Effects of gas leaks in oil flow on single-phase flowmeters

The effect of gas entrainment in oil on the performance of a range of single-phase flowmeters has been investigated experimentally using the National Standard Multiphase Flow facilities at NEL. The flowmeters tested were 4-inch and 2-inch positive displacement, venturi, helicoidal and flat-bladed turbine meters and 2-inch U-tube and 1.5-inch straight tube Coriolis meters. The flowmeters were tested in oil flow with gas fractions up to 15% by volume. The aim of the project was to quantify the effect of second-phase fluid components on the basic uncertainty of a range of single-phase flowmeters and, as a consequence, identify which generic types of single-phase flowmeter were most suitable in applications where such components may be present. These tests have provided evidence of the suitability of particular flowmeters for two-component flow applications. Comparisons have been made between generic type and size of flowmeter. At low gas fractions, the positive displacement and venturi flowmeters were more accurate than the other meters and estimated the total flowrate to within ±2%. Over 9% gas fraction, there was an improvement to the response from some of the flowmeters with increasing gas fractions. This was considered to be indicative of improved mixing in the flow.     

Water flow measurement in large bore pipes: an experimental comparison between two different types of insertion flowmeters

In this paper the metrological behavior of two different insertion flowmeters (magnetic and turbine types) in large water pipes is described. A master-slave calibration was carried out in order to estimate the overall uncertainty of the tested meters. The experimental results show that (i) the magnetic insertion tested flowmeter performs the claimed accuracy (+/- 2%) within all the flow range (20:1); (ii) the insertion turbine tested meter, instead, reaches the claimed accuracy just in the upper zone of the flow range.     

Investigation into calibration performance of small volume prover for hydrocarbon flow

Several kinds of commercial flowmeters, namely, Coriolis flowmeters, turbine meters, ultrasonic flowmeters, and positive displacement flowmeters, have been calibrated using the primary standard for hydrocarbon flow measurement in Japan (which is based on static and gravimetric methods with a flying start and finish) and a small volume prover (SVP) at the same calibration condition in order to investigate the performance of the SVP. The differences in calibration results for the mechanical flowmeters between the primary standard and the SVP apparently depend on the flow rate, although the results show agreement within 0.04%. The computer-based flowmeters, which have a time delay in the output pulse signal, indicated larger differences due to the effect of the sudden flow rate change caused by the proving action of the SVP at larger flow damping times.     

Installation effects on vortex shedding flowmeters

Numerous measurements of the effects of pipe fittngs on vortex shedding flowmeters are carried out as a contribution to flow metering standards. A water test line of 150 mm diameter is used in the experiments covering a Reynolds number range of about 2 × 10⁵ to 10⁶. The effects of six kinds of piping configurations are examined at various upstream straight pipe lengths and all four kinds of liquid vortex shedding flowmeters, which were commercially available in Japan, are tested. The vortex shedding flowmeters are compared with a turbine meter in experiments designed to evaluate reproducibility of measurements. The uncertainty of the measured data is estimated at about 0.1%. It is found that the magnitude of each installation effect strongly depends on the design of the flowmeter. The experimental results are presented in detail and a table is given of the minimum upstream straight pipe lengths needed to suppress the effects to less than 0.5% for each of the tested flowmeters. This can be used as guidance in the installation of vortex shedding flowmeters.     

Uncertainty analysis of the high pressure closed loop gas flow standard facility in NIM

High pressure air flow standard facilities, including the pVTt facility, sonic nozzle facility and closed loop facility were built in NIM at the end of 2014. The high pressure closed loop gas flow facility was the first closed loop facility in China. The system has 4 sets of 100 mm diameter turbine meters for the reference meters with a flow range of (40–1300) m³/h and a pressure range of (190–2500) kPa. To avoid uncertainties introduced during installation, the reference meters were designed to be calibrated in situ using the sonic nozzle facility. The uncertainty in the pressure measurement was reduced by installing an absolute pressure transducer in the manifold upstream of the reference meters, with differential pressure transducers used to measure the pressure drops across the reference flow meter and the test flow meter. The relative expanded uncertainty for the test meter can reach 0.20% (k = 2) as verified by comparison the sonic nozzle facility and the closed loop facility measurements.     

