Measurement of Water in Oil Pipelines using Capacitance Method

This project entitled “Measurement of Water in Oil Pipelines using Capacitance Method” is closely related to oil & gas industry especially from the aspect of safety. To minimize the internal corrosion of oil pipelines due to the presence of water, capacitance method is introduced to detect the amount of water present in oil-water mixture. Being cheap, safe and non- intrusive, this method is suitable for two-phase fluids with low conductivity and large permittivity difference such as oil and water. However, different configurations of electrodes will produce different results in terms of linearity of response. In this project, by utilising ANSYS Maxwell software, two common configurations of electrodes i.e. concave and double rings electrodes are designed to compare their linearity of response towards changes in water content in oil-water mixture

Liquid Holdup Measurement in Crude Oil Transportation Using Capacitance Sensors and Electrical Capacitance Tomography: Concept Review

Liquid holdup is one of the most significant parameters in multiphase flow.Accurate measurement of liquid holdup is required to calculate pressure drops in oil and gas wells which is essential in analyzing the well production, performance, well designing and optimization. This study reviewed different methods used in measuring liquid holdup and highlighted the most effective methods currently used in multiphase combinations. More importantly, liquid holdup measurements using capacitance sensors in slug flow, bubble flow, churn flow, annular flow and coaxial flow are discussed. The features considered during the review include, electrode material, angle of rotation, curvature and guard electrodes. The operational issues observed when using capacitance based sensors were highlighted. In single capacitance sensors like the helical arrangement which has high sensitivity, error in symmetry and inability to measure fluids with lower dielectric constants were however observed. Concave sensors are more accurate for phase shift detection but lower sensitivity compared to the helical type. From the knowledge and technical gaps identified from literature, this study proposed Electrical Capacitance Tomography tool with dual capacitance sensor for effective liquid holdup measurement in oil and gas transportation pipelines because of its ability to determine the dielectric permittivity distribution inside the pipeline from external capacitance measurements with real-time imaging of the multiphase flow

ANALYSIS OF THE ELECTRICAL CHARACTERISTICS IN MULTIPHASE FLOW THROUGH THE WIRE-MESH SENSOR

Many studies on the characterization of electrical properties of multiphase fluid are found in the literature. One of the main motivations of these efforts has been the development of instrumentation for the measurement of volumetric fraction using electrical sensors. Although one can find a variety of instruments for that purpose, relatively few works in the open literature present studies on the best range of measurement frequency and its effect on permittivity models. An experimental and theoretical study is presented, where the best frequency to measure the volumetric fraction in two and three-phase mixtures is selected. Several permittivity models are applied to measure the volumetric fraction. The fluids used in the experiments were tap water, deionized water, mineral oil, isopropyl alcohol and hexane. Known volumes of fluids were mixed until obtaining a homogeneous mixture. The data were taken by a 1×4 wire-mesh sensor (WMS) immersed in the mixture. The WMS had a gap between planes of 1.4 mm, the wires were 3 mm apart from each other and the diameter of the wires was of 0.2 mm. The experimental system consisted of a generator, an oscilloscope and conditioning circuits (formed by operational amplifiers). A frequency scan was performed between 7000 Hz and 20 MHz for each mixture. A total of 60 logarithmically spaced frequencies were applied

Capacitive wire-mesh sensor measurements in oilwater flow

Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.In this paper, a capacitive wire-mesh sensor was applied to investigate viscous-oil in water dispersed flow in a transparent acrylic section of 26-mm-i.d. and 12-m-length. The sensor was used to obtain in-situ volumetric phase fractions (holdup) and phase distributions in the pipe cross-section. Two mixture permittivity models from the literature, Maxwell– Garnett and Power–Law were applied to calculate the oil volumetric phase fractions in order to compare with the phase fraction measured via quick-closing valves technique (QCVs). In these models the relation is modified as function of a variable parameter. This paper presented a new attempt to find a suitable relation for holdup measurements in oil-water dispersed flows.cf201

