Research On The Electromagnetic Flow Measurement Method Of Chemical Flooding High Viscous Oil-gas-water Multiphase Flow

Oil-gas-water multiphase flow is commonly existing in oil wells when oil field development entering the middle and late period.Measuring the flow rate of oil-gas-water multiphase flow accurately that is of great importance to oil production process control and efficient development.But for the chemical flooding development oil field,there are still many problems wiht downhole multiphase flow measurement.The outflow type electromagnetic flow measurement method with large measurement errors for measuring the high viscous fluid in injection wells of chemical flooding oilfield;There is no feasible method and logging technology to solve the flow rate measurement problems of high viscous oil-water two-phase flow and oil-gas-water three-phase flow.In order to solve the problem,the response characteristics of the outflow type and packer type electromagnetic flow sensors are studied in this paper by the method of combining theory with experiment.Three flow rate measurement methods are proposed as following: The method for measuring the flow rate of high viscous single-phase flow in injection wells;The method for measuring the total flow rate of high viscous oil-water two-phase flow in production wells;The three-phase flow measurement method based on the fusion of multiple sensors of packer type electromagnetic flow sensor,optical fiber probe sensor and conductance holdup sensor.In order to carry out theoretical analysis of the outflow type and packer type electromagnetic flow sensors,the insulator boundary condition are applied to the outer surface and inner surface of the outflow type and packer type electromagnetic flow sensors respectively,and the basic differential equation of the electromagnetic flow sensor are solved by using Green's function method,the response equations of the outflow type and packer type electromagnetic flow sensors are obtained respectively.By using the method of separation variables and solving Green's function,the mathematical models of the weight function of the outflow type and packer type electromagnetic flow sensors are obtained respectively.By using the magnetic field theory of magnetic dipole,the mathematical models of magnetic induction intensity function of the outflow type and packer type electromagnetic flow sensors are obtained by solving vector magnetic potential respectively.According to the mathematical analysis of the response equation,the weight function and the magnetic induction intensity function,the theoretical models of the outflow type and packer type electromagnetic flow sensors are established respectively.In order to study the output characteristics of the outflow type and packer type electromagnetic flow sensors under the influence of weight function,magnetic induction intensity function and flow state,through the numerical analysis of the theoretical models of the outflow type and packer type electromagnetic flow sensors,the distribution characteristics of the weight function and magnetic induction intensity in the annular and circular measurement areas and their effects on the induced potential are studied,the relationship between flow state and output characteristics of sensors in annular measurement area and circular measurement area are illustrated,the reason of measurement error of the outflow type electromagnetic flow sensor is revealed.The research results show that the output characteristics of the outflow type electromagnetic flow sensor in the annular measurement area are seriously affected by the velocity profiles distribution,the maximum deviation of induction voltage difference is about 10.2%;However,the output characteristics of the packer type electromagnetic flow sensor in the circular measurement area are less affected by the velocity profiles distribution,and the maximum deviation of the induction voltage difference is only 1.9%.Based on the numerical analysis of the theoretical models of the outflow type and packer type electromagnetic flow sensors,the response characteristics of the outflow type electromagnetic flow sensor in water and polymer solutions with different concentration/viscosity are analyzed by using the single-phase flow calibration device.The research results show that the response characteristics of the outflow type electromagnetic flow sensor in water are greatly affected by flow states,and the response characteristics in polymer solutions are not affected by the variation of concentration/viscosity of polymer solutions.The response characteristics of the packer type electromagnetic flow sensor in oil-water two-phase flow,water and high viscous polymer solutions are analyzed.It is found that the response characteristics of the packer type electromagnetic flow sensor are not affected by the variation of water-cut in oil-water two-phase flow.And the response characteristics of the packer type electromagnetic flow sensor in water and high viscous polymer solutions are not affected by the variation of concentration/viscosity of polymer solutions.In order to solve the engineering application problem that the outflow type electromagnetic flow measurement method with large measurement errors for measuring the high viscous fluid in chemical flooding injection wells,based on the calibration model of water laminar flow state constraint,a method of measuring the flow rate of high viscous fluid in chemical flooding injection wells by the outflow type electromagnetic flow sensor is proposed.The absolute values of full scale errors are less than 5.0%,which is 7.0% lower than that of existing instrument.In order to solve the engineering application problem that there is no feasible method for the flow rate measurement of high viscous oil-water two-phase flow in chemical flooding production wells,the total flow rate measurement method of oil-water two-phase flow using the regression equation of water calibration is proposed,and the full range errors are less than 5.0%.Finally,the validity and correctness of the two methods are verified by field tests.In order to solve the engineering application problem that there is no feasible method for the flow rate measurement of oil-gas-water three-phase flow in chemical flooding production wells,the method using packer type electromagnetic flow sensor-conductance sensors-fiber probe sensor combination technology for measuring oil-gas-water three-phase flow is carried out.Multisensor fusion flow rate measurement method of oil-gas-water three-phase flow is studied.Flow patterns of oil-gas-water three-phase flow are identified respectively in the multisensor fusion measurement space.Based on the analysis of the response rules of multiple sensors in oil-gas-water three-phase flow,the multisensor calibration charts and the multisensor combination interpretation model for oil-gas-water three-phase flow are established.This paper presents a method for measuring the oil-gas-water three-phase flow by multisensor fusion of packer type electromagnetic flow sensor,optical fiber probe sensor and conductance holdup sensor.Compared with traditional measurement methods,the influence of complex and variable flow patterns on three-phase flow measurement is avoided.Field tests show that the proposed method is suitable for the measurement of oil-gas-water three-phase flow in chemical flooding production wells.