OpendTect User Documentation version 4.2
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5.5. Manage

The "Manage" option can be reached in two ways:

5.5.1. Introduction

OpendTect keeps track of different files imported into or created by the system. Deleting, renaming and, in the case of seismic files, also merging of files are controlled from the Survey-Manage menu. Seismic file, horizon, and well management is called from this menu.

5.5.2. Attribute Set Management

The attribute set files can be managed from this window (See below). It is launched from Survey > Manage > AttributeSets... In this section, you can modify the attribute set name, set as default, remove etc. The window contains the buttons similar to that of general selection window.

5.5.3. Manage Faults

Fault management allows to manage the faults, different options are available: change disk location, rename, remove, copy etc. The fault management window can be launched either by pressing

button from manage toolbar, or from menu bar i.e. Survey > Manage> Faults...

This window will contain the list of faults interpreted and saved in the OpendTect project as shown below.

By highlighting the fault, use tools available on right.

is used to change the current disk location of selected faults.
is used to rename the selected fault.
locks the selected fault from interpretation.
is used to trash (delete) the selected fault.
is used to set a fault as default.
copies the faults.

Note: The top filter is used to filter-out the objects with selected names. For instance, to display all faults that start with letter F use "F*".

5.5.4. Manage FaultStickSet

This option allows the management of faultsticksets. Different options are available: Rename, toggle the faultstickset to read-only mode, copy it or set it as default.
The faultstickset management window can be launched either by pressing Manage faultstickset button from manage toolbar, or from menu bar i.e. Survey > Manage> FaultStickSet...

This window will contain the list of faultstickset interpreted and saved in the OpendTect project as shown below.

By highlighting the faultstickset (as shown in the figure above), use the tools available on the right.

is used to rename the selected faultstickset.
locks the selected faultstickset from interpretation.
is used to trash (delete) the selected faultstickset.
is used to set a faultstickset as default.
copies the faultsticksets.

5.5.5. Horizon file management window

5.5.5.1. Horizon manager 3D

To open the Surface file management window, choose the Manage horizons icon from the Manage data toolbar. In the left panel of the Surface file management window, the available horizons are displayed. In the right panel, the available attributes linked to the selected horizon will be displayed. It the bottom panel, information on the selected horizon is displayed (eg. location on disk, date last modified). At the base of the window the available disk space is noted.

Horizons can be renamed, locked, removed, copied, or their disk location can be changed. Attributes can be removed with the bin icon on the far right. The top filter is used to filter-out the objects with selected names. For instance, to display all horizons that start with letter D use "D*".

The following window is used to copy surface data and grids:

Stratigraphy

The user can assign stratigraphic markers to horizons by pressing Stratigraphy button.

Stratigraphic marker can be assigned to one or more horizons. The horizons will get the marker color, this will facilitate for example the well to seismic tie.
For more details on how to define stratigraphic markers and the subsequent units go to Manage Stratigraphy.

Relations

This option allows the check-crossing of horizons. To check conflicts with crossing horizons, select Survey > Manage > Horizon 2D/3D and press Relations...

The Horizon relation window pops up, Read Horizons ... The horizons are sorted automatically from top to bottom. Now Select the horizons you want to check crossings, then Check crossings...

Solving crossing conflicts:
To solve crossing conflicts select the horizon that will be modified. The software will check the number of positions where a conflict exits and modify the horizon by removing the conflict points or by changing the values to be equal to the overlying/underlying horizon.

5.5.5.2. Horizon manager 2D

To open the 2D Surface file management window, choose the Manage horizons icon from the Manage data toolbar. In the left panel of the Surface file management window, the available horizons are displayed. It the bottom panel, information on the selected horizon is displayed (eg. location on disk, date last modified). At the base of the window the available disk space is noted.

Horizons can be renamed, locked, removed, copied, or their disk location can be changed.

