WHO IS STILL LOOKING FOR OCEANIC METHANE HYDRATES?
7 FEBRUARY 2020 DANIEL ALLARD
If we tell you that 1 cubic centimeter of this ice releases up to 164 cubic centimeters of methane! Yes: 164 times the setting… Under particular temperature and pressure conditions, ice (H2O) can trap gas molecules, forming a sort of cage trapping the gas molecules. The resulting compounds are called gas hydrates or even clathrates (from the Latin clatatrus, encapsulated). The case that interests us here is that of methane hydrates, an ice that contains an enormous amount of gas.
A lot of gas!
Along the southeastern coast of the United States alone, an area of 26 square kilometers contains 000 Gt (billion tonnes) of carbon. This is more than 35 times the consumption of natural gas in the USA in 100!
Globally, it is even estimated that methane hydrates from the ocean floor contain twice as much carbon equivalent as all of the known natural gas, oil and coal deposits. Wow!
JAPAN ACTIVELY IN THE RACE
Because the Japanese government shut down most of the country's nuclear power plants following the Fukushima disaster and seismic surveys and exploratory drilling have highlighted the presence of around 1 billion cubic meters of methane off its coast East, Japan is currently at the head of the powers trying to exploit this "ice that is burning".
Japan Oil, Gas and Metals National Corporation (JOGMEC), which in 2013 succeeded in successfully extracting methane during a test off the Atsumi and Shima peninsulas using its research vessel Chikyu, was planning a second round of tests. in situ for 2015. For the moment, it has not been possible for us to learn more to confirm whether the 2015 phase has actually been carried out. The internet is silent.
Only the 2013 experiment, carried out 330 meters underground under 1 meters of sea depth is publicly documented. It consisted in causing a pressure drop to recover the gas, trapped with water in crystalline form in the surface sediments of deep ocean waters, under conditions of high pressure and low temperature. Gas had actually been obtained on the surface for 000 days (6 m120). Enough to then plan an extraction platform to be developed between 000 and 3 with a commercial exploitation in sight.
It is true that since then, the extraction of clathrates has been presented as a “potential ecological bomb”.
The Canadian authorities have also put an end to investments in the same direction, in particular after cooperation with Japan (see box). Because the extraction of clathrates is said to be dangerous and expensive.
For the first time, an interesting technological solution had been demonstrated at the Mallik site, in the far north of Canada. A rapidly international research site for the study of arctic natural gas hydrates in the Mackenzie Delta. In 2002, an enlarged consortium of seven international partners and more than 300 scientists and engineers had allowed the drilling of a well with a depth of 1 m for exploitation and two adjacent wells for scientific observation.
It is also thanks to the work at Mallik that Japan was able to confirm the technique of pressure drop - depressurization - as a process for recovering gas.
But Canada no longer believes it.
Critics fear, for example, that this type of exploitation will cause immense submarine landslides on the continental slope, causing very important tsunamis threatening the neighboring populations.
FRANCE IS SEEKING TO UNDERSTAND
What is certain is that in September 2015, forty geologists and chemists went out to the Black Sea, off the Romanian city of Constanta, to study the dynamics of methane hydrates, aboard the French oceanographic vessel " Why not ? »As part of the GHASS scientific mission.
This campaign was carried out by Ifremer in collaboration with German (GEOMAR), Romanian (GeoEcoMar), Norwegian (NGI) and Spanish (University of Barcelona) researchers.
Stakes of the GHASS campaign
Improve knowledge on methane hydrates and their stability in a context of global change;
Identify the hazards linked to the sedimentary deformation of the seabed (“submarine landslides”).
Knowledge about this exceptional energy resource is relatively recent, because it was not until 1996, in the Pacific Ocean, that the research vessel Sonne ascended from a depth of 785 meters, about 500 kg of hydrate. of methane.
Greenhouse gas par excellence, any handling of methane requires extreme care.