
Geochemical Sample Interpretation Engine
Synthesize geochemical data into petroleum system interpretations
What You Can Do
You can rapidly integrate multi-parameter geochemical datasets—Rock-Eval pyrolysis, biomarker distributions, stable isotopes, and molecular compositions—into coherent petroleum system interpretations. The skill transforms raw analytical parameters (Tmax, S2, biomarker ratios, δ13C values) into subsurface understanding of source rock potential, thermal history windows, depositional environments, and charge timing relative to trap formation. You'll identify thermal maturity stages, distinguish multiple source intervals in multi-sourced basins, and flag analytical anomalies that suggest contamination or stratigraphic mixing.
Features
converts Tmax and S2 values into Ro-equivalent maturation windows and thermal history stages
pattern-matches sterane and hopane ratios against source/depositional models and established classification schemes
synthesizes δ13C, δD, and δ15N data to constrain organic matter type and depositional paleoenvironment
distinguishes hydrocarbon contributions from different stratigraphic intervals and identifies charge mixing
establishes charge timing windows relative to trap formation and seal development
identifies contradictory parameters indicating mixed kerogens, contamination, oxidation, or secondary alteration
structures interpretations into risk-ranked charge scenarios for prospect evaluation
translates geochemical proxies (TOC, S1/S2, sulfur content, biomarker suites) into paleoenvironment reconstruction
Example Output
Example 1: Source Rock Characterization
Input: Tmax 435°C, S2 8.5 mg HC/g TOC, Pr/Ph 1.2, C29 abb% 65%, δ13C -27.5‰
Output:
- Maturity Stage: Early mature (Ro ~0.6%), within oil generation window
- Kerogen Type: Type II–III mixed, lacustrine to fluvio-deltaic origin
- Source Quality: Good petroleum potential (S2 >5), consistent with Type II kinetics
- Depositional Environment: Shallow lacustrine or deltaic system with terrigenous input (C29 sterane dominance, elevated Pr/Ph)
- Interpretation: Sample represents primary source rock interval; charge timing consistent with Neogene hydrocarbon generation
Example 2: Charge Attribution
Input: Oil sample biomarkers vs. three candidate source rocks (samples A, B, C)
Output:
- Primary Source (75%): Sample B (sterane and hopane ratios match oil within 1-2%)
- Secondary Component (25%): Sample C (C29 abb% elevated; minor mixing evident)
- Charge History: Sample B entered generation window ~15 Ma; Sample C contribution likely in-charge mixing during early migration
- Quality Flag: Oil maturity (Tmax ~442°C) exceeds source rocks individually; likely heating during deep burial or thermal contact
Example 3: Anomaly Detection
Input: Cuttings sample with Tmax 385°C, S2 0.3 mg/g (immature), but δ13C -33‰ (marine signature) and unusual sterane ratios
Output:
- Maturity Contradiction: Tmax and S1/S2 indicate immature kerogenic material
- Paleoenvironment Mismatch: δ13C suggests marine/lacustrine origin, yet sterane suite shows terrestrial dominance
- Risk Assessment: Possible mixing of immature terrigenous kerogen with recycled mature marine organic matter OR caving from overlying beds
- Recommendation: Verify stratigraphy; run reflectance microscopy to confirm kerogen immaturity
What's Included
- SKILL.md instruction file with interpretive workflows and parameter thresholds:
- Biomarker interpretation matrix: established ratio cutoffs for source/depositional discrimination (sterane ternary, hopane ratios, Tmax/maturity correlation)
- Thermal maturity lookup table: Tmax-to-Ro conversion and stage definitions
- Depositional environment classification framework: paleoenvironment inference from S1/S2, TOC, Pr/Ph, δ13C, and sterane suites
- Multi-sample synthesis template: workflow for integrating cuttings/core suites into stratigraphic interpretation and charge attribution
- Anomaly checklist: rapid screening for contamination, oxidation, mixed kerogens, and caving artifacts
Who It's For
- Exploration Geochemists — interpreting core and cuttings samples for prospect risk assessment and charge characterization
- PE&A Engineers — building defensible petroleum systems narratives and charge timing scenarios for volume estimation
- Development Geologists — determining source intervals and charge history in discovered fields to optimize drilling placement
- Basin Modelers — validating geochemical interpretations against maturity and thermal history outputs from basin simulations
- Regulatory/Compliance Geochemists — documenting hydrocarbon origin and source attribution for environmental or legal assessments
Best For
- Source rock screening and ranking in frontier/mature basins
- Multi-sourced basin charge attribution and mixing analysis
- Thermal maturity and charge timing reconstruction relative to trap geometry
- Depositional environment inference from paleoenvironmental biomarker and isotope proxies
- Quality control and anomaly flagging for geochemical datasets prior to PE&A workflows
- Rapid interpretation of published regional geochemical surveys for comparative contextual analysis