The following window is used to copy surface data and grids:

Note: The top filter is used to filter-out the objects with selected names. For instance, to display all horizons that start with letter D use "D*".

5.5.6. Pickset file management window

In this window, all available picksets are shown. When a pickset is selected, the properties of the pickset are displayed in the lower window. These picksets can be moved to a different location, they can be renamed, locked / unlocked, or removed or set as default by clicking one of the buttons on the right side of the window.

User can benefit by merging several pickset together using Merge Pickset Button.

Note: The top filter is used to filter-out the objects with selected names. For instance, to display all picksets that start with letter S use "S*".

5.5.7. Probability Density Functions management

This window allows the managements of Probability Density Functions. PDF may be either imported or extracted from crossplots, before being used for Bayesian Classifications or export.

Probability Density Functions can have either 2 or 3 dimensions. The above shown example has 3 dimensions, each taken from a seismic attribute. The icons on the right hand side allow to perform the following actions, respectively from top to botton: Rename, Lock/Unlock, Delete, Set as default and edit.

PDF Edition

PDF may be edited with respect to the names of the variables ("Names" tab, left), or in the table showing the stored values ("Values" tab, right). Changes applied in any of the two tabs will be saved only when pressing on "Ok". A popup window will give the choice to overwrite, save as a new, or cancel the changes.

The first icon right of the table launches a 2D viewer that displays the values seen in the table. If the PDF has 3 dimensions, the black arrows left and right are made to navigate through the bins of the third variable with increasing and decreasing values respectively.

The second icon in the table will perform a gentle smoothing of the PDF data. The smoothing is performed in the following way:

The algorithm collects all directly neighbouring points (thus not following the diagonal directions), given N neighbours in a step of 1 bin. The operator has to work in 1, 2 or 3 dimensions. N=2 for 1 dimension, N=4 in 2D and N=6 in 3D. Then the central sample value is added to the average of the neighbouring points, and the result is divided by 2. The centre therefore gets weight 1/2, while every neighbouring gets a weight of 1/2N.

This smoothing is rather gentle, and can be repeat by pressing repetitively in the smoothing icon.

5.5.8. 2D Geometry managment

2D Geometry is launched as shown below:

This window is used to manipulate the geometry of 2D seismic lines. The geometry consists of X-Y coordinate pairs for each trace of the 2D seismic, identified with a unique trace number (CDP most often). They are generally extracted from the SEG-Y trace headers or from an auxiliary file during import.

This window can be used to alter the coordinates of already imported 2D data. The geometry is separated from the actual 2D seismic data and 2D horizon that are solely referenced with respect to the trace number (CDP number). As a result the coordinates of the geometry can safely be edited without having to re-import the 2D seismic data and corresponding horizons.

This management window lists the linesets on the left handside, and the line names of the highlighted lineset on the right handside. Select the lineset first and then line, and click on the right icon to start the line geometry editor.

Line geometry editor

This editing window can be used to alter any trace number, X, Y values. Click on a field and type the new value. Changes with be saved on disk only after pressing "OK". Optionally one might want to update the geometry of the entire line by reading an text file (see below).

Line geometry import

Select the input ASCII file. You may display the input file by pressing the Examine button. The input file should be column sorted with one point per record (line).

The main work is to specify the presence of a file header and the file format definition. The header, if present, can be of fixed length (number of lines), or delimited on its last line by a keyword.

Predefined and saved file formats are available by pressing on the Open

icon. Otherwise the format must be manually specified. The Define button gives access to the format definition window.

You must specify in the format definition window the column numbers for the position, in terms of an X-Y pair, and optionally the trace number column. The coordinate units must be in the same units as the coordinates of the survey corner points. Inline/crossline value may be used instead of X-Y but it is not recommended because of the grid spacing. Also it is not recommended to alter (re-specify) the trace numbers since it may corrupt the already loaded data. Reading may be stopped at a specific line by providing the adequate keyword.

