Dynamic Imaging of Hydrate Specific Area Evolution during Xenon Hydrate Formation

Abstract

Gas hydrates are ice-like structures formed under high pressure and low temperature conditions. They are considered as a potential energy source due to their abundance and the increase in energy demand worldwide. A fundamental understanding of hydrate formation and dissociation kinetics is essential in order to improve gas productivity from natural hydrates reservoirs. This paper investigates the evolution of hydrate specific area during the process of hydrate formation using dynamic 3D synchrotron microcomputed tomography. Xenon hydrate was formed inside a high-pressure low-temperature cell, filled with silica sand partially saturated with water. The cell has a height of 70.2 mm and an inner diameter of 9.7 mm, and is capable of sustaining an internal pressure of 150 MPa. During hydrate formation and dissociation, full 3D images are acquired at a time resolution of 45 seconds and a spatial resolution of 5.38 ?m/voxel. The reconstructed images were enhanced and segmented, and direct volume and surface area measurements were obtained. Initially, the specific area of hydrate increased with increasing hydrate saturation up to a certain hydrate saturation threshold (9% hydrate saturation). After this threshold, hydrate specific area started to decrease with increasing hydrate saturation. This is an indication that the small crystals of hydrates tend to merge and form larger crystals during the process of hydrate formation.