Browsing by Author "Eyo, Edem Nsefik"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
Item Open Access Characterization of gas-liquid flows in annuli.(2019-07) Eyo, Edem Nsefik; Lao, Liyun; Falcone, GioiaGas–liquid two–phase flow in annulus is encountered during certain operations in the nuclear, chemical and petroleum industries. In the Oil and Gas industry, the knowledge of gas liquid two-phase flow in annuli is important during underbalanced drilling of wells and hole clean operations. This technique offers several advantages over the conventional drilling method including reducing formation damage, preventing fluid losses and enhancing the safety and efficiency of operation. Proper design of underbalanced drilling operations hinges on the accurate prediction and monitoring of gas-liquid two-phase flow parameters such as flow regimes, liquid holdup and pressure drop; however the complexities associated with two-phase flows coupled with complex geometry makes this difficult. Limited studies exist in literature for gas-liquid flow hydraulics in horizontal annuli and no studies have been undertaken on the effects of annulus eccentricity on two-phase flow parameters including flow regimes, liquid holdup and pressure drop. In order to provide an improved fundamental understanding of gas-liquid two-phase flow in horizontal annulus and give insight necessary for accurate model development, detailed systematic experimental studies are conducted at atmospheric conditions in horizontal concentric and fully eccentric annulus formed using a 3 inch outer and 2 inch inner pipes. Flow parameters including flow regimes, liquid holdup and pressure drop are investigated using high speed camera, conductance probes and pressure transducers, with air and water as testing fluids. Results show that annulus eccentricity affects the flow regimes, liquid holdup and pressure drop. Predictive models are compared with experimental data and new models are proposed for flow regime identification and liquid holdup prediction, while a new real-time objective flow regime identification tool is developed using Support Vector Machine (SVM). The data generated from this study can be used for developing models which would be incorporated into commercial software for study of flow through annulus.Item Open Access Gas-liquid flow regimes in horizontal annulus(Elsevier, 2018-12-22) Eyo, Edem Nsefik; Lao, LiyunGas-liquid flows in annulus channels are frequently encountered in the underbalanced drilling operation when the gasified drilling fluid is used. Accurate characterization of two-phase flow regimes in such conduits is critically important in order to gain a better understanding of the flow behaviours in the channels, thus to ensure a successful drilling operation achieved. In this paper experimental studies regarding gas-liquid flows in a concentric and fully eccentric horizontal annulus were reported. The test section setups of the flow loop have a length of 10.8 m, with outer and inner pipe diameters of 0.0768 m and 0.060 m respectively. Air and water at atmospheric pressure constituted the gas and liquid phases and the range of gas and liquid superficial velocities investigated during this study was 0.14–24 m/s and 0.15–2.78 m/s respectively. Flow regimes observed in both annulus setups by high speed camera imaging were dispersed bubble, elongated bubble, slug, wavy slug, churn, wavy annular and annular. A detailed description of the flow regimes with different features are presented together with high quality images. The local liquid holdup time series together with its probability density function (PDF) are used to gain more insights about the characteristics of the observed flow regimes. Effects of the annulus eccentricity on the observed flow regimes are also investigated. It is found that the annulus eccentricity affects the shape and structure of the elongated bubble, wavy annular and annular flow regimes. It is also observed that the annulus eccentricity causes the transition from elongated bubble to dispersed bubble to take place at higher liquid superficial velocities. It is also found that in the fully eccentric annulus causes transitions between different flow regimes to occur at higher liquid and lower gas superficial velocities when compared with that of concentric ones. An improved flow regime map is proposed based on gas and liquid Froude numbers by integrating the test results from this study with over 1000 data points found in literature.