| OpendTect User Documentation version 3.2 |
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The Import module is used to import seismic data, picksets, horizons and well tracks. Seismic data is imported from SEG-Y, SeisWorks, GeoFrame (IESX), or from dGB's CBVS (Common Binary Volume Storage) formatted files in other surveys. The SeisWorks and GeoFrame options are only available if you have a license for the data access module. Loading via SEG-Y is always possible, provided that the data is inline sorted. OpendTect can easily handle data volumes with irregular boundaries and gaps. However, strong irregularity (e.g. consistent non-constant steps between inlines and/or crosslines) throughout the volume may cause problems.
In order to import SEG-Y data, Select or create an input SEG-Y definition. A SEG-Y definition is not only a file, but also contains parameter settings needed to correctly load the file. The various options available to the user are depending on whether 2D or 3D data is loaded. See Section 4.3.1.1.2 for the segy definition settings.
2D data is stored in individual lines. Sets of individual lines can be grouped into Line Sets. When loading 2D data, one must be aware of this. When an individual line is loaded, it should be stored in a new group or an existing one.
Each 2D line can contain multiple data. For example, seismic data, acoustic impedance data, or any other attribute, like similarity or frequency. Usually, when starting up a project, only seismic data is available. During a project, new data is created which should be organized properly into attributes, Lines and Line Sets. The data hierarchy is graphically displayed below.
Seg-y input: For selecting the seg-y input, press the Define button.
Line name: Give a line name to your 2D SEG-Y input
Null traces. Null traces can be discarded or left inside the line (Pass).
Scale values. The data can be rescaled with a linear scaling function defined by factor and Shift. The output will be calculated with:
output = Factor * input + Shift
Store in Line Set. Choose or define the Line Set name where this new line will be added to. The data in a line can be given a name, e.g. Seis for seismic data, or AI for acoustic impedance data. Press Select to manually enter a name. Under Name the name of the Line Set is set, and under Attribute (if any) you can overrule the default Seis name.
The concept of Line Sets allows you to manipulate groups of 2D line simultaneously. You can always overrule group actions by applying an action to a single line from a set.
I need to import more, similar files: Pops up a new window where the parameters for importing multiple 2D lines are defined.(see picture below)
Input. Defines the root file name for the 2D SEGY files. The #L has the function of a wildcard, it can be any string. More characters can be around that #L, e.g. SetA_#L.sgy. This means that only the SEGY files starting with SetA_ will be loaded. That string (and nothing more) will also become the name of each line in the Line Set, and this string can also be used again in storing the SEGY setup for each file.
Store each setup as: This option stores the SEGY definition parameters of each loaded SEGY file, including the string #L as taken from the previous field.
If your SEG-Y definition is a 3D SEG-Y volume, these are the options you have in the import window:
SEG-Y input: Press the Define button to select the 3D SEG-Y input.
Volume subselection: You can import the complete file by ticking All (i.e. all traces), or only a selection of the volume (Sub-volume).
Null traces: Null traces can be discarded or left inside the volume (Pass).
Scale values: The data can be rescaled with a linear scaling function defined by factor and Shift. The output will be calculated with:
output = Factor * input + Shift
Output cube: Provide a name for the volume here.
Storage. OpendTect supports can store data internally in 8-, 16-, 32-, and 64-bit seismic data formats. 8 bit signed has a data range between -127 and +127. 8 bit unsigned ranges between 0 and 255. Similarly, 16-bit signed ranges between -32767 and +32767 (unsigned 0 - 65535). Per default, the data are stored in the same byte-format as the input (Storage is set to 0 - auto).
Adjust z range to survey range: With this option, the user can adjust his/her new scaled seismic to the survey range.
Optimize horizontal slice access. For better performance in loading time slices, set this option to Yes. This compromises some speed in loading crosslines, but it loads time slices significantly faster.
The options in the window that pops up when clicking the "Pre-stack" option are similar to the options in the 3D selection possibilities window.
