In many industrial applications, especially in the oil industry, the requirements of multiphase flow measurement pose numerous technological challenges as it oftentimes involve harsh media, strict safety regulations, access difficulties, long distances, and aggressive surroundings. The fluids produced from oil wells most often emerge as a multiphase mixture of oil, natural gas, water, and a variety of solids (sand, hydrates, and asphaltenes). It is generally recognized that multiphase flow metering (MFM), i.e. measuring the flow rates of the individual phases in a multiphase flow, could have many advantages in terms of costs, layout of production facilities, well testing, reservoir management, subsea and downhole metering. In this regard, the ultrasonic technique has been receiving increasing attention in the past years because it is noninvasive, fast responding, and suitable for operation in harsh environments. In the present paper, initially a review is made of selected commercially available separation-type and in-line MFM systems; the multiphase flow parameters measured in each system and the techniques used as well as general comments regarding the system performance are provided. Next, ultrasonic attenuation and transit time data are presented for oil-continuous oil-air-sand and oil-air-water mixtures in steel pipes. A discussion is also presented on attempts to sort out the air and sand concentrations in water-air-sand mixtures from ultrasonic signals. It is hoped that the data presented will help establish the potential of the ultrasonic technique for use in MFM systems in combination with or replacing specific instruments already in use.

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