电导式相关流量计应用于油井井下流量测量

本文提出了一种新型的电导相关流量计,其敏感元件采用两个电导传感器,该流量能够应用于高含水油井的油水两相流流量测量,在多相流动实验装置上进行的实验表明,该流量计测量的流速范围宽,线性好,该流量计已经在大庆油田进行现场试验,使用该流量计在井下测量的油水的总流量与地面计量结果对比良好。     

Investigations of uncertainties from hot water flowmeters using laser Doppler velocimetry

Electromagnetic flowmeters will be used as working standards for determining volumetric flowrates for hot water. Flowmeters for hot water can be calibrated by the well-known mass-time method only up to 100°C. But the district heat suppliers are greatly interested in flowrate measurements at higher temperatures in order to exactly calculate the delivered heat energy. The described one-point relative method using LDV is a time-saving procedure and allows the determination of the metrological performance of flowmeters as a function of flowrate and temperature above 100°C. The relative uncertainties in the determination of the flowrates are about 0.2%.     

Evaluation of flowmeters for heat metering

Heat flowmeters are expected to be reasonably priced, be very reliable, and have high measurement accuracy. Various types of heat flowmeters have been developed and they are widely used in large residential and industrial buildings. In this study, three types of heat flowmeters (turbine, electromagnetic and ultrasonic) were tested for accuracy, effect of installation position and vibration, durability and performance in the field for several installation positions and in the presence of vibration. We used a liquid flow standard system and a customized durability test system in accordance with the International Organization of Legal Metrology (OIML) R 75-2 heat meter testing method. The field test was conducted in eight different locations from winter to summer. All flowmeters were calibrated before and after the field test, and the measurement deviation and the relative expanded uncertainty were calculated. The mean deviations obtained were–0.21%,–0.07%, and 0.11%, with the relative expanded uncertainties 0.48%, 0.17%, and 0.40% for turbine, electromagnetic, and ultrasonic flowmeters, respectively. The results of position and rotation tests, mean deviations by rotation angles at 90°, 180°and 270°relative to 0°(horizontal position) were–1.24%,–1.07% and–0.80%, respectively. For the vibration tests at 1 m/s² and 5 m/s² vibration acceleration, the turbine flowmeter, the electromagnetic flowmeter and the ultrasonic flowmeter showed deviations that ranged from −0.2% to −0.5%, −0.6% (2.6 m³/h), and 0.0% (negligible), respectively. In the durability tests, the accuracy of all three types of heat flowmeters remained at ±1% or less, showing sufficient durability. In the field test, the deviation of the turbine flowmeter and the ultrasonic flowmeter showed ±2.5% or less deviation. However, the electromagnetic flowmeter seems to be inaccurate below 6.9% of the maximum flow rate.     

Design and development for amelioration of primary water flow standard and calibration systems

The present study outlines the efforts made to improve national primary water flow standards and calibration systems through design and development. The facility has been designed and developed in accordance with ISO 4185 standard in the flow range 0.03 m³/h to 650 m³/h to calibrate various types of flow meters up to DN200 (Nominal diameter) using 12 kg, 300 kg, 3000 kg, and 6000 kg weighing systems. In the flow range up to 530 m³/h, the expanded uncertainty in flow meter calibration in totalized mode is found to be ±0.01% to ±0.025% (k = 2), whereas it is ±(0.03–0.05) % (k = 2) up to DN200 size (test rigs) for mass flow rate (MFR) and volume flow rate (VFR) in the flow range 0.1 m³/h to 650 m³/h. The measurement uncertainty achieved is comparable to that of state-of-the-art water flow measurement capabilities available at numerous National Metrology Institutes (NMIs). Thus, the present designed and developed system at CSIR-National Physical Laboratory (CSIR-NPL) is a solution to maintain traceability to the users and industries.     

A regression-based model for prediction of flowmeters calibration cost in oil and gas industry

Measurement of liquid flowmeters is one of the most expensive processes in the oil and gas industry. Estimating calibration costs for such flowmeters in the oil and gas industry is complicated task for the decision-making team. The difficulties arise as a result of the presence of numerous uncertain factors that influence calibration charges such as the fabrication of special tools and spools. Consequently, this paper proposes a data-driven approach for estimating the calibration costs of flowmeters in oil and gas industry. A regression-based model is developed to predict the future calibration costs of flowmeters. The factors that affect the costs of calibrating flowmeters are identified from literature and interviewing local experts. The results indicated that the most important factors influencing the cost of liquid flowmeter calibration include flowmeter size, calibration method, flowmeter type, flowmeter class and calibration factor. The developed model is validated using 577 new data points of flowmeters calibration costs. The findings showed the uncertainty of the proposed model within 98% confidence level. An accurate calibration cost for liquid flowmeter will help to manage the operational and services costs.     

