hydraulic fracturing began as an experiment in 1947, and the first commercially successful application followed in 1950. as of 2012, 2.5 million "frac jobs" had been performed worldwide on oil and gas wells; over one million of those within the u.s. such treatment is generally necessary to achieve adequate flow rates in shale gas, tight gas, tight oil, and coal seam gas wells. some hydraulic fractures can form naturally in certain veins or dikes.