Experimental Study On Optimization Of Thermochemical Dehydration Parameters For Aging Oil At A Combined Station In Daqing Oilfield

During oilfield production,some produced liquids have not processed in a timely manner and have accumulated in the gathering and transportation system for a long time,resulting in long-term exposure to environmental factors such as temperature and light.On the other hand,due to the use of a large number of chemical agents and the accumulation of flocs in oilfield production,the emulsification of crude oil emulsions is severe and the stability is enhanced,resulting in the formation of aged oils that are difficult to treat,such as landing oil,floating oil on the upper part of the sewage sedimentation tank in the dehydration station,and waste oil in the recovery tank of the sewage treatment station.Currently,domestic and foreign oilfields mainly use the blending method to treat aged oil,but the composition of aged oil is complex and the water content is high.If treated together with conventional water containing crude oil,it will impact the crude oil system,easily leading to power failure of the electric dehydrator,affecting normal production,and also causing some quality indicators to fail to meet the requirements.The thermochemical dehydration method is simple in process and has wide adaptability.However,using thermochemical methods to treat aged oil is different from treating ordinary aqueous crude oil,there are higher requirements for the selection of demulsifiers and demulsification parameters such as dosing concentration,heating temperature,and settling time.Therefore,it is necessary to conduct research on optimization of thermochemical dehydration parameters.This article takes the aged oil from a joint station in Daqing Oilfield as the research object,mainly including the oil collection from the first and second settling tanks of the internal sewage station of the joint station,and the oil collection from the sewage settling tanks of the dehydration station,as well as the floating oil from the external fracturing backflow fluid recovery tank,the landing oil from the unloading point chemical oil tank,and the oil collection from the oily sludge treatment station of the joint station.By analyzing the physical properties and components of aged oil and conventional crude oil from different sources,the differences in pour point,density,viscosity,impurity content,ferrous sulfide content,resin,and asphaltene content between aged oil and conventional crude oil are compared,and the reasons why aged oil is difficult to treat compared to conventional crude oil are studied.In the thermochemical dehydration process of the joint station,sometimes aged oils from certain sources are treated separately,and sometimes aged oils from different sources are mixed for treatment.Therefore,in indoor thermochemical experiments,demulsifiers were selected from different sources of aged oils and mixed aged oils,and 1-4 demulsifiers with better dehydration effects were selected from 10 types of demulsifiers.Then,experiments were conducted to optimize the parameters of demulsifiers for aged oils and mixed aged oils from different sources,ultimately determining 1-2 types of demulsifiers and their optimal processing temperature,time,and concentration.Conduct on-site tests to determine the optimal demulsification parameters for the thermal chemical dehydration process of aged crude oil at a joint station in Daqing Oilfield,so that the water content of the treated aged crude oil is less than 1%..In thermochemical experiments,it was found that a transition layer was formed at the oil-water interface during the oil-water separation process,and the presence of the transition layer seriously affected the thermochemical dehydration effect,resulting in a decrease in the dehydration amount of aged oil.For the transition layer that is difficult to handle in thermochemical experiments,a transition layer dehydration experiment was conducted,using physical means to accelerate its dehydration through stirring.We studied and analyzed the effects of stirring speed,stirring time,heating temperature,and different sizes of containers on the dehydration effect of the transition layer,and compared the differences in the dehydration effect of the transition layer between different oil products based on their microscopic morphology.