Influence of flow disturbances on the performance of industry-standard LNG flow meters

In the last decade significant progress has been achieved in the development of measurement traceability for LNG inline metering technologies such as Coriolis and ultrasonic flow meters. In 2019, the world's first LNG research and calibration facility has been realised thus enabling calibration and performance testing of small and mid-scale LNG flow meters under realistic cryogenic conditions at a maximum flow rate of 200 m³/h and provisional mass flow measurement uncertainty of 0.30% (k = 2) using liquid nitrogen as the calibration fluid. This facility enabled, for the first time, an extensive test programme of LNG flow meters under cryogenic conditions to be carried out to achieve three main objectives; the first is to reduce the onsite flow measurement uncertainty for small and mid-scale LNG applications to meet a target measurement uncertainty of 0.50% (k = 2), the second is to systematically assess the impact of upstream flow disturbances and meter insulation on meter performance and the third is to assess transferability of meter calibrations with water at ambient conditions to cryogenic conditions. SI-traceable flow calibration results from testing six LNG flow meters (four Coriolis and two ultrasonic, see acknowledgment section) with water in a water calibration facility and liquid nitrogen (LIN) in the LNG research and calibration facility under various test conditions are fully described in this paper. Water and LIN calibration data were compared and it was observed that the influence of removing the meter insulation on mass flow rate measurement accuracy can be more significant (meter error > ±0.50%) than the influence of many typical upstream disturbances when the meter is preceded by a straight piping length equal to twenty pipe diameters (20D) with no additional flow conditioning devices, in particular for ultrasonic meters. The results indicate that the correction models used to transfer the water calibration to cryogenic conditions (using LIN) can potentially result in mass flow rate measurement errors below ±0.5%, however, the correction models are specific to the meter type and manufacturer. This work shows that the target measurement uncertainty of 0.50% can be achieved if the expanded standard error of the mean value measured by the meter is smaller than 0.40% (k = 2). It is planned to repeat these tests with LNG in order to compare the results with the LIN tests presented in this paper. This may reveal that testing with an explosion safe and environmentally friendly fluid such as LIN produces representative results for testing LNG flow meters.     

Calibration of hydrogen Coriolis flow meters using nitrogen and air and investigation of the influence of temperature on measurement accuracy

The performance of four Coriolis flow meters designed for use in hydrogen refuelling stations was evaluated with air and nitrogen by three members of the MetroHyVe JRP consortium; NEL, METAS and CESAME EXADEBIT.A wide range of conditions were tested overall, with gas flow rates ranging from (0.05–2) kg/min and pressures ranging from (20–86) bar. The majority of tests were conducted at nominal pressures of either 20 bar or 40 bar, in order to match the density of hydrogen at 350 bar and 20 °C or 700 bar and −40 °C. For the conditions tested, pressure did not have a noticeable influence on meter performance.When the flow meters were operated at ambient temperatures and within the manufacturer's recommended flow rate ranges, errors were generally within ±1%. Errors within ±0.5% were achievable for the medium to high flow rates.The influence of temperature on meter performance was also studied, with testing under both stable and transient conditions and temperatures as low as −40 °C.When the tested flow meters were allowed sufficient time to reach thermal equilibrium with the incoming gas, temperature effects were limited. The magnitude and spread of errors increased, but errors within ±2% were achievable at moderate to high flow rates. Conversely, errors as high as 15% were observed in tests where logging began before temperatures stabilised and there was a large difference in temperature between the flow meter and the incoming gas.One of the flow meters tested with nitrogen was later installed in a hydrogen refuelling station and tested against the METAS Hydrogen Field Test Standard (HFTS). Under these conditions, errors ranged from 0.47% to 0.91%. Testing with nitrogen at the same flow rates yielded errors of −0.61% to −0.82%.     