It is recommended to save the format definition for a later use and QC, by clicking on the save icon

. In pop-up window, write the name of the format and store it. The format can be stored at different levels (All surveys, This survey, Current OpendTect user level) depending on the usage. Press OK when done.

5.5.9. Seismic file management window

Seismic data should be managed from these windows. There are separate manager for post-stack volumes, post-stack linesets, 2D lines, pre-stack volumes and pre-stack linesets. They all use common management icons on their right hand side:

Change the location of the file on disk
Rename
Delete
Toggle read-only on/off
Set as the default object for its kind.

Note: The top filter is used to filter-out the objects with selected names. For instance, to display all volumes that start with letter S use "S*".

5.5.9.1. 3D Seismics file management

The 3D Seismic file management window lists post-stack volumes loaded in the survey. Information related to the selected volume is displayed on the bottom part of the window.

The following volume specific actions can be made from that window:

Copy the volume to another volume (different size, format, sampling rate, ...)
Merge several overlapping or consecutive volumes
Browse in the file
Access the pre-stack volume manager.

5.5.9.1.1. Copy cube

Any volume can be copied

into a new volume. All essential parameters can be set in the Volume subselection and Format / Scaling sub menus. Rectangular volumes are not required by OpendTect. Therefore null traces are dismissed by default. They can be added back with the "Null traces: add", within the inline/crossline range of the input volume. Larger volumes can be obtained while using the "add" option in conjunction with the volume subselection menu.

If the input cube is multi-component (e.g spectral decomposition cube with different components or SteeringCube), individual components of the cube can be copied. All components is set as default.

5.5.9.1.1.1 Volume sub-selection

This standard menu is available when importing/exporting a volume, line, or horizon, copying a cube or horizon, or processing an attribute.
In all those processes, the output might be limited with respect to the available input data. The limitation may be:

A rectangular part of the survey, possibly with a larger horizontal and vertical stepout
An area limited by an OpendTect polygon. The area within the polygon can be as well by decimated horizontal by using larger stepouts
A table of positions from an OpendTect pickset or from a text file. The text file should contain inline and crossline values without header
All: This last option will output the maximum number of trace with respect to the available data and possible stepouts

Notes:

The use of larger vertical stepouts will cause the data to be decimated in the given direction. Please note that an anti-alias filter (using the frequency filter attribute) should be applied before decimating data. The copy-cube does not do it.
The use of smaller vertical stepouts will cause the data to be interpolated with a polynomial interpolation. This is mostly appropriate for seismic data.
Volumes tagged as Vint, Vrms or Vavg are not using a polynomial interpolation of the input amplitudes, as soon as Z start, Z stop and/or Z step are changed. Instead they are converted to the corresponding time-depth relation that is linearly interpolated (vertically), before back converting the interpolated TD function to the input type.
The copy-cube option does not do lateral interpolation of the data (but it can decimate). Use the Velocity gridder step of the volume builder to laterally grid a coarse volume.

The copy

5.5.9.1.1.2 Format/scaling

This standard menu allows the change of the following elements:

Change between storage type. Please note that this might clip your data.
Scale the values given a linear equation.
Adjust the Z range to the survey range by repeating the bounding samples up and down.
Optimize the horizontal slice access. This will change the sorting mode in the volume on disk, and will cause inline/crossline accesses to be significantly slower based on the volume size.

5.5.9.1.2. Merge files window

Use this option to merge

small sub-volumes into one big cube. For example, OpendTect processing time can be reduced by distributing batch jobs (volume output) over multiple computers. This process can either be done automatically or manually. In the latter case, processing jobs are submitted to process sub-volumes on different remote computers. When all jobs are finished, the sub-volumes can be merged into a merged volume using this Merge files option.

When merging two cubes, the duplicate traces can be stacked when merging e.g. two seismic cubes (the merging cube will reduce noise) or the traces of the first cube can be used. Priorities are set in alphanumerical order, as the volumes appear in the manager from top to bottom.

