With 20 years of operations, multiphase flowmeters (MPFMs) using a combination of venturi and multi-energy gamma-ray absorption have gained acceptance in the oil and gas industry by demonstrating reliable measurement and operational robustness. Nonetheless, some challenging operating scenarios are encountered such as significant water salinity changes in multiphase and wet-gas flows and rapid detection of small water quantities during production. Although MPFMs are not affected by small water salinity changes, inaccurate flow rates can be calculated when water salinity significantly departs from the initial properties. To maintain measurement metrology as per specifications, the water-point should be manually modified to track variations; however, this operation is time consuming and may incur nonproductive time. The salinity change measured by a newly developed sensor can be provided seamlessly to MPFMs to automatically update the water point calibration, thus ensuring good flow rate measurement performance over a wider water salinity range. Extensive validations at several flow loop facilities and field tests, including frac flowback operations, demonstrate the robustness of the method in terms of hardware reliability and the delivery of high-quality data when used with MPFMs with digital connectivity, which opens the way to unmanned production monitoring operations. Interpreting multiphase mixture's dielectric constant and electrical conductivity simultaneously measured by the new microwave water salinity sensor at a high data acquisition rate shows that water salinity can be tracked online in the presence of oil, gas, and sand, and small water quantities down to 50 ppm (part-per-million) water volume fraction (WVF), from the typical ~1000-ppm WVF for the MPFM, can be detected rapidly in multiphase and wet-gas flows. This paper describes the working principles of the new sensor that enable additional capabilities to maintain accurate water-liquid ratio (WLR) measurement in situations where significant water salinity changes occur and to provide a rapid, much lower WVF detection level. Successful cases demonstrating an accurate real-time salinity monitoring in flow loop tests and in field operations are also presented.

Multiphase flowmeters (MPFMs) have been used since the early 1990's in the oil and gas industry and have gained acceptance in many environments. They have been considered the primary metering option for a wide range of applications - from heavy oil to wet gas. The combination of operational benefits, measurement robustness, demonstrable accuracy, and auditability has improved their status from new, unproven technology to that of the premium mainstream metering option. With more than a decade of experience acquired using a combination venturi and gamma-ray multiphase flowmeters, further gains in measurement quality and operational robustness have been achieved. We will illustrate how enhancements in fraction measurements using multi-energy gamma ray attenuation and a more comprehensive analysis of the gamma-ray spectrum have been developed and implemented to provide better measurement accuracy and stability, leading to enhanced performances in multiphase flow measurements. Another area of improvement that has been pursued is in the field of modeling of multiphase flows through a venturi. Historically, single-phase flow equations have been used, being adapted to multiphase flows by semi-empirical means to account for their complexity. While such models have proven robust for most standard applications, they can reach some limitations in particular conditions. We will present how a more dynamic model that considers the nature of the flow has led to improved accuracy of multiphase flow measurements. We present the scientific basis for the new enhancements as well as illustrate the accuracy gains achieved based on hundreds of flow loop test points, ultimately leading to the quantification of the accuracy gains obtained through those technological improvements.

With 20 years of operations, multiphase flowmeters (MPFMs) using a combination of venturi and multi-energy gamma-ray absorption have gained acceptance in the oil and gas industry by demonstrating reliable measurement and operational robustness. Nonetheless, some challenging operating scenarios are encountered such as significant water salinity changes in multiphase and wet-gas flows and rapid detection of small water quantities during production. Although MPFMs are not affected by small water salinity changes, inaccurate flow rates can be calculated when water salinity significantly departs from the initial properties. To maintain measurement metrology as per specifications, the water-point should be manually modified to track variations; however, this operation is time consuming and may incur nonproductive time. Interpreting the multiphase mixture's dielectric constant and electrical conductivity simultaneously measured by a new microwave water salinity sensor at a high data acquisition rate shows that water salinity can be tracked online in the presence of oil, gas, and sand, and small water quantities can be detected rapidly in multiphase and wet-gas flows. The detection of the first produced water is of paramount importance in many applications, such as for fields with high H2S production, where existing processing plants usually have limitations in treating produced water with dissolved H2S. Early detection of produced water in oil is required, enabling operators to take informed decisions about the oil production strategy as well as water treatment and corrosion protection plans. Extensive analyses in flow loops and field operations with the new microwave water salinity sensor demonstrate that the water detection limit is lowered from the typical ∼1000-ppm water volume fraction (WVF) for the MPFM to a remarkably low 50 ppm. This paper describes the working principles of a new sensor and method, that enable additional capabilities to maintain accurate water-liquid ratio (WLR) measurement in situations where significant water salinity changes occur and to provide a rapid, much lower WVF detection level. Successful cases demonstrating first-water detection in flow loop tests and in field operations are also presented.

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