Naruto Gas Field

The South Kanto Gas Field is the largest water-soluble gas field in Japan and extends widely across the southern Kanto region centered around Chiba Prefecture. INPEX discovered the Naruto Gas Field in the Naruto area of Chiba Prefecture. Water-soluble natural gas is dissolved in water known as brine in underground gas columns. This brine is pumped to the surface, the natural gas is separated and extracted and supplied to the surrounding areas.

Brine contains a high concentration of iodine, which, once refined, is primarily used as a raw material in chemical and pharmaceutical-related products. Chiba Prefecture is home to one of the world's largest brine deposits, and we export iodine as an international commodity to companies in Europe, the United States and Asia under the "INPEX IODINE" brand. Iodine in Japan is produced by seven companies, including INPEX, with approximately 80 percent of it produced in Chiba Prefecture, which has a large amount of water-soluble natural gas resources. INPEX outsources the brine production in Chiba Prefecture and manufactures iodine using the displacement method. The use of iodine is expected to expand and diversify in the future, notably as a raw material for perovskite solar cells, now widely considered as next-generation solar cells.