Select the input files from the multiple entry list and specify the Output file name. The user can remove the original files at a latter stage (use the remove button in the seismic file manager).

5.5.9.2. 2D Seismics file management

2D surveys in OpendTect are grouped in linesets. These linesets have their own manager (below), separate from the 2D line seismic manager.

The following actions can be applied on linesets, in addition to standard rename/delete options:

Copy all or part of the lineset to a new lineset.
Dump the geometry (positions) to a text file.
Access the pre-stack 2D seismic manager.

5.5.9.2.1. Manage 2D Seismic lines

The lines in the selected lineset are displayed on the left panel, and when a line is selected the attributes that are available to that line are shown on the right panel. The lines can be renamed and the attributes can be renamed and deleted. When all attributes are deleted from a line the line is automatically removed from the lineset.

When multiple lines are selected in the left panel, the attributes that are available to all selected lines are shown on the right. In this manner entire collections of attributes can be renamed and removedsimultaneously.

The following actions can also be made on the lineset:

Merge of several lines to a new line.
Extraction (projection) of 3D volumes along the 2D lines.
Export of the geometry to GoogleEarth.

5.5.9.2.1.1 Merge 2D lines

The merge method is either of these three:

Match trace numbers: Assumes the line are at the same location, containing different attributes to be stacked and referenced using the same trace number array.
Match coordinates: Same as above, but with different trace number arrays. Then the match will be based on coordinates, with a search radius to match the traces. Please note that traces will be renumbered in this mode.
Bluntly append. Append the line specified at the "Add" field line after the "First line". Please note that traces will be renumbered in this mode.

5.5.9.2.1.2 Extract 2D attributes from 3D volumes

All lines may be processed, or a selection of lines made in the lines manager before going to this window. The settings are trivial: The 3D volume must be selected and an attribute name must be provided.

Please note that the polynomial interpolation does not fit an application of this tool to 3D seismic data.

5.5.9.2.1.3 Export of 2D geometry to GoogleEarth

Manage > 2D Seismics > Select lineset > Manage Lines > Google Earth.
In this window, the Google Icon

launches the dialog (see below) to export the 2D lines geometry in to a *.kml file. Different methods are supported (Start/End or both etc.) for labeling the line-names in the Google Earth file. The line color field is also editable. The width represents the thickness of the lines. The Output file field specifies the output location and name of the exported file (Format - kml).

Export the 2D lines in a Google KML file.

5.5.9.2.2. Copy lineset

This utility window can be used to copy (backup) one attribute from a lineset.

Pressing on the select button of the first line will allow the selection of which line(s) should be copied to the new lineset:

Please note that currently only one attribute from the input lineset can be copied.

5.5.9.2.3. Dump 2D geometry

With this module,

an ASCII file with the geometry of one or all 2D lines in the current lineset can be generated. By default, the output file contains only the X/Y location of each trace of each line. Optionally, the trace number (loaded from the original file) can be included as the first column. Optionally, the user can output a Z value in the last column of the output file.

This export facility may be very practical when you want to generate a base map from 2D lines for a different software package.

5.5.9.3. Browse/Edit Cube Locations

Cbvs files can be browsed/edited (edit the cube locations, positions, trace samples, etc) by pressing the

icon. The window will pop up as shown below. In this window sample values can be changed by editing any cell (similarly to an MS Excel sheet). Editing is disabled if the cube is write protected.

Several options are available:

Brings you directly to a new position (inline/crossline).

Check selected trace information like: x/y coordinates, inline/crossline, vertical z ranges, number of samples.

Flip the five inline/crossline positions by considering the sixth column as central position of display.

Scroll to a new inline/crossline value. It acts like a horizontal scroll.

Show the 2D view of the current traces.

