Sitfal CLAS Lite Tutorial

CLAS® Tutorial

Computer Log Analysis Software

Código: CLAS_TUT Versión: 20151215

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CLAS® Tutorial

Computer Log Analysis Software

Table of ContentsCreate or open a Survey........................................................................................................3Data Import............................................................................................................................3

Single LAS Import..............................................................................................................3Basic Mode....................................................................................................................3Advanced Mode.............................................................................................................5

Multi LAS Import................................................................................................................7Adding Markers..................................................................................................................8

Presenting Information...........................................................................................................9Logplots...........................................................................................................................10

Log Settings (Templates).............................................................................................11Saving and Loading Templates...................................................................................15

Crossplots........................................................................................................................17Crossplots Settings (Templates).................................................................................18

Histograms.......................................................................................................................21Histogram Settings (Templates)..................................................................................22

Computing Log Curves........................................................................................................23Creating a Temperature Curve with Trend Curve............................................................23Obtaining porosity from density.......................................................................................24

Editing Log Curves...............................................................................................................25Correcting SP Drift...........................................................................................................25View and Edit numeric sample values.............................................................................27

Open-hole log interpretation................................................................................................28Clay Volume.....................................................................................................................28Creating Flag Log Curves................................................................................................30

Numeric (Math) Method...............................................................................................30Graphic (Crossplot) Method........................................................................................31


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Create or open a Survey

CLAS® is an OpendTect plugin. In this tutorial the F3 Demo survey provided with OpendTect will be used.

Data Import

Single LAS Import

Basic Mode

From top menu bar, go to CLAS->Well->Import->LAS Import to find the Import window:

The LAS Import window in Basic Mode allows to quickly select a LAS compliant file and import it in a new or existing Well.

To do so, click the Browse button, then navigate to the examples folder provided with CLAS usually at:

C:\Program Files\OpendTect\6.0.0\SITFAL\CLAS\Sample_Files


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Select the file SAMPLE-1.LAS and click Open

To load the log curves into an existing Well, open the Select Well combo and find the Wellin the list. Finally, click Import and Close to finish the import process.

To load the log curves into a new Well, click the Create Well button.

The Import Well Track window will show up. Load the surface coordinates, well elevation and total depth.

Enter the Output Well name and click Import. Then click Close and go back to the LAS Import window.


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Advanced Mode

To make changes to the LAS Import defaults and have more control over the incoming data, the Advanced Mode can be enabled.

This mode allows to select which curves to import, rename log curves, change the description field, assign units that were not automatically assigned and convert log curve units when importing.

Additionally, the Import Interval fields allow to select the depth range to import. An option to resample the incoming data is available. The If log exists field allows to change the default option to be performed when the imported log curve already exists within the Well.

NOTE: CLAS imports files preserving their original sampling and works without a specific sample rate allowing to preserve the original data and to mix different sample rates within a Well. It also allows to import and work with Core or Dip data that is not regularly sampled.

For special cases CLAS has a Default Sample Rate for Meters and Feet that can be changed at CLAS->Tools->Config Management


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On the Well Information tab, the Well Header information is loaded and can be edited by the user.

On the Parameter Information tab each Run info is loaded and can be edited.

New Runs can be added by clicking Create New Run.

All this information is preserved and can be later reviewed or changed in the

CLAS->Well->Well Editor menu.


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Multi LAS Import

To import multiple LAS files in batches the CLAS->Well->Import->Multi LAS Import menu can be used.

This window allows to import many LAS files at once.

Drag & Drop files from any folder or click the Add button to select multiple files.

Click Import and all selected files will be imported according to the following rules:

• If the LAS matches an existing Well, it will be imported into the existing well.

• If the LAS does not match, a new well will be created using the LAS file name.

The Log Details window will show the process results.


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Adding Markers

Under OpendTect through the Survey->Manage->Wells... menu, by selecting a well and clicking the Edit Markers button the Edit Well Markers window opens.

New markers can be loaded by typing in the Name and corresponding depth. Double-clicking the Color box allows to pick a new color.

Markers can also be imported from file, clicking the Import button.


