A log print from a LAS file
A LAS file is plain text, but a column of numbers says little until it is drawn as a log. Upload
the .las file (versions 1.2, 2.0, wrapped files and 3.0 are read) and you get a PDF in the
familiar layout:
- Track 1: gamma ray, SP and caliper or bit size.
- Depth track with labels at round depths.
- Track 2: resistivity curves on a logarithmic scale.
- Track 3: bulk density on 1.95 to 2.95 g/cm3, neutron porosity reversed (0.45 to -0.15 v/v, or 45 to -15 for percent), sonic and PEF.
- Extra tracks for up to eight other curves, each with its own scale.
Curves are put in tracks by their mnemonic (GR, RHOB, NPHI, ILD, LLD, AT90, DT…) and their unit, so a resistivity curve named after a tool still lands in the logarithmic track when its unit is ohm.m. Scales without a convention are taken from the data (1st to 99th percentile, rounded).
The depth scale follows the length of the log: 1:200 for a short interval, 1:500 or 1:1000 for a long one, so the print stays readable without running to hundreds of pages. Each page repeats the well name, field, company, file name and scale.
More than a picture
The same upload also gives the curves as CSV and Excel and a cleaned LAS 2.0 file (choose "Everything" under "Make"), and a picture of the first page appears right on the result page.
Pitfalls
- Curves whose mnemonic matches a known log but whose unit doesn't (raw counts under a resistivity-like name, for example) go to the extra tracks rather than the wrong scale.
- Time-indexed LAS files are drawn against time, spread evenly over the pages.
- LAS files without a depth unit are drawn as they are, with a note.
More about what this tool reads and writes: Well Log Converter (DLIS, LIS, LAS).