This young year has already seen methane hydrates back in the news—is commercial production getting closer? A report released by the US National Research Council in February says that hydrates, if proven technically safe, are an environmentally compatible and economically competitive energy resource. And South Korea announced a US$37 million resumption of hydrates drilling off its east coast for 1st April to 15th May this year.
Gas hydrates are those seemingly magical gases trapped inside frozen water molecules which make ice appear to burn. Their state is maintained by high pressures and cold temperatures usually found beneath permafrost or under continental shelves. Hydrates’ global abundance has been estimated to exceed the total of all other hydrocarbons combined.
Despite competition from potentially ample natural gas supplies like shales and growing popularity of LNG for some countries, hydrates may be saviours for others. Many industrialized nations lack ample shale sources, and LNG can be a pricey and uncertain alternative. For them, hydrates look pretty attractive.
South Korea reckons it has enough to meet the country’s needs for 30 years—and the big news is they’re planning commercial production by 2015. If they succeed it will be an offshore first. Japan is in the running too; it wants commercial hydrates production from its offshore Nankai Trough by 2016.
Now here’s the technical challenge. Methane gas flow by the simple depressurization technique has already been demonstrated onshore; and in fact has already happened in many traditional natural gas wells where pressures have dropped due to depletion in adjacent gas reservoirs. In fact it’s commercially feasible with current technology. The Mackenzie Delta’s Mallik production test well produced from 2,000 to 4,000 cubic metres per day on a six-day test in 2008.
But offshore can be much more tricky. Many offshore hydrates are in unstable sediments—sandy soils or gravels—and a weakening by decompression could have catastrophic results. Like the release of massive volumes of methane gas, a greenhouse gas several times more potent than CO2. Several academic papers have reported on such seafloor subsidence from conventional drilling which may have triggered gas hydrates dissociation. Let’s hope energy anxieties don’t trump common sense.