Where are the cores showing oceanic hydrates?
It is very difficult to recover hydrate in cores, because hydrate melts with the change in temperature and pressure when they are brought to surface. It is necessary to keep the pressure within the core. Different core equipments were built since this problem occurred when JOIDES drilling began (it was a main concern when I was a member of the JOIDES Safety Panel in the 1970s). Each new survey tests a new equipment (pressure corer like HYACE, HYACINTH, Fugro,..) and concludes that better equipment or a new survey is needed. The first industrial hydrate survey in Nankai Japan in 1999 did not recover any hydrate in the recovered cores and JNOC decided to get some hydrate core from permafrost sediments in Canada (logged since 1972 as Mallik 2) to know more on hydrate behaviour. But permafrost hydrate accumulations in Mallik (or Messoyakha in Russia) are completely different from oceanic hydrates, being gas fields in good sandy reservoirs trapped before the glaciation (about 2 million year
