Here is a pic taken near Trees City, Louisiana.  It shows several old metal derricks through the undergrowth.  These derricks were built specifically to drill one and only one well.  They were left standing over the well after it was completed and used for any subsequent remedial work (parted rods, repair downhole pump, etc) that needed to be done.  Such structures are still commonly seen in northwest Louisiana, but they are no longer used to drill a well.

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