the Log Blocking options available: 1. Automatic uniform: Automatically blocks the log with blocks of the given block size. 2. Automatic non-uniform: The defined average block size is used to determine the number of blocks within the depth range to be blocked by dividing the length of the range with the average block length. Based on the guide log response, the blocks are defined to describe the largest changes in that log response using a maximum-likelihood algorithm. In both cases, the smaller the defined average block size, the better the blocked description of the logs. 3. Single: A single block is inserted covering the defined depth range. 110

Draw Tool Used for manual editing of logs Inserts straight lines between user defined points (left mouse button) Simply click on the line ends and apply (right mouse button to end)

111

Math Tool The Math tool interface consists of a list of selectable Math options and a description of the operation. The next slides will discuss the Running Average, Clip and Median Filter for filtering noisy logs. As well, we will discuss some other important functions available in the eLog Math menu.

112

Running Average Filter The Running Average filter is sometimes used for removing noise spikes from well logs. The process is: An averaging window length is designed for the log. The values in the window are then added together. The sum is divided by the number of samples in the window to yield the average value. This computed average value then replaces the actual log value at the window center location. The window moves down a sample and the process is repeated. The result of the Running Average filter is similar to a low-pass frequency filter. The longer the averaging window, the smoother the result is. The big weakness of this method is that it is sensitive to spikes in the logs and, thus, it is not very robust. As well, the original log values are not retained after the averaging process.

113

Running Average Filter Example To demonstrate the Running Average, the filter will be applied to the following array with a window size of 3, repeating edge values in blue: x = [2 80 6 3] y[1] = Average[2 2 80] = 84 / 3 = 28 y[2] = Average[2 80 6] = 88 / 3 = 29 y[3] = Average[80 6 3] = 89 / 3 = 30 y[4] = Average[ 6 3 3] = 12 / 3 = 4 so y = [28 29 30 4] where y is the running average filtered output of x.

114

Running Average Filter Original Sonic Log

3 Pt Avg.

7 Pt. Avg.

11 Pt. Avg.

115

Clip Clip is another process commonly used for removing noise spike. The user identifies a maximum and minimum value in the log amplitudes. The algorithm then searches for these spikes and either replaces them with the user-specified clip value or replaces them with the preceding good value. The Well Explorer Summary Report can help with identifying the minimum and maximum range of values for a log – but the minimum and maximum clip values are still subjective. The weakness with this method is that noise spikes may still exist that are within the min/max limits.

116

Clip Original Sonic Clip & Replace by Clip & Replace by Log Preceding Value Min/Max Clip Value

117

Median Filter The Median Filter is a non-linear filtering technique, well-suited to removing noise from signal. The process is: The values in the window are sorted into numerical order; the median value (i.e., the sample in the center of the window) is determined; the median value then replaces the original log value at the window center location. The length of the window determines how long a noise burst has to be after which it is not considered noise and it will be retained. The general description of the median filter length is m = (2n + 1) where n is the length of noise. For example, in a 3 point median filter, noise samples of length n=1 will be removed. In a 15-point operator, noise trains of length 7 or less will be removed. When working with well logs, we generally want to remove noise spikes that are of length 1 or 2 samples. Median filter lengths of 3 and 5 are common for log filtering.

118

Median Filter Example To demonstrate the median filter will be applied to the following array with a window size of 3, repeating edge values in blue: x = [2 80 6 3] unsorted sorted y[1] = Median[2 2 80] = Median[2 2 80] = 2 y[2] = Median[2 80 6] = Median[2 6 80] = 6 y[3] = Median[80 6 3] = Median[3 6 80] = 6 y[4] = Median[ 6 3 3] = Median[ 3 3 6] = 3 And the result is: y = [2 6 6 3] where y is the median filtered output of x. The 1-point noise spike is effectively removed by the 3 point filter. For comparison, the running average filter results were: y = [28 29 30 4] 119

Median Filter Original Sonic Log

3 Pt Median

7 Pt. Median

11 Pt. Median

120

Filtering P-wave Logs In most cases, you do not have to think much about the consequences of filtering logs. The exception is the P-wave log. This log also has a depth-time table attached to it. Whenever you do any process to the P-wave log, you will also have to make a decision about what you want to do with the associated depth-time table. In most cases, you have two choices: recreate the depth-time table or use the depth-time table of the original log. If you have already applied check shot corrections or correlated to the seismic, you will want to use the depth-time table of the input P-wave log – otherwise you will have to reapply the check shot correction or re-do your correlations to the seismic.

