Separation of Bitumen from Brines Using Synthetic Membranes

Abstract

The extraction of petroleum from oil sands by SAGD (Steam Assisted Gravity Drainage) method involves the underground injection of steam to extract the oil. Steam loses its latent heat to petroleum deposits, and condensed process waters along with liquefied oil are collected and piped out of the well. After the oil-water separation, process water saturated with bitumen is to be separated and recycled back into the extraction process. As the steam boilers require high-purity feed water, it is proposed that synthetic membranes be used in the water-recycling scheme. Although membranes provide a high quality filtrate, the accumulation of contaminants on the membrane surface, known as fouling, hinders the filtration process and eventually compromises water quality. The objective of this project is to test the performance of synthetic membranes in this application, and perform physical and chemical modifications to the membrane and to the processed water to reduce the amount of foulants accumulating on the membrane surface. A total of 28 membranes are tested at two temperatures levels (45°C and 80°C). The pore size, the solution pH, the membrane type, the modification agents and the temperature are under investigation to determine the optimal conditions for fouling mitigation. It is concluded that high pH levels increase the permeation rate by reducing fouling. This is the result of hydroxyl groups sorbing water molecules into the membrane pores. Such chemical activity reduces foulant attraction to the membrane surface. As for pore size, large pore membranes show less fouling than small pore membranes at low temperature. The reverse trend is observed at higher temperature.