New technology for heavy oil exploitation wastewater reused as boiler feedwater

Steam Assisted Gravity Drainage (SAGD) or non-SAGD heavy oil recovery process uses a considerable amount high-pressure steam and produces significant amount of oily wastewater. Conventional water treatment and steam generation process is very complex, producing poor quality water for reuse and low energy efficiency. Using evaporation process to replace those conventional treatment processes first emerged in Albert, North America. This eventually resulted in introducing conventional drum boiler to replace once-through steam generator to produce steam. The paper introduces evaporation technology to treat heavy oil wastewater and produce high-quality boiler feed water. It also provides comparison data between evaporation and conventional process (warm lime softening and weak acid cation ion exchange) from technical and operational aspects. Conclusion is that evaporation provides an alternate approach to produced water treatment, which is simpler, more cost effective and more reliable, and reduces complexity of the steam generation system. Additional steps can be taken to recover all liquid waste streams for reuse in the plant, resulting in zero liquid discharge.