121

Log Maths Log Maths allows you to programmatically create your own mathematical function. The scripting language is based on the C programming syntax. Similarly, a Trace Maths and a Map Maths tool is available for seismic volumes and maps. Examples of Trace Maths and Log Maths scripts can be downloaded from the Hampson-Russell web site. 122

Log Maths Log Maths also has simply script functionality for easily creating classification logs.

123

Splice The Splice option has two different uses: to splice a portion of a log into another log, or to copy a log.

124

Transforms Tool The Transforms menu has the same format as the Math menu. It allows the same transform to be applied to multiple logs. A description of the function is also provided.

125

Castagna’s Equation

Castagna’s equation is an empirical relationship between Vp and Vs. ARCO’s original mudrock derivation (Castagna et al, Geophysics, 1985) is:

Vp = 1.16 Vs + 1360 m/sec The two coefficients can be changed to match your reservoir trend. This is one common method of estimating shear wave logs – but it does not apply to gas sands.

126

Gardner’s Equation Gardner’s equation is an empirical relationship between Vp and Density. The Gardner equation (Gardner et al, Geophysics, 1974) is:

ρ = 0.23VP

0.25

for V in ft/s and density in g/cc.

127

P- and S-Impedance The equations for the acoustic impedance (AI, Zp) and shear impedance (SI, Zs) are well known:

AI = ρVP SI = ρVS The transform simply multiplies the (P or S) velocity log with the density log. If the density log is missing, the system will then use a Gardner-type relation to estimate the density log. For wells with missing density logs, the transforms become:

1.25

AI = 0.23 ∗ VP 1.25 SI = 0.23 ∗ VS

128

Elastic Impedance and Elastic Density Connolly(1998) proposed an impedance concept for non-zero offsets called the Elastic Impedance (EI) : VS2 ( 1+ sin 2 θ ) ( −8 K sin 2 θ ) ( 1− 4 K sin 2 θ ) where K = 2 VP P S

EI (θ ) = V

V

ρ

Note that if θ=0o, far offset EI also reduces to Acoustic Impedance (AI), i.e.,

AI = ρVP

The Elastic Density log was also introduced in the same 1998 paper. The Elastic Density log is a log of type Density that is found by dividing the Elastic Impedance (EI) log by the P-wave log, i.e.,

Elastic _ Density (θ ) = EI (θ ) / VP The benefit of this log is that the P-wave log remains unchanged and, therefore the depth-time table remains the same. The elastic impedance information is now only contained within the density log. The product of the Elastic Density and P-wave log is the EI log which allows you to extract wavelets at different angles and still use the correct Depth-Time curve. 129

Faust’s Equation In many older fields, the only logs that are available are Resistivity logs. It has been observed that, in wet clastic rocks, the resistivity log and the Pwave sonic tend to track each other. A number of empirical relationships have therefore been derived to allow the geophysicist to derive a P-wave velocity from a resistivity log. The oldest relationship is from Faust (Geophysics, V18, p271-288):

VP = a ( Rd )

c

where a,c = constants R = resistivity d = depth

130

The FRM tool FRM is an acronym for Fluid Replacement Modelling.

• FRM uses the Biot-Gassmann rock physics equations to model the impact of the presence of fluids on log response. • Fluid replacement modelling requires input P-wave, density, Swave, and water saturation logs and information about the fluid and matrix properties. • FRM can also be used to correct Castagna S-wave log estimates for the presence of gas. • FRM also contains the Greenberg-Castagna method of shear wave estimation. The FRM tool is an important but complicated tool and is dealt with in more detail in the AVO course.

131

Log Cross-plots Cross-plot two logs with a third log as colour attribute. Regression functionality for determining relationships between logs. Identify zones on the crossplot and their location in the logs.

