DOE Big Hill composition-resolved light-end qualification
This benchmark qualifies a source-traceable C2-C4 composition view for refinery assay light ends. Known molecules are added as NeqSim standard components rather than being sent through a petroleum pseudo-component correlation.
Sources and provenance
The public U.S. Department of Energy Strategic Petroleum Reserve sources are:
- comprehensive Big Hill Sweet assay workbook: https://www.spr.doe.gov/reports/Assays/2024/BigHillSwAssay.xlsx
- Big Hill Sweet gas-chromatographic/PIANO workbook: https://www.spr.doe.gov/reports/Assays/2021/BigHillSwPIANO.xlsx
- DOE assay landing page: https://www.spr.doe.gov/reports/Crude_Oil_Assays.html
- report date recorded in both workbooks: 24 September 2021
DOE/SPR distributes these workbooks for informational use and does not provide a separate license statement. The regression freezes only the attributed numerical facts below; it does not redistribute either workbook.
Composition calculation
The comprehensive assay reports the aggregate C2-C4 cut as 1.70 mass% of whole crude. The PIANO workbook reports this debutanization composition on a weight basis:
| Component | Reported debutanization wt% | Normalized C2-C4 mass fraction | Mass in a 1 kg whole-crude basis, kg |
|---|---|---|---|
| ethane | 0.09 | 0.0013507429 | 0.0000229626 |
| propane | 10.38 | 0.1557856821 | 0.0026483566 |
| i-butane | 10.21 | 0.1532342789 | 0.0026049827 |
| n-butane | 45.95 | 0.6896292961 | 0.0117236980 |
| C2-C4 subset | 66.63 | 1.0000000000 | 0.0170000000 |
The normalization excludes DOE’s separately reported i-pentane, n-pentane, 2,2-dimethylpropane, and C6+ entries. Methane is reported as 0.00 wt% and is not invented. This is a transparent combination of two DOE views, not an independent compositional measurement.
Java and Python contract
Use AssayCut.withStandardComponent(componentName) on a mass-basis cut. During apply(), NeqSim preflights each identifier on a clone, reads the standard component’s authoritative molar mass from the Java thermodynamic system, converts the configured assay mass to moles, and then adds the known molecule with SystemInterface.addComponent.
The same Java behavior is available from Python through JPype. A standard component cannot also carry pseudo-component density, boiling-point, Watson-factor, boundary, or explicit molar-mass inputs. Volume-basis standard-component cuts fail closed because no independent light-end liquid-density conversion is claimed.
Acceptance and maturity
OilAssayCharacterisationDoeBigHillLightEndsTest requires:
- exact reproduction of DOE’s 66.63 wt% C2-C4 subset and normalized composition;
- exact reconstruction of the 0.017 kg gas slice on a 1 kg whole-crude basis within 1e-10 kg;
- positive finite standard-component molar masses and mole amounts;
- identical component amounts under reversed source order;
- no petroleum
_PCcomponent for a known molecule; - clone retention; and
- fail-closed unknown, duplicate, ambiguous, and volume-basis inputs without original-system mutation.
The implementation is O(n) in the number of assay cuts. The capability is qualified for DOE Big Hill C2-C4 composition ingestion and mass/mole bookkeeping.
Evidence boundary
This benchmark does not validate gas-liquid equilibrium, an EOS or mixing rule, flash recovery, C5-175 degF representative properties, full-crude light-end material balance, atmospheric product yields, vacuum fractionation, blending, or conversion models. The PIANO subset normalization is an inference explicitly recorded above. C5-175 degF representative-property qualification remains the next characterization dependency.