How do you assess crude oil compatibility for blending?

Crude compatibility assessment: Incompatibility causes - asphaltenes precipitation when mixing crudes with different solvent power. Mechanism - asphaltenes are stabilized by resins; paraffinic crudes (high SBN/saturates) can precipitate asphaltenes from heavy crudes. Tests: spot test (drop of crude on filter paper, look for ring), colloidal instability index (CII = saturates + asphaltenes)/(resins + aromatics), p-value (peptization value), and hot filtration test. Compatibility mapping - test all pairs of crudes in planned blend ratios. Consequences of incompatibility: fouling in preheat train, filter plugging, furnace tube coking, product instability. Mitigation: blend incompatible crudes at lower ratios, add aromatic flux, or process separately. Compatibility is critical for opportunity crude processing where diverse crudes are economically attractive.