DOE Big Hill terminal-cut boundary qualification

This benchmark qualifies one-sided boiling-boundary metadata against the public U.S. Department of Energy Strategic Petroleum Reserve Big Hill Sweet assay. It prevents an open terminal cut from being silently converted into a fabricated finite interval.

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 and no separate license statement. The regression freezes only the attributed 1050 degF+ terminal boundary, its 11.56 mass% yield and its 1.0089 reported relative density. The workbook is not redistributed.

Engineering contract

The DOE table reports a residue with a lower boiling limit of 1050 degF and no finite upper limit. NeqSim stores that value as 838.7055555556 K, reports that a lower limit is present, and reports that no upper limit or complete boiling range is present.

A one-sided limit does not determine a representative boiling point. It is therefore insufficient by itself for the existing inverse molecular-weight correlation. Pseudo-component generation must fail before mutating the thermodynamic system unless the caller also supplies either:

• an independently supported representative boiling point and density; or
• an explicit molar mass and density.

The focused generation control uses 650 g/mol only as an explicit engineering input to prove this API path and exact mass closure. DOE does not report that value, and this qualification does not validate it. A separate terminal-Watson qualification uses DOE’s reported SG and UOP K values to derive a representative boiling temperature without turning the open boundary into a finite interval.

Acceptance and maturity

OilAssayCharacterisationDoeBigHillTerminalBoundaryTest requires:

• exact Fahrenheit-to-Kelvin preservation of the DOE 1050 degF+ lower limit;
• Kelvin, Celsius and Fahrenheit terminal-limit inputs to agree numerically;
• independent lower/upper presence views and unchanged complete-range semantics;
• contradictory limits or representative values to fail without partial cut mutation;
• one-sided metadata to survive thermodynamic-system cloning;
• missing representative properties to fail before adding any component; and
• an explicitly characterized terminal cut to generate with the existing exact mass-closure gate.

The capability is qualified for terminal-bound metadata and fail-closed pseudo-component preparation. It is O(1) per boundary assignment and does not alter thermodynamic calculations.

Stop boundary

This evidence does not choose a representative boiling point or molecular weight for the DOE residue, infer C2-C4 gas composition, split a plus fraction, validate critical properties or VLE, match atmospheric product yields, change a column solver, or qualify vacuum fractionation. Those remain separate #3305 engineering contracts.