132

Cross-plots Many different data sets can be analyzed in a cross-plotted in a project. Also, each cross-plot analysis is stored in the software and can be recalled using the Cross-plot Archives. It is a good idea to give each cross-plot a name so that you can identify and view it later in the project. i.e., the well-log xplot of the PImpedance vs. S-Impedance

133

Cross-plots For each cross-plot analysis, you will probably want to identify areas on the cross-plot. These areas are called zones. The zones are defined from the cross-plot axes (type, units and range). The set of zones for each cross-plot is called the zone filter. It is a good idea to give these separate and identifiable names for better visual displays and to help you in your work.

Zones Zone Filter 134

Cross-plots Zones are easily edited. Edit Zone Handles

Bulk Shift Zones

Overlapping Zones

135

Cross-plots You can also display and create well logs of the cross-plot interpretation.

136

Exercise 5: eLog From your current Geoview database, click on the eLog button…

and Start New Project. Call the project blackfoot.

137

The eLog main window will appear and you will be prompted to select a well. Choose the 08-08 Well and click Open. The well log data will appear in the eLog window. Click on the View > Display Options to set the viewing parameters.

138

On the Layout page, click on the Clear All Tracks button. Now select to display just the Gamma Ray (GR). Click OK.

139

Click on Edit Logs. Select Block > Automatic non-uniform and 1 m block size. Click Apply.

Click Ok on the subsequent message window. 140

Click on the Vertical Zoom button a few times to zoom in on the log. Log Blocking can be used to simplify logs and reduce the amount of data in a well log. With modern computers, there is no longer such a need to block logs. However, blocking the Gamma Ray log may be a helpful process to repair the smearing effect of the moving log tool and improve the definition of sedimentary bed layers. Click Ok to finish editing the logs, give the blocked Gamma Ray log a new name, such as GR_1m_Block, and click OK to save the log.

141

In the eLog Display Window, click View > Display Options to change the display parameters. On the Layout menu page, select to Display Only Active Logs and deselect the Original Log Curves option. On the Curves page, set the parameters as shown below with Fill Option = Fill By Amplitude, Fill Colour = Use Color Key and Curve for Ampl = the blocked Gamma Ray log. Click Ok.

142

In this display, low Gamma Ray values are more easily identified with the green fill color. Low gamma ray values are a good indicator of sands. We can improve the interpretation of this well by examining the other logs.

143

Fortunately, the petrophysicist has created a log display template file that we can import into this project. The name of the file is called Blackft_Petrx_baseView.vwtmp. We can import this file so that all the log displays will be consistent with the other petrophysical work. Click on the View > Display Options menu and then go to the Template page. Click the Load… button.

Find the file called Blackft_Petrx_baseView.vwtmp in the HRS_DATA\geoview_data directory and load it into the project. Click OK on the Parameter Menu. 144

The eLog Display should now appear like the following. By overlaying logs and using color fill, the interpretation of the well logs is greatly enhanced.

145

Low Gamma Ray values are indicators of clean sands. Deflections in the SP curve are indicative of bed permeability.

The separation of the Medium and Deep Induction logs indicate a difference in fluids with distance from the well bore caused by drilling mud invasion. A higher resistivity in the deep induction log indicates hydrocarbons.

When the Neutron Porosity log and the Density log are plotted in this manner, large separations indicate shales, close separations indicate sands and reverse separations indicate gas sands.

146

Further analysis can be performed by cross-plotting the well logs. On the side menu bar, click on the Crossplot > Vp/Vs vs AI …

Include other well logs such as the Gamma Ray and the Porosity log by adding them to the selection list.

147

Only include the 08-08 well.

Set the sampling to use the original domain values. Provide more details to the Plot Name such as: wlxplot_Zp_vs_VpVs 148

Click Next >> (twice). On the Set Domain Ranges page, select to crossplot the data from the TOP GLAUC VALLEY to the BASE GLAUC VALLEY tops. Click OK to display the Crossplot.

149

The crossplot window will appear: Note that the Color Key is currently displaying the vertical depths of the crossplotted P-Impedance and Vp/Vs pairs.

We can display the color to another attribute such as Gamma Ray. Select the Gamma Ray from the color selection list.

150

Your crossplot should now look like this with the Gamma Ray values plotted in color.

