No, you may not but other do.
Start here.
http://www.eia.gov/energyexplained/index.cfm?page=oil_home
If the East Texas field was found by accident
The East Texas oil field is a stratigraphic trap in the Eagle Ford-Woodbine group of the Cretaceous sedimentary layer. Because of the known geology in the area they continued to search that area for years even after the first attempts did not find oil.
Except they weren’t searching. The facts you relate are ex post facto. Meaning: if you know you have stumped your toe after you stump your toe. . None of the Shell geologists had a clue of what they were dealing with until the independents started poking hole sin the ground. Ironically, they knew more about the deep formations they are now exploring than that did the sands in which oil was. Had been drilling in the La fields of course and the East Texas field lay to the west off the map. Anyway, a better place to look at is the appalachian fields, with their proximity to other “fossil” deposits. The deeper these fields get, the more one wonders how the deposits got there.