Should, within the term of any lease, developments within the field for which the grant was made to the holder of the lease present the opportunity to the holder of the lease to be more effective, efficient and economical through the use of a substance or material other than those for which the lease was originally made, the holder of the lease may petition the Council which, with such requirements or limitations as it deems necessary to protect public health, safety and welfare, may allow the use of such substances under the terms and conditions of the lease.