well-log-evaluation

well-log-evaluation is a skill for Claude Code, Codex from SteadfastAsArt/geoscience-skills. It costs 41 tokens per session (3,285 once invoked), scanned A, original, MIT.

A workflow for evaluating well log files, which contain measurements recorded by instruments in an oil or gas well. It covers loading data, checking its quality, analysing rock properties, classifying rock layers, and creating visualisations.

In plain words
What is it for?
Use it to load LAS or DLIS files, clean and combine curves, estimate properties such as porosity and water saturation, classify lithology, and create 3D well views.
Why use it?
It organises the many steps needed to turn raw well measurements into formation-evaluation results and visual displays.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to load LAS or DLIS files, clean and combine curves, estimate properties such as porosity and water saturation, classify lithology, and create 3D well views.

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Install with agentmods
npx agentmods add skills/steadfastasart/geoscience-skills/well-log-evaluation
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add SteadfastAsArt/geoscience-skills --skill well-log-evaluation
Clone the repo
git clone --depth 1 https://github.com/SteadfastAsArt/geoscience-skills

Made for: Claude Code, Codex.

Its marketplace also offers this one on its own, as the plugin well-log-evaluation — /plugin install well-log-evaluation after adding the marketplace above.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for well-log-evaluation

README.md
[![agentmods](https://agentmods.dev/badge/skills/steadfastasart/geoscience-skills/well-log-evaluation/github.svg)](https://agentmods.dev/skills/steadfastasart/geoscience-skills/well-log-evaluation)
Your own site
<a href="https://agentmods.dev/skills/steadfastasart/geoscience-skills/well-log-evaluation"><img src="https://agentmods.dev/badge/skills/steadfastasart/geoscience-skills/well-log-evaluation/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for well-log-evaluation

Your own site · 80×15
<a href="https://agentmods.dev/skills/steadfastasart/geoscience-skills/well-log-evaluation"><img src="https://agentmods.dev/badge/skills/steadfastasart/geoscience-skills/well-log-evaluation.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 41 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,285 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00041 $0.03285
Opus 5.5 $0.00016 $0.01314
Sonnet 5.5 $0.00008 $0.00657
Haiku 4.5 $0.00004 $0.00329

Measured 1mo ago against content hash 93c064c88fff, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

well-log-evaluation scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

workflows/well-log-evaluation/SKILL.md · 301 lines

How it starts

The opening of the file, as written. The whole thing — 301 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Well Log Evaluation Workflow

End-to-end pipeline for formation evaluation, from loading well log files through quality control, petrophysical analysis, lithology classification, and multi-dimensional visualization.

Skill Chain

lasio/dlisio     welly           petropy         striplog        pyvista
[File I/O]   --> [QC & Prep]  --> [Petrophysics] --> [Lithology] --> [3D Viz]
  |               |                |                 |               |
  LAS parsing     Despike          Vshale calc       Facies log      3D well
  DLIS frames     Normalize        Porosity          Intervals       Fence diagram
  Curve extract   Merge curves     Sw, Perm          Correlation     Property vol

Decision Points

Question If Yes If No
LAS format (.las)? Use lasio for loading Check DLIS format
DLIS format (.dlis)? Use dlisio for loading Check file type
Multiple wells or curve QC needed? Use welly for management Use lasio directly
Full formation evaluation (Sw, phi, Vsh)? Use petropy Compute manually with numpy
Need lithology column or stratigraphic log? Use striplog Skip to visualization
3D well trajectory visualization? Use pyvista Use matplotlib for log plots

Step-by-Step Orchestration

Stage 1: Data Loading (lasio / dlisio)

The LAS example below assumes depth in metres, GR in API, bulk density in g/cm³, and resistivity in ohm-m. Inspect the headers and convert other units before continuing. The DLIS block is an alternative inspection entrypoint; select a frame, map mnemonics, and supply the same units before Stage 2.

import lasio
import numpy as np
import pandas as pd

# Load LAS file
las = lasio.read('well_A.las')
df = las.df().rename_axis('DEPT').reset_index()
null_val = float(las.well['NULL'].value)
df = df.replace(null_val, np.nan)
if las.curves[0].unit.strip().lower() not in {'m', 'metre', 'meter'}:
    raise ValueError('Convert the depth basis to metres before this example')
if (len(df) < 2 or not np.isfinite(df['DEPT']).all()
        or not np.all(np.diff(df['DEPT']) > 0)):
    raise ValueError('QC the depth basis: require finite, strictly increasing samples')

# Inspect available curves
print(las.curves.keys())  # ['DEPT', 'GR', 'RHOB', 'NPHI', 'RT', 'DT']
well_name = las.well['WELL'].value

Read the full file on GitHub · 301 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 1mo ago Changed · +56 lines 93c064c88fff
  2. 2mo ago First seen · 245 lines · 41 tokens per session scan A 6aca23f5276c

Subscribe to this mod's changes

well-log-evaluation is a skill published in the GitHub repository SteadfastAsArt/geoscience-skills (73 stars, last pushed 1mo ago), licensed MIT. It adds 41 tokens to every session and 3,285 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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