43 CFR §3137.112

1. (a)If you demonstrate to BLM that reasons beyond your control prevent you, despite reasonable diligence, from starting actual or constructive drilling, reworking, or completing operations, BLM will extend all committed NPR-A leases as if you were performing constructive or actual drilling or reworking operations. You are limited to two extensions under this section.
2. (b)You must resume actual or constructive drilling or reworking operations when conditions permit. If you do not resume operations—
   1. (1)BLM will cancel the extension; and
   2. (2)The unit terminates (see § 3137.131 of this subpart).