The equilibrium asphaltene particle shape, size and size distribution were investigated by Confocal Scanning Microscopy (CSLM). Using CSLM, better quality images of asphaltene particles were obtained. The 3-D reconstruction from 2-D images capability of CSLM was used to visulaize the shape of the asphaltene particles. They were found to be highly non-spherical. With the CSLM operating in the fluorescence mode using incident light of 586 nm, it was found that freshly precipitated asphaltene particles gave strong fluorescence. However, if the sample was exposed to air, the fluorescence intensity quenches over a period of 24–48 hours indicating chemical changes, possibly oxidation, was taking place. Contrast to this, in a dry nitrogen atmosphere, the asphaltene particles maintained their fluorescence over the entire period when the experiment was carried out. Fluorescence emission by asphaltene particles provides yet another alternative for its size and size distribution determination especially for samples with a dark background. Imaging of such system would be less dependent on the incident light intensity. Asphaltene samples prepared at the industrially more relevant low bitumen to solvent ratios are being investigated by this method.

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