On Kinetics of Scale and Gas Hydrate in Oil and Gas Pipelines



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Scale formation is a widespread problem in a wide range of industries such as oil and gas, water desalination and food processing. Conventional solutions for this problem including mechanical removal and chemical dissolution are inefficient, costly, and sometimes environmentally hazardous. Surface modification approaches have shown promises to address this challenge. However, these approaches suffer from intrinsic existence of solid-liquid interfaces leading to high rate of scale nucleation and high adhesion strength of the formed scale. Here, we report a new surface called magnetic slippery surface in two forms of Newtonian fluid (MAGSS) and gel structure (Gel-MAGSS). These surfaces provide a liquid-liquid interface to elevate the energy barrier for scale nucleation and minimize the adhesion strength of the formed scale on the surface. Performance of these new surfaces in both static and dynamic (under fluid flow) configurations is examined. These surfaces show superior anti-scaling properties with an order of magnitude lower scale accretion compared to the solid surfaces and offer longevity and stability under high shear flow conditions. We envision that these surfaces open a new path to address the scale problem in the relevant technologies. In the second part, we present an in-situ method on kinetics of gas hydrates. Gas hydrate formation is one of the high-risk and common flow assurance challenges in subsea oil production plants. The modern strategies for hydrate mitigation have switched from thermodynamic inhibition to risk management. In these new mitigation strategies, hydrate formation is allowed as long as they do not lead to plugging of the pipelines. Thus, understanding of growth kinetics of gas hydrate plays a critical role in risk management strategies. We report a new highly accurate approach to probe kinetics of gas hydrate formation. This approach is based on hot-wire method, which probes the thermal properties of the medium surrounding the hot-wire. As the thermal properties of gas hydrate and its initial constituents are different, variation in these properties is used to probe kinetics of hydrate growth front. Through this in-situ method, we determined kinetics of cyclopentane hydrate formation in both static and dynamic conditions (flow condition). The findings show that the hydrate formation rate in static condition is 6.7´10-4 kgm-2s-1, while in dynamic condition, this growth rate drops to 4.51´10-6 kgm-2s-1. To our knowledge, this is the first reported growth rate of cyclopentane hydrate. This in-situ approach allows to probe kinetics of hydrate formation where there is no optical access and provides a tool to rationally design risk management strategies for subsea infrastructures.



Gas hydrate, Growth kinetics, Hot wire method, Flow assurance, Magnetic slippery surfaces, Scale resistant, Salt nucleation, Salt adhesion, Magnetic gel