5.5.9.4. Pre-stack seismic manager

This window is opened from the (poststack) seismic manager. It manages loaded pre-stack data (left: 3D, right: 2D).

Most options are common to the other managers: change file location, rename, lock, delete.
The copy cube and merge blocks of lines options work similarly to the 3D post-stack seismic manager and are available only for 3D pre-stack.

Pre-stack data stores are present on the disk in a folder of the same name within the survey ("Seismics" sub-folder). This folder contains one file per inline for quicker access, plus auxiliary files. The manager will display information about the entire pre-stack data store: Folder name, number of files etc.

A pre-stack specific option allows creation of a pre-stack data store from two or more post-stack volumes. This can be used to create pre-stack data from a partial stack volume for AVO attributes extraction.

A specific offset must be set in front of each volume.

Please note that no new file is written to the disk. Therefore deleting a post-stack volume used in the pre-stack data store will cause problems. Please use same option to remove or modify the previously set multiple volume selection.

5.5.10. Manage Stratigraphy

Manage Stratigraphy window can be launched by pressing

icon from OpendTect manage toolbar or from Manage Horizon.
This window is designed to arrange the stratigraphic markers and the geological sub-units. The user can create a specific information about the project and the different regional markers of his/her interpretation. This window is organized as units/sub-units that are bounded by different stratigraphic markers. These markers define the top and base of each units. So, depending upon user's description, markers can be the name of seismic horizons or well markers and the units the names of epochs/eras.

To start, the user should notice that there are two ways to display the stratigraphy tree, the time view and the tree view. The time view is chosen to display the absolute geological time while the tree view view show an overview of unit/sub-unit as leaves.

Stratigraphy window: The time view is displayed

Stratigraphy window: The tree view is displayed

This chapter can be divided in two sub-chapters: Regional Markers and Stratigraphic Units.

1- Regional Markers:
The regional markers are the boundaries of the stratigraphic units. These markers are added on the right-hand panel. Right click on the ---None--- word in the regional markers panel. And in the pop-up menu select the Create New... option. In the Create/New marker window, write an appropriate name for the stratigraphic marker and optionally provide the color. Press Ok to add the marker. The inserted marker can then be assigned/linked as as a top and base of the stratigraphic unit.

>>>>>

2- Stratigraphic Units:
On the left hand side of this window, the units are classified in a way that the top and base of each unit belong to certain marker marker. For the initial unit, right-click on no_code, the stratigraphic unit editor will pop up:

In this window, give a name of the unit area, the description, color, the age and lithology.
The minimum requirement for creating a new unit is simply to define the name.

To add a lithology: Click on "Edit" then give the name, and optionally specify porosity then add as new, click on OK.

To add a sub-unit, right-click the unit name and select Create sub-unit, and define it in the same manner as a unit. Description and lithology of the unit can be added now or edited later.

Stratigraphic unit properties: Properties such as unit/sub-unit description and lithology can be defined or edited by right-clicking on the unit/sub-unit name and selecting Properties. A unit/sub-unit specific lithologic name can be entered directly into the Lithology field. However, for lithologies that may occur in multiple units/sub-units, a lithology can be defined and made universally available by clicking the Select button next to the Lithology field. In this Select Lithology window, the lithology type can be named, and added to a list that will be made availiable for all units/sub-units in this session. (Depending on your Save settings, these lithologies can be available outside of this session.) These options can also be defined when the unit/sub-unit is first added.

Save as: The defined stratigraphy can also be saved at different markers, e.g. Survey levels, OpendTect data level, User level, or Global level. For instance, if it is saved at Survey level, the stratigraphy will only be available for this survey. Alternately, if it is saved at a higher level, it will not be limited to only the survey in which it was defined.

Assign Marker boundary:
This option links the regional markers with stratigraphic units. Right-click on boundary or unit/sub-unit then click on assign marker boundary select regional markers top and bottom that are the appropriate boundaries for the unit/sub-unit.

