LasViewer software can be used for viewing and plotting oilfield well-log data, that is stored in LAS files.
LasViewer is a 64 bit application, and is available for download from the Microsoft Store for Windows-10, at
LAS files are ASCII files that are used to store and share oilfield well-log data.
The current version supports LAS version 2.0 files. A valid LAS version 2.0 file contains five sections that include the ~Version, ~Well, ~Curves, ~Parameters and ~Ascii sections. These are also referred to as the ~V, ~W, ~C, ~P and ~A sections. The ~P section optional, all the other sections are mandatory.
A LAS file can be loaded by either selecting the File->Load LAS File option under the main menu. Alternatively, just drag and drop the file onto the tree-view list area. Drag and drop supports loading multiple files with one action.
Once a LAS file has been loaded, all the curves in the file will be shown in the tree-view list on the left side. The hierarchy of the tree-view is shown below.
- Company Name
- Well Name
- Dataset Name (LAS file)
All LAS files from the same well will be grouped together. To view the data from another LAS file, click on the LAS filename in the tree-view.
Clicking on either of the Company Name or Well Name will display the information about the well that was loaded from the LAS file.
Right clicking on the Dataset (LAS filename) also gives options for viewing the raw data from the ~V, ~W, ~C and ~P sections of the LAS file header. Note that the "Right Click" menu is not available until a normal click has first been performed on the Dataset.
The window directly to the left of the main form is the QuickView plot. After a LAS file is loaded, the first curve in the list which should be the Depth curve, will be displayed here. Clicking on a curve name in the tree-view list will cause that curve to be displayed in the QuickView plot. If the "Alt" key is depressed while clicking on a curve name, the curve data will be displayed instead.
The curves are displayed on the QuickView plot with a fixed format. The depth is scaled so that the whole data set fits on the page. Log curves are displayed with a pre-defined format. Log curves can wrap once, when they exceed the plot scale. A curve will change color to pink, when it is wrapped.
For log curves that don't have a format that is pre-defined, these are displayed with a linear scale and scaled so that the minimum and maximum values fit into the window. They are also plotted with a gray curve color.
Right clicking on the QuickView plot gives an option for copying the current image, so it can then be pasted into another document.
The figure above shows two features available after loading the data. On the left is a data view that is obtained by holding the "Alt" key down when clicking on a log channel name. The drop-down menu that appears when right-clicking on either the Company, Well and Dataset name is shown on the right.
Right clicking on the tree-view give options for deleting a Dataset, for deleting all the data from a Well, and for deleting all the data from a Company. There must always be at least one Dataset left in a well, and always one Well left in a Company. To delete these items, simply select item that has a higher heirarchy.
Individual channels in a LAS can be deleted the same way. To delete multiple channels, select the first channel as normal, then hold down the control key to select subsequent channels. Finally, right click on the highlighted channel and select "delete".
The "Log Plot" panel is on the right side of the main form is for making composite log plots and cross-plots.
The Log Plot panel is used for making multi-column plots and allows user defined formatting. As with the QuickView plot, the curves are initially displayed using pre-defined formatting options, but these can be easily changed later.
Right clicking on a specific track of the plot shows a drop-down menu. Some of these menu options are track dependent, while others apply to the entire plot.
Drop down menu options from the Log Plot panel
- Add track - adds a new log track to the right of the last track.
- Insert track - inserts a new track immediately to the right of the currently selected track.
- Delete track - deletes the currently selected track.
- Add Log Curve - presents a selection of log curves to be added to the currently selected track.
- Clear Log Curves - deletes all log curves from the currently selected track.
- Change Track width - by default, a log track is 200 pixels wide. This menu offers alternatives values for the track width.
- Change Log Plot parameters - to change the plotting scale and other parameters for all the logs displayed on the currently selected track.
- Depth axis scale - by default, the depth scale is chosen to fit all the data in the display window. The menu option allows change the depth scale.
- Copy Image - copies the current plot to the clipboard, so it can be pasted into another document.
- Print - prints the current image. Printing to a PDF file is a good option, to save the log plot to a disk file.
- Reset (delete all) - deletes all the tracks and plots reverts back to initial conditions.
On the right side of the Log Plot panel is the Crossplot button. Clicking this will bring up a new window that allows cross-plotting curves of the currently selected data set.
The depth units are specified inside the LAS file, and the file will be loaded referenced to those depths units. The depth unit can be changed after loading by right clicking on the dataset, and selecting the "change depth unit" option.
VSP waveform data
The current version also supports displaying VSP waveform data that is loaded from files in LDF format.
The process of loading and displaying LDF file is similar to LAS files discussed above. The QuickView plot will only show a depth-time plot, while the waveforms can be viewed from the Log Plot panel. When VSP waveform data is loaded, some of the options available in the drop-down menu will be different, but these should be self explanatory, if loading and displaying LAS files is understood.
One complication with LDF files (and also with SEGY files in a future release), is that these files do not contain information on the Company Name or Well Name. Therefore, these have to be specified upon load. If other data has already been loaded, then the existing Company/Well names will be offered as choices. Similarly, the depth unit required for the data to displayed in will need to be specified.
26-May-2018. First release