Peter Flemings John Germaine Hugh Daigle Stephen C. Phillips Joshua O’Connell Yi Fang 2022 <p class="abstractnoin">This work experimentally explores porosity, compressibility, and the ratio of horizontal to vertical effective stress (<i>K</i>₀) in hydrate-bearing sandy silts from Green Canyon Block 955 in the deep-water Gulf of Mexico. The samples have an in situ porosity of 0.38 to 0.40 and a hydrate saturation of more than 80%. The hydrate-bearing sediments are stiffer than the equivalent hydrate-free sediments; the<span>&nbsp;</span><i>K</i>₀<span>&nbsp;</span>stress ratio is greater for hydrate-bearing sediments relative to the equivalent hydrate-free sediments. The porosity decreases by 0.01 to 0.02 when the hydrate is dissociated at the in situ effective stress. We interpret that the hydrate in the sediment pores is a viscoelastic material that behaves like a fluid over experimental time scales, yet it cannot escape the sediment skeleton. During compression, the hydrate bears a significant fraction of the applied vertical load and transfers this load laterally, resulting in the apparent increased stiffness and a larger apparent<span>&nbsp;</span><i>K</i>₀<span>&nbsp;</span>stress ratio. When dissociation occurs, the load carried by the hydrate is transferred to the sediment skeleton, resulting in further compaction and a decrease in the lateral stress. The viewpoint that the hydrate is a trapped viscous phase provides a mechanism for how stiffness and stress ratio (<i>K</i>₀) are greater when hydrate is present in the porous media. This study provides insight into the initial stress state of hydrate-bearing reservoirs and the geomechanical evolution of these reservoirs during production.</p> application/pdf 10.1306/01132221002 en American Association of Petroleum Geologists Compression behavior of hydrate-bearing sediments article