151

We can highlight areas on the crossplot and identify them on the well logs. Click the Zones button and select Add… “Zone Filters” are collections of crossplot zones. You can have many Zone Filters in a project and a separate name can be used to distinguish the Filters. Similarly, the Zones can be distinguished with proper names. Change the current filter name to “08-08: Zp vs VpVs”.

Change the name of the Current Zone to “gas” 152

Change the zone Drawing Mode to Polygon. Double clicking the Color Selection will allow you to change its color. Change the color to red.

153

Click the outline over the set of data points as shown. The points will be highlighted red. A right mouse click will close the polygon.

Click Apply on the Add Zone Menu.

The points will now be colored within the zone. 154

Click the Cross Section option to see these zones located on the computed Impedance and Vp/Vs Ratio logs. You may need to zoom in.

155

The highlighting of points is two-way: you can also highlight a section of log on the cross section and see where it is on the cross-plot. First, select the drawing tool on the cross-section.

Then, draw a rectangle around the log pairs that you want to highlight on the crossplot. The selected points will flash on the crossplot. The flashing is disabled by clicking on the other icon. 156

Let’s add some more interpretation to our crossplot. On the Add Zones menu, click Add new zone at the Current Zone Selection list and name the new zone “wet”. Change the color to yellow.

157

Add the wet sand zone something like this …>

158

Add another zone called shale, and set the color to grey. Select the zone around all the high gamma ray values and click Apply. Click Ok to save the Crossplot filter.

159

We can make a new crossplot with the other data that we included. Select Porosity from the y selection list.

The crossplot now displays Porosity versus P-Impedance. We can filter out the shale data based on the Gamma Ray values. Click Filter > Filter Points to remove the high gamma ray values associated with shales.

160

In this example, filter out the gamma ray values that are greater than 50. Click OK.

161

We can now use the crossplot data to determine a relationship between the acoustic impedance and porosity for the sands.

On the crossplot window, chose the Regression > Least Squares option.

Keep the defaults for the Regression Menu and click Ok. 162

A regression line appears on the crossplot. The regression and the normalized standard error for the line is given at the bottom of the crossplot window. Finally close the crossplot window (File > Exit) or use the exit door icon.

Click Yes to save the crossplot in the project. 163

In the Log Display window, click on the Eye icon to display the Display Parameters Menu for eLog. Go to the Layout tab. On the bottom right of the menu, choose the Zone Filter that we just created by clicking on the […] selection button. Choose the Computed Impedance as the X log and Computed Vp/Vs as the Y log.

164

On the Layout matrix, select to display the Computed Cross Plot Zone in it’s own track.

165

On the Curve menu, set the Computed Cross Plot Zone display options as shown.

Start Ampl = 0, End Ampl = 3, Color = Grey, Fill Option = Fill By Amplitude, Fill Color = Use Color Bar, Area = to Edge on Left, Curve for Ampl = Computed Cross Plot Zone. Click Ok to display the projected crossplot log. 166

The projection of the well log crossplot interpretation verifies our previous well log interpretation. This indicates that a successful pre-stack seismic inversion could allow us to identify gas sands, wet sands and shales.

167

Let’s display the Vs log. In the View Display menu, display the DTS log in a new track and click OK. We can see that we only have the Vs log in the bottom part of the well.

168

Let’s try and create a Shear wave log for the upper part of the well. Click on Transforms…

Select the Castagna’s Equation and choose all the defaults on all the pages. We’ll only create the transform in the 08-08 well.

Click Ok on the Transforms menu and then click OK on the subsequent warning message.

169

The new Shear wave log is added to the Log Display window. It now extends to cover the same range as the DT log. Note also that the Computed Vp/Vs log and the Computed Cross Plot Zone logs have changed. The new cross-plot log is missing the interpreted gas sands. This is because the Castagna equation applies only to wet sands. 170

Click on the eyeball menu and deselect the Display Only Active Logs. Add the DTS log to the same track as the Castagna Shear Wave.

In the Curves tab menu, change the Shear wave log to have the same units and the same log range. Click Ok.

171

The two logs are now shown in the same track. Now we will create a new Shear wave log that uses the actual well log and uses the Castagna transform where we don’t have the shear wave log.

172

Select Math > Merge and the 08-08 well. Select the two Shear wave logs and set the Output Log Type to S-wave and units m/s. Click Next >.

