Influence of salt and acrylamide copolymer on the stability and TOG of brine/crude oil emulsions

The formation of water/oil (w/o) emulsions is undesirable for the oil industry since they negatively impact extraction and transport. Resins and asphaltenes are considered the main interfacially active natural components responsible for the stability of these emulsions, although other parameters can also affect this stability. Injection of polymer solutions is one of the methods aiming to increase oil production, but its influence on w/o emulsions' stability and the quality of the separated water is still not clear, mainly for heavy oils. Therefore, in this work we used a heavy oil to prepare w/o emulsions without and with 450 ppm of acrylamide copolymer (FLOPAAM AN 125) in brine, without and with 650 ppm of demulsifier in the oil phase. The influence of the salt concentration on the stability of the w/o emulsions and on the total oil and grease (TOG) of the separated water was evaluated by the bottle test and fluorimetry, respectively. Increasing salinity in the range of similar to 35,000 ppm to similar to 63,000 ppm was associated with lower emulsion stability and TOG of separated water. These parameters then remained almost constant from similar to 63,0000 to 90,000 ppm of salts, except the emulsion containing only acrylamide copolymer, in which the stability kept decreasing. The acrylamide copolymer and demulsifier provoked a decrease in the emulsion stability, although the effect of both together was not additive. Low TOG was achieved using only the demulsifier. Acrylamide copolymer alone provoked a decrease in the quality of the separated water, an effect that was enhanced in the presence of the demulsifier.