In steam assisted gravity drainage (SAGD) operations, skim oil recycled to a free water knockout (FWKO) often results in poor water quality and rag formation at the oil/water interface. To improve water quality and demulsification efficiency in the presence of skim oil recycle, it is necessary to understand the status of oil and solids in the produced water throughout the process. In this paper, the effect of skim oil on the water/oil separation in SAGD operations was studied. Dynamic optical fluid imaging (DOFI) technology was used to characterize oil and solids concentrations, oil droplet sizes, and the associated size distributions in the produced water collected from various vessels in a SAGD process. The DOFI analyses show that skim oil recycle caused more oil and solids to be sent to the FWKO, treater and induced gas flotation (IGF) outlet waters and finally to oil removal filters (ORF). The increased oil in water led to more oil droplets, especially more numerous small oil droplets remaining in the produced water. These small oil droplets are more challenging to remove than larger oil droplets, resulting in deteriorated water quality. Skim oil recycle decreased the oil removal efficiency of the IGF vessel and increased fouling of ORF filters by oil and solids. Fourier transform infrared spectroscopy analysis of the solids collected from the produced water in the presence of skim oil recycle indicated that the solids are bitumen-coated fine quartz and clays. Demulsification studies show that application of dual reverse emulsion breakers could help improve water quality and alleviate the negative effects due to the solids from skim oil addition.

在蒸汽辅助重力排水（SAGD）操作中，将脱脂油回收到自由水分离器（FWKO）中通常会导致差的水质和油/水界面处的碎屑形成。为了在脱脂油循环的情况下提高水质和破乳效率，有必要了解整个过程中采出水中油和固体的状况。本文研究了脱脂油对SAGD作业中水油分离的影响。动态光学流体成像（DOFI）技术用于表征在SAGD过程中从各个容器收集的采出水中的油和固体浓度，油滴尺寸以及相关的尺寸分布。DOFI分析表明，脱脂机油的循环利用导致更多的机油和固体被送到FWKO，处理机和诱导气浮（IGF）出口水，最后到达除油过滤器（ORF）。水中油的增加导致更多的油滴，尤其是产出水中残留的更多小油滴。这些小油滴比大油滴更具挑战性，导致水质恶化。脱脂油再循环降低了IGF容器的除油效率，并增加了油和固体对ORF过滤器的污染。在脱脂油再循环的情况下，从采出水中收集的固体的傅里叶变换红外光谱分析表明，固体是沥青涂层的细石英和粘土。