Resourceful and harmless treatment of the steam-assisted gravity drainage produced fluid

Abstract

The steam-assisted gravity drainage (SAGD) process is an effective technology for heavy crude oil extraction. SAGD produced fluid (including oil, water, and sludge) that has strong stability and difficult separation characteristics. It is very necessary to thoroughly separate SAGD produced fluid, as it can lead to environmental pollution and resource waste. In this study, a combined process of thermochemical treatment and electrocoagulation was proposed to deal with SAGD produced fluid. The influence of such parameters as type and structure of surfactants, temperature, stirring rate, and current density were examined on the separation efficiency of SAGD produced fluid. The results indicated that the oil recovery rate was 99%, with the oil and suspended solids content (4.4 and 0.58 mg/L, respectively) in the water meeting the reinjection standard (oil content <15 mg/L, suspended solids <3 mg/L) and the oil content in the sludge (1 wt%) attained the solid waste disposal standard (<2 wt%). The combined separation process of SAGD produced fluid allowed the obtaining of qualified oil, sludge, and water, with oily sludge and waste water simultaneously eliminated. Therefore, this process achieved oil and water resource utilization, as well as harmless sludge treatment, which would achieve great economic benefits and application prospects in the oil field.