This is an incredible story of the first "Sanish" well in North Dakota. It was drilled in 1953 and considered the first "Bakken zone" discovery. It produced 279,000 barrels in six years before "casing problems forced the plugging of this well" according to "Allen" at this discussion group. A replacement well, another vertical well, near the original well is still producing; to date this 160-acre spacing unit has produced a total of 1.3 million barrels of oil. The well came in at 150 barrels/day.
In case that link is broken, or that site is lost, the well in question that produced for six years was the Woodrow Starr #1. It's "replacement, still active, is the Woodrow Starr 1A.
An article published in 1969 provides additional detail.
Short history of the Bakken, by Julie LeFever, undated but appears to have published in September, 2004.