Applying The Full Borehole Conductance Sensor To Measuring Water Cut Of Oil-water Two-phase Flow

The full borehole conductance water cut meter which measures water cut of producing well in the no-flow-concentrating state has guiding significance to the research and development of a new-type water cut meter and can continuously measure water cut of high-yield well.A new-type of full borehole conductance sensor for measuring water cut of two-phase flow has been designed and analytical model's, simulative and experimental study on the full borehole conductance sensor is carried out.Electric field simulation calculation has been carried out applying mathematical model and ANSYS software through Laplace equation in corresponding boundary conditions, which determines the distributing of sensitivity field of the sensor: Electric field diverges from electrode to metal casing wall. The electric field near the electrode is higher than that far from the electrode. Uniform electric field is gained in a certain area of the well bore by adding shielded electrodes.Experimental rig is designed. Static experiment research is performed and the feasibility of the principle is verified. Influence of water salinity, contamination and several other factors on response of the sensor has been studied. The experiment shows that the sensor is sensitive to the insulating material. The closer the insulating cylinder to the electrode is, the more sensitive the sensor will be. Influence of water salinity on response of the sensor has not been found in the experiment. Contamination has effect on the sensor. Sensitivity of the sensor is very low in the influence area of contamination. Influence of the effect of electric double layer on the full borehole conductance sensor has been overcome by using the alternating constant current source of 20KHz and the blocking capacitor.Principle experiment prototype is designed and has been used for dynamic experiments on multi-phase flow experimental rig. The perfect experiment conclusion is gained. Surface of electrodes is processed, which effectively reduces the influence of contamination on measure. The instrument has resolution at a set of points with the flow rate 10m3/d~200m3/d and the water cut 50%~100%. The instrument has good stability and when the flow rate is more than 60m3/d the instrument has good repeatability and high precision. The trends of analytical model, simulation and experiment are accordant with each other. This method has the advantages of adapting to high water cut, high flow rate and continuous measurement. It has application value in continuous measurement for flow parameter of oil-water two-phase flow in high-yield well. These results may establish important theoretic and experimental basis for the research on field prototype.