A method and device for online magnetic resonance multiphase flow detection

Most multiphase flow separation detection methods used commonly in oilfields are low in efficiency and accuracy, and have data delay. An online multiphase flow detection method is proposed based on magnetic resonance technology, and its supporting device has been made and tested in lab and field. The detection technology works in two parts: measure phase holdup in static state and measure flow rate in flowing state. Oil-water ratio is first measured and then gas holdup. The device is composed of a segmented magnet structure and a dual antenna structure for measuring flowing fluid. A highly compact magnetic resonance spectrometer system and intelligent software are developed. Lab experiments and field application show that the online detection system has the following merits: it can measure flow rate and phase holdup only based on magnetic resonance technology; it can detect in-place transient fluid production at high frequency and thus monitor transient fluid production in real time; it can detect oil, gas and water in a full range at high precision, the detection isn't affected by salinity and emulsification. It is a green, safe and energy-saving system.