Select the input SEG-Y input file at the Input file field. The file needs to be sorted in inlines. When a SEGY file is selected, a Name for this SEG-Y setup is automatically created, but you can overrule it by just typing something else. This is the name this SEG-Y file and its access definitions will be known by in OpendTect. Use the wild card character "*" in the Input file to replace the file number in the file name to read in multiple files. For example to read a SEG-Y data set that consists of 5 physical files. Ensure that the filenames include numbers 1 to 5. For example to read in the files named segy_1, segy_2, segy_3, segy_4 and segy_5, specify "segy_*" in the Input File/device field, switch on Multiple files and specify 5 in the # files field.
The Examine option dumps the content of the EBCIDIC header, the binary header and the header of a few traces. You can indicate the number of traces in the Number of traces field. From this information it should be possible to determine where all relevant information (like inline and crossline numbers, trace numbers, XY co-ordinate positions) is stored.
The Scan button runs through the entire file (or a specific munber of traces) and produces all kinds of relevant information like the x and y range, inline and crossline range, value range and clipping information, a suggested survey setup, etc.
The rest of the options depend on whether you are loading 2D or 3D data.
The trace number, the X and the Y coordinate bytes are essential. The other information is optional. The default values (see below in the section about 3D settings) can be overruled.
OpendTect needs inline/xline numbers or X/Y coordinates, not both. If positioning is defined by inline/xline, you must also specify whether inline and crossline numbers are stored in 2 bytes or 4 bytes. Apart from positioning information the import module expects the start time, sample interval and the number of samples to be set in the trace header. Optionally these values can be overruled. The default byte locations are:
SEG-Y start time = delrt, byte 109.
SEG-Y sample interval = dt, byte 117 (specified in usec).
SEG-Y number of samples = ns, byte 115.
SEG-Y co-ordinate scaling = scalco, byte 71.
The first step is to define the SEG-Y access parameters. Just press the "Select" button to select the Input file. Now press the "Examine" button. This step is very important for pre-stack data. Since this data type requires correct offset and azimuth information, make sure that the coordinates are right. It is also possible to derive the inlines from the tape or trace header. In this case, be sure to specify the correct byte size (2 or 4).
pre-stack 3D
pre-stack 2D
As shown above, it is possible to overrule the seg-y start time, the seg-y sample interval (in milliseconds), the number of samples and the coordinate scaling. By default the byte locations are;
SEG-Y start time = delrt, byte 109.
SEG-Y sample interval = dt, byte 117 (in milliseconds)
SEG-Y number of samples = ns, byte 115
SEG-Y coordinate scaling = scalco, byte 71
This module enables exchange of data between projects. The original CBVS (Common Binary Volume Storage) file can be located with a standard file browser. Some cbvs volumes are stored in several sub files. These can be recognized by the ^01 or ^02 (etc.) in the filename. To import the complete volume, select the base file without any ^xx marks.
The Cube type needs to be specified in order to give it the correct label for the software.
The Import mode indicates if the file should only be left at its original place and just be linked to the current survey (Use in-place), or if the volume should be copied entirely into the current survey directory (Copy the data).
The other options are the same as in the Seismic SEG-Y access window.
This particular import option is included in OpendTect as a plugin. It also functions as an example of how to build your own plugins and how to include documentation about it.
User can import simple ASCII or Binary file by using plain file Seismic I/O Plugin. This can be reached via Survey > Import > Seismic > Simple File > 3D or 2D etc. You can also import simple prestack 2D/3D seismic files.
In the import seismic window, select the file type (ASCII or Binary) and browse the input file location. As a secondary option, you can also examine the input file by pressing Examine button. The simple file can be either sorted in XY positions or Inline/Xline pairs. If, in the file, the trace start position exists, select 'Yes' for Traces start with a position. Otherwise, you can select 'No' and define the inline/xline start positions and steps manually. Similarly, if the sampling information is not in the input file, select "No" and fill the sampling information boxes.
Optionally, you can scale the cube before loading as well by mentioning the amount of shift and the corresponding factor. Either pass or discard the null traces before loading.
Store the output cube/2D Line set by writing name in Output Cube field.
