Burgeoning growth in the nation's shale plays in recent years has made hydraulic fracturing (fracking) the technique by which most natural gas is produced in the United States, accounting for about two-thirds of total domestic marketed gas production last year, according to the Energy Information Administration (EIA).

"In 2000, approximately 26,000 hydraulically fractured wells produced 3.6 Bcf/d of marketed gas in the United States, making up less than 7% of the national total," EIA said. "By 2015, the number of hydraulically fractured wells had grown to an estimated 300,000, and production from those wells had grown to more than 53 Bcf/d, making up about 67% of the total natural gas output of the United States."

The results may vary from other sources because of the types of wells included in the analysis, update schedules of source databases, and the specific types of natural gas volumes analyzed, EIA said.

Fracking also accounts for about half of U.S. crude oil production, the agency said.

The dramatic increase in production associated with fracking was revealed through a profile of marketed gas production using well completion and production data from IHS Global Insight and DrillingInfo Inc.

Natural gas production from fracking has primarily come from shale and other tight rocks in the Marcellus, Utica, Bakken, Eagle Ford, and the stacked Permian Basin formations in Texas and New Mexico, EIA said, but it isn't limited to shale plays and horizontal wells.

"Hydraulic fracturing has been successfully used in directional and vertical wells, natural gas and oil wells, and in non-tight formations and reservoirs. To date, most natural gas from hydraulically fractured wells has come from Lower 48, onshore tight rock formations."

Despite its dominance in the field, fracking remains a contentious issue in several states, and this year became an issue debated by presidential candidates (see Shale DailyApril 15).

The Environmental Protection Agency's Science Advisory Board has released two draft reports this year that tweaked its landmark assessment last year that fracking poses no "widespread, systemic impacts" to drinking water (see Shale DailyFeb. 18Jan. 8June 4, 2015).