President Clinton will send Jesse Jackson to Nigeria this week to try to stop a civil war from erupting in the country as a three-week-old strike by oil workers continues. The workers walked off the job after Mashood K.O. Abiola, the democratically elected President who was removed in a coup last year, was placed under arrest by the country's military government. The strike has paralyzed transportation and industry and has increased fears that an all-out armed confrontation may develop between the military and supporters of Abiola. Given Nigeria's population of 88.5 million, major civil strife could cause another wave of refugees that would dwarf the exodus from Rwanda, which had a population of 8.2 million.