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neqsim-h2s-phase-partitioning

neqsim-h2s-phase-partitioning is a skill for Claude Code, Codex from equinor/neqsim-community-skills. It costs 110 tokens per session (2,588 once invoked), scanned A, original, Apache-2.0.

An educational calculation of where hydrogen sulfide, or H2S, goes between gas, oil, and water in a separator train. A separator train is a series of process vessels that split a wellstream into these phases.

In plain words
What is it for?
Use it to convert measured gas H2S to wellstream H2S, estimate H2S in each output stream, create lookup factors for larger models, and screen sour-service risk against the stated standard threshold.
Why use it?
H2S measured in separator or export gas is not the same as H2S in the original wellstream. Accounting for pressure, temperature, water, and composition gives a more relevant estimate and checks the material balance.

Skill for Claude CodeCodex

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

not rated 4repo today A scan 110 tokens original Apache-2.0

Good fit Use it to convert measured gas H2S to wellstream H2S, estimate H2S in each output stream, create lookup factors for larger models, and screen sour-service risk against the stated standard threshold.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/equinor/neqsim-community-skills/neqsim-h2s-phase-partitioning
View source ↗ equinor/neqsim-community-skills equinor.github.io
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 equinor/neqsim-community-skills --skill neqsim-h2s-phase-partitioning
Clone the repo
git clone --depth 1 https://github.com/equinor/neqsim-community-skills

Made for: Claude Code, Codex.

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README.md
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<a href="https://agentmods.dev/skills/equinor/neqsim-community-skills/neqsim-h2s-phase-partitioning"><img src="https://agentmods.dev/badge/skills/equinor/neqsim-community-skills/neqsim-h2s-phase-partitioning.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 110 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,588 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 $0.00110 $0.02588
Opus 5.5 $0.00044 $0.01035
Sonnet 5.5 $0.00022 $0.00518
Haiku 4.5 $0.00011 $0.00259

Measured 11d ago against content hash 958269ffcf50, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

neqsim-h2s-phase-partitioning 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 11d ago.

The scan reads SKILL.md. This mod also ships 4 executable files (src/h2s_partitioning/__init__.py, src/h2s_partitioning/model.py, tests/test_e300_workflow.py, …), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

skills/subsurface/neqsim-h2s-phase-partitioning/SKILL.md · 125 lines

How it starts

The opening of the file, as written. The whole thing — 125 lines — stays where its author put it; the contents beside it link to each section on GitHub.

H2S Phase Partitioning and Separator-Gas to Wellstream Conversion

Use this skill to turn a measured separator gas H2S into a wellstream H2S, and to see where H2S goes in a separation train. Gas H2S is what is routinely measured; the reservoir and well question (souring versus injected-water fraction) is about the wellstream. The two differ by the gas/oil/water split, which depends on pressure, temperature, water fraction and composition.

When to Use

  • Convert measured separator or export gas H2S (ppmv) to wellstream H2S (mol fraction or ppmv) per well or per test.
  • Build a lookup factor = wellstream H2S / gas H2S versus water mole fraction to embed in a larger model.
  • Report H2S in oil (ppmw), produced water (mg/L) and each gas stream for a train, with mass-balance closure.
  • Screen sour service: H2S partial pressure against the ISO 15156-2 / NACE MR0175 threshold of 0.3 kPa.
  • Feed the next step in the souring chain: neqsim-reservoir-souring-correlation (fit per-well correlation versus seawater fraction).

Inputs

  • Dry wellstream composition (mole fractions) from the process model, PVT report or E300 file; or use the default demonstration composition.
  • Water mole fraction of the wellstream (use water_mole_fraction(water_sm3_d, dry_kmol_d) from rates).
  • SeparatorStage(temperature_c, pressure_bara) list, first stage first, and which stage the gas measurement belongs to.
  • Measured gas H2S in ppmv (dry, in the stage gas).

Outputs

  • ConversionResult: wellstream H2S (mol fraction, ppmv), conversion factor, full TrainResult and warnings.
  • TrainResult: per stage gas ppmv, oil ppmw, water ppmw and mg/L, pH2S in kPa, and the fractions of H2S leaving with gas, oil and water.
  • conversion_factor_curve(...): (water_mol_fraction, factor) table for plugging into a setup.

Engineering Method

  1. Build the wellstream with SRK-CPA (SystemSrkCPAstatoil, mixing rule 10) including water and H2S; multiphase check on.
  2. Flash through ThreePhaseSeparator stages. Gas leaves each stage, oil feeds the next stage, water drains with its dissolved H2S.
  3. Gas H2S ppmv is monotonic in wellstream H2S, so the back-calculation is a log-space bisection on wellstream H2S to match the measured value (tolerance 1e-6 relative). A measurement outside the reachable bracket raises ValueError rather than extrapolating.
  4. In the dilute limit gas H2S is linear in wellstream H2S, so one probe level gives the factor curve.

Read the full file on GitHub · 125 lines

Files

What ships with it

6 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 11d ago First seen · 125 lines · 110 tokens per session scan A 958269ffcf50

Subscribe to this mod's changes

neqsim-h2s-phase-partitioning is a skill published in the GitHub repository equinor/neqsim-community-skills (4 stars, last pushed today), licensed Apache-2.0. It adds 110 tokens to every session and 2,588 once invoked, about $0.0004 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 2026-10-26.

Scientific
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