re: Just bought 40 acres

As long as your land is included in the unit and the well is producing, the 10 year clock is stopped. Once the well ceases production, the 10 year clock starts. If another well is drilled within 10 years, the clock stops and is reset again.

A unit is when all or part of your land is combined with surrounding lands into one "pool" and a well is drilled to produce the minerals. Generally, the land pooled into a unit is all in the same section, but that's not always necessarily true. If you know what section-township-range your property is in, I can check the production around your property and see what might be going on.