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Characterizing water-in-oil emulsions with application to gas hydrate formation.

机译:表征油包水型乳液并应用于天然气水合物的形成。

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This thesis implements nuclear magnetic resonance (NMR) techniques to directly measure water-in-oil emulsion properties and gas hydrate formation. This thesis introduces a novel application of the pulsed field gradient with diffusion editing (PFG-DE) NMR technique to measure drop size distributions of emulsions. The PFG-DE technique agrees with the standard pulsed field gradient (PFG) technique for a variety of emulsions. For the first time, this thesis utilizes the PFG-DE technique, coupled with the Carr-Purcell-Meiboom-Gill (CPMG) technique, to directly measure and quantify gas hydrate formation in emulsified systems. These unique data for black oil emulsions aid in developing effective flow assurance strategies.;To elucidate emulsion formation mechanisms in well defined shear fields, this thesis implements Taylor-Couette flow to form water-in-oil emulsions. A range of oil viscosities is considered by selecting two crude oils that differ in viscosity, and each crude oil is matched with a model oil of similar viscosity. For the low viscosity crude/model oil systems, the computational fluid dynamics (CFD) simulations show that the intensity of Taylor vortices increases at higher rotational speeds, and this leads to multimodal drop size distributions. For the high viscosity crude/model oil systems, the CFD simulations show that the flow field is simple shear for all rotational speeds. The high viscosity crude oil emulsions exhibited multimodality for all rotational speeds investigated, while the corresponding model oil emulsions exhibited broad, smooth drop size distributions.;In contrast to Taylor-Couette flow, this thesis also examined emulsification in complex flow conditions with inhomogeneous shear using a six bladed Rushton turbine. This work supplies transient drop size distributions for two crude oils. This work provides emulsion formation and stability characteristics for both high and low mixing speeds, as well as comparisons to established models that predict emulsion drop size in turbulent flow.;Recent evidence suggests a relationship between water-in-oil emulsion morphology and gas hydrate blockage formation. An experimental setup to measure emulsion properties during gas hydrate formation was constructed, and the resulting NMR measurements indicate that for three of the four oils investigated, gas hydrate shells form around the water drops with thickness approximately equal to 1 mum.
机译:本文采用核磁共振(NMR)技术直接测量油包水乳液的性质和天然气水合物的形成。本文介绍了脉冲场梯度与扩散编辑(PFG-DE)NMR技术在乳剂液滴尺寸分布测量中的新应用。 PFG-DE技术与各种乳液的标准脉冲场梯度(PFG)技术一致。本文首次利用PFG-DE技术,结合Carr-Purcell-Meiboom-Gill(CPMG)技术,直接测量和定量乳化系统中的天然气水合物形成。这些独特的黑油乳剂数据有助于制定有效的流量保证策略。为了阐明在明确定义的剪切场中乳剂的形成机理,本论文采用泰勒-库埃特流动法形成了油包水型乳剂。通过选择两种粘度不同的原油,可以考虑一定范围的油粘度,并且每种原油都应与粘度相似的模型油匹配。对于低粘度原油/模型油系统,计算流体动力学(CFD)模拟表明,泰勒涡流的强度在更高的转速下会增加,这会导致多峰液滴尺寸分布。对于高粘度原油/模型油系统,CFD仿真表明,对于所有转速,流场都是简单的剪切。高粘度原油乳液在所研究的所有转速下均表现出多峰性,而相应的模型油乳液则表现出宽而平滑的液滴尺寸分布。与泰勒-库埃特流相比,本文还研究了在不均匀剪切条件下使用复杂剪切条件下的乳化作用。六叶片Rushton涡轮机。这项工作提供了两种原油的瞬时液滴尺寸分布。这项工作提供了高和低混合速度下的乳液形成和稳定性特征,并与预测湍流中乳液滴大小的已建立模型进行了比较。最新证据表明油包水乳液形态与气体水合物堵塞之间存在关系编队。建立了用于测量天然气水合物形成过程中乳液性质的实验装置,所得的NMR测量结果表明,对于所研究的四种油中的三种,在水滴周围形成了天然气水合物壳,厚度约等于1微米。

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