Government sources revealed on June 28 that China set up a movable drilling rig near the Japan-China median line in the East China Sea in its attempt to undertake unilateral development of gas fields. This new equipment, which is a semi-submersible model that can be used for deep sea drilling, is different from the rigs China has been using in shallow waters. The government is monitoring further developments because this may lead to the construction of a new offshore platform.
According to several government sources, the new KAN TAN IV drilling rig was observed to have been set up on the Chinese side near the bilateral median line in late June. At this point, it appears that the rig has not started test drilling. The Foreign Ministry has lodged a protest with China that “unilateral gas field development is unacceptable.”
The KAN TAN IV can be tugged to a desired location and partly submerged by injecting water. The drilling rigs on the Chinese side spotted by the Japanese government up until now were jackup rigs with their legs planted on the sea floor and their hulls raised above the sea surface for drilling.
Semi-submersible rigs are capable of drilling in the deep sea. They are less affected by currents and more stable than jackup types. KAN TAN IV is capable of drilling up to a depth of 600 meters, which is much deeper than the 120-meter capability of the KAN TAN VII found nearby in May. Both the KAN TAN IV and the KAN TAN VII are operated by the state-owned Sinopec Group Shanghai Ocean Petroleum Bureau.
The Japanese government is analyzing the motive behind China’s installation of a semi-submersible rig. China has reneged on its cooperation agreement with Japan and engaged in unilateral development of gas fields, setting up 16 drilling facilities on the Chinese side of the median line. It is possible that it may speed up the construction of a 17th offshore platform.
Meanwhile, the Japan Coast Guard announced on June 28 that the Chinese research vessel “Kexue” was spotted conducting unauthorized surveys in Japan’s exclusive economic zone (EEZ) 132 kilometers west of Iotori Island of Kumejima, Okinawa.
This area is known to have deposits of mineral resources. “Kexue” also conducted unauthorized surveys here in April 2014. It is reckoned that the ship took samples of the seafloor at that time, so the latest surveys were probably also being undertaken for scientific analysis.