Measurement and corresponding states modeling of asphaltene precipitation in Jilin reservoir oils

The asphaltene precipitation of two reservoir oil samples collected from Jinlin oil field has been studied under pressure and with/without CO2-injection conditions. No asphaltene precipitation was detected during the pressure depletion processes without CO2 injection. For the CO2-injected oil systems, the effects of operating pressure, injected CO2 concentration, and multiple-contact on the onset and amount of asphaltene precipitation were studied under the reservoir temperature. No asphaltene precipitation was observed when the operating pressure is remote from the minimum miscibility pressure (MMP). However, appreciable asphaltene precipitation was detected when the operating pressure approached or exceeded the MMP. The amount of asphaltene precipitation increased with the concentration of injected CO2. A generalized corresponding states principle (CSP) for prediction of asphaltene precipitation data is produced and reported here. The proposed CSP theory complements the scaling equation for asphaltene precipitation under the influence of n-alkane precipitants. Based on literature data and the data measured in this work, the parameters and exponents of a corresponding states equation capable of describing the asphaltene precipitation behavior in the studied high-pressure CO2-injected crude oil systems are reported. D 2003 Published by Elsevier B.V.