A properly executed oil and gas lease is a valid transfer of oil and gas property from one owner to another. Unless there are specific provisions in the lease which establish conditions for termination, the lease continues to be valid so long as the operator complies with all of their lease obligations.
Landowners who believe that an existing oil or gas lease is no longer valid should always seek the advice of an experienced attorney.
Indiana law governing oil and gas leases can be viewed at: http://www.in.gov/legislative/ic/code/title32/ar23/ch7.html
Indiana law regarding lapse of mineral interests can be viewed at: http://www.in.gov/legislative/ic/code/title32/ar23/ch10.html