Temperature effects on solubility of asphaltenes in crude oils

•Asphaltenes solubility in crude oils is affected by temperature.•Heithaus and Hildebrand solubility parameters characterize the solubility of asphaltenes.•Asphaltenes solubility in crude oil is analyzed by automated flocculation titration.•Asphaltenes solubility increases with temperature for six different crude oils.•Asphaltenes changes phase at higher temperatures. Asphaltenes, the heaviest fraction in crude oil, are linked to severe problems in petroleum industry. Asphaltenes are either in dissolved state or in colloidal dispersion form in crude oil. Temperature has a significant role in dissolving the asphaltenes in continuous phase of crude oil. However, there are differing views on the effect of temperature on solubility and precipitation of asphaltenes. In this work, an investigation was carried out on the effect of temperature on solubility of asphaltenes for six different crude oil samples in the temperature range of 20–95°C, using automated flocculation onset titration. The test results are interpreted in terms of the Heithaus parameters and using Hildebrand's solubility parameter. The experimental data, the Heithaus parameters and the Hildebrand solubility parameter show that solubility of asphaltenes increased with increase in temperature and possible phase transition of asphaltenes takes place with the increase in temperature.