Measurement of gas and liquid flow rates in two-phase pipe flows with distributed acoustic sensing

Accurately measuring gas–liquid two-phase flow rates in pipelines is critical for optimizing production processes. Distributed Acoustic Sensing (DAS) has emerged as a promising technique for conducting long-term measurements of pipeline flow rates. The effectiveness of DAS in measuring two-phase flow rates is evaluated in this study. An experimental setup was designed to simulate a gas–liquid two-phase flow, employing DAS to detect acoustic signals along its length. Based on the results, a method for measuring single-phase and two-phase flow rates with DAS was developed. Key findings include: (1) As flow rates increase, the vibrational energy the flow induces also rises. Vibrational energy from single-phase gas flow is significantly weaker than that from liquid-containing flows. (2) An increase in liquid flow rate results in a negative shift in the detected characteristic operating frequency. (3) The spectrum reveals two dominant frequency bands, with low liquid and gas flow rates exhibiting narrower main bands, lower energy levels, and strong autocorrelation.