5.5.11. Wavelet management window

This window provides management tools for wavelets. The left panel shows the available wavelets. The selected wavelet is visualized on the right panel. The information on the properties of the active wavelet is shown in the lower panel. The following actions can be performed:

Import a wavelet
Generate a synthetic wavelet
Extract from seismic data (2D/3D)
Taper a wavelet
Rotate the phase of a wavelet
Merge several wavelets

Rename a wavelet

Lock a wavelet

Remove a wavelet

Set as a default wavelet for this survey

Get a wavelet from another survey

Display a wavelet's properties dialog

Change polarity

Manually rotate a wavelet

Taper a wavelet

Note: The Filter is used to filter-out the objects with selected names. For instance, to display all wavelets that start with letter W use "W*".

5.5.11.1. Import wavelet

The import wavelet dialog box pops up, if Import button in the wavelet manager is pressed. Please follow the instructions in Import Wavelet section.

5.5.11.2. Generate synthetic wavelets

Generate a wavelet

Two types, "Ricker" and "Sinc" are available.

5.5.11.3. Statistical Wavelet Extraction

Statistical wavelet can be extracted from the seismic data in this module.
The User first needs to choose between a 3D volume or a 2D line.

If the 3D volume is used, the window below pops up.

It is recommended to use a sub-selection of the seismic data, e.g. every 10th inline/crossline, and to use horizons to guide the extraction. The extract length of the seismic data should be at least 1 second TWT.

The wavelet length should never be too small (min 50ms), or too large (200ms max). A rule of thumb is that the first side lobe should be fully contained in the wavelet.

The extraction is performed using the following workflow:

Seismic traces are extracted and tapered
The autocorrelation of the seismic traces is computed, using the length of the desired wavelet
The frequency spectrum of the autocorrelation is computed.
The square root of the modulus of the frequency spectrum is taken, the zero Hertz component is muted to zero.
The inverse FFT is computed.
The zero phase wavelet is the real part of the inverse FFT output

The output phase rotation cannot be set in the current version. It is being implemented.

The Wavelet extraction in 2D line is shown below:

5.5.11.4. Rotate phase

The phase of wavelets can be altered and saved using the following slider:

The new phase will be set when pressing "Ok".

5.5.11.5. Taper a Wavelet in Time or Frequency Domain

A wavelet tapering window is launched by pressing the

icon from the wavelet management window. A wavelet is tapered in time or a frequency domain, which is selected from the top of the panel (see below).

In time domain, the selected wavelet is tapered by selecting a tapering percentage (%), which is set from the slider available at the bottom of the window. This is done by moving the slider left or right. Additionally, the amplitudes at zero frequency can also be muted by setting check to mute zero frequency check box.

In frequency domain, the tapering can be applied to both ends of an amplitude spectrum i.e. high and low frequencies. This is applied with a given slope (dB/Octave) value and placing the slider to an appropriate min/max position (Hz). The red line in the amplitude spectrum shows the resultant tapering pass, which is updated according to the given settings.

5.5.11.6. Merge synthetic wavelets

Two or more wavelets can be stacked using this option. The wavelets can be 'Normalized' and/or 'Center' at maximum amplitude/energy.

5.5.12. Well management window

The available wells imported in the project are shown on the left. Wells can be renamed, locked, removed or set as default with one of the buttons in the centre of the window:

Renames the selected well

Toggles the well to be read only(locked)/editable(unlocked)

Removes the selected well

Sets as a default

The loaded track, checkshot and time/depth model can be edited using the lower left row of icons:

Well Track editor

Checkshot Data editor

Depth/Time Model editor

Also markers should be imported and managed from the following icon:

Markers editor

The loaded logs are displayed on the right hand side, for the selected well. They can be renamed, removed, or exported with the buttons right of the log names. For removal and export, multiple logs can be selected.

