79,000,000 BO
This is the Huasteca Oil Company, Cerro Azul No. 4 well, now a monument maintained by the village of Cerro Azul and Pemex, along the east coast of Mexico, west of Tuxpam. The well head and surrounding park acts as sort of a tombstone to a great well and an important era in Mexico's history. I prefer to think of it as a monument to hope.
This well was drilled in late 1915 and when it blew out in February of 1916 its estimated flow rates exceeded 260,000 BOPD. It stopped producing in commercial quantities sometime in the mid 1990's. Its cumulative production is believed to be in the neighborhood of 79,000,000 barrels of oil.
The Cerro Azul 4 is often touted as the biggest, most productive oil well in world history. If you'd like to know more about this monster, please read Oily Stuff's description of it, here.
Was it actually the most "productive" well in Mexico, or, for that matter, in the entire world?
Nah.
Stay tuned, please.