Modern
hydraulic fracturing technology was developed starting in the 1980s by
George P. Mitchell, who developed the technology for use in shale formations. Starting around the mid to late 2000s the technology began being adopted by energy companies in the United States, leading to a surge of petroleum and natural gas production.
Shale gas and
shale petroleum reserves exist in other countries as well.
The economics of shale petroleum is such that it would not be feasible prior to 1973 under historical conditions. Adjusted for inflation, the break-even price of $35 per barrel of petroleum that shale needs to break-even didn't occur until the 1980s, and even then only became nearly constant starting in the late 1990s.
Shale gas could probably have a compelling economic case in many nations, as pipelines and especially liquefied natural gas terminals are expensive and complicated to build.
I'm wondering if the technology could have been adopted earlier, perhaps as a way of increasing production if the energy crises had not occurred. If that were the case, could shale petroleum and gas act as a cap of sorts on energy prices, leading to a permanent situation of inexpensive fossil fuels, at least by modern standards? 1960s/1970s prices were in the $20 per barrel range when adjusted for inflation, but $35 is fairly low relative to the prices that have prevailed since 1973.