(a) Any lease or portion of a lease committed to an oil and gas agreement that contains a general provision for allocation of oil or gas will continue in effect so long as the lease or portion thereof remains subject to the agreement; provided, that there is production of oil or gas in paying quantities under the agreement prior to the expiration date of such lease.

(b) A well that is drilled and completed on a lease committed to a unit agreement, and that is capable of production in paying quantities on a lease basis, will extend the term of all expiring Federal leases committed to the unit agreement for the term of the unit agreement and so long as the well is capable of production in paying quantities.