Mechanical behavior of hydrate-bearing sands with fine particles under isotropic and triaxial compression

Abstract

The presence of fine particles has a significant impact on the mechanical behavior of hydrate-bearing sediments. In this study, a series of isotropic compression and triaxial tests were conducted using a customized testing system for the hydrate-bearing sediment. Carbon dioxide hydrate was formed in the host sediments, which were mixtures of sand and silty-sized quartzitic or illite fine particles. The isotropic and triaxial compression tests offered valuable datasets of the compression and the swelling indices, yielding stress, strength, stiffness, and dilatancy for hydrate-bearing sediments. The results highlighted that the addition of illite particles enhances compressibility but restricts stiffness and dilatancy. The strength is highly increased by hydrate saturation and less dependent on the mineralogy of fine particles. The cohesion is significantly enhanced by the hydrate saturation due to cementation. With the increasing hydrate saturation, the angle of internal friction increases slightly at lower hydrate saturation but it decreases slightly at higher hydrate saturation. The experimental results and mechanism analysis can be used to assess the stability of the hydrate reservoir under methane-carbon dioxide replacement and provide a reference to estimate the mechanical properties of the methane hydrate reservoir.