Shale has become the largest source of gas production in the U.S. as new technology continues to lower drilling costs.

Shale gas wells surpassed production from nonshale wells in 2013, the Energy Information Administration (EIA) said in a report. In 2013, shale gas accounted for 40% of the country’s total gas production of 82 billion cubic feet per day (Bcf/d).

New technology has enabled producers to shift production to shale resources that are now easier to reach and have lower drilling costs, the EIA said.

In six years, shale production has increased to 33 Bcf/d in 2013 from 5 Bcf/d in 2007, according to the EIA’s Natural Gas Annual.

In 2007, shale gas wells made up 8% of total gas produced in the U.S. At the time, about 63% of shale gas came from Texas.

Since then, the distribution of shale gas production by state has changed significantly, the EIA said.

Texas, Pennsylvania, Louisiana and Arkansas accounted for 26 Bcf/d, or 79%, of U.S shale gas production in 2013.

Regional highlights include:

  • Texas: Shale gas production increased to 11 Bcf/d in 2013 from 3 Bcf/d in 2007. Most of its shale gas production growth came from the Barnett, Eagle Ford and Haynesville-Bossier plays.
  • Pennsylvania: Became the second-largest shale gas producing state in 2013, producing 8 Bcf/d, with almost all the growth coming from the Marcellus play. Shale gas production from the Utica play is increasing, but this volume remains small by comparison.
  • Louisiana: Grew production to 4 Bcf/d in 2013 from producing a minimal amount of shale gas in 2007. All of this growth came from the Haynesville play.
  • Arkansas: Became the fourth-largest shale gas producing state, accounting for 2.8 Bcf/d, or 9%, of U.S. shale gas production in 2013. All of its shale gas production growth came from the Fayetteville play.

Gross gas production in the U.S. from nonshale wells decreased by 25% in 2013 to 31 Bcf/d from 41 Bcf/d in 2007, the EIA said.

Production from nonshale wells in Texas, Louisiana and the Gulf of Mexico made up 56% of total U.S. gross production from nonshale natural gas wells in 2007. However, the states’ combined share has declined to 41% in 2013.

Even though production from nonshale gas wells has decreased on a national basis, production from nonshale wells in some states, notably Colorado, the sixth-largest gas producing state, increased since 2007, the EIA said.