Prince Abdulaziz "already told the press the OPEC+ production cuts are likely to continue and this affirmation helped firm up the market" into Monday trading.
Al-Falih, who'd taken over the energy portfolio from longtime oil minister Ali al-Naimi, was tasked with playing a key role in Prince Mohammed's economic overhaul of the country.
The understudy is now playing the lead.
Prince Abdulaziz bin Salman's appointment to energy minister, which broke House of Saud tradition of having someone outside the royal family in charge of the oil industry, further consolidates power around Crown Prince Mohammed bin Salman as he attempts to ramp up his Vision 2030 plan.
In March, Reuters reported the U.S. has already approved the sale of nuclear power technology to the Saudi kingdom.
While Baghdad has argued that it needs higher oil production to get more oil revenues-which account for 90 percent of its government proceeds- to rebuild a country damaged by decades of wars, OPEC's second-biggest oil producer has been putting a spoke in the cartel's wheel to have all members fully compliant with the cuts. After studying management at King Fahd University in Dhahran, he first became an adviser in the energy ministry in the late 1980s. "He attended more OPEC meetings than any current OPEC official".
"One of the primary listings is going to be local but we are also ready for listing outside", Nasser said on the sidelines of the World Energy Congress in Abu Dhabi.
The change in leadership may offer a "signal that we could see a possible shift in strategy at the September 12th OPEC+ strategy meeting in Abu Dhabi", said Edward Moya, senior market analyst at Oanda, in an email update.
Al-Falih's biggest achievement of his three-year term was managing OPEC's agreement with Russian Federation, which saw the world's No. 2 exporter agree to formal curbs on production for the first time as the global oil market adjusted to a flood of American shale oil.
A few days later, Iraq's Oil Minister Thamer Ghadhban said on Sunday that Iraq would be cutting its oil production starting in October and will stick to the OPEC production cuts.
Raghu said that "without a favourable resolution to the dispute, OPEC's production cuts will not result in a sizeable uptick of oil prices".
Last week, Falih was replaced as chair of Saudi Aramco just as efforts are being stepped up to prepare the state oil company for an initial public offering.
Even with more time to focus on the oil market, Prince Abdulaziz will confront the same tough challenges as Al-Falih.
Still, that's considerably below the $80-$85 a barrel that analysts say is needed to balance Saudi Arabia's budget.
Oil futures hit a six-week high on Tuesday, rising for a fifth day on optimism that OPEC and other countries may agree to extend production cuts in a bid to support prices. Now the trade war is putting pressure on demand, prompting analysts to ask whether further output cuts will be necessary next year.
His relationship with the crown prince will be critical. They come from different generations - MbS is more than 20 years younger and Prince Abdulaziz had never been seen as part of his inner circle.
While Prince Mohammed's programme is ultimately created to wean Saudi Arabia's economy off its addiction to oil, in the short term he needs a higher oil price to finance his plans. In that role, he oversaw a breakthrough in talks with fellow OPEC member Kuwait to resume output in the neutral zone between the two countries after a four-year halt.
He declined to comment on oil prices. A challenging oil market may test ties between between the two princes.