The Development of Fibre-Optic Chemical Sensors for Subsea Applications

  • Gary R. McDowell

Student thesis: Doctoral ThesisDoctor of Philosophy (PhD)

Abstract

This work describes the development and characterisation of luminescence based temperature and hydrate inhibitor fibre-optic sensing methodologies for flow assurance purposes within the oil and gas industry.

Two temperature sensitive sensors were prepared. The first is based on the luminescence lifetime quenching of a rare-earth lanthanide complex, Tris(dibenzoylmethane) mono(l,10-phenanthroline) europium (III), Eu(DBM)3Phen,immobilised in polystyrene (PS) and polyether ether ketone (PEEK) polymers. The sensor is temperature sensitive in the range of ambient temperature to 70 °C with a sensitivity of 3.99 ps/°C and 3.59 ps/°C within PS and PEEK respectively. The second sensor is based on the luminescence emission peak wavelength shift of semiconductor quantum dot (QD) nanoparticles immobilised in sol-gel thin films.The QD sensors are sensitive from ambient temperature to 120 °C with a sensitivity of ~0.1 nm/°C. The capability of implementing the sensors into point and distributed temperature sensors (DTS) is demonstrated.

Lastly, the development of a novel in-line fibre-optic hydrate inhibitor sensor is described using the fluorescent solvatochromic probes Merocyanine 540 (MC540)and 3,3’-diethylthidicarbocyanine iodide (DTDCI). The change in the fluorescence properties with varying ratios of two common hydrate inhibitors, monoethyleneglycol (MEG) and methanol in water over the full concentration range (0-100%) is demonstrated. Sensor characterisation was performed using various fibre-optic configurations and in chemical compositions that mimic an oil flow line. The in-line sensing capability is demonstrated using an industrial flow loop system developed atFMC Technologies. This technology has opened the possibility of the measurement and control of hydrate inhibitors in real-time, leading to improved flow assurance and substantial economic benefits.
Date of Award2015
Original languageEnglish
Awarding Institution
  • Glasgow Caledonian University
SupervisorSheila Smith (Supervisor), Mahesh Uttamlal (Supervisor) & Peter Wallace (Supervisor)

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