Mexico City — A nine-month oil well blowout that gushed more than 3 million barrels of oil into Gulf of Mexico waters has been capped successfully, the Mexican state oil monopoly Pemex announced Monday. A company spokesman said the well, in the Bay of Campeche, was sealed just before midnight Sunday. The Ixtoc 1 well, 10,000 feet below the seabed, blew out of control last June 3, fouling Texas and surrounding Mexican beaches. For six weeks after the accident Ixtoc spewed oil at a rate of 30,000 barrels a day. The flow rate subsequently was reduced by stuffing the wellhead with steel balls and cement.