It's "not unreasonable" to expect oil prices at $60 a barrel by the end of the decade, Royal Dutch Shell CEO Ben van Beurden told CNBC's "Managing Asia."

To be sure, that's not a large rise from current levels.

Brent crude rose 0.38 percent to trade at $58.66 a barrel in Wednesday Asia trade, after hitting a 26-month high on Tuesday, while U.S. crude was higher by 0.5 percent at $52.14 at 12:00 p.m. HK/SIN.

Van Beurden said forecasting oil prices in the short term was "very difficult," but he still expected gains.

"I do think oil prices are going to go up over time as a result of the tightening of the market," he said. "It's not unreasonable to expect that if you want to make financial projections going out in the future, you want to make projections around $60 oil by the end of the decade."

He noted that growth in oil demand has been fairly consistent, increasing approximately 1.6 million to 1.7 million barrels a day, with the exception of outlier years affected by events such as the financial crisis.

Supply in the oil markets, however, was a considerably more complicated picture, he explained.

"It's a mix of OPEC, it's shales, it's large complex projects and they each have their own dynamic in terms of response time to prices ... And on top of it, there's a lot of sentiment that is feeding the markets," van Beurden said.

But the slim gains in oil prices didn't appear likely to have an out-sized impact on the company's performance.

Royal Dutch Shell expects to have a "significant, higher amount" of free cash flow with oil at $60 a barrel than when it was at $90 years ago, van Beurden said.

"Nobody can predict how it's going to play out," he said, adding that those in the commodity business needed to be prepared for downturns.

"Therefore, our mindset needs to be building resilience. And you do it with a 'lower forever' mindset," he said.

By ensuring that projects had the lowest possible break-even price, the company would be able to survive even if oil prices came down further, van Beurden said.

"If you have a strategy that is predicated on really trying to understand what the future of the oil price is going to be, and then betting on it, I think you're basically betting the company. So you should never have that as a philosophy," he explained.

Oil prices spiked early this week after Turkish President Recep Tayyip Erdogan warned about cutting off a pipeline carrying oil from the semiautonomous Kurdish region in Iraq to Turkey. The threat came after Kurds voted in an independence referendum which was opposed by several countries, including the U.S. and Turkey, Reuters reported.