HOUSTON  Oil prices fell below $90 a barrel on Monday for the first time since February because of the economic slowdown, even though production in the Gulf of Mexico had not fully recovered from hurricane destruction three weeks ago.

The price decline of recent weeks, from a record high for crude oil of $147.27 a barrel during the trading day on July 11, has been breathtaking for energy analysts and traders, some of whom had predicted during the summer that the price would cross the $200 threshold by 2010 or sooner.

Now, amid weakening global demand, prognosticators are talking about prices going down to $70 or even lower.

“The buying frenzy that engulfed the oil market in the beginning of the year is about to go into reverse,” declared Phil Flynn, an analyst at Alaron Trading, in a note to investors on Monday, “and the myths that oil bulls tried to feed us are coming apart at the seams.”