Design of a Conductance and Capacitance Combination Sensor for water holdup measurement in oil–water two-phase flow

Oil–water two-phase flow widely exists in the process of petroleum industry. The liquid holdup measurement in horizontal pipeline is very important and difficult. In this work, a Conductance and Capacitance Combination Sensor (CCCS) system with four conductance rings and two concave capacitance plates is designed and validated for its measurement performance of in situ water holdup through dynamic experiments. A set of fast electronic switches controls the conductance rings and the capacitance plates alternatively set up each own sensing field in the same sensing volume. This configuration ensures the water holdup estimation in the range from 0% to 100% regardless of flow direction. A set of quick closing valves was used to acquire the in situ holdup for the on-line calibration of the CCCS system. The theoretical correlations of conductance sensor and capacitance sensor were established to make the real-time measurement convenient. A real-time measurement method by CCCS system is provided based on the fusion of the conductance and the capacitance measurement without flow pattern recognition. This method delivers an average error of 1.06% for the CCCS system measuring the water holdup of oil–water two-phase flow, with a standard deviation of 0.038 and a relative error less than ±5%.     

Accurate mass flow and density of bubbly liquids using speed of sound augmented Coriolis technology

Speed of sound augmented Coriolis technology utilizes a process fluid sound speed measurement to improve the accuracy of Coriolis meters operating on bubbly liquids. This paper presents a theoretical development and experimental validation of speed of sound augmented Coriolis meters. The approach utilizes a process fluid sound speed measurement, based on a beam-forming interpretation of a pair of acoustic pressure transducers installed on either side of a Coriolis meter, to quantify, and mitigate, errors in the mass flow, density, and volumetric flow reported by two modern, dual bent-tube Coriolis meters operating on bubbly mixtures of air and water with gas void fractions ranging from 0% to 5%. By improving accuracy of Coriolis meters operating on bubbly liquids, speed of sound augmented Coriolis meters offer the potential to improve the utility of Coriolis meters on many existing applications and expand the application space of Coriolis meters to address additional multiphase measurement challenges.The sources of measurement errors in Coriolis meters operating on bubbly liquids have been well-characterized in the literature. In general, conventional Coriolis meters interpret the mass flow and density of the process fluid using calibrations developed for single-phase process fluids which are essentially incompressible and homogeneous. While these calibrations typically provide sufficient accuracy for single-phase flow applications, their use on bubbly liquids often results in significant errors in both the reported mass flow, density and volumetric flow. Utilizing a process fluid sound speed measurement and an empirically-informed aeroelastic model of bubbly flows in Coriolis meters, the methodology developed herein compensates the output of conventional Coriolis meters for the effects of entrained gas to provide accurate mass flow, density, volumetric flow, and gas void fraction of bubbly liquids.Data presented are limited to air and water mixtures. However, by influencing the effective bubble size through mixture flow velocity, the bubbly liquids tested exhibit decoupling characteristics which spanned theoretical limits from nearly fully-coupled to nearly fully-decoupled flows. Thus, from a non-dimensional parameter perspective, the data presented is representative of a broad range of bubbly liquids likely to be encountered in practice.     

Modeling temperature effects on a Coriolis mass flowmeter

Coriolis mass flowmeters are used for many applications, including as transfer standards for proficiency testing and liquified natural gas (LNG) custody transfer. We developed a model to explain the temperature dependence of a Coriolis meter down to cryogenic temperatures. As a first step, we tested our model over the narrow temperature range of 285 K to 318 K in this work. The temperature dependence predicted by the model agrees with experimental data within ± 0.08 %; the model uncertainty is 0.16 % (95 % confidence level) over the temperature range of this work.Here, basic concepts of Coriolis flowmeters will be presented, and correction coefficients will be proposed that are valid down to 5 K based on literature values of material properties.     

A new calibration facility for water flowrate at high Reynolds number

A new test facility has been constructed for the National Metrology Institute of Japan (NMIJ) and the National Institute of Advanced Industrial Science and Technology (AIST) for calibration of feedwater flowmeters used in nuclear power stations at Reynolds numbers of up to 18 million. This very large Reynolds number is achieved in a 600 mm pipe at a flowrate of 3.33  m³/s (12,000  m³/h) and a water temperature of 70  ^°C. This calibration facility consists of a circulation loop with four pumps and four reference flowmeter sets, a prover system, a heating and cooling unit, and other components. The expanded uncertainty of this facility is 0.077%. The present paper describes, in detail, the new facility, the calibration method of the reference flowmeter, experiments for flow field, uncertainty estimation, and the results of an example calibration.     

