winze; well
Technical term used in mining for a winze (a vertical or inclined underground passage) and in oil/gas contexts for a well. Not a general-purpose word for 'well'.
Drilling a well requires advanced technology.
Many old winzes remain in this mine.
Compound of 坑 (mine shaft, pit) and 井 (well). The exact historical derivation is uncertain, but the kanji combination directly reflects the technical meanings.