Shale fields could add 7,299 trillion cubic feet of natural gas and 345 billion barrels of oil to global reserves, according to a US Energy Information Administration report released Monday.
These potential contributions represent a 47% increase in gas reserves and an 11% increase in oil reserves.
Basins of shale oil and gas around the world:
The United States ranked second globally in terms of "technically recoverable shale oil resources" and fourth in terms of "technically recoverable shale gas resources."
Shale has already transformed the US energy market, and the EIA report attempts now to "quantify the potential global significance of the shale boom."
The report explicitly mentions its own shortcomings, suggesting that the estimates are "highly uncertain and will remain so until they are extensively tested with production wells." Economic viability is not assessed in the report.
Development of shale requires use of the controversial drilling technique of hydraulic fracturing or 'fracking,' which is still banned in some countries including France and Bulgaria.
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Sources: US EIA; Phys.org; The BBC