The detailed environmental studies and assessments that have been conducted on the exploration program and the comprehensive land-use studies carried out in response to sections 6505(b) and (c) of this title shall be deemed to have fulfilled the requirements of section 102(2)(c) of the National Environmental Policy Act (Public Law 91–190) [
42 U.S.C.
4332
(2)(C)], with regard to the first two oil and gas lease sales in the National Petroleum Reserve-Alaska: Provided, That not more than a total of 2,000,000 acres may be leased in these two sales: Provided further, That any exploration or production undertaken pursuant to this section shall be in accordance with section
6504
(a) of this title.