So many interesting solutions for this problem.

In Alberta, it was common for a major oil company to sell a marginal oilfield to a penny-stock operator. The major oil company would assign its liabality to the new owner as conditon of the sale. The new owner would run the field for a few years. Then declare bankruptcy. The major company doesn't pay for the abandonment. There's orphaned wells all over the place. Rumors were that many of these fields were sold for $1.

In my town, a gas operator abandoned a well drilled in the 1920s that was within a residential area. They got the service rig on the hole---and found the wellhead went back to the days when oilfield fittings were not standardized. The local machine shop got same extra business. Residents were told a service rig would be operating only two days. But it turned into 10.