Abstract
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.
Highlights
Cemented sand, Pinkert [35] showed that, unlike cemented sand, methane-hydrate-bearing sediments (MHBS) can be mechanically characterized without using a cohesion property, i.e., stress–dilatancy relationships for cemented sand vary depending on cement content, while those of MHBS are the same regardless of hydrate content
Because the hydrate droplet was tested in a gassy environment, it is hypothesizes that if the experiments would have been conducted in a wet environment, a significantly lower adhesion would have been measured, just as WS MHBS did not show an overall cohesive nature
The unique mechanical features are discussed by comparing the mechanical behavior of GS to water-saturated (WS) MHBS
Summary
Methane-hydrates have attracted increased interest in recent years as a potential energy source due to the existence of extensive methane-hydrate-bearing sediments (MHBS) around the world [1,2,3,4,5,6]. Taken together, these reserves are estimated to contain double the productive energy potential of all known fossil fuel resources [7,8,9]. Investigations of the mechanical behavior of MHBS, which is most commonly studied using laboratory tools, are needed
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