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Presenting Information

Before using any of the imported wells, they must be opened. To do so, right-click the Wellentry on the Tree Scene and select Add.

Then, load the wells by selecting them on the list

The wells will be displayed under the tree.


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Logplots

The fastest way to open a Logplot is to right-click over a Well name and select the option CLAS Logplot. If not, the menu CLAS->View->Logplot will open a new window for the first available Well. A different well can be selected later under the Well combo at the top.

A very basic template is already available. Click the arrow on the upper right corner to show the header for each log curve.

Moving the mouse cursor over the Logplot area, automatically updates the Depth field on the bottom left corner with the actual depth value at which the mouse cursor points to. Also, the values of each log curve at that depth is updated on each log curve header.

Tracks and Curve headers can be dragged to a different position to alter the template.

On the status bar, the buttons can be used to plot the logs in horizontal or vertical modes. The Zoom and Scale sliders can be used to change the view, and the Reset button will return the Logplot to 1:1000 scale and a zoom that fits the width of the window. To set a fixed scale, the user can select a standard scale from the combo or type in a value.


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Log Settings (Templates)

Right-click over the Logplot to get the Log Settings window. This window allows to make changes over the Logplot Template.

The Curves tab allows to add, remove or change the settings for each log curve.

• Track: select the track on which the data will be displayed.

• Log/Alias/Value: a static number, a log curve Alias (denoted by the {brackets}) or aLog curve name can be selected to be displayed in the previously selected track.

• Left Scale and Right Scale: used to define the scale of the data to be plotted.

• Lin/Log: select the type of scale to use. Log scales only allows values greater thanzero on the Left Scale and the Right Scale value must be higher than the Left Scale (ie: 0.2 to 2000 for Resistivity logs).

• Backup: select the type of backup scale when the values go outside the Left and Right scales.

◦ None: no data is plotted outside the normal scale.

◦ Left: when the values are outside the Left Scale, the data is plotted from the Right side with a new scale, ie: with a scale 0 to 200, the new scale for the overplotted data will be -200 to 0.

◦ Right: when the values are outside the Right Scale, the data is plotted from the Left side with a new scale, ie: with a scale from 0 to 200, the new scale for the overplotted data will be 200 to 400.

◦ L&R: both the left and right modes.

◦ x10: when the values go outside the range on the Right Scale they plot from the Left side using a scale 10 times bigger, ie: with a scale from 0 to 10, the newscale for the overplotted data will be 0 to 100.

◦ x5: similar to x10, but the scale is 5 times the original scale.


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• Plot Type: select how the information will be presented on screen:

◦ Line: draws a line connecting each data sample. Its color and width can be changed, as well as the line type (continuous, dashed, dotted, etc.)

◦ Dip: for each sample, it displays a symbol where the sample data value locates the symbol at the track (from left to right), and a secondary data (from another log curve) controls the angle of its direction.

◦ Sym: for each sample, it displays a symbol. The size of the symbol can be fixed,or controlled by secondary data (from another log curve).


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◦ Color: fills the track with colors according to a Color Scale and data values.

• Visible: turns on or off the display of that row.

The Tracks tab controls the available tracks and its properties.

Each row represents a Track. Track properties are:

• Name: displayed in the Curves tab and the Logplot header.

• Depth: if enabled, it plots the Depth as Text in that track.

• Width: controls the width of the Track proportional to each other on the screen and fixed size in inches when printing.

• Divs/Dec controls the amount of divisions on a Linear scale. If the log curves displayed on that track are in logarithmic scale, the decades are automatically derived from the Left and Right Scales. The first curve on that track has priority and controls which type of scale it has.

• Freq: the frequency used to plot the Depth text labels. Zero means auto; depth label frequency will change according to the logplot scale.


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The Shading tab allows to shade log curves:

By selecting the Track, the Curve/Value fields will display available curves. Shadings can be configured between a numeric value and a log curve or between two log curves.

The Markers tab allows to turn on or off the well markers on the logplot.


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Saving and Loading Templates

Templates changes are automatically stored for the actual Well and will be loaded the nexttime the view is opened. To use the same template on a different well it must be saved with a name, and then loaded in another Well.

