Data loading

The data loading has been briefly addressed in two sections. The first section will guide in loading the 2D/3D SEG-Y data, while the second will guide in loading well data.

The details of each section will be described in Import Seismic chapter.

3.1.3.1. Load Seismic (2D/3D)

The loading of SEG-Y data is done via Import sub menu under survey main menu (Survey > Import >

Seismic > SEG-Y...)

To start loading of 3D SEG-Y Volume, follow the steps:

1. Go to Survey >Import > Seismic >SEG-Y... In SEGY Tool window choose File type: 3D Volume to import the SEG-Y data.

2. In the Input SEGY field, select and locate the input segy file.

3. Set check to the Multiple files to import more segy files. Write the number of files in the first text field and number of steps (e.g. Vol-1, Vol-2, Vol-3, ... Vol-n). Where 'n' is number.

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4. Select the input file type: 2D/3D-Pre or Poststack data.

5. Select the number of traces that will be examined to display the trace header information.

6. Optionally, if you want to overrule the number of samples, set check to this field and fill the correct number of samples.

7. Select an appropriate SEG-Y file format.

8. If the bytes in a header have to be swapped, it can be set here.

9. Press Ok to proceed further

10. The SEG-Y Scan and SEG-Y Examiner window will launch in next step. Fill the appropriate byte locations in the SEG-Y scan window. Write the output cube name and press OK to start loading the segy file.

3.1.3.2. Load Well data

In OpendTect, the well data has been organized into four (4) sub categories: Well tracks, Logs, TD Models and Markers. Each category is either loaded via Survey > Import menu or Well manager. In this section, we will cover how to load/setup a complete well in OpendTect.

Load Well track and Time to depth Model (via Import): To load a well track, go to the main menu bar and select Survey - Import - Well - Ascii - Track. The Import Well Track window will be launched.

In the Well Track file field select the input well track file. The Well track file should contain three main columns i.e. X, Y, TVDSS (True Vertical Depth Sub Surface) and optional MD (Measure Depth) column. The file header can be defined in this window. Click the Examine button to view the input file before loading, and to determine the header type. See Import - Well section to learn how to set the file headers (fixed size/variable). The format definition is used to specify the columns (XYZ) definition and unit system of the input ASCII file. Optionally, a vertical well can also be defined if the file doesn't exist. This is done by setting uncheck to Well Track File field. In this case, specify the XY coordinates and depth range (default meters).

In the depth to time model field, locate and select the appropriate time-depth file. Specify the file header and format definitions. If the time-depth model/checkshot does not exist, set uncheck to this fill to set a constant velocity model to load the well. Later on the time-depth model/checkshot can be imported via the Well Manager. Additionally, specify whether the file is a checkshot data or not.

The additional information (Well ID, Operator, State, Country) can be included in the well track by selecting the Advanced/Optional button.

Name the Output well and press Go, to complete the loading of well track. It will return a message,

"Well track imported successfully". Press Ok to close information window. Press Dismiss to exit.

Note: The surface coordinates and elevation above surface are defined from the well track file. In normal cases, these definitions will be in the first line of the well track file. If the well track file starts below the datum (KB, Kelly Bushing), you will need to manually adjust these parameters in the well track file before importing it as a well track. Elevation above the surface is normally considered positive if the reference datum is above sea level. Conversely, if the elevation reference is below sea level, you can define the negative values in the elevation as those above the surface elevation reference.

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Load Logs & Markers (via Well manager): Launch the Well manager . Here you will find the loaded well track(s) from the previous step in the left panel.

To import Logs, select the recently loaded well and press theImport button. In pop-up window, select the input LAS log file, and then examine the file. The remainder of the window will be automatically filled in from input file. Importantly, if you only want to load certain logs, highlight only the wanted logs. (By default all available logs will automatically be highlighted.) Press Ok. The logs will be loaded and will appear in the right panel.

To import Markers, select the recently loaded well and press the Markers button. In pop-up window, select the Read file button and follow the same steps as before when loading Ascii files. Alternately, instead of reading a file, you can manually type in the depth, name and assign marker colors.

Updating well tracks, checkshot data, and depth to time models can also be done in this Well file management window.

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