All oil and gas leases issued by the commissioner of public lands prior to the effective date of this act [section] are declared to be valid and existing contracts with the state according to their terms and provisions where:

A. made in substantial conformity with law; B. the terms have not expired;

C. all rentals have been paid and accepted by the commissioner of public lands;

and D. the leases have not been canceled by the commissioner of public lands for nonperformance by the lessee or any assignee.

The obligations of the state and the commissioner to observe and conform to the terms and provisions of these leases are recognized.