Methods for determining asphaltene stability in crude oils

Different tests used to predict asphaltene stability in crude oils, such as colloidal instability index, colloidal stability index, Stankiewicz plot, qualitative-quantitative analysis, stability cross plot, Heithaus parameter, toluene equivalence, Bureau of Mines correlation index – toluene equivalence, and oil compatibility model are reported in this work. In addition, SARA fractionation, asphaltene flocculation point, P-value, S-value, separability number, stationary column stability test, compatibility test, and spot test are disclosed. Using experimental data reported in literature, each test is carried out in order to evaluate its accuracy finding that some tests predict the asphaltene stability better than other ones. It was found that qualitative-quantitative analysis and stability cross plot behaved better than colloidal instability index and Stankiewicz plot.