An additional 15 trillion standard cubic feet of gas have been proven at Saudi state oil company Aramco’s Jafurah field, Energy Minister Prince Abdulaziz bin Salman said on Sunday.

Reserves at Jafurah have reached 229 trillion cubic feet of gas and 75 billion barrels of condensates, Prince Abdulaziz said in a statement on state news agency SPA.

Saudi Arabia is working on developing its unconventional gas reserves, which require advanced extraction methods such as those used in the shale gas industry.

Jafurah is the kingdom’s largest unconventional non-oil associated gas field and it is potentially the biggest shale gas development outside of the United States. In 2020, the Jafurah field was estimated to require investments of $110 billion.

Saudi Aramco expects output to reach 420 million cubic feet per day of ethane by 2030, it said on its website. The Jafurah field would produce some 630,000 barrels per day of gas liquids and condensates by 2030, it said.