Title:
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Applications of quartz crystal microbalance technology in petroleum engineering, demonstrated by studies of wax, asphaltenes, hydrates, ice, diesel additives and anti-deposition coatings
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This thesis describes the development and uses of equipment and methods based upon the use of quartz crystal microbalance (QCM) technology for measurements involving major Flow Assurance issues, namely wax, asphaltene and hydrate in addition to ice formation in processing facilities, deposition of diesel performance additives in injectors and evaluation of anti-depositional paint coatings. For wax, the use of QCM for accurate measurements of the solubility of wax in synthetic binary and quaternary mixtures of n-alkanes is demonstrated and validated against literature data and model predictions. The use of the QCM for measurements of wax appearance temperature (WAT) and wax disappearance temperature (WDT) for stabilised and live reservoir fluids is presented. The development of QCM based equipment for investigating the effect of temperature gradient on wax deposition tendency at ambient and high pressure is described. The development and validation of the application of QCM technology for comparing and optimising dose rates for wax inhibitors at atmospheric and high pressure is presented. Wax case studies employing the developed equipment and methods are included. In the case of asphaltenes the potential use of QCM based equipment for measuring asphaltene onset in standard solvent titration measurements is shown. In addition by comparing step-wise and continuous injection results, potential errors in asphaltene stability measurements are highlighted. QCM tests with live fluids show that asphaltene onset can be readily detected in reservoir fluids at high pressure/high temperature conditions. In addition reversibility of asphaltene deposition can be demonstrated. Measurement of the effectiveness of asphaltene inhibitor treatments in terms of reducing solids deposition is demonstrated at operating conditions. Asphaltene case studies using the developed equipment and methods are presented. With hydrates, the development of QCM based equipment for measurement of hydrate dissociation points is presented. The use of QCM to identify solids forming in a dew pointing and mercaptan removal unit is described. The development of high pressure/high temperature equipment to detect deposition of diesel performance additives in injectors is presented. Finally the evaluation of anti-deposition coatings for scale and wax is described.
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