Creep behaviours of methane hydrate-bearing sediments

Abstract

Natural gas hydrates, as a new energy source, are attracting more and more attention. Safe and efficient exploitation has become one of the hot issues in current studies. In order to investigate the creep behaviour of sediments containing methane hydrates, a series of triaxial compression tests and creep tests was conducted under various conditions. First, stress–strain curves were drawn, and then the failure strength of the sediments was obtained. Next, on the basis of creep tests, the creep curves were recorded. The results showed that the attenuation- and steady-creep stages always existed during creep, but the acceleration-creep stage just appeared under higher-temperature and higher-stress conditions. The creep test results indicated that the confining pressure, temperature and stress level affected the creep characteristics of sediments, such as the initial strain ε 0, the rheological initial time t m, the rheological initial strain ε m, the failure time t f and the failure strain ε f. The findings suggested that, during the creep tests, more hydrate dissociation accelerated the damage to the sediments’ strength under higher stress level, temperature or confining pressure.