Production has resumed at the Pateke-3H well, in the offshore Taranaki Basin.
Pateke is one of four producing wells at the Tui area oil fields. It was shut in late June because of problems with its artificial lift system.
Initial attempts to restart it were hampered by technical problems.
New Zealand Oil & Gas owns 12.5% of the well, with AWE, Mitsui E & P and Pan Pacific Petroleum the other venture partners.