The largest oil field on the planet is the Gahwar field in Saudi Arabia.   There about 50 "giant" fields in the world.  Two in the continental U.S.  East Texas, discovered in the 1910's and North Slope in 1964.  In my experience regulation  of the industry was strict in California.  Bizarre sometimes in states that had no previous oil production.  Lax in Oklahoma until the `70's.   Offshore was regulated by the Coast Guard until about then afterwards the Mineral Management Services Department was created and jurisdiction transferred to the Department of Energy.  Now over seen by Rick Perry.  Oh, in Texas the industry has long been regulated by the Railroad Commission.  My favorite was Plaquarmine Parish, on the west bank of the Mississippi as you crossed the river from New Orleans.  Can drive south about 80 miles with the river on your left and mud flats (of Gulf) on you right.  Parish commissioner got rich from 5 cent transport tax (per barrel) on pipelines across parish.