Characterization of the dissolved organic matter in steam assisted gravity drainage boiler blow-down water

The presence of high concentrations of dissolved organic matter (DOM) and total dissolved solids (TDS) in the boiler blow-down water (BBD) causes severe equipment fouling during the SAGD operation. For effective BBD management, a detailed understanding of the BBD chemistry is important. In this work, BBD DOM was fractionated using ion-exchange resins into hydrophobic and hydrophilic acids, bases and neutral fractions. Fluorescence excitation emission contours established discerning signatures of the organic fractions. The molecular weight distribution of the DOM was determined through filtration of BBD using membranes of different molecular weight cut-offs (MWCO). The effect of acidification on the BBD DOM and the mechanism of silica-DOM co-precipitation in presence of high salt concentration was determined. The DOM consisted mostly of low molecular weight compounds. Hydrophobic acids present in the BBD were predominantly humic acids and not naphthenic acids as observed in oilsands process affected waters.