There could by a shortage of oil supply by 2020 if investment flows continue at their current rate, Saudi Arabia's energy minister Khalid A. Al-Falih has warned.
Al-Falih told CNBC that prices today are "comfortable" but he worries about future investment.
"I believe if the investment flows that we have seen the last two or three years continue in the next two or three years, we will have a shortage of oil supply by 2020.
"We know, from what we have seen in the last couple of years, that prices around the current level and below are not attracting enough investment. We know the level of decline, natural decline, that existing production is undergoing, and we know that demand is picking up at, you know, 1.2 to 1.5 million barrels a year.
"So between increase in demand and natural decline, we need millions of barrels every year to be brought to the market, which requires massive investment."