Study On Flow Characteristics Of Gas-saturated Crude Oil And Gas-Saturated Emulsion

In the process of oil field gathering and transportation,the production of well flow is often transported in the condition of mixed transmission.Under the pressure of pipeline,the crude oil in the pipeline usually contains a certain amount of gas,which improves its fluidity.Therefore,it is important to study the flow characteristics of dissolved gas crude oil and dissolved gas emulsion to improve the efficiency and reduce the energy consumption in oil field gathering and transportation.In this paper,the effects of pressure,temperature,water content and oil properties on the saturation solubility of carbon dioxide in crude oil and emulsion were studied by a high-pressure reactor.On the basis of experimental study,the effects of pressure,temperature and water content on the viscosity of saturated gas dissolved crude oil and emulsion were analyzed.In the experimental range of 40℃-70℃ and 0-1.4MPa,the maximum viscosity reduction rate of the crude oil used in the experiment can reach 40.28%.In the range of 35℃-53℃ and 0-1.0MPa,the maximum viscosity reduction rate of crude oil emulsion at different water content can reach 62.36%(10% water cut),44.87%(20% water cut)and 58.11%(30% water cut)respectively.The method of determining wax precipitation point based on the increase of activation energy has solved the problem that the wax precipitation point can not be measured by DSC method under the pressure system.On the base of the experimental study,the influence rule of dissolved gas pressure on wax precipitation point of gas-saturated crude oil is obtained.In the range of dissolved gas pressure 0.6MPa-1.4MPa,the wax precipitation point of 1# crude oil can be reduced by 2℃-7℃,and the wax precipitation point of 2# crude oil can be reduced by 4℃-8℃.The viscosity prediction formula of gas-saturated crude oil is corrected by using the experimental data.The viscosity prediction formula of gas-saturated emulsion is established(the maximum relative error is 37.62%,and the average relative error is 17.02%).The hydraulic and thermodynamic calculation method of oil and gas gathering pipeline is determined.The software of hydraulic and thermal calculation for oil and gas gathering pipeline is compiled by C# language,and a case is calculated by using the software.It is concluded that the dissolved gas has great influence on the pressure drop of the gathering pipeline in low water cut condition,and the highest pressure drop of the pipeline can be reduced by 19.83%.