Compressive characteristics of methane hydrate-bearing sands under isotropic consolidation

Abstract

Depressurization is an effective method to produce methane gas from methane hydrate reservoirs. However, during gas production, sediments consolidate due to increasing effective stress. Revealing the compressive characteristics of methane hydrate-bearing sands during consolidation is essential for an accurate understanding of sediment properties and for the development of a constitutive model. Therefore, a series of isotropic consolidation tests was performed on sand in which methane hydrate was artificially generated, and its compressibility characteristics were evaluated. Furthermore, to assess prolonged production, creep compressive behavior was investigated. The experimental results showed volumetric strain due to increasing confining stress decreased with increasing initial methane hydrate saturation. Particle crushing during consolidation was inhibited by the presence of methane hydrate. It was confirmed that the increase in the effects of methane hydrate on soil compressibility followed a power function with the increase in methane hydrate saturation. Creep deformation was observed during the stress holding period regardless of the presence of methane hydrate. Creep behavior during the stress holding period was related to the extent to which the creep component had dissipated before the stress holding period in the past. A theoretical concept for creep strain was proposed based on the experimental results.