173

Name the output log S-wave_merge.

On the next page, select to use the original measured DTS shear wave log. The rest of the log will be filled with the predicted Shear wave log.

174

The new merged Shear wave log is added to the display. Also notice that the Cross-Plot Log is also updated. This is because the new S-wave which is used to compute the Vp/Vs log is now the active shear-wave log.

175

Let’s re-examine the Active Logs again. In the Log Display window, the Active P-wave, S-wave and Density Logs are denoted with an *.

Now click on the eyeball menu, Layout tab and click on the Active Logs… button. Click on the S-wave Active Logs cell. Notice that all S-wave logs are available. Selecting any log will make it active. Click Cancel. 176

We can now move our interpretation to another well. Rather than opening the previous log display template, we can save the current log display as the default project template. Select the Display Only Active Logs option on the layout tab page. Then, on the bottom of any menu, select to Save settings as project template and then select Yes on the following warning window.

Click Ok to close the Parameter menu window.

177

Now click Open Well… from the sidebar menu.

Select Well 05-16 and Open in new window and Use project template when open.

Click Open.

178

A new eLog window will open with 05-16 well. This well does not have a S-wave log and so the Computed VpVs Ratio log is not available nor is the Computed Cross-plot. Also, notice how spiky the DT and the Computed Impedance log are. Filtering the DT log will help to remove the noise spikes and create a better Impedance log. You can try this if you have time.

179

Now, click Project > Save. The software will determine that there are differences now between the external Geoview database and the eLog project database. Click Yes to see what these changes are.

The software found the new blocked Gamma Ray log in the project – which is not found in the Geoview database. Click Deselect All to choose not to import these logs at this time. Now click OK. -- End of Exercise 5 --

180

Exercise 6: Log Classification The exercise is designed to illustrate how to quickly create logs condition classified logs. For example, we want to create a simple log based on porosity with the following values: 1 = Poor Porosity ( < 7%) 2 = Average Porosity 3 = Excellent Porosity ( > 20%).

First, click on Open Well and select 0108 and open in a new window.

181

We will apply the process to multiple wells that contain a Porosity log. First, select Math > Log Maths

Then add the first 4 wells to the Selected Wells list.

182

Select the Porosity log and set the Output Log Type to a new class called Porosity_Classes with unit = unitless.

183

The output logs will be called Porosity_Classes_math by default. On the “Set log variables” page, select the “Define simple script” option.

184

Using the drop down selection lists, enter the first condition for Porosity values less than 0.07. Then Add the next statement: THEN Output = 1.

185

Continue on to add the other statements: eg.: OR Porosity > 0.07 AND Porosity 0.2 THEN Output = 3.

When you are finished, click the OK button to create the new logs in the four wells.

186

The new log is now added to the well.

187

-- End of Exercise 6 --

Seismic Data Loading STRATA / AVO / ELOG Input seismic data is not copied to a project during loading. It is only registered. So operations such as cutting trace length are not possible.

.prj

Input data 188

Created SEG-Y’s are in the seismic.dir Seismic volumes created within HRS are, by default, placed in the seismic.dir directory in the project .prj directory.

189

Information Files When a SEGY volume has been ‘loaded’, an information folder and information file (.inf) are created, with exactly the same name as the SEGY. These files are read by the project whenever the SEGY is used again

If subsequent loading does not seem to recognise the changes you are trying to make, it is beneficial to delete the information folder and file so that they are not re-read by the loading process.

190

Loading Seismic using .vol If the folder and .inf file are kept together with a SEGY that has previously been ‘loaded’ to HRS or created by HRS, it is possible to avoid the scanning stage of loading by reading the .vol file found in the folder.

191

Seismic Loading

Unless there are separate source and receiver XY’s for pre-stack data, select ignore receiver X&Y coordinates

The slider bar can be used to check header values throughout the volume

192

Seismic Loading: Coordinate Scalars

Sometimes coordinates may be scaled by 10, 100, 1000 or -100, etc.

193

Seismic Loading: XY Corner Points

If no coordinates are present in the trace headers, it is still possible to define XYs by corner points, or origin and orientation. 194

Seismic Loading: volume in parts

If a single volume is divided amongst more than one dataset, this method will recombine them into a single volume.

