Special Course: Investigation of CH4-CO2 Swapping in Gas Hydrates

Description

Natural gas hydrates occur abundantly in permafrost regions and deep oceans sediments. The idea of this project is to investigate the possibility of methane production with simultaneous storage of CO2 by injection of carbon dioxide and flue gas. The key driver for hydrate swapping is the difference in the thermodynamic stability of CH4 and CO2 hydrates as CO2 hydrates are more stable than CH4 hydrates. This stability difference (fugacity/chemical potential difference) means that a spontaneous swapping reaction should occur. Recovery of CH4 is achieved using either pure CO2 or flue gas (CO2+N2). Most research work in hydrate swapping has been focused around structure I hydrates (sI) but other forms of hydrate deposits are also known (e.g. structures II and H – sII and sH) and the behavior here is less well studied and understood. Research Objective In this study, we will investigate influence of pure CO2 as well as flue gas (CO2+N2) injection on various hydrate structures and their thermodynamic stability during the hydrate swapping process. The special course will start with a literature survey on production of natural gas from hydrates, focusing especially on natural gas production by injection of CO2 and flue gas. sI, sII and sH hydrates will be formed using appropriate hydrocarbon gases and gas mixtures. The swapping reaction will be studied using various setups, including a high-pressure micro differential calorimeter, stirred tanks reactor, a rocking cell rig and flooding equipment. Flue gas will be used at different concentrations of CO2 and N2. Examples of the kinds of studies we are interested in are: • Thermodynamic stability of gas hydrates (sI, sII, sH) before and after flue gas injection; • Heat flow change during swapping; • Equilibrium curves for different gas hydrates will be measured as well as modelled using (for example) the CSGM software. Comparison of model and measurements can give an insight into the recovery % of CH4 and the storage % of CO2 in hydrate. • Influence of flue gas injection pressure on thermodynamic stability of gas hydrate and heat transfer; • Evidence of structural transformation between structures during hydrate swapping; • The effect of pore size and saturation on hydrate swapping for various solid media will be examined (sandstone, silica gel etc.)

Period	10 Sept 2018 → 7 Dec 2018
Examinee	Ermis Proestakis, Kianoosh Moeini, Athanasios Poulios & Julio Perez Santiago
Examination held at	CERE – Center for Energy Ressources Engineering
Degree of Recognition	Local