The Board of Educational Lands and Funds shall require lessees of such oil and gas leases, and assigns thereof, to furnish bonds to the state in such form and substance as may be prescribed by the board, and in amounts adequate to indemnify the state against loss, damage or detriment by reason of the failure of the lessee to fully discharge the obligations contained in the lease, or assignment thereof; Provided, that a blanket bond may be accepted by the board to cover more than one lease issued to the same lessee.