Shale gas in the United States
Shale gas in the United States is an available source of unconventional natural gas. Led by new applications of hydraulic fracturing technology and horizontal drilling, development of new sources of shale gas has offset declines in production from conventional gas reservoirs, and has led to major increases in reserves of U.S. natural gas.
Source: Wikipedia — Shale gas in the United States (CC BY-SA 4.0)