To do so, use the Save and Load Parameters buttons.

Project Templates are stored inside the actual Survey and can be used on different wellsinside the same project.

User Templates are stored inside the user's home directory and can be used in any well from any Survey.

Change Type to User Templates and select the 6-track_interp template. Then click Apply to set it. The Logplot will change.


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Crossplots

Crossplots can be displayed using the menu CLAS->View->Crossplot

Crossplots have the following properties and tools:

• Multi-Well: several wells can be displayed in the same window.

• Multi-Log: several Y-Axis can be added.

• Symbols: can change according to the Well or the Log Curve.

• Colors: can be solid, depending on the Well or the Log Curve, or they can be controlled by a Color Scale and a Log Curve value.

• Data: can be turned on or off on the right panel.

• Matrix Lines: can be overlayed.

• Regression: this tool allows to draw or compute a regression curve.

• Polygon: drawing allows to select points to Export or create a Flag Log Curve.

• Points: are interactive. Placing the mouse cursor over a point shows its informationand interactively shows its position at the logplot. Pointing the mouse cursor to the logplot highlights the point in the crossplot.


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Crossplots Settings (Templates)

Right-click over the Crossplot to get the Crossplot Settings window. This window allows to make changes over the Crossplot Template.

The Wells tab allows to add, remove or change wells, depth interval, and if enabled, the Symbol or Color that represents points for that well.

CLAS allows to set the depth intervals as numbers or by selecting Markers from a list.

To display the Symbol column and enable the wells to control the Symbol, check the Well controls the symbol box. The symbol shape and size can be changed by clicking on the Symbol column for the well row.


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The X-Y Curves tab controls the X-Axis and Y-Axis log curves.

Options for this tab include:

• X-Curve: a Log Curve Alias or Log Curve Name and its scales.

• Y-Curve: one or many Log Curve Alias or Log Curve Names and its scales.

• Log Curve controls the symbol: option to make each Y-Axis controls the symbol shape and size.

• Log Curve controls the color: option to make each Y-Axis controls the symbol color.

• Use Step: a Log Curve or Alias to define the sampling of the crossplot. CLAS is sample independent so it can present the crossplot points according to non-regular sampling rate (ie: crossploting log curve data vs. core data).


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The Z Curve tab defines the Color Scale and log if the Z Log Curve controls the color option box is checked. A log curve and its scales must be defined.

The Matrix Lines tab allows to enable or disable the overlays for Matrix Lines.


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Histograms

Histograms can be displayed using the menu CLAS->View->Histogram

Histograms can plot:

• Multiple well and log data.

• Bars with different colors and transparency.

• Cumulative frequency curve.


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Histogram Settings (Templates)

Right-click over the Histogram to get the Histogram Settings window. This window allowsto make changes over the Histogram Template.

For each row, the following data must be entered:

• Well: select a well from the list of available wells.

• Curve: select a Log Curve or Log Alias.

• Start and End Depth: set the interval to use, by numbers or markers.

• Line: select the line thickness, color and transparency.

• Shading: enable or disable painting the bars.

The Options section allows to:

• Set a Graph Title.

• Set a Left and Right Scale.

• Set the amount of bars.

• Set the Y scale. Zero means automatic scale.

• Show Cumulative Curve.


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Computing Log Curves

Creating a Temperature Curve with Trend Curve.

From CLAS->Calculus->Trend Curve the Trend Curve window can be opened.

Curves can be created using two different methods:

• Gradient: enter a Surface value and a Gradient.

• Points: values entered manually to a table or loaded from a text file can be interpolated to create a log curve.

For any of the two methods, the Output Unit can be set, and an Output Log Curve namemust be entered.

For every operation that outputs a log curve, the Use Step combo must be set. It controls the sample frequency of the output log curve. Selecting or entering a number will regularly space the information. Selecting another existing log curve will make the output log curve have the same sample spacing (regular or not) as the Use Step log curve.

Compute From and To define the compute interval. The output log curve will only be created between those depth values. Depth values are always Measure Depth. Markers can be used to set this interval, or values can be typed.

