Modeling investigation of gas hydrate decomposition: thermodynamic approach and molecular dynamic simulations

• Main Author: Kondori, Javad
• Format: Thesis
• Language: English
• Published: Memorial University of Newfoundland 2019
• Subjects: Canada; permafrost; Alaska; Siberia
• Online Access: https://research.library.mun.ca/14003/; https://research.library.mun.ca/14003/1/thesis.pdf

In the last few decades, there has been a great interest in the hydrate reservoirs for energy storage and source purposes. It has been proven that hydrates can contribute to ocean carbon cycling, global climate change, and coastal sediment stability. The permafrost and offshore environments contain enormous quantities of methane in the form of gas hydrates. In addition, the natural gas has been recently produced worldwide including in Alaska, Siberia, Japan, and North West Territories of Canada. However, the gas hydrates formation may lead to various forms of blockages in oil/gas production and transportation processes, resulting in high capital and operating costs. Detailed experimental and modeling investigations of hydrate formation and decomposition can assist to better understand the mechanisms involved in gas production from hydrates. Thus, it is important to determine the equilibrium hydrate-forming conditions so that a systematic parametric sensitivity analysis is conducted to identify the vital process and thermodynamic parameters affecting this occurrence. This project focuses on the hydrate formation/dissociation conditions where equations of state and molecular dynamic (MD) simulations are used. Giving further information, this study provides a reliable model to determine the gas hydrate formation and decomposition conditions of pure, binary, and ternary systems of hydrate gases where the van der Waals Platteuw model is utilized by combining with extended UNIQUAC model and PC-SAFT equation of state. In addition, MD simulations are conducted to investigate the microscopic mechanisms/phenomena and intermolecular forces involved in gas (pure and mixture) hydrate decomposition, where the molecular interactions, structures, and behaviours of hydrate systems need to be appropriately explored. Through a systematic design of simulation runs, the impacts of temperature, pressure, cage occupancy, and inhibitors on the hydrate dissociation are studied. Furthermore, the diffusion coefficient, density, and heat ...