油水两相超声成像修正路径追踪重建方法

Modified Ray Tracing Image Reconstruction for Oil-water Two Phase Ultrasonic Tomography

油水两相流广泛存在于石油工业的开采和储运过程中,对其流动状态的可视化检测具有十分重要的价值。超声层析成像方法具有非侵入、无辐射、安全便携等优点,但超声在油水两相界面存在折射现象,致使其成像结果存在较大误差和严重伪影。针对该问题,提出一种修正路径追踪的超声成像图像重建方法:通过定量分析超声在非均匀两相介质中传播的衰减机制,构建超声绝对成像基本模型;使用路径追踪方法定量表征传播中的非线性折射现象,并将衰减成像结果转化为路径追踪所需的声速分布信息。仿真结果表明,所提修正路径追踪非线性表征方法对重建图像精度有明显提升,可以实现油水两相流动的在线非侵入测量,离线高精度成像。

Oil-water two-phase flows is widely existed in the mining and transportation process of petroleum industry,where the visualized measurement processes vital importance.Ultrasonic Tomography(UT)is a non-invasive and non-radioactive sensing modality in industrial Process Tomography.However,facing the refraction effect of ultrasound wave at oil-water interfaces,the accuracy of reconstructed image is with large error and serious artifacts.A modified ray tracing image reconstruction algorithm is proposed.The amplitude attenuation during ultrasound propagation is quantitatively modeled to form absolute UT model.The nonlinear refraction effect is characterized in the form of iterative update of sensitivity matrix,followed by which the sound speed mapping transfers the reconstructed attenuation image to sound speed distribution for ray tracing computation.Numerical tests indicate that the proposed method significantly improves the reconstruction accuracy,which demonstrate its benefits in conducting oil-water two-phase flow high accurate imaging.