Experimental validation of the calculation of phase holdup for an oil–water two-phase vertical flow based on the measurement of pressure drops

The performance of metering the phase holdup of an oil–water two-phase vertical flow has been investigated based on the measurement of the gravity and frictional pressure drops. A U-tube, in which the same flow patterns can be obtained in downward and upward vertical flows, is designed to measure both gravity and fractional pressure drops. During the experiments, the mixture velocities of the oil and water are in the range of 0.28–4.65 m/s and the oil volume fraction from 0 to 1.0. The results show that the oil holdups calculated are satisfactory with the absolute error of ±10%. The method presented in this work can be used to verify the results of tomography due to its simplicity and therefore is sufficient enough to be applied in industry.     

Prediction of oil rates using Machine Learning for high gas oil ratio and water cut reservoirs

Allocated well oil rates are essential well performance evaluation. Flow meters are not reliable at high gas-oil ratio (GOR) and high water-cut (WC). Most of the available formulas are based on Gilbert-type formulas with neglecting the differential pressure across the choke. Adaptive network-based fuzzy inference system (ANFIS), and functional networks (FN) were used to generate different models to predict the production rates for high GOR and WC wells. A set of data (550 wells) was obtained from oil fields in the Middle East. GOR varied from 1,000 to 9,351 scf/stb, WC ranged from 1 to 60%. Around 300 wells were flowing under critical flow conditions, while the rest were subcritical. The developed AI models were compared against the previous published formulas. For each AI method, two models were developed for subcritical flow and critical flow conditions. The average absolute percent error (AAPE) in the subcritical flow for ANFIS and FN were 1.25, and 0.95%, respectively. While in the critical flow, the AAPE values were 1.1, and 1.35% for ANFIS and FN models, respectively. All developed AI models outperform the published formulas by 34%. The findings from this study will significantly assist production engineers to predict the oil rate in real-time without adding any cost or field intervention.     

双转子燃油流量计校准试验及结果

在航空发动机性能和工作特性试飞中,燃油流量的准确测量对发动机工作指标和性能计算有着重要的影响。和传统单转子流量计相比,双转子燃油流量计有响应更快、重复性好、精度高、量程更宽广等优点,被广泛地应用在航空领域。通常,航空发动机由于安装空间的原因,燃油流量计的进出口平直段难以满足整流的需要。因此,需要装机后对燃油流量计再次进行校准。本文通过标准流量台对安装试验件的某型双转子流量计进行校准,将试验结果与厂家提供的校准曲线进行对比,发现有一定的偏差。通过对校准结果的不确定度合成,其结果小于2‰。还得到了K因子校准特性曲线图,为双转子流量计的工程应用提供了技术支持。     

The consistency of pressure effects between three identical Coriolis flow meters

Coriolis flow meters are one of the most popular flow measurement technologies in the world today for high accuracy measurement of single-phase liquids, gases and even slurries. They are capable of measuring both mass and density directly and can also infer the volume flow. They can be installed in challenging process environments and have been successfully deployed with non-Newtonian fluids, high viscosity fluids, pulsating flows and even at extreme temperatures and pressures.However, it is known that operating most Coriolis flow meters at a pressure which differs from the original calibration pressure requires compensation else significant measurement errors will occur. Pressure compensation coefficients appear to vary by manufacturer, meter geometry and sensor material. Furthermore, the manufacturer published pressure compensation coefficients are not fully traceable. To date, there has not been sufficient research exploring the consistency of the pressure compensation for identical Coriolis flow meters.This paper presents the findings of a research conducted at the TÜV SÜD National Engineering Laboratory (NEL) Elevated Pressure and Temperature (EPAT) oil flow facility to investigate the pressure effect uniformity for matching Coriolis devices. The first stage of the experimental programme calibrated three identical DN80 Coriolis flow meters at a range of pressures with no pressure compensation applied. A pressure compensation coefficient was then derived from the data and the Coriolis meters were then calibrated at two alternative pressures to ascertain the robustness of the coefficients and whether the compensation could be extrapolated successfully.From the experimental results, it can be concluded that the pressure effect for the three DN80 Coriolis flow meters was extremely repeatable and consistent with a discrepancy of less than 0.025% between the devices at 80 bar. Whilst the mass flow was significantly affected by fluid pressure, the fluid density did not appear to be influenced. The pressure corrected results were also well within the manufacturer specification of ±0.1%.