注入剖面井下流量计校准曲线拐点研究

Inflection Point of Calibration Curve of Injection Profile Downhole Flowmeter

为了提高注入剖面井下流量计的校准精度,实现量值有效传递,在计算层流、紊流临界流量的基础上,提出30m^3/d以下加密流量点的方法,并进行室内校准。结果表明,超声波和电磁流量计的校准曲线在层流临界流量点附近均存在拐点;超声波流量计校准曲线在拐点以下符合多项式规律,拐点以上符合线性规律;电磁流量计校准曲线拐点上下符合线性规律,上斜率略小于下斜率,不同但比较接近。

In order to improve the flowmeter calibration precision in injection profile well and to realize the effective value transfer,the flow point densification was proposed below 30 m^3/d on the basis of calculating the critical flow rate of laminar flow and turbulent flow,and was calibrated indoor.The result shows that both calibration curves of ultrasonic and electromagnetic flowmeter have a turning point near the critical flow rate in laminar flow.The calibration curve of ultrasonic flowmeter conforms to the polynomial rule below the inflection point,and conforms to the linear rule above it.The calibration curve of electromagnetic flowmeter conforms to the linear rule near inflection point,and the upper slope is slightly smaller,different from but close to the lower one.