wildcat well vs oiler

wildcat well and oiler both are nouns.

Word	Noun	Adjective	Verb	Adverb
wildcat well	Yes	No	No	No
oiler	Yes	No	No	No

As nouns, oiler is a hypernym of wildcat well; that is, oiler is a word with a broader meaning than wildcat well:

wildcat well: an exploratory oil well drilled in land not known to be an oil field
oiler: a well that yields or has yielded oil

Other hypernyms of wildcat well include oil well.

wildcat well (noun)	oiler (noun)
an exploratory oil well drilled in land not known to be an oil field	a cargo ship designed to carry crude oil in bulk
	a well that yields or has yielded oil
	a worker who oils engines or machinery