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Summary Drift-flux modeling techniques are commonly used to represent two and three-phase flow in pipes and wellbores. Unlike mechanistic models, drift-flux models are continuous, differentiable and relatively fast to compute, so they are well suited for use in wellbore flow models within reservoir simulators. Drift-flux models require a number of empirical parameters. Most of the parameters used in current simulators were determined from experiments in small diameter (2 inch or less) pipes. These parameters may not be directly applicable to flow in wellbores or surface facilities, however, as the flow mechanisms in small pipes can differ qualitatively from those in large pipes. In order to evaluate and extend current drift flux models, an extensive experimental program was initiated. The experiments entailed measurement of water-gas, oil-water and oil-water-gas flows in a 15 cm diameter, 11 m long plexiglass pipe at 8deviations ranging from vertical to slightly downward. In this paper, these experimental data are used to determine drift-flux parameters for steady state two-phase flows of water-gas and oil-water in large-diameter pipes atinclinations ranging from vertical to near-horizontal. The parameters are determined using an optimization technique that minimizes the difference between experimental and model predictions for holdup. It is shown that the optimized parameters provide considerably better agreement with the experimental data than do the existing default parameters. Introduction Multiphase flow effects in wellbores and pipes can have a strong impact on the performance of reservoirs and surface facilities. In the case of horizontal or multilateral wells, for example, pressure losses in the well can lead to a loss of production at the toe or over production at the heel. In order to model and thereby optimize the performance of wells or reservoirs coupled to surface facilities, accurate multiphase pipeflow models must be incorporated into reservoir simulators. Within the context of petroleum engineering, the three types of pipeflow models most commonly used are empirical correlations, homogeneous models and mechanistic models. Empirical correlations are based on the curve fitting of experimental data and their applicability is generally limited to the range of variables explored in the experiments. These correlations can be either specific for each flow pattern or can be flow pattern independent. Homogeneous models assume that the fluid properties can be represented by mixture properties and single-phase flow techniques can be applied to the mixture.

This paper reports the performance of a research prototype of a new multiphase flow instrument to non-invasively measure the phase flow rates, with the capability to rapidly image the flow distributions of two-(solids, gas or oil in water) and three-phase (gas and oil in water) flows. The research prototype is based on the novel concepts of combining vector Electrical Impedance Tomography (EIT) sensor (for measuring dispersed-phase velocity and fraction) with an electromagnetic flow meter (EMF, for measuring continuous-phase velocity with the EIT input) and a gradiomanometer flowmixture density meter (FDM), in addition to on-line water conductivity, temperature and absolute pressure measurements. EIT-EMF-FDM data fusion embedded in the research prototype, including online calibration of reference conductivity and online compensation of conductivity change due to the change of fluids' temperature or ionic concentration, enables the determination of mean concentration, mean velocity and hence the mean flow rate of each individual phase based on the measurement of dispersed-phase distributions and velocity profiles. Results from recent flow-loop experiments at Schlumberger Gould Research (SGR) will be described. The performance of the research prototype in flow-rate measurements are evaluated by comparison with the flow-loop references. The results indicate that optimum performance of the research prototype for three-phase flows is confined within the measuring envelope 45%-100% WLR and 0%-45% GVF, which is the sweet point of the measurement system. Within the scope of this joint research project funded by the UK Engineering & Physical Sciences Research Council (EPSRC), only vertical flows with a conductive continuous liquid phase will be addressed.

▪ Abstract Online, continuous, two-phase flow measurement is often necessary, particularly in the oil and gas industry. In this article, we describe some of the commercially most important techniques for gas-liquid, gas-solid, liquid-solid, and liquid-liquid flows, and provide associated illustrative sketches and regime maps. These techniques involve Venturi pressure drop, Coriolis, electromagnetic, and cross-correlation flow meters, gamma-ray absorption and gradio-manometer densitometers, and local electrical and fiber-optic sensors, for which we describe the principles of operation and interpretation. References are given to more comprehensive texts and papers; these are representative rather than exhaustive. It is emphasized that empirical calibration is the norm and that detailed fluid-mechanical analysis has so far played little part in instrument design and operation.

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