New Insights into the Mitigation of Asphaltene Deposition and the Utilization of Asphaltene Deposits

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dc.contributor.advisorVargas, Franciscoen_US
dc.creatorKhaleel, Aishaen_US
dc.date.accessioned2019-08-01T20:36:24Zen_US
dc.date.available2020-08-01T05:01:08Zen_US
dc.date.created2019-08en_US
dc.date.issued2019-07-26en_US
dc.date.submittedAugust 2019en_US
dc.date.updated2019-08-01T20:36:25Zen_US
dc.description.abstractAsphaltene deposition is an ongoing flow assurance problem in the oil and gas industry that is associated with huge economic loss. Different aspects to this problem which includes asphaltene stability, asphaltene deposition and asphaltene characterization has been studied over the past few decades. Despite the extensive research in this area, a reliable technique to mitigate this flow assurance problem has not been identified. In this work, we propose a novel chemical free mitigation technique to prevent asphaltene deposition. In the proposed technique, dead oil collected at the wellhead is recycled back into the wellbore to reduce asphaltene precipitation. The stabilization effect of the dead oil reinjection was verified by calculating the solubility parameter, the phase envelope and the amount of asphaltene precipitated using a thermodynamic model; Perturbed Chain - Statistical Associating Fluid Theory (PC-SAFT). A shift in the asphaltene onset pressure (AOP) curve and a reduction in the amount of asphaltene precipitated was observed for four light oils from the Middle East. Results have shown that asphaltene precipitation can be eliminated by the simple reinjection of dead oil. It is well known that asphaltenes are a polydisperse mixture of molecules with a broad distribution of sizes and molecular characteristics. However, for simplicity asphaltenes have been assumed to be a monodisperse mixture and their deposition tendency has been evaluated accordingly. In this work, we have performed a series of experiments to investigate the effect of asphaltenes polydispersity and aromaticity on their deposition tendency. We have compared asphaltene deposition for two model oils with the same total amount of asphaltenes but different asphaltene polydispersity distribution using a high pressure – high temperature packed bed deposition column. Although asphaltenes used in both oils were extracted from the same source, a drastic difference in the amount of asphaltene deposited was observed. Additionally, using UV-vis spectroscopy, we were able to show some similarity between aromaticity of asphaltene sub-fraction from different sources. This can be an indication that asphaltenes from different sources are not very different, and different behavior can be explained by the polydispersity of the asphaltene mixture. Asphaltene deposition problem is not limited only to upstream operations. Thus a number of researchers have studied the removal of asphaltenes through adsorption. Due to asphaltenes low value and limited applications, there was no research interest in retrieving the material. However, asphaltenes have a rich chemical structure and possess a semiconductor-type conductivity. In this work, we have investigated the utilization of asphaltenes as an active layer in organic photovoltaic (OPV) devices. A low power conversion efficiency was observed and this was justified by asphaltenes high association rate. Asphaltenes aggregates might add surface defects, which reduces the carrier mobility and thus the efficiency of the device. Thus, asphaltenes were chemically modified to reduce their tendency to aggregate. This was done by oxidizing asphaltenes in concentrated nitric acid and concentrated sulfuric acid, where the oxidation was thought to disaggregate asphaltenes nano-domains. The oxidation reaction resulted in a blue fluorescent quantum dots. The findings presented in this dissertation will help understand asphaltene deposition and the behavior of asphaltenes from different sources. This will allow a better understanding to the fundamentals behind asphaltene deposition and allow a better characterization of this poorly defined solubility class material. Additionally, this work contributes to adding value and the utilization of this waste by product from the oil and gas industry.en_US
dc.embargo.terms2020-08-01en_US
dc.format.mimetypeapplication/pdfen_US
dc.identifier.citationKhaleel, Aisha. "New Insights into the Mitigation of Asphaltene Deposition and the Utilization of Asphaltene Deposits." (2019) Diss., Rice University. <a href="https://hdl.handle.net/1911/106174">https://hdl.handle.net/1911/106174</a>.en_US
dc.identifier.urihttps://hdl.handle.net/1911/106174en_US
dc.language.isoengen_US
dc.rightsCopyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.en_US
dc.subjectAsphaltenesen_US
dc.titleNew Insights into the Mitigation of Asphaltene Deposition and the Utilization of Asphaltene Depositsen_US
dc.typeThesisen_US
dc.type.materialTexten_US
thesis.degree.departmentChemical and Biomolecular Engineeringen_US
thesis.degree.disciplineEngineeringen_US
thesis.degree.grantorRice Universityen_US
thesis.degree.levelDoctoralen_US
thesis.degree.majorChemical Engineeringen_US
thesis.degree.nameDoctor of Philosophyen_US
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