Simple 3D Seismic File Import Window
Simple 2D Seismic File Import Window
Simple pre-stack 3D Seismic File Import Window
Simple pre-stack 2D Seismic File Import Window
In 3.2 OD version, Picksets can be imported into Opendtect. The input file has to be a three-column Ascii file (inline-crossline-time or X-Y-time).
You can get Z value from the pickset ASCII file using 3 different options :
Get Z values from Input file
Select the input Ascii file and type the name for the pickset in OpendTect at Output PickSet.
Get Z values from Constant Z
Get Z values from Horizon
Optionally, each pick can be loaded and displayed as a vector field. The 4th, 5th, and 6th column of the ascii file will then have to contain the vector length R (a non-negative number), the dip (-90 - 90 degrees, positive numbers are downward), and the azimuth (0 - 360 degrees, 0 is the Y-direction, 90 is the X-direction).
Another option is to import your pickset as Polygon. This is typically done when picking faults or picking contour in Common Contour Binning.
It is possible to define the format by specifying the necessary information in the following window:
The first option is the type of data loaded: X/Y, Inl/Crl, and in which column the parameter will be found. The Z value column and unit has to be defined also. The Z units can be seconds, milliseconds, or microseconds.
Then it is possible to save the format by clicking in the following icon: 
, the following window becomes available:
Click on the format, then it will be possible to edit it in the name for format line. Chose if this definition has to be stored for all surveys, this survey or my user ID only
If you click in the import Horizons, the following options are available:
The format of horizon import is ascii files. Three options are available:
- Import a 3D geometry
- Import 3D attributes
- Import 2D Geometry
These three options are explained in the next sub-chapters.
Select the input Ascii file and the Output Horizon, i.e. the name of the horizon in OpendTect. The selected Ascii file can be examined with Examine and scanned with Scan file. Examining displays the Ascii file in a separate window. Summary information on the horizon geometry and data values is provided by scanning the file.
A single horizon can consist of several sub-horizons or patches, e.g. one patch on either side of a big fault. In that case, select all files of these patches using the Shift key, and import these simultaneously into one horizon. The horizon will appear with a single name in OpendTect, but the patch structure remains available.
The file format is either X-Y-2WayTime or Inline-Crossline-2WayTime. The 2WayTime may be either in ms or s; the software can handle this smartly. A Z scaling option allows shifting of the horizon position and scaling of the horizon values. The Shift value should always be provided in seconds. The Undefined value can be provided. The option to interpolate the horizon to a regular grid by filling the undefined parts is available. This utility is described in Horizon Fill holes section.
When attributes are available in the 4th column of the input file (and beyond), the Attribute info button becomes active. Select the attributes you want to import and give them a name.
It is possible to define the format by specifying the necessary information in the following window.
the first option is the type of data loaded: X/Y, Inl/Crl, and in which colon the parameter will be found. The z value colone and unit has to be defined also. The Z units can be seconds, milliseconds or microseconds.
Then it is possible to save the format by clicking in the following icon: , the following window becomes available:
Click on the format, then it will be possible to edit it in the name for format line. Chose if this definition has to be stored for all surveys, this survey or my user ID only
It is possible to define the format by specifying the necessary information in the following window:
The first option is the type of data loaded: X/Y, Inl/Crl, and in which column the parameter will be found. The z value colone and unit has to be defined also. The Z units can be seconds, milliseconds, or microseconds.
Then it is possible to save the format by clicking in the following icon: , the following window becomes available:
Click on the format, then it will be possible to edit it in the name for format line. Chose if this definition has to be stored for all surveys, this survey or my user ID only
The Import 2D Horizon also allows to import the 2D Geometry. After the window is launched, select the Input ASCII file and the corresponding 2D line set. User can also examine the file to be imported by pressing Examine button. Add new horizon or overwrite to and existing one. The File header specifies the header information in the input file. If the header exists in the file, user can select Fixed size (number of header lines) or Variable (End of Header 'word').
The format definition is used to specify the definition of input file format (as shown below). In format definition, user can add the necessary information of the input file. The first field is used to define the undefined values format in the file.
