Removal of oil from produced water by coalescence/filtration in a granular bed

Oil production generates a significant amount of water byproduct known as produced water. Following primary gravity separation, produced water is normally disposed of by injection into the formation from which it came. However, high amounts of suspended solids or oil in the produced water may cause clogging of the injection formation. This study evaluated the effectiveness of coalescence/filtration in treating two produced water samples obtained from Saskatchewan heavy oil production sites. In the coalescence/filtration experiments, percentage removals of oil and suspended solids were observed to be as high as 97 and 91 percent, respectively. Mechanisms of filtration and coalescence were identified and observed through experimental data and mathematical models. The maximum coalescence efficiency observed was three percent at the lowest flow rate. Coalescence efficiencies decreased with increasing flow rate, Experimental data for single anti two-phase flow were shown to fit the Carmen-Kozeny filtration equation. Coalescence/filtration satisfied a first order rate equation using the Crickmore model.