He was known as the “maestro,” the man whose every word was dissected by oil traders and moved markets. For two decades,Saudi Arabia’s oil minister, Ali al-Naimi, was the architect of Saudi economy. Mr. Naimi’s successor, Khalid al-Falih, is a big supporter of the king’s agenda and now will be charged with the complicated task of sharply cutting the state’s persistent dependence on oil. While the symbolism of the moves was clear, energy experts say they expect no quick or easy change in policy. Sharp departures in economic policy have been the exception rather than the rule for the conservative kingdom over many decades. And Mr. Falih wasted little time in trying to calm markets amid fears that already volatile oil prices could quickly become even more volatile. “Saudi Arabia will maintain its stable petroleum policies,” he said in a statement issued on Sunday. “We remain committed to maintaining our role in international energy markets and strengthening our position as the world’s most reliable supplier of energy.”