Provide: Write the exact value of undefined values that are in the input file.
Keyword: Or just write the keyword of undefined values starting at certain column.
Fixed: If the undefined values start at certain column, user can specify the row and column position.
In the 2D file format, user needs to input the column positions of line name, X/Y or Trace nr, and Z-Values (with corresponding units). To save the format definition into a filem press save icon 
. Press OK after saving the file definition format. User will come back to Import 2D horizon window.
User can also interpolate the horizon while importing or select 'No' in the interpolate field. The 'Display after import' is a secondary field. If checked it will display the horizon in the scene after loading.
This window can be accessed by chosing in Survey>Import>Fault as follows:
It is possible to define the format by specifying the necessary information in the following window:
The first option is the type of data loaded: X/Y, Inl/Crl, and in which column the parameter will be found. The z value column and unit has to be defined also. The Z units can be seconds, milliseconds, or microseconds.
It is also possible to save the format by clicking in the following icon: , the following window becomes available:
After clicking on the format, it will then be possible to edit it in the name for format line. User should choose this if this definition has to be stored for all surveys, this survey, or my user ID only.
In this menu, only the well track is imported. Once the well track is defined, well logs can be added in File - Manage - Wells.
The well track data in the Input Ascii file should be in X-Y-Z[-MD] format, where Z is the vertical depth from the reference surface where t=0, i.e. TVDSS (in meter or in feet). Optionally, a fourth column with the corresponding depth along the borehole (Measured Depth) can be provided here, too. The MD should be in the same units as Z. The values should be separated by blank characters (i.e. space or tab). An example input well track looks like this:
1869119.42 555550.22 850 1000
1869119.42 555550.22 1850 2000
1869119.42 555550.22 2350 2500
1869119.42 555550.22 2850 3000
1869119.42 555550.22 3350 3500
1869119.42 555550.22 3850 4000
1869119.42 555550.22 4350 4500
1869119.42 555550.22 4850 5000
1869119.42 555550.22 5350 5500
1869119.42 555550.22 5573 5723
You could also supply only the correct MD value in the forth entry of the first line of the well track file. The software automatically calculates the other MD values. The example above would then look like this:
1869119.42 555550.22 850 1000
1869119.42 555550.22 1850
1869119.42 555550.22 2350
1869119.42 555550.22 2850
1869119.42 555550.22 3350
1869119.42 555550.22 3850
1869119.42 555550.22 4350
1869119.42 555550.22 4850
1869119.42 555550.22 5350
1869119.42 555550.22 5573
When MD is supplied (either only the first value or along the complete track), the surface location and the surface elevation become optional.
If your survey Z-unit is time, you should also provide a Depth to Time model. The first column should contain the depth values, and the second column the corresponding time values in seconds. An example looks like this:
1000 0.1822
2000 0.3684
2500 0.4606
3000 0.5444
3500 0.6276
4000 0.7120
4500 0.7934
5000 0.8764
5500 0.9552
5723 0.9930
The depth values can be either in MD or in TVD Sub Surface. The default is MD, toggle the Model is TVDSS option if your ascii file is in TVD Sub Surface. This surface" should be the same surface as the reference surface in the X-Y-Z ascii file mentioned above.
The Elevation from surface is the difference between MD=0 and the reference surface where t=0s (or Z=0m if your survey Z-unit is meter or feet). If MD=0 is above the reference surface (which usually is the case), this number is positive. Fill in the well name as you would like it to appear in OpendTect in the Output well field. In the example above, the Elevation from surface is 150 ft. But, if you choose to include the first MD value in the well track (1000ft in the fourth column in the example), you do not have to supply the surface elevation separately.
In the Optional information block you can provide extra information on the well. This information is not used by OpendTect and only serves as extra information for the user.
See Section 4.5.4 for the well manager, where logs can be added to a well.
See Section 4.5.4 for the well manager, where markers can be added to a well.
This option enables the import of wavelets. First, the input file should be selected and examined. Second, the file header and information content should be selected. Finally, a name for the wavelet should be defined.
