Experimental and modeling investigations of temperature effect on chemical inhibitors of asphaltene aggregation

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In this work, both experimental and theoretical procedures were performed to investigate the effect of temperature, ranging from 25 to 65 °C, on the performances of dodecyl benzene sulfonic acid (DBSA), benzoic acid (BA) and salicylic acid (SA) as chemical inhibitors of asphaltene aggregation in an undiluted dead crude oil. DBSA was found the most efficient inhibitor in size reduction of aggregates at all applied temperatures due to its acid-base interactions with asphaltenes. The size reduction by DBSA was 19% compared to free-additive oil at 65 °C. But SA increased asphaltene aggregates size by 2% at 65 °C. The temperature rise significantly accelerates the rate of asphaltene aggregation and so the effectiveness of inhibitors was reduced at high temperatures. The population balance modeling was employed in which a novel size-dependent relation was considered for collision efficiency. Fractal dimension, as an input of the model, was measured from experimental data at different temperatures and time intervals. Due to minor changes in fractal dimensions, an average value of 2.5 was considered for fractal dimension. The modeling results revealed that the collision efficiency is decreased by both efficient inhibitors and decrement of temperature. Considering a size-dependent collision efficiency halved the error of the model on average in comparison to a size-independent collision efficiency.