Renames the selected log(s)

Removes the selected log(s)

Exports the selected log(s)

Logs can also be imported from ascii files or created using mathematical expressions from the well management window.

Other relevant information is indicated at the bottom of the window.

Note 1. It is recommended to give logs the same name across wells. For example, the master density log should be called RHOB in every well. This enables the selection of one set of logs in all wells. Please note that logs names and marker names are case sensitive during multiple selections.

Note 2. The top Filter is used to filter-out the objects with selected names. For instance, to display all wells that start with letter W use "W*". This works only with text, not numbers or symbols.

5.5.12.1. Simple Multi-Wells Creation

Multi-wells can be imported or edited through well manager or Import > Well menu. The multi-wells manage button is used to pop up the Simple Multi-wells Creation window. This window contains editable fields. The new wells can be created in either way i.e. manually or through importing them. The Read file button can be used to import an ASCII file containing all well information.

Select the input file (as shown below) and provide the appropriate format definition settings. To provide the format definition, the selected input file can be examined by pressing the Examine button. If the file contains the header lines, those lines can be eliminated by providing the file header information.

The file format definition is provided by pressing the 'Define' button. In the format definition window, the default 'col:0' values can be modified according the the input file. When the correct file format is defined, the wells can be imported by pressing 'OK' button in the multi-wells creation window. By default the wells are loaded with a constant velocity. The velocity data or the time-depth model can be provided while importing the Time-depth model.

The simple multi-well file can now be imported and displayed after creation:

5.5.12.2. Well Track Editor

This table shows the import relation between the X and Y coordinates (first two columns), the TVDSS depths (Z, third column) and measured depths in the fourth column. This table is fully editable: Double-click on a cell to edit it, type and new number and press enter or select another cell. Please note that other values will be recomputed to reflect the changes.

The "Update display" button allows the user to update the displayed well track in the scene to be updated based on the actual table content. Optionally a whole new track file can be read from a file and replace the existing data, like during track import.

During edition the depths may be displayed in feet. Please note that this flag will be kept in the survey defaults and will apply in other windows. However it is only a display setting and the data on disk will not be affected.

The following window appears after having pressed "Read new" in the edit well track window. The import settings are fully similar to that of the import step.

5.5.12.3. Checkshot and Time-Depth models

Wells in OpendTect can have two different types of Time/Depth models:

An optional checkshot model, often the first available time/depth model or a measured checkshot survey.
The Time/Depth model, that is always the active time/depth model for the well, used for data extraction and visualization.

The main differences in usage are:

If a Time/Depth model is flagged as being a checkshot model during import, the Time/Depth model will be a copy of the Checkshot model.
If a Time/Depth model is not flagged as being a checkshot model during import there will be no checkshot model for this well.
Checkshot models may be used during synthetic-to-seismic ties to constraint the output Time/Depth model. On the contrary the time/depth model provides the actual input mapping when starting the well tie.

Both types have a similar editing window. It shows the mapping between measured depths and two-way traveltime, respectively in the first and second columns. Depths are displayed either in meters or in feet (toggle at the bottom of the window), and times are always displayed in milliseconds. These tables are fully editable: Double-click on a cell to edit it, type and new number and press enter or select another cell. The "Update display" button allows the user to update the displayed well data (track, markers and logs) in the scene to be updated based on the actual table content.

The following window appears after having pressed "Read new" in the edit Checkshot/Time-Depth model windows. The import settings are fully similar to that the import step. The export button allows the data seen in the table to be exported in the same format to an output ASCII file.

5.5.12.4. Markers Management

Well markers can be entered, imported and loaded from this window.

Edit markers. Individual markers can to be added or deleted right-clicking the mouse on an existing well marker in the marker table and choosing the appropriate command. To edit the name or value, double click in the appropriate cell. Levels can be set according to the stratigraphic framework, but please note that marker names and color will be updated according to the framework when setting a level to a well marker.

