Even if you drill in Alaska it will not change the amount of oil imported, lowest shipping cost is the shortest point from supply to market. There are several oil shipping charts on the web.
Oil is a fungible commodity.
An increase in global supply brings a decrease in price.
Drilling in Alaska, and offshore California, and offshore Louisiana, puts royalties and tax money into American tax bases. It pays wages to American workers, pays profits to American contractors and investors, instead of paying taxes and royalties to some other country’s treasury and putting some other country’s people to work.