Laboratory analysis of carbon dioxide hydrate-bearing sands

Gas hydrates are ice-like compounds composed of water molecules that encapsulate natural gas molecules in a very compact form. Three groups of CO2 hydrate-bearing sand specimens were formed using a specialized triaxial test apparatus at different temperature and different pressure to examine the physical effects, such as stress and deformation changes, of hydrate dissociation on the surrounding soil. The triaxial test data indicate: (1) the higher the pressure, the higher hydrate content; (2) the lower the temperature, the higher hydrate content; (3) the greater the amount of gas hydrate initially present in the specimen, the greater the reduction of effective stress upon dissociation and the lower strength; and (4) dissociation of even a small percentage of gas hydrates will cause a dramatic reduction in the soil strength and could lead to failure.