CBET-EPSRC: Enhancing the CSMHyK fluid dynamics calculations via the inclusion of a stochastic model of hydrate nucleation, agglomeration and growth

汉弗莱·戴维爵士于1811年发现了笼形水合物。水合物是由水和气体形成的固体结构，例如，甲烷世界各地丰富的天然气水合物矿藏可以为未来提供丰富的能源资源，以及长期的二氧化碳储存。天然气水合物可用于高科技应用，包括创新的海水淡化和天然气储存过程。Carolyn Koh教授在她与Dandy Sloan教授合著的书中概述了水合物：天然气体的包合物水合物，第3版，CRC出版社，2007。该建议涉及石油和天然气管道中的水合物堵塞。这种堵塞可能导致管道破裂，造成泄漏和环境灾难，生产中断，甚至生命损失。管理水合物的传统方法是添加热力学抑制剂（THI），例如，甲醇。THI将水合物稳定的条件转变为较低的Ts和较高的Ps。然而，大量的THI是必要的，这对操作的经济性及其环境影响都有负面影响。在防止管道中水合物形成的新兴有前途的技术中，使用“低剂量水合物抑制剂”（LDHIs），其在低浓度下有效。事实上，LDHIs的性能取决于油的组成、水的盐度、温度等。LDHIs包括动力学水合物抑制剂（KHIs）和防聚剂（AAs）。这个及时的项目将发展一个基本的理解关于AA如何运作。该项目建立在重要的先前结果。例如，Koh教授和她的团队产生了关于LDHIs性能的大量实验数据，并开发了广泛的实验表征能力，以探测不同长度尺度的AA（从微观，使用微机械力测量，到宏观，使用流动回路）。Striolo教授采用分子模拟来发现可能的分子机制，这些机制负责LDHIs（特别是AA）的性能。模拟结果导致了新的LDHIs配方，环境友好，最近在一项专利申请中公开。为了广泛采用LDHIs，需要开发可靠的模型，准确描述水合物堵塞形成的可能性作为工艺条件的函数。该项目将改变已经与行业标准多相流模拟器OLGA相结合的开创性软件CSMHyK。CSMHyK（1）准确描述了管道中的多相输运;（2）使用可靠的状态方程来预测水合物的热力学稳定性;（3）使用工作假设来预测水合物的形成。为了使后者的功能，一个重要的参数是成核过冷，这是作为一个输入参数，目前估计从实验流动回路的结果，从而缺乏predictable.To渲染CSMHyK预测，它建议开发一个模型，基于动力学蒙特卡罗（KMC），定量描述的水合物种群动态系统条件的函数。新模型将允许从业者量化LDHIs的影响，这是目前不可能的，以及将来自微观实验和分子模拟的分子水平信息纳入风险评估的制定中。NSF-EPSRC牵头机构协议提案建立在2018年8月4日提交给EPSRC的兴趣表达的基础上，该协议于2018年9月19日获得批准。该项目受益于强烈的工业兴趣和既定的合作。Striolo和Koh之间的合作是由他们的工业合作伙伴Halliburton和皇家学会国际合作赠款促成的。Striolo和Stamatakis在一个项目中合作，在该项目中实施KMC来研究流体传输。

Sir Humphrey Davy discovered clathrate hydrates in 1811. Hydrates are solid structures formed by water and gases, e.g., methane. The abundance of natural gas hydrate deposits across the world could provide abundant energy resources for the future, as well as long-term CO2 storage. Natural gas hydrates can be exploited in high-tech applications including innovative water-desalination and gas-storage processes. Prof. Carolyn Koh overviewed hydrates in the book she co-authored with Prof. Dandy Sloan: Clathrate Hydrates of Natural Gases, 3rd Ed., CRC Press, 2007.This proposal is concerned with hydrate plugs in oil & gas pipelines. Such plugs can lead to pipelines ruptures, causing spills and environmental disasters, production interruptions, and even loss of life.The traditional approach to manage hydrates is adding thermodynamic inhibitors (THIs), e.g., methanol. THIs shift the conditions at which hydrates are stable to lower Ts and higher Ps. However, large amounts of THIs are necessary, which negatively affects both the economics of the operations and their environmental impact. Among emerging promising technologies to prevent hydrates formation in pipelines is the use of 'low dosage hydrate inhibitors' (LDHIs), effective at low concentrations.Among other limitations, the wide applicability of LDHIs is impeded by a current lack of understanding of how LDHIs function. In fact, LDHIs performance depends on oil composition, water salinity, temperature, etc. LDHIs include kinetic hydrate inhibitors (KHIs) and anti-agglomerants (AAs). This timely project will develop a fundamental understanding regarding how AAs function.The project builds on significant prior results. For example, Prof. Koh and her group produced extensive experimental data regarding the performance of LDHIs, and developed extensive experimental characterisation capabilities to probe AAs at different length scales (from the microscopic, using micromechanical force measurements, to the macroscopic, using flow loops). Prof. Striolo employed molecular simulations to discover possible molecular mechanisms that are responsible for the performance of LDHIs (in particular, AAs). The simulation results led to new LDHIs formulations, environmentally benign, recently disclosed in a patent application.To widely adopt LDHIs, it is required to develop reliable models that accurately describe the likelihood of hydrate plugs formation as a function of process conditions. This project will transform the pioneering software CSMHyK, which is already coupled with the industry-standard multiphase flow simulator OLGA. CSMHyK (1) describes accurately multi-phase transport in pipelines; (2) uses reliable equations of state to predict the hydrates thermodynamic stability; and (3) employs working assumptions to predict hydrates formation. To enable the latter feature, an important parameter is the nucleation sub-cooling, which is treated as an input parameter currently estimated from experimental flow-loop results, thus lacking predictability.To render CSMHyK predictive, it is proposed to develop a model, based on kinetic Monte Carlo (KMC), to describe quantitatively the hydrate population dynamics as a function of system conditions. The new model will allow practitioners to quantify LDHIs' effects, which is currently not possible, as well as to include molecular-level information from microscopic experiments and molecular simulations into the formulation of risk assessment.This NSF-EPSRC Lead Agency Agreement proposal builds on an Expression of Interest submitted to EPSRC on 04/08/2018, which was approved on 19/09/2018. The project benefits from strong industrial interest, and from established collaborations. The collaboration between Striolo and Koh was enabled by their industrial partner Halliburton and by a Royal Society International Collaboration grant. Striolo and Stamatakis collaborate in a project in which KMC was implemented to study fluid transport.