Business Activities

Nakajo Oil and Gas Field

The onshore Nakajo oil and gas field in Niigata Prefecture is JX's exploration and production base in Japan. Our target is to ensure a continuous supply of natural hydrocarbon as fuel and chemical material to customers including industries and local communities. Discovered in 1957, the Nakajo oil and gas field is composed of three different types of hydrocarbon accumulations: non-associated natural gas, natural gas dissolved in water, and black oil.
The Nakajo field has produced more than five billion standard cubic meters of natural gas since the first production in 1959, and continues to yield a significant volume of gas and crude oil. In addition, crude iodine is extracted from kansui, the water in which natural gas is dissolved, and exported as a raw material for the production of pharmaceuticals and chemicals.
The field also provides invaluable training opportunities for technical staff including geoscientists, engineers and operators. A field training program is also offered to undergraduate university students studying natural resource engineering.

Crude Oil and Natural Gas

> Natural gas produced from underground reservoirs is gathered at a central processing plant. The gas is processed to sales specifications and delivered to regional customers through pipelines.

> Crude oil associated with the natural gas is separated, processed and stored in storage tanks, and then delivered to customers in tankers.

Clude Oil and Natural GasWells for natural gas dissolved in water
Clude Oil and Natural GasWells for non-associated natural gas
Clude Oil and Natural GasGas compressor station
Clude Oil and Natural GasOil and gas are accumulated in sandstone reservoirs at a depth of 500 to 2000 meters below ground level.
Clude Oil and Natural Gas Central processing plant
Clude Oil and Natural Gas Crude oil storage tank


Iodine, a halogen, occurs sparingly in the form of iodides in kansui, which is salt water produced with dissolved gas at a concentration of 70 to 80 milligrams per liter. Crude iodine is recovered from kansui and exported to customers worldwide.

Iodine Product Iodine Product


Iodine has many everyday applications. Its main areas of use include medical applications such as X-ray contrast media and gargles, sterilizers, fungicides, feed additives, photo-sensitizers and polarizing films for liquid crystal displays.

A variety of Applications (estimated)

※Process Flow

Iodine is extracted from kansui using the 'blow-out' method:

> Kansui, separated from natural gas, is fed to the mixing tanks, where an oxidant is added.
> The mixed fluid is fed into a 'blower', where iodine is evaporated into the air.
> Iodine is recaptured from the air with a reducing agent, creating an absorbent solution.
> Iodine is crystallized from the solution using an oxidant, melted to remove impurities, cooled to solidify, then flaked and packed in drums.

Nakajo Iodine Factory Nakajo Iodine Factory

A Package of Export

※Product Specifications

Purity More than 99.7%
Non-Volatile Materials Less than 0.05%
Sulfate Less than 0.02%
Chlorine/Bromine Less than 0.005%