Abstract
Flow velocity field measurement is important for analyzing flow characteristics of oil–water two-phase immiscible flow in vertical well. Digital particle image velocimetry (DPIV) is an effective velocity field measurement method that has overcome single point measurement limitation of traditional instruments. However, multiphase flow velocity fields generated by DPIV are often accompanied by local false vectors caused by image mismatching, which leads to measurement results with low accuracy. In this paper, the reasons for oil–water two-phase immiscible flow image mismatching in inner diameter 125 mm vertical pipe is identified by studying the DPIV calculation process. This is mainly caused by image noise and poor window following performance that results from poor deformation performance of the interrogation window. To improve deformation performance of the interrogation window, and thus improve the accuracy of the algorithm, iterative closest point (ICP) and moving least squares (MLS) are introduced into the window deformation iterative multigrid algorithm in DPIV postprocessing algorithm. The simulation showed that the improved DPIV algorithm had good matching performance, and thus the false vector was reduced. The experimental results showed that, in light of the present investigation, on average, the improved DPIV algorithm is found to yield an accuracy improvement of ~6%; the measurement uncertainty and reproducibility of the improved DPIV algorithm were 0.149 × 10−3 m/s and 1.98%, respectively.
Highlights
Flow velocity field measurement is important for analyzing the flow characteristics of oil–water two-phase immiscible flow, which directly affects the interpretation of logging data and design of logging instruments [1,2]
The time interval is 0.006 s, and the measurement area size is 124 mm × 124 shows the flow velocity fields measured by the window deformation iterative it multigrid an (WIDIM)-digital particle image velocimetry (DPIV) algorithm and the IM-WIDIM-DPIV
The reasons for the low DPIV image matching rate were studied in this paper
Summary
Flow velocity field measurement is important for analyzing the flow characteristics of oil–water two-phase immiscible flow, which directly affects the interpretation of logging data and design of logging instruments [1,2]. (2) Compared to small-scale laboratory investigations, the largerthe measurement accuracy Algorithms in their application filed, they doifnot spatial domain increases the these illumination issuesare andeffective oil droplets shielding problems, especially perform well for oil–water two-phase immiscible flow measurement in an inner diameter 125 mm vertical upward pipe. Oil droplets are small in inner diameter 125 mm vertical upward pipe, with good follow ability, and could be used as tracer particles to obtain the shooting direction cumulative average flow velocity distribution information in the plane. The following problems exist in the application of the WIDIM algorithm in DPIV to oil–water two-phase immiscible flow velocity field measurement in an inner diameter 125 mm vertical pipe. An inner diameter 125 upward pipe, and the flow velocitytwo-phase distribution characteristics in plane are mm vertical upward pipe, and the flow velocity distribution characteristics in plane are studied
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