| In order to study the properties of saturated live oil in gathering pipeline of carbon dioxide flooding,based on different proportions of CO2 and CH4 mixture gas source,the experiment pretreated Changqing oil and Caoqiao oil by using self-made saturated dissolved gas crude oil processing device under simulated stratum conditions?25MPa?80°C?,and then through step by step depressurizing get four saturated dissolved gas crude oils under gathering and transportation conditions?03.5MPa?:CO2 saturated live oil,CH4 saturated live oil,n?CO2?:n?CH4?=9:1 saturated live oil,n?CO2?:n?CH4?=8:2 saturated live oil.After the properties and rheology of the saturated live oil of gathering pipeline is studied by gas chromatograph,DSC,the instrument of measuring dissolved gas properties of saturated live oil,high pressure rheometer and other instruments.The experimental resulted about treated and untreated Changqing crude oil of show that saturation content decreased and the content of aromatics,resins,asphaltenes and density increased about treated crude oil by scCO2.Paraffin wax and microcrystalline wax content increased so that wax precipitation point and wax crystallization increased,which caused pour point,viscosity and yield value increased.The experimental resulted about treated and untreated Caoqiao crude oil of show that saturation content and aromatics increased,but resins and asphaltenes increased.The average particle size of asphaltene particles and viscosity increased.For the saturated live oil which treated by the same dissolved gas,the solubility increased with the increase of pressure and decreased with the increase of temperature,the bulk coefficient increased with the increase of pressure and increased with the increase of temperature,density decreased with the increase of pressure and decreased with the increase of temperature,abnormal point and wax precipitation point decreased with the increase of pressure,viscosity decreased with the increase of pressure and decreased with the increase of temperature,freezing point decreased with the increase of pressure,yield value decreased with the increase of pressure.After the treatment with four dissolved gas for Changqing crude oil,in the same temperature and pressure,the relative relationships of the solubility Rs,the bulk coefficient Bo,the pour point Tz,the viscosity?and the yield value of the Changqing crude oil are Rs?CO2?>Rs?9:1 mixture gas?>Rs?8:2 mixture gas?>Rs?CH4?,Bo?9:1 mixture gas?>Bo?8:2 mixture gas?>Bo?CO2?>Bo?CH4?,TZ?CH4?>TZ?CO2?>TZ?8:2 mixture gas?>TZ?9:1 mixture gas?,??CH4?>??CO2?>??8:2 mixture gas?>??9:1 mixture gas?,?y?CH4?>?y?CO2?>?y?8:2 mixture gas?>?y?9:1 mixture gas?.For the Caoqiao saturated live oil which treated by the different dissolved gas,in the same temperature and pressure,the relative relationships of the solubility is Rs?CO2?>Rs?9:1 mixture gas?>Rs?8:2 mixture gas?>Rs?CH4?.Because of the barrier effect of asphaltene on the dissolution of methane molecules,the synergistic swelling effect of CO2 and CH4 can be reflected under higher pressure so that the bulk coefficient of CO2 saturated live oil is most under 2MPa and the bulk coefficient of 9:1 saturated live oil is most over 2MPa.When the pressure is low,the solubility of methane is less in Caoqiao crude oil.The synergistic effect of methane and carbon dioxide is weak for Caoqiao crude oil.The amount of dissolved gas was the main role for viscosity reduction.The greater the solubility was,the better viscosity reduction was.The solubility of methane enlarged in Caoqiao crude oil with the increase of pressure.Methane increased the intermolecular distance so that it promoted the swelling of carbon dioxide to crude oil.The synergistic swelling of methane and carbon dioxide was the main role for viscosity reduction.The greater the bulk coefficient was,the better viscosity reduction was. |
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