Colloid and surface interaction understanding in warm lime softening of SAGD produced water treatment

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Suncor uses both surface mining and steam-assisted gravity drainage (SAGD) to recover bitumen. In SAGDoperations, almost all the steam injected is recovered as produced water at the surface. It is highly desirable torecycle the maximum possible amount of water of SAGD process to reduce operational costs and overall waterconsumption. The percentage of produced water recycled depends on the performance of the chemicaltreatment process consisting of a warm lime softening unit, an After Filter, and a weak acid cation exchangeunit. The chemical treatment of SAGD produced water is a complicated process with a lot of factorsinfluencing its performance. A wide range of colloid and interface science related phenomena are involved inSAGD produced water chemical treatment and need to be fundamentally understood. The basic understandingof these phenomena will lead to improved practice of SAGD produced water treatment. A series of jar testswill be carried out in synthetic waters to evaluate the impact of chemicals including type and dosage on thecoagulation of CaCO3 and Mg(OH)2 particles as well as total suspended solids (TSS) and total organic carbon(TOC) removal. By comparing the water characterization data of the synthetic waters before and aftertreatment, correlations will be constructed to correlate the performance of CaCO3 and Mg(OH)2 coagulationand TSS/TOC removal to chemicals species and dosage. The information obtained will be used to elucidate thecoagulation and removal mechanisms. Basic questions like how coagulant interacts with the feed TSS/TOC ofthe synthetic waters as well as formed CaCO3 and Mg(OH)2 particles will be answered.