DOE Big Hill assay sulfur qualification
This benchmark qualifies assay-carried total-sulfur inputs and bulk sulfur reconstruction against the public U.S. Department of Energy Strategic Petroleum Reserve Big Hill Sweet assay.
Source and provenance
The source is the DOE/SPR Big Hill Sweet comprehensive assay workbook:
- workbook: https://www.spr.doe.gov/reports/Assays/2024/BigHillSwAssay.xlsx
- DOE assay landing page: https://www.spr.doe.gov/reports/Crude_Oil_Assays.html
- report date recorded in the workbook: 24 September 2021
DOE/SPR publicly distributes the workbook with an informational-use disclaimer. No separate license statement was found. The regression freezes only attributed mass yields, total-sulfur values and the reported whole-crude result; it does not redistribute the workbook or reproduce a proprietary standard.
Calculation
For resolved assay mass fractions $w_i$ and cut total-sulfur mass fractions $S_i$, NeqSim uses the explicit linear mass-basis rule:
\[S_{bulk}=\sum_i w_iS_i\]Mass- and liquid-volume-basis assays share the existing authoritative basis resolution. Volume yields are converted with cut specific gravities before sulfur is aggregated. Every positive-yield cut must carry sulfur data; otherwise the calculation fails closed.
Frozen DOE matrix
| Non-overlapping cut | Mass yield, % | Total sulfur, mass % |
|---|---|---|
| C2-C4 gas | 1.70 | 0.0 assumed |
| C5-175 degF | 5.22 | 0.0008 |
| 175-250 degF | 8.32 | 0.0026 |
| 250-375 degF | 12.55 | 0.019 |
| 375-530 degF | 16.19 | 0.096 |
| 530-650 degF | 13.18 | 0.313 |
| 650-850 degF | 18.44 | 0.534 |
| 850-1050 degF | 12.84 | 0.752 |
| 1050 degF+ | 11.56 | 1.334 |
The source does not report total sulfur for the C2-C4 gas cut. The benchmark assigns zero to that 1.70 mass% cut as an explicit screening assumption; it is not presented as a measured DOE value. With that assumption, the reconstructed result is 0.40867518 mass%, compared with DOE’s whole-crude 0.409 mass%. The absolute difference is 0.00032482 mass%, below the predeclared 0.001 mass% source-precision gate.
Acceptance and maturity
OilAssayCharacterisationDoeBigHillSulfurTest requires:
- exact mass-yield closure and analytical mass-weighted sulfur arithmetic;
- agreement with DOE whole-crude sulfur within 0.001 mass%;
- fraction and mass-percent inputs to agree to numerical precision;
- input-order independence;
- a volume-basis analytical control using density-resolved mass fractions;
- missing sulfur for a positive-yield cut to fail closed;
- valid sulfur inputs to remain between zero and one; and
- property queries not to add or modify thermodynamic components.
The capability is qualified for linear assay sulfur bookkeeping over this frozen public matrix. The calculation is O(cuts), non-iterative and does not alter thermodynamic or process calculations.
Stop boundary
This evidence does not create elemental thermodynamic components, propagate sulfur into pseudo-components, predict sulfur species, perform hydrotreating chemistry, estimate emissions, apply nonlinear blending, certify a product specification or qualify a conversion unit. Those require separate #3305 contracts and validation.