Add markers. Markers can be loaded from a file by clicking the Read file button. The following window will then be displayed:

Select the input ASCII file. The main work is to specify the presence of a file header and the file format definition. The header, if present, can be of fixed length (number of lines), or delimited on its last line by a keyword.

Predefined and saved file formats are available by pressing the Open

icon. Otherwise the format must be manually specified. The Define button gives access to the format definition window.

You must specify in the format definition window the column numbers of the marker name and depth. Please mind the spaces in the marker names that can break the fixed column format. For that reason it is recommended to have the depth in the first column, and to specify column 2 as the position of marker names. Then all strings found in column 2 and up will be used to form the marker names. Depths can be either measured depths or TVDSS depths. Data loading can be stopped at a specific line by providing the adequate keyword.

It is recommended to save the format definition for a later use and QC, by clicking on the save icon

. In pop-up window, write the name of the format and store it. The format can be stored at different levels (All surveys, Current survey, Current OpendTect user level) depending on the usage. Press OK when done.

5.5.12.5. Logs import

Logs can be imported to a well from input text files.

Import Logs: The file should be in LAS format, in either MD, or TVDSS. Alternatively, the log files can be pseudo-LAS, meaning LAS (with one line of data per depth value) with the header replaced by a one-line definition: "Depth Gamma Sonic" etc. Do not use quotes, names should be separated by blank characters (spaces or tabs). For both LAS and pseudo LAS, the following units can be recognized. The recognition process is case insensitive.

Once the file has been selected all recognized logs will be shown right of "Select logs". They will all be highlighted. Only the selected logs will be imported, therefore un-select logs you do not wish to import. The depth interval to load can be limited to a smaller range than the file content. The start depth, stop depth and step written in the LAS files are not used; Instead the depths found on the same line as the amplitudes will be used.

In pseudo LAS, the user has to put the units directly behind the log name in parentheses, e.g. Depth(ft) Density(g/cc). Below are examples of text string that will match units:

Time: s, msec, usec
Distance: m, feet, f, ft, in
Density: kg/m3, g/cc, g/c
Velocity: m/s, ft/s, , f/s, feet/s, km/s
Sonic: s/m, us/ft, usec/f, us/m, usec/m
Acoustic Impedance: kg/m2s, kg/m2us, g/ft2s
Fraction (porosity, water saturation): %, PU, or blank for unitless
Permeability: k
Gamma Ray: API
Electric Potential: V
Resistance: ohm
Compressibility: 1/Pa
Temperature: K, deg.C, deg.F
Pressure: Pa, bar

5.5.12.6. Logs creation

Logs can be created from log-log computations:

The same syntax as the mathematics attributes should be used, with the following changes:

The computation is done in the depth domain. No upscaling is performed.
The inputs logs have probably different Z ranges. The output Z range will be a regular array defined by the user in front of "Output MD range". The input values are first computed along this array.
If "Fill empty sections" is not set for any log then the output will be defined where all logs do exist. Otherwise the input log that must be filled will be interpolated. In the shallow and deep parts the input log will be extrapolated by copying the data from the first and last sample respectively. This interpolation/extrapolation is done prior to computation.
An automatic assignment of well logs based on the expression names is attempted when pressing "Set".

5.5.12.7. Logs export

All or a selection of logs can be exported to an output text file. The input well must be selected, together with the logs to be exported, before pressing the export icon.

The logs can be exported with respect to MD and TVDSS depths, optionally together with X-Y or Inline/Crossline positions. The depth range and step will specify the regular array on which the input logs will be interpolated prior to the export. The output file will be a column sorted ASCII file.

5.5.12.8. Export of well surface positions to GoogleEarth

The well locations (surface coordinates) can be exported in google earth using the following icon

. Select a selection of wells (CTRL-left click to select several wells) to be exported in the popup window, and specify a filename for the kml file to be created. Press Ok, and open this file in GoogleEarth.

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