1

2

3

First, load all the files at the same time…

195

Seismic Loading: volume in parts

Merged volume indicates the parts will be formed into a single dataset.

196

Seismic Loading: volume in parts

It is important that the volume name is identical for all parts.

197

Seismic Loading: Multi-2D Seismic Lines

Select 2D line Select Grouped volume

This method allows you to load multiple 2D seismic lines and group them together into an easy-to-manipulate volume.

198

Seismic Loading: Multi-2D Seismic Lines

Wells are tied to the nearest 2D line and the distance to the line is calculated. You may change this if you want.

199

Seismic Loading: Multi-2D Seismic Lines

Cursor movements in the seismic window will be tracked on the map. Each 2D line can be shown in turn using the pull down box below.

200

SeisLoader SeisLoader is our experimental seismic loading utility program, available to all HRS users. In the future, this interface will be available in all of our software. SeisLoader does have some additional software features that could be of interest. For example, the ability to view individual traces within the file without loading.

201

SeisLoader Also, various QC plots can be viewed.

202

SeisLoader As well, SeisLoader has the ability to edit the SEGY file headers. For example, to add in the angle value for an angle stack.

203

Data Explorer Data Explorer is in all the current HRS software programs and provides details of all data within the project.

204

Data Explorer Including the history of each volume

205

Data Explorer And the exact location

206

Deleting Seismic Deleting seismic can be done in the Data Explorer window.

Created by HRS Input SEGY

207

Exercise 7: Seismic Data Loading In the eLog window, select Seismic > Open From SEG-Y File… and select the seismic.sgy file in the Seismic directory.

208

Choose the 3D option and Next >. On this page, we will choose the volume name to be the same as the file name. Click on Header Dump… to view the SEGY file headers.

209

The EBCDIC header may show useful information about the byte locations, but it cannot be relied upon. Change to Display the Trace Headers.

210

In this dataset, the seismic information regarding the data location is written into the Trace Headers. In this case, each data word is a 4 byte integer. Each cell represents one data word. The IL / XL (181, 185), and X / Y (73, 77) are shown. After verifying the header bytes, Close the window.

211

On the Next page, fill in the correct byte locations. Also, select to Ignore the Receiver X & Y coordinates. You can use the slider bar at the bottom to view all the trace header values in the file. Click on the Detail Specification… button.

212

SEGY’s imported from some interpretation systems eg Seisware, may not contain the fields in the red box, but they are readily entered

The start time is worth checking Click OK to exit this window.

213

Click Next> on the data loading menu. The system will now scan the data. Click Yes to begin the scan.

After scanning, the software’s interpretation of the volume geometry will be shown and can be edited if necessary. Click OK.

214

The software then opens up two windows: the Well To Seismic map menu and the seismic window. The Well To Seismic Map displays the seismic Inline/Xline location that is closest to the well’s X & Y surface location. Click Ok.

215

To verify that the volume is correct, click on ‘View’ and then ‘Base Map’

216

In the base map, click on ‘View’ and then ‘Show Fold’

217

It is possible to move around the volume by either selecting IL’s or XL’s or by double clicking in the basemap Select Crossline 49.

218

On the Base Map, click on Arbitrary Line > Start Drawing…

Click Next > on the first page.

219

Select Create new nodes at well locations… From the well list, select the following wells and click Ok.

220

Click the Update graph from table to see the location of this line. Alternatively, you could have created the line on the Base Map. Click Next > and Ok to create the SEGY file of the arbitrary line.

221

The resulting file is a SEGY file of a 2D line. The red and grey inserted lines represent logs that are in the plane of the 2D line and the grey logs represent the projected out-of-plane logs.

222

Click on the eyeball menu to access the seismic display parameters. Select the Insert tab. Change the Inserted Curve to Gamma Ray. Select the Tops tab and select All Tops and Names on the Left. Click Ok.

223

Click on File > Exit all seismic windows and the File > Exit Project in the eLog window.

Click No to not export the new well logs into the external Geoview database.

224

Now, using the Windows Explorer, open up the C:\HRS_DATA\geoview_data folder.

