Viscometric Determination of the Onset of Asphaltene Flocculation: A Novel Method

TLDR

The method relies on observing a viscosity rise in crude oil–asphaltene suspensions when a n‑paraffin (n‑pentane, n‑heptane, or n‑nonane) induces asphaltene flocculation. Graphically, the flocculation onset is identified by comparing the viscosity curve of the analyte with that of a reference system prepared in polar/non‑precipitating solvents such as toluene, benzene, or THF. The technique accurately determines the flocculation onset by measuring viscosity changes as crude oil is diluted with a precipitating n‑paraffin (n‑pentane, n‑heptane, or n‑nonane).

Abstract

Abstract A new technique for the determination of the onset of asphaltene flocculation has been developed through accurate viscosity measurements of a crude oil being diluted with a precipitating agent (n-pentane, n-heptane, n-nonane). This detection method is based on experimental observations of an increase in the viscosity of a crude oil-asphaltene-precipitating agent suspension in which asphaltene particle aggregation occurs. The key point in this development is the phenomenon of asphaltene flocculation induced by the addition of a n-paraffin hydrocarbon (i.e. n-heptane, n-pentane, n-nonane) to crude oil. The onset of asphaltene flocculation is detected graphically, and its location is enhanced by comparison of the analyte curve with a reference system. The reference system was developed using polar and non-precipitating solvents (i.e. toluene, benzene, THF).