Experimental Study On Supercritical CO₂ Extraction Of Oily Sludge In The Oilfield

Due to the incapability of current processing technology,oily sledge was not processed properly and some secondary pollution may be created.Therefore,it is of great importance to develop a cost-efficient and non-hazardous technique to deal with the oily sledge produced by the oilfield.Based on a thorough understanding of the characteristics of the oily sledge samples,an equipment setup for super-critical fluid extraction was designed and produced to conduct extraction experiments with super-critical CO₂.Firstly,the influence of three parameters,including temperature,pressure and time,on the oil extraction with pure super-critical CO₂fluid was examined.The experiment results indicate that the oil extraction efficiency of super-critical CO₂ will be enhanced with increasing pressure and experimental period.However,the influence of temperature on the extraction was complicated.With ever-increasing temperature,the extraction efficiency would at first decreases then increases.In the next stage,six different entrainers were selected based on the literature review.Then the effect of these six different entrainers on the efficiency of oil extraction with entrainer-added super-critical CO₂ was investigated.Furthermore,experiments were conducted at 60?and 10 MPa to investigate the influence of three parameters,including temperature,pressure and mole ratio of entrainer,on the extraction efficiency of entrainer-added super-critical CO₂.The experiment results demonstrate that entrainer can increase the extraction efficiency of super-critical CO₂.A phenomenon was found that the extraction efficiency of nonpolar entrainer is the best and the efficiency of the strong polar entrainer is the worst.It is also found that liquid entrainer was more effective than gas entrainer.Besides,the increase of experimental temperature,pressure and mole ratio of entrainer can have a positive effect on the extraction efficiency of super-critical CO₂.