The Response Characteristic Of Electromagnetic Flow Meter In Polymer Solution

Along with the development of tertiary oil recovery technique of Daqing Oilfield in recent years, the downhole electromagnetic flow meter is already widespreadly used for injection polymer profile logging and flowrate adjustment of injection polymer wells. For the limition of calibrating condition, at present electromagnetic flow meters are calibrated with water media in laboratory. In field testing the calibrated chart carried out in water are used to compute the flowrate of polymer solution. This makes the measuring flowrate in field different from practical injection flowrate, so electromagnetic flow meter cann't solve the flowrate test downright in injection polymer well. In order to solve this problem, the studies of flow measurment and calibrating method of memory electromagnetic flow meter are carried out in polymer solution. According to simulation well's experiments and field tests, the calibrating method of memory electromagnetic flow meter of measuring flowrate in injection polymer well is obtained. The measuring error is minished greatly and the injection polymer profile is monitored well.According to the principle of long tube electromagnetic flow meter, the response equation of downhole electromagnetic flow meter is deduced in theory. The three vector expressions of response equation are solved, the analytical expression of weighting function is solved with Green function. The vector expression of magnetic induction is solved also by introduced magnetic dipole model. The analytical expressions of velocity of Newtonian fluid and non-Newtonian fluid are solved on the condition of laminar flow in annular space.When works in downhole, memory electromagnetic flow meter is centered in oil tube by centralizer. So annular space is formed between instrument and oil tube. The measured liquid (water or polymer solution) flows through this annular space. In order to research the magnetic field distribution of electromagnetic flow meter in annular space, electromagnetic flow meter's sensor model is established by the finite element analytical method and its magnetic field distribution is also simulated and studied. The affection of ferromagnetic impurity flowing through measuring field is also simulated and studied. In order to research the influence on flow measurement of velocity profile changes in annular space caused by instrument offcenter or inclination etc., velocity profile in annular space is simulated and studied by the finite element analytical method. The simulation study can provide guidance for field application of the instrument.