The US Geological Survey (USGS) said that it assessed in Texas the largest oil deposit ever discovered in the country, the agency announced this week.

The USGS says an estimated 20 billion barrels of oil, 16 trillion cubic feet of associated natural gas and 1.6 billion barrels of natural gas liquids were located in the Wolfcamp shale in the Midland Basin area of the Permian Basin province in west Texas.

The discovery is valued at $900 billion, based on the current West Texas Intermediate $45 per barrel price.

This is the largest deposit ever found in the United States and is three times bigger that the one in the North Dakota Bakken-Three Forks oilfields assessed in 2013.

“The fact that this is the largest assessment of continuous oil we have ever done just goes to show that, even in areas that have produced billions of barrels of oil, there is still the potential to find billions more,” said Walter Guidroz from the USGS Energy Resources Program.

“Changes in technology and industry practices can have significant effects on what resources are technically recoverable, and that’s why we continue to perform resource assessments throughout the United States and the world,” he added.

Midland Basin Map USGS Midland Basin Photo: USGS Oil and gas companies have recently rushed over to the Texas province and have been using horizontal drilling and hydraulic fracturing, also known as “fracking.” More than 3,000 horizontal wells have been drilled and completed in the Midland Basin Wolfcamp section, the USGS says.

The agency says that although it has assessed oil and gas resources in that area, this is the first assessment of continuous resources in the Wolfcamp shale. The Wolfcamp shale is also in the Delaware Basin area of the Permian Basin province, however it was not included in the assessment.

The Permian Basin contains a set of basins and other geologic formations in western Texas and southern New Mexico, the USGS says. The area is one of the most productive for oil and gas in the country.