Well Log Viewer

Well logging is one of the most critical data acquisition methods in petroleum engineering and geoscience. During or after drilling, logging tools are lowered into the wellbore to measure formation properties such as natural radioactivity (gamma ray), electrical resistivity, bulk density, neutron porosity, sonic transit time, and many others. These measurements provide continuous depth-indexed profiles of the subsurface geology, enabling engineers and geoscientists to identify lithology, estimate porosity and water saturation, detect hydrocarbons, and correlate formations across fields.

The LAS (Log ASCII Standard) format, developed by the Canadian Well Logging Society, is the most widely used file format for storing and exchanging well log data. LAS 2.0, introduced in 1992, remains the dominant version in use today. A LAS file is a plain text file organized into sections: the ~V (Version) section specifies the LAS version and wrap mode; the ~W (Well) section contains well identification information such as well name, UWI, location coordinates, and depth range; the ~C (Curve) section lists the mnemonics, units, and descriptions of each logged curve; the optional ~P (Parameter) section stores additional well parameters; and the ~A (ASCII Data) section contains the actual numeric log values arranged in columns corresponding to the curve definitions.

Standard well log display conventions use a multi-track layout. The gamma ray (GR) log is typically displayed in Track 1 with a 0-150 API scale, using green fill to distinguish sand (low GR, typically below 75 API) from shale (high GR). The resistivity logs (deep, medium, and shallow investigation depths) are displayed in Track 2 on a logarithmic scale from 0.2 to 2000 ohm-m. High resistivity often indicates hydrocarbon-bearing zones. Track 3 conventionally shows the porosity curves: bulk density (RHOB) on a 1.95-2.95 g/cc scale and neutron porosity (NPHI) on a 0.45-0 (reversed) scale. Crossover between these curves can indicate gas-bearing zones, making the porosity track one of the most important for quick-look interpretation.

This viewer parses LAS 2.0 files entirely in your browser using JavaScript. No data is uploaded to any server, making it safe for proprietary well data. The tool automatically detects available curves, assigns them to appropriate tracks with standard display conventions, and generates an interactive multi-track log plot using Plotly.js. You can toggle individual curves, adjust the depth range, view curve statistics, and export the data as CSV for further analysis.

Built by Groundwork Analytics, an AI and engineering company that builds digital tools and deploys AI agents for the energy industry. We help operators, service companies, and engineering teams automate workflows, optimize operations, and make better decisions with their data. Get in touch or email us at info@petropt.com. Mehrdad Shirangi (Stanford PhD) specializing in reservoir simulation, production optimization, and AI/ML applications for upstream oil and gas.