Experimental study on pressure fluctuations in multiphase flow with phase-separated boosting recombined transport

Multiphase transport systems are critical in oilfield operations, especially under challenging conditions involving wide variations in gas–liquid ratios and severe fluctuations in wellhead flow rates. The phase-separated boosting recombined transport (PSBRT) system, which independently boosts gas and liquid phases before recombination, shows high adaptability and flow stability. However, its pressure fluctuation characteristics are still lack of systematic understanding. In this study, field-scale experiments of pressure fluctuation behavior of PSBRT system were carried out under actual oilfield conditions. Four operation states were set up in the experiment: dual shutdown, pump-only operation (PO), compressor-only operation (CO) and dual operation (DO). High-frequency pressure data were analyzed using peak-to-peak values, probability density functions, and fast Fourier transforms. Results indicate that under PO state, the system pressure fluctuation is the smallest; more pronounced fluctuations are observed under the CO and DO state. The quasi-linear superposition characteristics of fluctuation energy caused by pump and compressor are confirmed by experimental results, and the deviation is less than 5%. Frequency domain analysis shows that the pressure energy is mainly concentrated at frequencies much lower than those generated by the equipment, and under the DO state, energy migration toward lower frequencies is also observed. This study clearly reveals the main control mechanism of pressure fluctuation in PSBRT system, and provides an important theoretical basis for pressure prediction and stable operation control of multiphase transport system.