EFFECTS OF TEMPERATURE AND PRESSURE ON ASPHALTENE PARTICLE-SIZE DISTRIBUTIONS IN CRUDE OILS DILUTED WITH N-PENTANE

The effects of temperature (0-150-degrees-C) and pressure (0-5.6 MPa) on the size distribution of asphaltene particles (or agglomerates), fo rmed as a result of diluting the crude oils with n-pentane, were studi ed using a modified laser particle analyzer. Four crude oils, ranging from an asphaltic condensate to a heavy oil-sand bitumen, were tested in this investigation. The average size of asphaltene agglomerates ran ged from 266 to 495 mum. The results suggest that the mean asphaltene particle size increases with pressure and decreases slightly with temp erature; however, no trends were evident with the molar mass of crude oils. Although the particle size distributions in most cases were unim odal and described adequately by the log-normal distribution function, bimodal distributions were also identified in certain cases.