The crippled undersea well has not spewed oil since July 15, when it was sealed with a temporary cap. In the coming days, BP will intersect the original well deep underground with a relief well, injecting mud and concrete to ensure the well is dead. Retired Coast Guard Adm. Thad Allen, the federal spill response chief, said Saturday he was ordering BP to conduct more tests and offer more-detailed plans for dealing with potential complications before giving the go-ahead to complete the relief well.