Investigation Of Flow Characteristics Of Added-water Heavy Oil And Its Model Oil

With the large-scale exploitation and utilization of extra heavy oil,super heavy oil and oil resources in the harsh natural environment,the technology of multiphase flow with distinct technical and economic advantages has been developed.Oil-water transportation technology,as one kind of multiphase technology,has attracted more and more attention from the petroleum industry,but there are still some problems to be further studied.Focusing on the characteristics of oil-water two-phase flow structure and analysis on flow pattern transition,pressure drop calculation,critical parameters testing of added-water heavy oil transportation,and production of model oil of emulsified heavy oil,this paper has carried out the following works:(1)A visual oil-water two-phase flow loop is designed and built,and the pipeline,with a fully functional measuring instrument and control system,is 20 meters in length.Unlike the domestic similar device design,this device uses T-type inlet,so oil and water can entry the pipeline in two separate phases.The design thought is conducive to observe a variety of flow patterns,and more close to the added-water gathering and transportation pipeline of heavy oil in oil field.The design of the device lay a solid foundation for further theoretical study.(2)A study on the characteristics of main flow patterns,flow pattern transitions and influencing factors of oil-water two-phase flow is carried out.The basic flow patterns are divided into four types:stratified flow,dispersed flow,annular flow and intermittent flow.Model oil-water two-phase flow pattern maps constituted by model oil of three kinds of viscosity grades are drew.The influence of the viscosity and pipe diameter on the structure of the flow patterns and the development of the oil-water flow pattern is analyzed.In addition,the differences between stainless steel pipe conveying heavy oil and acrylic pipe conveying mineral oil are analyzed.(3)The study on the pressure drop of the flow patterns with water as the dominant phase is carried out.Water as the dominant phase is an important feature of added-water heavy oil transportation,and oil-in-water dispersed flow and core annular flow are important components.The key of pressure drop calculation of oil-in-water dispersed flow lies in mixture viscosity calculation.Based on the mixture viscosity calculation of the oil-in-water dispersed flow,this paper modified Roscoe&Brinkman model in order to consider the difference between the rigid sphere assumption and the droplet deformation,breakup and coalescence in dispersed flow.The model is applicable to the pressure drop calculation of the oil-in-water dispersed flow containing more than 30%oil of low viscous or medium viscous.(4)Focusing on the core annular flow,this paper modifies the calculation method of the friction factor in the Bannwart equation,introducing the correction factor of the pipe wall roughness into the Zigrang equation to account for the influence of oil adhesion to the pipe wall.A linear correlation between the correction factor of the pipe wall roughness and the oil core viscosity is developed.If is proved that the modified model is applicable to predict the pressure drop of the annular flow in horizontal acrylic pipe.(5)The experimental study on the key parameters design of' the added-water heavy oil transportation is carried out.This paper takes two kinds of super heavy oil as examples and the critical water addition ratio was tested using the flow loop and the critical transportation temperature was tested using hot water pipe carrying experiments.The field experiments show that the key parameters determined by this method are of great reference value for the design and operation of added-water heavy oil transportation,and for oil wells of low liquid production,the risk of tube blockage can be reduced effectively.(6)Compare the difference between the properties of common model oil and emulsified heavy oil in the gathering and transportation pipeline,and develop a scheme for producing modified model oil with a similar flow properties with the emulsified heavy oil.In this paper,the difference between the two kinds of common high-viscosity model oil(industrial mineral oil and dimethyl silicone oil)and the crude oil of the same viscosity and their influence on the added-water transportation are analyzed from three aspects:rheological properties,interface characteristics and emulsifying properties.White oil is selected as the base oil,and the emulsified FZ super heavy oil is set as a reference.By analysing the experimental temperature,water ratio,the type of emulsifying agent and referring to the stability of emulsified model oil,the preparation plan for producing the model oil for FZ emulsified heavy oil is finally achieved.