Sand Particle Content Monitoring in Sand-Water Two-Phase Flow Based on Distributed Acoustic Sensing

Precise control and measurement of the sand particles in sand-water two-phase flows are essential for pipeline safety monitoring and economic accounting. Nowadays, the measurement of sand particles in sand-water conveying systems relies on point measurement schemes such as invasive electrical resistance probes, which invade the pipeline and can irreversibly damage the fluid pressure, especially when multi-point measurements are required. To solve this problem, we propose a dynamic peak-seeking (DPS) method based on the highly sensitive distributed acoustic sensing (DAS) system to enhance the sand detection in sand-water flows with strong background noise. As the sensing medium, the backscattering enhanced optical fiber (BEOF) is placed in straight-line shape to form continuous distribution of sensing units for quantitative identification and localization sand particles content. The experimental results indicate that there is a significant impinging signal as the sand particles in the sand-water flow impacts the pipe wall. The proposed method enables the detection of sand particles concentration as low as 0.02 wt.% at a flow rate of 2.5 m/s. Moreover, the continuous distribution of multiple sensor units allows high-accuracy localization of sand particles erosion areas. The approach presented in this study enables non-invasive and highly sensitive online detection of pipeline sand particle content, which will exhibit great potential for future pipeline integrity management.