Sand velocity and hold-up characteristics are very important in the design and operation of oil-gas-sand multiphase production and pipeline transportation systems, since they have a strong influence on their hydrodynamics. This work investigates the actual dynamic behaviour of the sand in a continuously operating air-watersand slug flow using digital image analysis technique. Our experiments, while confirming that the behaviour of sand particles in gas-liquid-solid three phase intermittent flows is far from being well understood, provide a more detailed and comprehensive database on sand behaviour, which is essential for a better understanding of gas-liquid-solid slug flow during multiphase production and pipeline transportation. Digital image analysis technique has been used successfully to make accurate measurements of sand velocity and holdup spatial distributions under conditions analogous to oil-gas-sand multiphase slug flow in pipelines connected to sand management wells (low to moderately high sand loading). The experimental results reported show the existence of strong non-uniformities in both sand velocity and holdup profiles. Both shape and non-uniformity of the sand holdup profiles does vary across the pipe cross-section with sand loading, superficial gas and liquid velocities. Sand velocity distribution profiles indicate that convective and dispersive mixing due to gas bubble wakes and liquid slug length are important parameters for the multiphase slug flow investigated. Experimentally, this work presents an original database, which is essential for a better understanding of sand behaviour during gas-liquid-solid multiphase production and pipeline transportation. The experimental results also provide a sound basis to assess the predictive capabilities of existing sand particle velocity models. It was found that existing models failed to predict the measured sand particle velocity. The failure could be due to gas-liquid-solid flow mechanisms that are not well captured by existing sand particle velocity models. Sadly, our experiments have confirmed that the behaviour of sand particle in gas-liquid-solid three phase intermittent flows is far from being well understood. The study has also shown that empirical models are not very reliable for complex operation such as oil-gas-sand multiphase production and pipeline transportation because of their inability to predict small changes in the flow system. Work is in progress to simulate dynamic behaviour of sand velocity and holdup profiles in gas-liquid-solid three-phase slug flow.
Measurement of sand velocity and hold-up distributions in multiphase slug flow using digital image analysis techniques
Multiphase Production Technology '05, 12 ; 171-185
2005
15 Seiten, 10 Bilder, 1 Tabelle, 48 Quellen
Conference paper
English
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