A turning point in the oil market is on the horizon amid a sharp drop in investments and a lack of fresh conventional discoveries, Saudi Aramco's chief executive said on Monday. "A lack of investment is definitely not helping, so if that continues over the next couple of years there will be an inflection point," Amin Nasser said on the sidelines of the World Petroleum Congress in Istanbul.

Oil market watchers are constantly fretting over the balancing of supply and demand. Many have focused on the supply dynamics since oil's drop in mid-2014, as U.S. shale has compounded a global glut of the commodity. But, Nasser believes this could change in the coming years and people could start worrying about whether there is enough oil to meet demand.

About $1 trillion in investments have already been lost since a decline in oil prices from 2014, Nasser said in a speech early on Monday. He explained that while unconventional oil and gas investments had been positive for the industry, they alone would not be sufficient over the long term to meet needed demand.

Earlier in the day, the CEO of Saudi Aramco - the state-owned oil company of the Kingdom of Saudi Arabia - told a conference that 20 million barrels per day of new production would be required in order to meet demand growth and offset a national decline of developed fields. Since the start of 2017, oil prices have slipped over 17 percent to less than $50 a barrel.

When asked whether Saudi Aramco could be poised to delay its initial public offering (IPO) given investor concerns over both its price and timing, Nasser stressed the company's investment plans would be "geared towards the long term." He added the state oil giant remained on track to sell around 5 percent of its business in an initial public offering next year.