High-efficiency separation for SAGD produced liquids

Demulsification of steam-assisted gravity drainage (SAGD)–produced liquid from the Xinjiang oil field was investigated in this study. The heavy crude oil in the produced liquid presents a high density, high viscosity, high resin and asphaltene contents, and high acid value. Thus, this liquid is difficult to separate. The effect of cationic deoiling agents on the separation of the SAGD-produced liquid was tested. W590 showed the highest separation efficiency among the deoiling agents surveyed. Zeta-potential experiments revealed that cationic deoiling agents could neutralize negative charges on the oil droplet surface and significantly reduce the oil content in the separated water. After the produced liquid was settled with 220   mg/L W590 at 90   °C for 1   h, the oil content in the water could be rapidly decreased to 198.0   mg/L and the water content in the produced liquid could be reduced from 86.2% to 22% to obtain a W/O emulsion. In the second process of separation, the demulsifier FC20 was applied. Under an electric field, the water content in the emulsion to which 30% diesel oil had been added could be reduced to 1.0% with 300   mg/L FC20, a 750   V/cm electric field for 20   min, and a settling time at 90   °C for 4   h.