Free Online LAS File Viewer: Well Log Tracks in Your Browser
Choose a LAS file, or press the demo button to see the viewer working. Your file never leaves this page.
What a LAS file is
Nearly every well log on earth eventually travels as a LAS file: a plain text standard from the Canadian Well Logging Society that carries the depth column and every measured curve, from gamma ray to resistivity to density, along with the header information that says what each curve means. The format is wonderfully durable and wonderfully unreadable: open one in a text editor and you face a wall of numbers. This viewer turns that wall back into what a log analyst actually reads, real tracks side by side against depth.
How to use it
Drop in a LAS 2.0 file, or press the demo button to load a synthetic well. The viewer lists every curve the file contains: tick up to five and they draw instantly as tracks with a shared depth axis. Each track scales itself to the data, and curves that span more than a factor of twenty with all positive values, which in practice means resistivity, switch automatically to a logarithmic scale, exactly as a printed log would show them. Null values, the famous minus 999.25, are honored as gaps rather than drawn as spikes. When the display looks right, download it as an image or print it to PDF.
Privacy matters with well logs
Log data is often confidential, sometimes contractually so. This viewer parses the file entirely inside your browser: nothing is uploaded, nothing is stored, and the page works the same if you cut your network connection after it loads. That makes it safe for a quick look at a file you could not paste into an online service, which is precisely when a fast viewer is most useful.
Honest limits
The viewer reads standard LAS 2.0, including wrapped data sections, and shows up to five curves at once. It is a viewer, not a petrophysics package: no environmental corrections, no crossplots, no editing. For calculations, export your file with the LAS to CSV converter next door and take the columns wherever you need them, or push the numbers through the porosity and saturation equations in the encyclopedia.
Related Calculators and Reference
- LAS to CSV Converter: turn the same file into a spreadsheet.
- SEG-Y Trace Viewer: the seismic sibling of this tool.
- Wyllie Time Average Equation: porosity from the sonic curve you just plotted.
- Archies Equation: water saturation from the resistivity track.
- Canadian Well Logging Society: keeper of the LAS standard.