wellhead

The place where a spring breaks out of the ground; the source of water for a stream or well.

• Leaue the troubled streames, And liue as Thriuers doe at the Well head.
• It is a singular circumstance, that within a quarter of a mile of the well-head of the Wye, arises the Severn.

The source of something; a fountainhead.figuratively

• [H]e likened was to a welhed / Of euill words, and wicked ſclaunders by him ſhed.
• [...] a bull was not merely a stud animal worth so much, due to go to the butcher in a little while. It was a vast wonder-beast, a well-head of the great, furnace-like passion that makes the worlds roll and the sun surge up [...]

The surface structure of an oil well etc.