OpendTect User Documentation version 4.2
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Chapter 5. Menu - Survey

Table of Contents

5.1. Select/Setup Survey
5.2. Session
5.3. Import
5.4. Export
5.5. Manage
5.6. Preload

5.1. Select/Setup Survey

5.1.1. Description

The Survey module is used to select, create and/or modify surveys. A survey defines the geographical boundaries of an OpendTect project and relevant positioning information such as the relationship between inline/crossline and X/Y co-ordinate systems. Each survey (project) stores its data in a separate directory that needs to be specified along with the survey reference name. Moreover,the Survey rotation angle is displayed, this angle shows the deviation from the Geographic North.

5.1.2. Survey selection window



Select an existing survey from the list of surveys on the left or create a new one with "New"... (see below). The boundaries of the survey are depicted in the graphics field on the right. The Notes field is a free-format text field to store relevant survey notes.

WARNING: Remove... will remove the entire project from disk!

Set Data Root. When you installed OpendTect, you selected an OpendTect data directory, where all your surveys are stored. With this option you can change this general OpendTect data directory.



X/Y <-> I/C. In the position conversion window there are two modes available for coordinate conversion: Manual / File. In Manual mode, you specify a inline/crossline pair, or a X/Y pair, and press the corresponding arrow key to obtain the position in the other domain. In File mode, you browse the input file and create new output file. By specifying the corresponding type conversion (XY to IC or IC to XY) and pressing GO button, the desired conversion is written on output file.



Export to Google Earth/Maps. This feature is used to export the selected survey boundary in a *.kml file, which is accessible via Google Earth. The dialog box contains the editable fields for the survey box. The area of the survey box is filled with the selected colour. The width is the horizontal thickness of the survey outline. The border height is the altitude of the line with respect to the ground. The Output file field is an output location of the *.kml file. On 'Ok' the file (*.kml) is written at the specified path, which can be opened directly in Google Earth.


Nevertheless you will first need to specify the correspondence between X-Y coordinates and latitude/longitude in one location of the survey:



Only after pressing "OK" you will be able to provide an output filename.

5.1.3. New/Edit Survey setup window

To launch the survey setup window select "New" or "Edit" button in survey selection window. The following window will appear on your screen.



All fields in above window are mandatory.

Survey name: In the text area specify the OpendTect survey name.

Location on disk: Specify a directory on disk where the OpendTect survey would be stored. The directory would be turned in to the OpendTect survey location.

Survey type: For the survey type, there are three options;



Note:
1- Select only 3D, if the survey will contain only 3D type data set. Select both 2D and 3D, if the survey will contain both 2D and 3D type data set. If the survey will contain only 2D type data set, select only 2D.
2- Ranges/Coordinate settings are described in the following section.

5.1.3.1. Survey Ranges

The survey ranges are the inline, crossline and Z-ranges of the defined survey. The ranges define a 3D survey area for 3D seismic surveys and 2D grid area for 2D seismic surveys. These fields can be filled manually, by scanning a SEG-Y file (2D/3D), using set for 2D only option in Ranges/coordinate settings, or by copying the ranges from another survey. If the Workstation Access plugin is available, one will see the Get from GeoFrame or Get from Seisworks option in the drop-down menu.



The set for 2D only option is especially used to create a 2D seismic survey. Set the average trace distance and the x and y coordinate ranges, and these will automatically be translated into suitable survey settings.

Click on the Scan SEG-Y file(s) button to select a SEG-Y file. In the new window, you set the SEG-Y settings, see also SEG-Y scan section. Pressing OK will start scanning the file(s). After scanning, you'll get a file report containing sampling info, data statistics, and survey setup. The "Survey ranges" and "Coordinate settings" will be filled in automatically.

The Z range is specified in milliseconds, meter, or feet. The steps are incremental Z-steps of the survey i.e. the seismic sampling rate.

5.1.3.2. Coordinate settings

The relationship between inline/crossline and X/Y can be specified in two ways. The easy way is to specify three points, two of which must be on the same inline. Due to rounding off errors, this method may not be 100% accurate.

In the "Advanced" option, the exact transformation from one co-ordinate system to an other can be specified. The "Apply" button can be used to verify results graphically and to check the co-ordinate transformation formula.



Note: Read more about Coordinate Settings under the Chapter-3 (How to .. Setup 2D/3D Survey > Coordinate Settings).
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