Effect of Miscible Nitrogen Injection on Instability, Particle Size Distribution, and Fractal Structure of Asphaltene Aggregates

Precipitation, aggregation, and breakup of asphaltene particles are studied under natural depletion and nitrogen injection processes by means of high pressure filtration and a photographic procedure coupled with image analysis. Filtration results show that nitrogen destabilizes asphaltenes extremely, and the problem is more severe for heavier crude samples. Bimodal histograms of particle size distribution show two agglomeration mechanisms: cluster aggregation dominant around bubble point pressure and diffusion limited far away. The fractal structure of aggregates is also altered by gas injection; it is observed that the flocculent masses grow in size and become more compact and organized when the cluster aggregation increases.

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