Japan announces first gas production from seabed methane hydrate
09 May 2013
On March 12, a Japanese state-owned oil and gas company said it had successfully extracted natural gas from methane hydrate deposits from under the seabed off Japan. Japan Oil, Gas and Metals National Corporation (JOGMEC) said an exploration vessel had successfully drilled 300 metres below the seabed into deposits of methane hydrate, an ice-like solid that stores gas molecules but is difficult to extract safely.
A methane hydrate block on the seabed - Photo: USGS
The tests were carried out by the deep sea drilling vessel Chikyu operated by JAPEX, which remained on site east of Japan continuing the flow tests until the end of March. The methane recovered is being flared from the rear of the specially-adapted vessel.
Safety was a major issue, and the company asked shipping and air traffic to stay clear of the Chikyu as it carried out the test drilling programme.
Production testing will continue for the next two years, with commercial production starting in 2016, if all goes according to plan.
"Methane hydrates available within Japan's territorial waters may well be able to supply the nation's natural gas needs for a century," the company said.
The immediate discoveries in Japan's Eastern Tankai Trough are thought to hold 40 trillion cubic feet of methane, equal to eleven years of gas imports for Japan. The company describes the gas as "burnable ice", saying the main difficulty is freeing it from a crystaline cage of water molecules by lowering the pressure.
JOGMEC says the experimental test should help it better understand dissociation behavior of the substance under the seabed and the impact to the surrounding environment.
Methane hydrates are recognised as a potential energy resource but may also contribute to geo-hazards such as seafloor landslides. It is thought that earthquakes and the release of gas hydrates caused the largest-ever landslide, the Storegga Slide in the Norwegian Sea, around 8,000 years ago.
The US Geological Survey says methane hydrates offer an "immense carbon reservoir", twice all other known fossil fuels on earth. However, it warns that the ecological impact is "very poorly understood".
For the oil and gas industry, methane hydrates are known to be a major hazard when drilling for deepwater oil, and existing practice is to avoid methane-bearing areas during conventional drilling.
They are stable in the extreme cold and crushing weight of the seafloor and sub-seafloor environment, but can be dangerous if they build up inside the drill column of a well. If destabilised by heat or a decrease in pressure, methane hydrates can quickly expand to more than a hundred times their initial volume, sufficient to crack most pipes.
There is speculation that methane hydrates may have been the source of the gas that caused the explosion on the Deepwater Horizon drilling rig in 2010.
Hydrate formation also foiled BP’s initial effort to contain the Deepwater Horizon blowout. The first containment device deployed was a 100-ton dome but gas hydrate crystals clogged it soon after it was positioned over the wellhead, preventing the diversion of the leaking oil to the surface
The breakthrough comes after 17 years of research and several hundred million dollars of investment. In 2008, JOGMEC carried out a six-day continuous period of production of methane from hydrate reserves held deep in permafrost in Canada, using the depressurisation method.
Canada, the USA, Norway, South Korea and China are involved in similar development programmes.
The US has a research programme underway in collaboration with the oil industry, authorised by the Methane Hydrate Research and Development Act of 1999. The National Methane Hydrates R&D Program is based at the National Energy Technology Laboratory (NETL) of the Department of Energy.
The National Academy of Sciences provided a briefing for Congress in 2012 on the energy potential of methane hydrates based on its report which asserts that "no technical challenges have been identified as insurmountable" in the pursuit of commercial production of methane hydrates.
Test drilling to recover gas from methane hydrates has also taken place in Alaska. ConocoPhillips has developed a technology that has possible advantages over the depressurisation technique used by JOGMEC.
The technology, C02 injection, preserves the hydrate structure, whereas depressurisation essentially dissolves the hydrate and can prevent surface subsidence where hydrates are shallow. Also, exchanging CO2 for methane in the hydrate provides a place to potentially sequester C02 underground.
US-based operators have not pushed ahead with gas recovery from methane hydrates primarily because of the glut of natural gas from shale gas, whereas large energy importers such as Japan see the technology as a key way to reduce expensive imports and improve long-term energy security.
Japan's LNG imports hit a record 87.3 million metric tons last year after the country shut down most of its nuclear power plants following the Fukushima nuclear disaster two years ago.