Study On Measurement Characteristics Of Electromagnetic Flowmeter In Injection Polymer Profile Well Logging

In Daqing Oilfield, the four-electrode electromagnetic flow meter in well is widely used in injection polymer profile logging. Because of the changing of the polymer's flow characteristic, which leads to the result that flow velocity profile of polymer has a great impact on the measurement characteristic of electromagnetic flow meter, it is needed to investigate theoretically magnetic field characteristic of electromagnetic flow meter and flow field characteristic in injection polymer profile well logging. In this paper, the Finite Element Method (FEM) is used to examine magnetic field distribution characteristic of electromagnetic flow meter in well, and based on that, flow field characteristic at the practical well logging condition is examined with CFD technique.In order to study magnetic field characteristic, the model of magnetic field distribution is established according to the geometry structure of the instrument, and magnetic induction intensity,magnetic field intensity and magnetic flux distribution have been obtained in the annulus space between the instrument and the pipe by numerical simulation. And then the effect on magnetic field distribution is analyzed when the instrument is eccentric or scrap iron exists in the pipe. The research results show that magnetic field distribution of the four-electrode electromagnetic flow meter is basically homogeneous, which lays on the foundation for the linear output of flow measurement response.Flow field characteristic has been studied from the basic concept of hydrodynamics, then flow velocity profile in the casing and tubing is calculated respectively, and flow velocity distribution of different fluids has been found. Then the flow velocity distribution at the measurement section of the instrument is analyzed when the instrument is in casing or tubing. Above that, the ratio of centre flow velocity to average flow velocity is calculated for different viscosity, and the law of the ratio changing with the polymer's concentration has been obtained. Finally, comparing the experiment result with theoretical analysis, the reasonable interpretation is given to the experiment result。...