Kjell-Eivind Frøysa

Høgskulen på Vestlandet | HVL · Department of Electrical Engineering

The reliability of water quality measurement is crucial for sustainable use of ocean resources, climate and ecosystem models, and industrial applications. However, measurement stations in remote locations face limitations in terms of power, communication, and maintenance, posing challenges for data quality. Even though some basic (near) real-time...

Ultrasonic transit time difference flow meters are today industrially accepted for custody transfer measurements of oil and for natural gas. Such meters are currently planned to be used also subsea and in remote operations, where the calibration possibilities are few. In such applications the speed of sound measured by these meters will be a pow...

This extended abstract covers the speed of sound of natural gas at pressures above 100 bar. It is shown how the compressibilitt factor and the isentropic exponent changes a lot with pressure and temperature and how these parameters affect the speed of sound. The work is part of the scenario of building accurate metering stations for natural gas at...

In this paper we give an overview of factors and limitations impairing deep-sea sensor data, and we show how automatic tests can give sensors self-validation and self-diagnostic capabilities. This work is intended to lay a basis for sophisticated use of smart sensors in long-term autonomous operation in remote deep-sea locations. Deep-sea observati...

Ultrasonic transit time difference flow meters are today industrially accepted for custody transfer measurements of oil and for natural gas. Such meters are currently planned to be used also subsea and in remote operations, where the calibration possibilities are few. In such applications the speed of sound measured by these meters will be a powerf...

Synopsis Threaded fasteners are some of the most important machine elements. They often take on critical tasks where they are subjected to cyclical loading and are thus susceptible to fatigue damage. Typically fatigue cracks initiate in the thread root on the first loaded thread and grows in a thumbnail shape until fatigue fracture occurs. Both the...

Custody transfer oil metering stations are traditionally equipped with spare meter runs and proving device with on-site calibration possibilities for the proving device. Whereas the CAPEX and OPEX of such layouts are high, the metering uncertainty is low and the economic risk related to measurement errors is low. Currently, there is a major focus...

This paper describes a computational fluid dynamics (CFD) analysis that was performed to understand the observed characteristics in a gas export metering station at an offshore installation on the Norwegian Continental Shelf. The metering station has two parallel metering runs, each equipped with an ultrasonic flow meter. The metering station has f...

Transit-time flow meters based on guided ultrasonic wave propagation in the pipe spool have several advantages compared to traditional inline ultrasonic flow metering. The extended interrogation field, obtained by continuous leakage from guided waves traveling in the pipe wall, increases robustness toward entrained particles or gas in the flow. In...

Ultrasonic transit time difference flow meters are today industrially accepted for custody transfer measurements of oil and for natural gas. Such meters are currently planned to be used also subsea, where the calibration possibilities are few. In such subsea applications the velocity of sound measured by these meters will be a powerful input for es...

Current focus on cost-effective developments of new hydrocarbon fields aims at exploiting the capacity of existing production units to the maximum using a number of tie-ins to subsea developments. This results in increasingly complicated process flows, where individual multiphase streams may or may not be measured. This increased complexity makes d...

This paper will address the analysis carried out in order to understand and correct flow meter effects on the Gjøa gas export metering station. The metering station consists of two parallel metering tubes, each equipped with a multipath ultrasonic flow meter with an upstream flow conditioner. The header upstream of the two metering tubes has T-ben...

This paper describes the course of events which led to the discovery of a significant mis-measurement on Gjøa platform’s gas export from the operator's point of view. The mis-measurement has persisted since Gjøa's start-up, almost five years ago. The paper closes with lessons learnt from a two year long investigation and tries to clear up some comm...

Custody transfer oil metering stations are traditionally equipped with spare meter runs and proving device with on-site calibration possibilities for the proving device. Such a layout is expensive (CAPEX and OPEX). The gain is that metering uncertainty is low to secure national and company income. Currently, there is major focus on cost-reduction i...

A " Handbook of uncertainty calculations-Ultrasonic fiscal oil metering stations " [1] is being developed in a cooperation between NFOGM, NPD, Tekna and CMR, addressing fiscal metering of oil using multipath ultrasonic transit time flow meters (USM). The many different approaches to calculating the uncertainty of ultrasonic oil metering stations ha...

The trend in subsea petroleum production systems in offshore field developments points towards integrated production and processing facilities at the seabed along with more extensive use of multiphase transportation technology. The SOFA (Subsea On-line multiphase Fluid sampling and Analysis) system designed by Christian Michelsen Research in cooper...

Ultrasonic gas flow meters may be influenced by pressure and temperature in several ways. Change of the meter body's cross-sectional area (the "pipe bore") influences directly on the amount of gas flowing through the meter. Change of the ultrasonic path geometry (i.e. change of the inclination angles and lateral chord positions, caused by e.g. spoo...

A " Handbook of uncertainty calculations-Ultrasonic fiscal oil metering stations " [1] is being developed in a cooperation between NFOGM, NPD, Tekna and CMR, addressing fiscal metering of oil using multipath ultrasonic transit time flow meters (USM). The many different approaches to calculating the uncertainty of ultrasonic oil metering stations ha...

The known acoustic methods for obtaining the pressure reflection coefficient from a buffer rod based measurement cell are presented, along with 2 new generic approaches for measuring the pressure reflection coefficient using 2 buffer rods enclosing the liquid to be characterized in a symmetrical arrangement. An acoustic transducer is connected to e...