If the Output Log Curve already exists before computing, the newly computed samples will be merged with the existing samples, overwriting all existing samples in the computed interval, and preserving existing samples outside the computed interval.

If you press the Compute button, the temperature curve will be created.


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Obtaining porosity from density

Through CLAS->Calculus->Density menu porosity, density or matrix can be obtained.

The input parameters are:

• Compute: Porosity (also Matrix and Density can be computed)

• Density Curve: a numeric value, Log Curve Alias or Log Curve Name

• Matrix and Fluid Density: a numeric value, Log Curve Alias or Log Curve Name.

The input units are automatically set if the input curve has known units. If the input curve unit is set to None, the user can change the value of the Unit box to set it.

Press the Compute button to generate the Density Porosity curve.


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Editing Log Curves

Log editing in CLAS is interactive, and it is done inside the Logplot window.

Correcting SP Drift

To correct the SP drift, the log curve must be plotted in the Logplot window. With a right-click in the Logplot area, the pop-up menu shows up and the Edit->Baseline option enables the editing mode.

The mouse cursor changes to a crosshair, and the user has to select a log curve to edit byclicking over its line.

If more than one log curve is below the mouse cursor, different options will appear on the Logs section. Selecting one log curve changes the information below.

Once selected, the Edited Curve fields allow to set a new Log Curve Name for the output,the new scale, color and the Clay Line Value.


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Click OK to close the window and an editable temporary log curve will show up, overlayed on the track.

Using the mouse cursor to click on each shale point, the edited curve interactively changes and a trend curve is shown between points. With CTRL+click points can be removed.

When finished, right-click over the Logplot area to show the pop-up menu and select SaveEdited Log. The new log curve will be added to the actual Template.


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View and Edit numeric sample values

Using the Tabular Editor the user has the ability to view or change the information manually. This window is found under the CLAS->Edit->Tabular Editor menu.

Depth and Value columns data can be edited manually by typing in new values. Using themouse right-click over the table, the pop-up menu allows to Insert, Delete, Copy and Paste data.

Since CLAS is sample independent only one log curve can be displayed at a time. Samples can be removed or inserted at any point.

Depth values can be edited but they must remain between the previous and next values as the column values must always be in ascending order.

To store an edited table the Apply button must be clicked.


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Open-hole log interpretation

Clay Volume

Use the CLAS->Analysis->Clay Volume menu to open the Clay Volume window.

One or many log curve types can be used toghether to compute the clay volume. Each logtype will have its individual output log curve. The Total Clay Volume output log curve will be the result of the minimum of all computed log types.

The Outputs tab allows to set the output log curves name and units.


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If the computed log curve is already set in the Logplot template, it will immediately appear. If not, it must be added to the template. Any further changes or computes will instantly reflect the changes in the Logplot or Crossplot.


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Creating Flag Log Curves

Numeric (Math) Method

CLAS has a powerful math engine that can be used to perform formulas and logic functions that can be accessed by the CLAS->Edit->Math Editor menu.

Inputs are:

• IF: When checked, CLAS will evaluate the expression in this box. If the result of the expression is 0 (false) the ELSE math expression will be performed. Any other validnumeric value will be considered 1 (true), hence, the THEN math expression will be performed.

• THEN: This math expression will be evaluated when IF is unchecked, and when its checked and its result is true.

• ELSE: This math expression will be evaluated when IF is checked, and its result is false.

• Variables: These variables are math expressions just as IF, THEN and ELSE. You can type in any math expression.

• Output: Enter the output log curve name and its unit or keep default.

Help button opens a complete description of each field and all available functions.


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Graphic (Crossplot) Method

In a ND Crossplot (using the previously computed DPHI log curve) right-click over the Crossplot area and select the Select Points Start menu.

Digitize a polygon around the values by clicking to place a node and double-clicking to finish. Then right-click again and select the Select Points End menu.

Once done, right-click one more time to select the Create Flag Log Curve menu. This window will open:

Enter the output Flag Log Curve Name and click OK.


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The output should look similar to this example:

Green (left): Math flag

Red (right): Crossplot flag


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