In this folder, we can see all the original data plus the two databases that you created in this workshop and the eLog project.

Click on the Seismic directory to view its contents. Notice that we have the original SEGY file as well as a .inf file and a directory, all with the same name as the SEGY file.

225

Also notice that you can navigate into the project directory. If you explore deep enough you will find the internal.wdb, the internal well database.

If you view the project folder while the project is open in eLog, you will see a number of temporary directories. This is for crash protection. Doing a File > Project Save will write the temporary directories to the permanent directories. If you open the the project after it has crashed, the system will see the temporary files and realize that it exited abnormally last time. You are then given an opportunity to attempt to open either the unsaved project (i.e., read the TMP directories) or open the last saved version (i.e., the permanent directories) of the -- End of Exercise 7 -project.

226

Moving a Project The links between the 3 parts are important.

.wdb

.prj Input seismic data 227

Moving a Project This example shows a well database and project that has been moved.

228

Redirecting a moved .wdb In Geoview, we can open up the recently moved well database without problem…

Database Open

229

Redirecting a moved .prj But opening up the project, we may start to see some warning messages…

230

Moving a Project The first warning message says that the project previously was tied to a different well database that is no longer found…

231

Destinations for Input Data Geoview / Well Explorer

STRATA / AVO / ELOG /etc..

.wdb Logs, Tops, Culture & Deviated Geometry

.prj

Seismic & Horizons 232

HRS Projects and Well Databases When a user launches the eLog (or any other HRS ) software, the system forces the user to open a project: either an existing project or start a new project. When a project is created for the first time, the well log database shown in Geoview (called the external database) is used in the project. The name of the well database that the project is using is displayed in the lower right corner of the eLog main window.

Changes that are made to the well logs in the project are stored in the project in an internal well database. Changes made to the well logs in the project do not automatically appear in Geoview – until the databases are synchronized.

233

External and Internal Databases Geoview / Well Explorer

STRATA / AVO / ELOG / etc…

.wdb The external database

internal.wdb

.prj

234

Moving Input Data When the seismic SEGY file is moved, it’s a good idea to also move the information tag-along files.

Input data moved as a set of 2 files and 1 folder

235

Moved Input Data 1 When you try and open the seismic in project that has recently been moved, the software will display this warning message, asking you to select the directory where the files are now located.

Looking for the information tag-along files

236

Moved Input Data 2

Simply select the directory where the moved seismic files now exist.

237

The Help Menu

Help > About Geoview This will display the program information screen with the • software version number, • compilation date, and • software support contact information.

238

The Help Menu

Help > View Runtime Messages This will display the software runtime debugging messages. This information can be useful in debugging difficult issues. The information is written to a file on the disk.

239

The Help Menu Help > System Tests This will allow the user to perform basic system tests to ensure that their system is operating correctly. Help > Internal Data Viewer (dbEditor) Hampson-Russell information files are stored in binary format. This viewer will allow you to view the information in ASCII format and edit it, if necessary. However, only do this if a HRS technical support person tells you to do this – you can badly corrupt your well database and projects if you are not careful.

240

The Help Menu Documentation

Guides are tutorials that describe the basic workflow for each program.

New Features document the new features in major release updates such as CE8R1.

241

The Help Menu Documentation: Hampson-Russell Assistant

The Hampson Hampson--Russell Assistant is a searchable documentation utility that describes the program operation in detail.

242

Knowledgebase More documentation can be found on the CGGVeritas website under Hampson-Russell > Knowledgebase. The Knowledgebase is a categorized repository of PDF documents of various topics and is available to everyone.

243

Summary Geoview is the Hampson-Russell program launcher and also holds the well database. The Well Explorer is used to manage the well database. The Well Explorer is the program that is used to load the wells into the database, view the logs, the base map, the 3D well paths and the well log statistic reports. Depth-time curves and P-wave logs are always tied together. The default depth-time curve is computed internally by the software and can be modified by applying check shot corrections or by correlating to the seismic. eLog is the program that allows log filtering, log cross-plotting and analysis, log maths, log transforms and log correlation. Hampson-Russell Software projects use two databases: the external Geoview database and the internal project database. Logs generated or edited in eLog are only applied to the internal database and can be exported back to the Geoview well database later.

244