SAN FRANCISCO (MarketWatch) -- Oil futuresrallied on Friday, tacking on 2.5% for the week, after briefly topping $100 a barrel shortly before of the close of trading on the New York Mercantile Exchange. Prices found support from a rally in U.S. equities and as heating oil and gasoline prices climbed on the back of strong demand expectations and worries fo tight supplies. March crude rose $2.04, or 2.1%, for the session to settle at $99.88 a barrel on Nymex - the highest close of this year. March natural gas fell 16 cents, or 3.2%, to settle at $4.775 per million British thermal unit, extending its losses after Thursday's report showing a smaller-than-expected U.S. supply decline. Prices fell 3.4% for the week.