PRO Flow Assurance

Asphaltene Screening & Stability Predictor

Rank crude oils for asphaltene precipitation risk from SARA composition or a field PVT proxy, then flag depletion trajectories against de Boer and Hirschberg-style screening limits.

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Crude Input Basis

Use measured SARA where available. PVT proxy is for early screening only.

Saturates wt%

Aromatics wt%

Resins wt%

Asphaltenes wt%

Operating P/T Trajectory

Initial pressure psia

Minimum pressure psia

Initial temp degF

Minimum temp degF

Reservoir pressure psia

CII

(Saturates + Asphaltenes) / (Aromatics + Resins)

ASI

(Sat/Arom) x (Res/Asph) - 1

AOP flag

Verdict

de Boer-Style Density Pressure Screen

Point location uses estimated live-oil density and Pres - Pbubble. Bands are qualitative screening zones.

Density

-- g/cc

Recommendation

Screening Method

CII: Larger values indicate a heavier paraffinic/asphaltenic fraction relative to aromatic and resin peptizers. CII below about 0.7 is treated as stable, 0.7 to 0.9 as metastable, and above 0.9 as high risk for this early screen.

CII (Colloidal Instability Index) = (Saturates + Asphaltenes) / (Aromatics + Resins). This is distinct from the Asphaltene Stability Index (ASI), de Boer plot, or Yen-Mullins thermodynamic models. We use CII because it requires only SARA composition, with no high-pressure PVT or AOP measurements.

de Boer plot: Uses live-oil density and pressure margin above bubble point. Light oils near bubble point receive higher risk because compositional changes during depressurization can destabilize asphaltenes.

Hirschberg-style flag: Estimates whether the depletion path crosses a plausible onset pressure envelope above bubble point. It is a screening flag, not a replacement for laboratory AOP or solids deposition testing.

References & Attribution

de Boer, R. B., Leerlooyer, K., Eigner, M. R. P., and van Bergen, A. R. D. SPE 24987, 1995, "Screening of Crude Oils for Asphalt Precipitation."
Hirschberg, A., deJong, L. N. J., Schipper, B. A., and Meijer, J. G. SPE Journal, 1984, "Influence of Temperature and Pressure on Asphaltene Flocculation."
Wang, J. X. and Buckley, J. S. SPE 64994, "A Two-Component Solubility Model of the Onset of Asphaltene Flocculation in Crude Oils."
McCain, W. D., "The Properties of Petroleum Fluids," for oil gravity and PVT property context.
Open-source plotting: Chart.js, MIT License, github.com/chartjs/Chart.js. License text stored as LICENSE_chartjs.txt.
Topic-specific OSS reviewed: profesorperez/asphaltene_depressurization, MIT. No calculation code was copied because it is MD post-processing notebooks rather than screening functions.

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