A spokesperson confirmed that Mitchell passed away on Friday in Galveston, Texas.
No further details were immediately available, but the spokesperson said they would be forthcoming.
The legendary Texas oilman, formerly the head of Mitchell Energy, defied doubters by applying a combination of horizontal drilling and high-volume slickwater fracturing to the Barnett, turning the field outside Fort Worth into one of the biggest gas plays in the US.
The technology he pioneered in the 1990s over 10 years of experimentation has turned the the US into an onshore oil-and-gas producing behemoth.