las-js is a zero-dependency JavaScript library for parsing .Las file (Geophysical well log files).

Currently supports only version 2.0 of LAS Specification. For more information about this format, see the Canadian Well Logging Society product page.

How to use

• Installing

  NPM

  $npm install las-js

  Yarn

  $yarn add las-js

  Browser

  <script defer src="https://cdn.jsdelivr.net/npm/las-js/dist/browser.js"></srcipt>

• Usage

  import/require las-js module

  Node

  // common js
  const { Las } = require('las-js');
  // esm
  import { Las } from 'las-js';
  const myLas = new Las(`./sample/example1.las`);

  You can also pass LAS file contents directly to constructor

  // common js
  const { Las } = require('las-js');
  const fs = require('fs');
  const data = fs.readFileSync(`./sample/example1.las`, { encoding: 'utf8' });
  // add loadFile: false to constructor options
  const myLas = new Las(data, { loadFile: false });

Browser

las-js adds a global class Lasjs

const input = document.getElementById('file-input');
input.addEventListener('change', async e => {
  const file = e.target.files[0];
  const myLas = new Lasjs(file);
});
// or
const myLas = new Lasjs('https://raw.githubusercontent.com/iykekings/las-js/master/src/__test__/sample/A10.las'); // url - only on browser

• Read data

  Use Laspy.data to get a 2-dimensional array containing the readings of each log, Or Lasjs.dataStripped to get the same as above but with all rows containing null values stripped off

  async function read() {
    try {
      const data = await myLas.data();
      console.log(data);
      /**
         [[2650.0, 177.825, -999.25, -999.25],
          [2650.5, 182.5, -999.25,-999.25],
          [2651.0,180.162, -999.25, -999.25],
          [2651.5, 177.825, -999.25, -999.25],
          [2652.0, 177.825, -999.25, -999.25] ...]
        */
  
      const dataStripped = await myLas.dataStripped();
      console.log(dataStripped);
      /**
       [[2657.5, 212.002, 0.16665, 1951.74597],
       [2658.0, 201.44, 0.1966, 1788.50696],
       [2658.5, 204.314, 0.21004, 1723.21204],
       [2659.0, 212.075, 0.22888, 1638.328],
       [2659.5, 243.536, 0.22439, 1657.91699]...]
       */
    } catch (error) {
      console.log(error);
    }
  }

• Get the log headers

      // ...
      const headers = await myLas.header();
      console.log(headers);
      // ['DEPTH', 'GR', 'NPHI', 'RHOB']
     // ...

• Get the log headers descriptions

      //...
      const headerAndDescr = await myLas.headerAndDescr();
      console.log(headerAndDescr)
      // {DEPTH: 'DEPTH', GR: 'Gamma Ray', NPHI: 'Neutron Porosity', RHOB: 'Bulk density'}
      // ...

• Get a particular column, say Gamma Ray log

      // ...
      const gammaRay = await myLas.column('GR');
      console.log(gammaRay);
      // [-999.25, -999.25, -999.25, -999.25, -999.25, 122.03, 123.14, ...]
      // ...

      // ...
      // get column with null values stripped
      const gammaRay = await myLas.columnStripped('GR');
      console.log(gammaRay);
      // [61.61, 59.99, 54.02, 50.87, 54.68, 64.39, 77.96, ...]
      // ...

  Note this returns the column, after all the data has been stripped off their null values, which means that valid data in a particular column would be stripped off if there is another column that has a null value at that particular row

• Get the Well Parameters

  Presents a way of accessing the details of individual well parameters.

  The details include the following:

    1. descr - Description/ Full name of the well parameter
    2. units - Its unit measurements
    3. value - Value

    // ...
    const well = await myLas.wellParams()
    const start = well.STRT.value // 1670.0
    const stop = well.STOP.value // 1669.75
    const null_value = well.NULL.value //  -999.25
    // Any other well parameter present in the file, can be gotten with the same syntax above
    // ...

• Get the Curve Parameters

  Presents a way of accessing the details of individual log columns.

  The details include the following:

    1. descr - Description/ Full name of the log column
    2. units - Unit of the log column measurements
    3. value - API value of the log column

    // ...
    const curve = await myLas.curveParams()
    const NPHI = curve.NPHI.descr // 'Neutron Porosity'
    const RHOB = curve.RHOB.descr // 'Bulk density'
    // This is the same for all log column present in the file
    // ...

• Get the Parameters of the well

  The details include the following:

    1. descr - Description/ Full name of the log column
    2. units - Unit of the log column measurements
    3. value - API value of the log column

    // ...
    const param = await myLas.logParams(); // 'BOTTOM HOLE TEMPERATURE'
    const BHT = param.BHT.descr // 'BOTTOM HOLE TEMPERATURE'
    const BHTValaue = param.BHT.value // 35.5
    const BHTUnits = param.BHT.units // 'DEGC'
    // This is the same for all well parameters present in the file
    // ...

• Get the number of rows and columns

      // ...
      const numRows = await myLas.rowCount() // 4
      const numColumns = await myLas.columnCount() // 3081
      // ...

• Get the version and wrap

      // ...
      const version = await myLas.version() // '2.0'
      const wrap = await myLas.wrap() // true
      // ...

• Get other information

      // ...
      const other = await myLas.other()
      console.log(other)
      // Note: The logging tools became stuck at 625 metres causing the data between 625 metres and 615 metres to be invalid.
      // ...

• Export to CSV

  For node, this writes a csv file to the current working directory, with headers of the well and data section only for node. For browser, this returns a File Blob, that can be downloaded by using URL.createObjectURL

      //...
      await myLas.toCsv('result')
      // result.csv has been created Successfully!
      //...

  result.csv

  | DEPT | RHOB | GR | NPHI | | ---- | ------- | ------- | ----- | | 0.5 | -999.25 | -999.25 | -0.08 | | 1.0 | -999.25 | -999.25 | -0.08 | | 1.5 | -999.25 | -999.25 | -0.04 | | ... | ... | ... | ... | | 1.3 | -999.25 | -999.25 | -0.08 |

  Or get the version of csv with null values stripped

      // ...
      await myLas.toCsvStripped('clean')
      // clean.csv has been created Successfully!
      // ...

  clean.csv

  | DEPT | RHOB | GR | NPHI | | ---- | ----- | ---- | ----- | | 80.5 | 2.771 | 18.6 | -6.08 | | 81.0 | 2.761 | 17.4 | -6.0 | | 81.5 | 2.752 | 16.4 | -5.96 | | ... | ... | ... | ... | | 80.5 | 2.762 | 16.2 | -5.06 |

• Browser and Node Supports

  las-js is written in typescript and compiles to es6.

  • Browser Supports IE 10 and 11 - (doesn't yet support url) Doesn't support Opera Mini
  • Node Tested 0n 8, 10 and 12

• Support

  las-js is an MIT-licensed open source project. You can help it grow by becoming a sponsor/supporter.Become a Patron!