The United States and Canada are the only major producers of commercially viable natural gas from shale formations in the world, according to the U.S. Energy Information Administration (EIA).

About a dozen other countries have drilled exploratory test wells.

China is the only country outside North America that has registered commercially viable production of shale gas. But the volumes contribute less than 1% of the total natural gas production in that country.

In comparison, shale gas as a share of total natural gas production in 2012 was 39% in the United States and 15% in Canada.

Shale gas dry production in the United States averaged 25.7 billion cubic feet per day (Bcf/d) in 2012, while total dry production averaged 65.7 Bcf/d.

In Canada, total dry natural gas production from the two major shale plays—the Muskwa-Otter Park shale formation in the Horn River Basin of northern British Columbia and the adjacent Montney Basin that spreads over British Columbia and Alberta—averaged 2.0 Bcf/d in 2012, while total Canadian production averaged 14.0 Bcf/d.

Gross withdrawals from Horn River and Montney averaged 2.5 Bcf/d in 2012, and reached 2.8 Bcf/d by May 2013.

The potential for higher production from these two plays is currently constrained by limited pipeline infrastructure, the EIA said.