The Plug-in Method For Measuring Oil-water Two-phase Flow At Low Fluid Velocity And High Water-cut

With long term exploitation of oil field, the most onshore oilfields in China havebeen entering into the middle-late stage of oil recovery. Because of long timewater-flood recovering and low permeability character in oil reservoir, thecharacteristics of oil-water two-phase flow in oil well is in flow condition of low fluidvelocity and high water-cut. Therefore, the measurement method for oil-watertwo-phase flow at such conditions is a significant issue to improve the oil wellproduction performance and optimize oil reservoir management.We design a new plug-in conductance sensor to measure the parameters ofoil-water two-phase flow at flow condition of low fluid velocity and high water-cut.We optimize the geometry of plug-in conductance sensor using finite element analysismethod and design a signal conditioning module of the conductance sensor. Weconduct an experimental flow loop test of low flow rate and high water-cut oil-watertwo-phase flow, in which the total flow rate is range from0.5m3/day to7m3/day andwater-cut from10%to100%. In experiment, three typical oil-in-water flow patternsare observed including oil slug flow, oil bubble flow and very fine oil bubble flow.The innovative research results of this study are as follows:1. We analyze the electric field distribution characteristics of the plug-inconductance sensor using finite element analysis method; we also study the fluid fielddistribution characteristics around the center-body using the numerical simulationmethod; we optimize the geometry of plug-in conductance sensor from the views ofelectric field and fluid field distribution. The dynamic experimental results show thatthis conductance sensor has good measurement characteristics both in phase volumefraction and cross-correlation velocity under different flow patterns includingoil-in-water oil slug flow, bubble flow and very fine bubble flow.2. Based on the measured individual phase holdup, we extract the flowparameters in drift model. In addition, according to the cross-correlation measurementresult, we establish the total flow rate prediction model. The dynamic experimentshows that a high precision prediction of the total flow and individual phase volumefraction have been made at the flow conditions of total flow rate from the range0.5m3/day to7m3/day and the water-cut from10%to100%. 3. We analyze the flow characteristics of oil-water two-phase flow at low flowrate and high water-cut using recurrence plot and recurrence quantification analysis.We find that the recurrence rate, determination and entropy can differentiate thevariations of dynamic characteristics of oil-water two-phase flow.