Every oil and gas lease, including leases of tide and submerged lands, executed under this chapter, shall specify a period of not to exceed three (3) years, as specified by the commission in the invitation for bids, subject to extension by the commission as provided in this chapter, as the drilling term of the lease within which the lessee may commence operations for the drilling of a well for oil or gas, and, providing that, if lessee fails to commence such operations and to thereafter diligently prosecute them, the lease shall terminate.