Japan’s Modec is hailing the successful testing of technology that could enable the exploitation of shallow methane hydrate resources, which have been discovered in the nation's offshore waters.
Being able to develop methane hydrates would be a welcome boost for the country's energy security — Japan relies heavily on liquefied natural gas imports as it has very limited domestic conventional oil and gas production.
Modec said that the drilling performance tests conducted in October 2022 using a simulated soft mud ground that simulated a large-sized ice ground with the same strength as shallow methane hydrates confirmed the drilling performance has reached a level that enables the efficient harvesting of methane hydrates, even in 100% content of shallow methane hydrate ground.
Modec added it aims to provide technologies for the manufacture and operation of offshore production facilities for methane hydrates, a seabed resource in the seas around Japan, by applying the technologies it has cultivated through the construction and operation of floating production, storage and offloading vessels.`
The company noted it had earlier used a simulated soft mud several tens of metres below the seabed with 20% content of shallow methane hydrates and the performance was confirmed to be sufficient to efficiently harvest granular methane hydrate in the soft mud.
“With the continued cooperation of the Kitami Institute of Technology, we installed four steel tanks with a diameter of about three metres at the Okhotsk Regional Innovation Research Park in Kitami City, Hokkaido, and began to prepare for the test this time by producing a large-sized ice in the drilling tanks about one metre thick, simulating 100% content of shallow methane hydrate ground by naturally accumulating ice by layering and integrating commercial ice and water,” explained Modec.
The company confirmed that the ice in the tanks had solidified sufficiently on 31 January and it subsequently conducted six days of drilling tests, utilising the Wirth reverse circulation rig provided by HMH.
“As a result of drilling four large-sized ice in the drilling tanks using three different types of drilling bits with different characteristics and changing parameters, we confirmed that the drilling performance reached a level that allows efficient recovery even in 100% content of shallow methane hydrate ground, and succeeded in obtaining basic data necessary for estimating the drilling performance of actual drilling equipment, and for selecting actual drilling bits and equipment,” added Modec.
Based on the basic data obtained from the two drilling performance tests, Modec will now develop the optimum combination of drill bits and equipment for various target areas for development of shallow methane hydrate in different conditions, and conduct simulations of the required power and drilling capacity to confirm the effectiveness and commercial profitability of this harvesting technology.
The technology development, which was commissioned by Japan’s Agency for Natural Resources and Energy, an agency under the Ministry of Economy, Trade and Industry, is intended to develop harvesting technology using extensive vertical drilling methods with disk-shaped, large diameter drill bits.