Measurement of Water in Oil Pipelines using Capacitance Method

This project entitled “Measurement of Water in Oil Pipelines using Capacitance Method” is closely related to oil & gas industry especially from the aspect of safety. To minimize the internal corrosion of oil pipelines due to the presence of water, capacitance method is introduced to detect the amount of water present in oil-water mixture. Being cheap, safe and non- intrusive, this method is suitable for two-phase fluids with low conductivity and large permittivity difference such as oil and water. However, different configurations of electrodes will produce different results in terms of linearity of response. In this project, by utilising ANSYS Maxwell software, two common configurations of electrodes i.e. concave and double rings electrodes are designed to compare their linearity of response towards changes in water content in oil-water mixture

Experimental investigations of two-phase flow measurement using ultrasonic sensors

This thesis presents the investigations conducted in the use of ultrasonic technology to measure two-phase flow in both horizontal and vertical pipe flows which is important for the petroleum industry. However, there are still key challenges to measure parameters of the multiphase flow accurately. Four methods of ultrasonic technologies were explored. The Hilbert-Huang transform (HHT) was first applied to the ultrasound signals of air-water flow on horizontal flow for measurement of the parameters of the two- phase slug flow. The use of the HHT technique is sensitive enough to detect the hydrodynamics of the slug flow. The results of the experiments are compared with correlations in the literature and are in good agreement. Next, experimental data of air-water two-phase flow under slug, elongated bubble, stratified-wavy and stratified flow regimes were used to develop an objective flow regime classification of two-phase flow using the ultrasonic Doppler sensor and artificial neural network (ANN). The classifications using the power spectral density (PSD) and discrete wavelet transform (DWT) features have accuracies of 87% and 95.6% respectively. This is considerably more promising as it uses non-invasive and non-radioactive sensors. Moreover, ultrasonic pulse wave transducers with centre frequencies of 1MHz and 7.5MHz were used to measure two-phase flow both in horizontal and vertical flow pipes. The liquid level measurement was compared with the conductivity probes technique and agreed qualitatively. However, in the vertical with a gas volume fraction (GVF) higher than 20%, the ultrasound signals were attenuated. Furthermore, gas-liquid and oil-water two-phase flow rates in a vertical upward flow were measured using a combination of an ultrasound Doppler sensor and gamma densitometer. The results showed that the flow gas and liquid flow rates measured are within ±10% for low void fraction tests, water-cut measurements are within ±10%, densities within ±5%, and void fractions within ±10%. These findings are good results for a relatively fast flowing multiphase flow

