Development of a magnetoelastic resonance sensing system for water cut applications.

Swanepoel, Liam (2018-12)

Thesis (MEng)--Stellenbosch University, 2018.

Thesis

ENGLISH ABSTRACT: Precise measurement of the water fraction in oil (i.e. water cut) is of critical importance in numerous applications. In the oil and gas industry, for example, knowledge of the amount of water production and where it comes from is necessary before any remedial action can be taken. Currently, cost-effective, reliable and accurate measurement technologies capable of full range three phase measurements are not commercially available. The development of an ultra-low power, low-cost, wireless and non-corrosive resonance sensor is considered. The sensor is based on magnetoelastic technology that has been implemented by an amorphous ribbon and electromagnetic interrogation. The magnetoelastic ribbon’s resonant frequency is dependent on the vibrational damping effect of the surrounding medium, which in turn is determined by the dynamic viscosity of the medium. This enables distinguishing all three gas, water, and oil phases with measured sensor signal amplitude changes of 75% and 99% and resonant frequency shifts of 0.46% and 3.88% respectively, compared to the gas phase. The sensor shows sensitivity in the water-cut range from 10% - 90% WC and is characterised by a linear response from 10% - 80% WC. When immersed in water/oil emulsions the sensor power consumption ranges from 160 nW to 500 nW. A rapid decay of the magnetic properties has been observed in high salinity solutions due to corrosion of the sensor material, which represent typical environments in industrial applications. A solution for this has been found through coating the sensor ribbons with Teflon by dip coating, acting as an anti-corrosion layer that enables sensor deployment for extended periods of time in harsh environments. This study shows that a magnetoelastic resonance sensor possesses the required characteristics and sensitivity which make it suitable for use in water-cut applications. The possibility of inline WC measurement has been explored through the design of a modified sensor housing. The sensor incorporates a set of excitation and detection coils and allows the flow of liquid across the amorphous ribbon surface. Tests conducted in a flowrate controlled water flow loop show a shift of 150 Hz in resonant frequency from flowrates of 0.2 m/s – 0.63 m/s due to the increased surface drag on the sensor surface. However, this is considered insignificant as viscosity induced shifts are in the kHz range, therefore concluding that the sensor is insensitive to variations in flow rate. Furthermore, the sensor system design is expanded as a Portable Readout Device (PRD) capable of in-field measurements. The design consists of a battery powered microcontroller circuit that integrates with a smartphone via a mobile application. The peak frequency data sampled from the sensor is displayed on the smartphone. The PRD sampling algorithm has been tested with a 100% correlation in sampled data compared to a bench setup using Helmholtz coils and an oscilloscope. The PRD consumes 3.25 W of power during sampling and is capable of remote operation through the implementation of Bluetooth connectivity.

AFRIKAANSE OPSOMMING: Die akkurate monitering van waterinhoud in olie is belangrik in menige toepassings. Met die olie en gas industrie as voorbeeld, moet daar inligting wees oor die waterinhoud in ruolie voor enige poging om die olie uit die grond uit te haal kan begin. Tans bestaan daar geen koste effektiewe, betroubare en akkurate waterinhoud moniteringstelsel vir vol-spektrum drie-fase monitering nie. Die ontwikkeling van ‘n lae-drywing, lae-koste, koordlose en korrosie bestande resonansie sensor word oorweeg. Die sensor is gebaseer op magneto-elastiese tegnologie wat geïmplementeer is met ‘n metaal strokie en elektromagnetiese induksie. Die metaal strokie se resonante frekwensie word beïnvloed deur die dinamiese viskositeit van die omliggende medium. Dit bemoontlik die identifisering van al drie fases naamlik: gas, water en olie. Die sein wat gemeet word deur middel van induksie ervaar amplitude demping van 75% en 99% en resonante frekwensie veranderinge van 0.46 % en 3.88 % vir water en olie onderskeidelik, gemeet relatief tot lug as gas media. Die sensor is sensitief vir veranderinge in media van 10% - 90% water inhoud, maar kan liniêr gekarakteriseer word tussen 10% - 80% waterinhoud. Tydens monitering in olie en water emulsies wissel die elektriese drywingsbehoeftes tussen 160 nW en 500 nW. ‘n Spoedige afname in magnetiese karakteristieke en werking word gesien na gebruik in hoë soutinhoud media, wat aandui dat die sensormetaal korrodeer. ‘n Oplossing is gevind deur die sensor met ‘n laag Teflon te bedek deur middel van dip-dekking. Die Teflon laag beskerm die sensormetaal teen korrosie en laat die gebruik in korrosiewe omgewings vir lang periodes op ‘n slag toe. Hierdie studie bewys dat ‘n magneto-elastiese sensor die nodige sensitiwiteit en karakteristieke besit vir gebruik in water-in-olie moniterings toepassings. Die in-lyn implimentering van die sensor in ‘n pyplyn is ondersoek deur die ontwikkeling van ‘n aangepaste sensor omhulsel. Die omhulsel bestaan uit ‘n primêre en sekondêre induktor waarop die metaal strokie gemonteer is. Die ontwerp van die sekondêre induktor stel die medium in staat om oor die sensor oppervlak te vloei. ‘n Totale verskuiwing in resonante frekwensie van 150 Hz is gemeet vir vloeitempo’s van 0.2m/s tot 0.63 m/s. Hierdie verskuiwing is as gevolg van toenemende sleur kragte wat inwerk op die sensor oppervlak, maar word ignoreer in die lig van kHz grote-orde verskuiwings wat gemeet word as gevolg van veranderinge in media viskositeit. Die sensor word dus beskou as onsensitief tot veranderinge in die media vloeitempo. Die sensor sisteem word uitgebrei deur middel van ‘n handtoestel vir buitelug metings. Die sisteem is geïntegreer met ‘n mikrobeheerder wat met ‘n battery aangedryf word en kommunikeer met ‘n slimfoon. Die slimfoon lewer instruksies aan die mikrobeheerder en word ook gebruik om die data vanaf die sensor sisteem te toon aan die verbruiker. Die algoritme wat in beheer is van die monitering van die sensor is getoets teenoor ‘n ossilloskoop en Helmholtz induktors met 100% korrelasie in metings. Die operationele sensor sisteem verbruik slegs 3.25 W drywing en skakel met die slimfoon deur draadlose Bluetooth kommunikasie.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/105093
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