The agreement is for the supply and purchase of 0.5 million tonnes of LNG a year between 2009 and 2014 and 0.925 million tonnes of LNG a year between 2015 and 2023.
"Kansai Electric is an original customer of the NWS Venture and we are very pleased to have signed this agreement in what is a milestone year for the NWS Venture," said North West Shelf Australia LNG president John Banner.
"2004 marks 15 years of LNG supply, as well as the completion of a major expansion of our LNG production facilities, including a fourth LNG train, a second offshore trunkline and a ninth LNG ship.
“Today’s agreement reflects the long-term commitment and support from the NWS Venture’s Japanese customers and a business relationship with Kansai Electric that will span 35 years."
The Kansai Electric Power Company is Japan’s second biggest power company and provides electricity to 13 million customers in Japan's Kansai region.