Metering of two-phase slug flow

This thesis describes the development of a novel system, for metering of two-phase (gaswater) slug flows. The approach combines a model for stable slug flow, a non-intrusive set of conductance sensors, and appropriate closure relationships. This system allows each of the parameters in the model to be determined. The slug flow model is analysed, to determine the sensitivity of the phase flowrates to each measurement parameter. A metering system is then proposed which combines ring-shaped electrodes, electronic instrumentation, and processing software. The ring electrodes are optimised, for the measurement of the phase fraction and the translation velocity. New instrumentation is developed to activate the electrodes, with high measurement accuracy and a wide bandwidth. Analysis software is developed, to process the sensor data, provide suitable closure relations, and deliver the flowrates. A unique feature of this software is its ability to calculate uncertainty margins in the predicted flowrates. The NEL multiphase facility is used, to obtain data for developed, horizontal, gas-water slug flow in a 4-inch pipe. The data span the range of liquid phase superficial velocities 0.1 m s⁻¹ to 1.0 m s⁻¹ , and gas phase superficial velocities 0.6 m s⁻¹ to 6.0 m s⁻¹. The analysis software is used to obtain the flowrate predictions and estimates for the uncertainty margins. The stable slug flow model does not give good results. The relative error in the gas phase prediction is between 10% and 100%, and for the liquid phase prediction, between 50% and 500%. The uncertainty margins are also of comparable magnitude. Proposals for improving the accuracy of the translation velocity measurement, and for directly measuring the local velocities in the slug body (using a pressure transducer) are presented. These proposals aim to reduce the uncertainty that is caused by the use of the empirical closure relationships in the model.This thesis describes the development of a novel system, for metering of two-phase (gaswater) slug flows. The approach combines a model for stable slug flow, a non-intrusive set of conductance sensors, and appropriate closure relationships. This system allows each of the parameters in the model to be determined. The slug flow model is analysed, to determine the sensitivity of the phase flowrates to each measurement parameter. A metering system is then proposed which combines ring-shaped electrodes, electronic instrumentation, and processing software. The ring electrodes are optimised, for the measurement of the phase fraction and the translation velocity. New instrumentation is developed to activate the electrodes, with high measurement accuracy and a wide bandwidth. Analysis software is developed, to process the sensor data, provide suitable closure relations, and deliver the flowrates. A unique feature of this software is its ability to calculate uncertainty margins in the predicted flowrates. The NEL multiphase facility is used, to obtain data for developed, horizontal, gas-water slug flow in a 4-inch pipe. The data span the range of liquid phase superficial velocities 0.1 m s⁻¹ to 1.0 m s⁻¹ , and gas phase superficial velocities 0.6 m s⁻¹ to 6.0 m s⁻¹. The analysis software is used to obtain the flowrate predictions and estimates for the uncertainty margins. The stable slug flow model does not give good results. The relative error in the gas phase prediction is between 10% and 100%, and for the liquid phase prediction, between 50% and 500%. The uncertainty margins are also of comparable magnitude. Proposals for improving the accuracy of the translation velocity measurement, and for directly measuring the local velocities in the slug body (using a pressure transducer) are presented. These proposals aim to reduce the uncertainty that is caused by the use of the empirical closure relationships in the model

Electrical Capacitance Volume Tomography: Design and Applications

This article reports recent advances and progress in the field of electrical capacitance volume tomography (ECVT). ECVT, developed from the two-dimensional electrical capacitance tomography (ECT), is a promising non-intrusive imaging technology that can provide real-time three-dimensional images of the sensing domain. Images are reconstructed from capacitance measurements acquired by electrodes placed on the outside boundary of the testing vessel. In this article, a review of progress on capacitance sensor design and applications to multi-phase flows is presented. The sensor shape, electrode configuration, and the number of electrodes that comprise three key elements of three-dimensional capacitance sensors are illustrated. The article also highlights applications of ECVT sensors on vessels of various sizes from 1 to 60 inches with complex geometries. Case studies are used to show the capability and validity of ECVT. The studies provide qualitative and quantitative real-time three-dimensional information of the measuring domain under study. Advantages of ECVT render it a favorable tool to be utilized for industrial applications and fundamental multi-phase flow research

Monitoring gas void fraction in two-phase flow with acoustic emission

The two-phase gas/liquid flow phenomenon can be encountered over a range of gas and liquid flow rates in the chemical engineering industry, particularly in oil and gas production transportation pipelines. Monitoring and measurement of their characteristics, such as the gas void fraction, are necessary to minimise the disruption of downstream process facilities. Thus, over the last decade, the investigation, development and use of multiphase flow metering system have been a major focus for the industry worldwide. However, these meters suffer from several limitations in some flow conditions such as Slug flow regime. This research presents experimental results correlating Acoustic Emission measurements with Gas Void Fraction (GVF) in a two-phase air / water flow. A unique experimental facility was modified to accommodate an investigation into the applicability of the Acoustic Emission (AE) technology in monitoring two-phase gas\liquid flow. The testing facility allowed for investigations over a range of superficial liquid velocities (0.3 to 2.0 ms-1) and superficial gas velocities (0.2 to 1.4 ms-1). The influence of several variables such as temperature, viscosity and surface roughness were also investigated. Measurements of AE for varying gas void fractions were compared to conductive probe measurements and results showed a direct correlation between the AE energy and the gas void fraction. It is concluded that the GVF can be determined by measurement of Acoustic Emission and this forms the major contribution of this thesis.EThOS - Electronic Theses Online ServiceGBUnited Kingdo