A stability of at least one foulant within a hydrocarbon-based fluid sample may be determined where the hydrocarbon-based fluid sample may have or include, but is not limited to a hydrocarbon fluid and foulant particles. The fluid sample may have a viscosity ranging from about 0.5 cSt to about 5000 cSt. The hydrocarbon-based fluid sample may be centrifuged, and a laser light (in the near-infrared region) with a detector may be applied to the hydrocarbon-based fluid sample. At least one transmittance measurement from the laser light passing through the hydrocarbon-based fluid sample may be used to measure foulant flocculation. A foulant stability reserve measurement may be obtained by comparing a first transmittance measurement of the centrifuged hydrocarbon-fluid sample to a second transmittance measurement of a non-centrifuged hydrocarbon-fluid sample.