Prediction of the mechanical response of hydrate-bearing sands

In recent years there has been an increasing interest in production of methane gas from hydrate-bearing sediments, located below the permafrost in arctic regions and offshore within the continental margins. In order to simulate the geomechanical response of the hydrate accumulation during gas production, comprehensive evaluation of the sediments' properties is imperative. This paper presents an analysis of the mechanical properties of methane-hydrate-bearing sediments determined through numerical simulation of drained triaxial compression tests on three different sand types. The adjustment of the numerical to the experimental results was performed for the entire stress-strain curves and therefore enables a good understanding of the material constitutive relations. New constitutive relations are suggested for the hydrate-related properties. An optimization process was used, finding separately the soil skeleton-related coefficients and the hydrate-related coefficients. The values of the obtained coefficients associated with the hydrate were found to have minor deviations from each other, for the three examined sand types. By separating the soil skeleton and the hydrate-related response, this paper suggests a prediction method for the mechanical response of hydrate-bearing sands.