A pairie oil well.
oil well definition by Webster's New World
Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio. Used by arrangement with John Wiley & Sons, Inc.
a well that supplies petroleum either naturally or by means of a pumping system
oil well definition by American Heritage Dictionary
A hole drilled or dug in the earth from which petroleum flows or is pumped. Also called oiler.