Dynamic 3D imaging of gas hydrate kinetics using synchrotron computed tomography

Zaher Jarrar,Khalid Alshibli,Jongwon Jung,Riyadh Al-Raoush,J.S Mccartney,I Tomac

doi:10.1051/e3sconf/202020511004

Abstract

The availability of natural gas hydrates and the continuing increase in energy demand, motivated researchers to consider gas hydrates as a future source of energy. Fundamental understanding of hydrate dissociation kinetics is essential to improve techniques of gas production from natural hydrates reservoirs. During hydrate dissociation, bonds between water (host molecules) and gas (guest molecules) break and free gas is released. This paper investigates the evolution of hydrate surface area, pore habit, and tortuosity using in-situ imaging of Xenon (Xe) hydrate formation and dissociation in porous media with dynamic three-dimensional synchrotron microcomputed tomography (SMT). Xe hydrate was formed inside a high- pressure, low-temperature cell and then dissociated by thermal stimulation. During formation and dissociation, full 3D SMT scans were acquired continuously and reconstructed into 3D volume images. Each scan took only 45 seconds to complete, and a total of 60 scans were acquired. Hydrate volume and surface area evolution were directly measured from the SMT scans. At low hydrate saturation, the predominant pore habit was surface coating, while the predominant pore habit at high hydrate saturation was pore filling. A second-degree polynomial can be used to predict variation of tortuosity with hydrate saturation with an R2 value of 0.997.

Highlights

Natural gas hydrates are ice-like structures in which a large amount of gas is trapped within a crystal structure of water [1, 2]
This paper investigates the evolution of hydrate surface area, pore habit, and tortuosity using in-situ imaging of Xenon (Xe) hydrate formation and dissociation in porous media using dynamic 3D synchrotron microcomputed tomography (SMT)
This paper investigated the evolution of hydrate pore habit, surface area, and tortuosity during Xe hydrate formation and dissociation in porous media

Summary

Introduction

Natural gas hydrates are ice-like structures in which a large amount of gas (mainly methane) is trapped within a crystal structure of water [1, 2]. This paper investigates the evolution of hydrate surface area, pore habit, and tortuosity using in-situ imaging of Xenon (Xe) hydrate formation and dissociation in porous media using dynamic 3D SMT. The beam can be reflected from a grazing incidence mirror which reflects energies below some cutoff that depends on the mirror coating and grazing incidence angle. This is referred to as “pink beam” and can result in a tunable broad bandwidth with. A pink beam can use up to 1 ms exposure time, which makes it ideal for monitoring dynamic processes such as hydrate dissociation [13, 14]

Materials and experimental setup

Image reconstruction and analysis

Surface area measurements during hydrate formation

Tortuosity evolution during hydrate dissociation

Conclusions