Dilation behavior of gas-saturated methane-hydrate bearing sand

The geotechnical properties of methane-hydrate-bearing sediments (MHBS) are commonly investigated in the laboratory by using artificial hydrate formations in sandy specimens. Analyses of MHBS saturated with gas or water (in addition to methane-hydrate) showed significant mechanical differences between the two pore-filling states. This paper discusses the unique dilatancy behavior of gas-saturated MHBS, with comparison to water-saturated test results of previously-published works. It is shown that the significant compaction of gas-saturated samples is related to internal tensile forces, which are absent in water-saturated samples. The conceptual link between the internal tensile forces and the compaction characteristics is demonstrated through mechanical differences between pure sand and cemented sand. The paper establishes the link between internal adhesion in gas-saturated MHBS and the unique dilation response by using a stress-dilatancy analysis.