A new method for measuring the pressure reflection coefficient in a buffer rod configuration is presented, together with experimental results for acoustic measurements of the liquid density, based on the measurement of the liquid's acoustic impedance. The method consists of using 2 buffers enclosing the liquid in a symmetrical arrangement with a tr...

Ultrasonic gas flow meters (USMs) may be influenced by pressure and temperature in several ways. Change of the meter body's cross-sectional area (the "pipe bore") influences directly on the amount of gas flowing through the meter. Change of the ultrasonic path geometry (i.e. change of the inclination angles and lateral chord positions, caused by e....

The trend in subsea petroleum production systems in offshore field developments points toward integrated production and processing facilities at the seabed along with more extensive use of multiphase transportation technology. The SOFA (Subsea On-line multiphase Fluid sampling and Analysis) system designed by Christian Michelsen Research is an auto...

In offshore separators, gravity is used for the separation of water, oil and gas. In practice, there may in addition be a sand layer in the bottom of the separator, an emulsion layer between the water and the oil layers, and a foam layer above the oil. This means that a separator is a complex dynamic system. Mapping of interfaces (and of thickness...

An analytical, approximate solution of the inviscid KZK equation for a nonlinear pulsed sound beam radiated by an acoustic source with a Gaussian velocity distribution, is obtained by means of the renormalization method. This method involves two steps. First, the transient, weakly nonlinear field is computed. However, because of cumulative nonlinea...

Multipath ultrasonic transit time flow meters (USMs) are today extensively used by industry for volumetric flow metering of natural gas, for fiscal measurement, check metering, etc. As natural gas is typically sold on basis of mass or energy, the density and/or calorific value (GCV) of the gas is measured in addition. In current fiscal metering sta...

Multipath ultrasonic transit time flow meters (USM) represent an alternative to conventional meters for fiscal gas flow measurement. When the meter is installed close to bend(s), the flow profile can be quite complex, with asymmetric axial and transversal flow profiles. To investigate the accuracy of the measurement in such situations, computationa...

USM technology is today recognized as a competitive alternative for fiscal flow metering of gas, and is also considered for fiscal metering of oil and petroleum products. However, there are un-exploited potentials to reduce systematic errors, achieve higher accuracy, and to improve measurement traceability, giving perspectives for further developme...

Multiphase ultrasonic transit-time meters for gas and liquid flow measurement (USM) have already been developed to a stage where they are considered as competitive alternatives to the more conventional orifice plate, turbine and positive displacement meters for fiscal metering of natural gas and oil products, particularly for transmission line appl...

Results and progress from an ongoing R&D program related to the Kongsberg Metering MPU 1200 multipath ultrasonic gas flow meter are presented. The results are outcomes of an R&D Joint Industry Programme (JIP) conducted by Kongsberg Metering (KOS) in a cooperation with Christian Michelsen Research AS (CMR), Statoil, Norsk Hydro and Phillips Petroleu...

Measurements of ultrasonic phase velocity and attenuation in emulsions have been carried out over a frequency range 250 kHz to 14 MHz for volume fractions of dispersed phase varying from 2% to 80%. The experimental data have been compared to theoretical predictions based on multiple scattering models. At volume fractions up to 50% a good agreement...

An analytical, approximate solution of the inviscid KZK equation, for a finite amplitude pulsed sound beam radiated by a Gaussian source, is obtained by means of the renormalization method. The method involves two main steps. First, the transient quasilinear field is obtained under an integral form. However, this weakly nonlinear approximation brea...

The weakly nonlinear propagation of a pulsed sound beam generated by a real sound source in a homogeneous fluid is considered. The investigation is based on the weakly nonlinear approximation of the Khokhlov–Zabolotskaya–Kuznetsov nonlinear parabolic equation. It is discussed how diffraction and absorption alter the pulse. Analytical and numerical...

The linear propagation of a pulsed sound beam generated by a sound source of finite extent in a homogeneous fluid is considered. The investigation is based on the linear approximation of the Khokhlov-Zabolotskaya-Kuznetsov parabolic equation, the validity of which is discussed by comparison with the solution of the wave equation. The effects of dif...

We present an algorithm for the assessment of the relative severity of mutations in the phenylalanine hydroxylase gene from untreated serum phenylalanine concentrations in hyperphenylalaninemia patients with complete genotype data. The algorithm was tested in 30 hyperphenylalaninemia children whose both mutations were determined, and the results co...

An algorithm for numerical solution of the KZK nonlinear, parabolic equation is developed. It is a new and faster version of the Bergen code algorithms starting with Aanonsen et al. [J. Acoust. Soc. Am. 75, 749–768 (1984)]. The computational time on the nonlinear term is reduced, and the possible numerical instabilities when studying pulsed sound p...

Linear and nonlinear propagation of pulsed sound beams is considered. The combined effects of diffraction, absorption, and nonlineartry are discussed within the linear and the weakly nonlinear (quasilinear) approximation of the Khokhlov‐Zabolotskaya‐Kuznetsov nonlinear parabolic equation. For the special case of a Gaussian on‐source amplitude distr...

The linear and nonlinear propagation of a pulsed sound beam generated by a real source in a fluid is considered. The source can be plane or weakly focusing. The investigation is based on a linear and quasilinear solution of the Khokhlov‐Zabolotskaya‐Kuznetsov nonlinear parabolic equation. Analytical and numerical results are presented. The evolutio...