Shell says it is having to react ever more quickly to crises as it models its "scenarios" responses to world political and economic events.

Addressing delegates at this week's Shell Energy and Technology Forum near Paris, Shell fuels strategy adviser, Jean Cadu, outlined how the oil producer attempts to predict future outcomes, although the volatility of such large scale events such as the so-called Arab Spring, make forecasting not an exact science.

"We have a team of people looking beyond 15 years - many of the investments Shell makes have a very long lead time," said Cadu. "It takes a long, long time to convince government, city, region, whatever, to let Shell dig holes and produce oil. Normal time span is ten years, beyond, it is a big challenge.

"Scenarios is a mental construction of a possible future, but it is not what the future will be, it is a sort of caricature of what the future will be. Shell started this scenario approach 40 years ago, it is not something we started yesterday.

"We had one big crisis every decade in the past. Now, at less than ten-year intervals, these crises are coming and coming. Things we have not imagined in the past have happened. The stress it puts on the guys who design scenarios is it puts social and economic pressure. The social elements are becoming more and more important."

Cadu highlighted challenges such as increasing migration from rural areas to cities - particularly in China - bringing congestion and energy supply issues to the fore.

However, new resources were being found even in mature regions such as Europe, that were not envisaged a decade ago, while gas for example is taking a larger proportion of energy.

"The amount of energy required by the world in 2050 is truly amazing," said Cadu, who added Shell was continuing to mull the establishment of a gas-to-liquid facility in the US to add to its two existing plants in Malaysia and Qatar.

"Most of that [demand] is being driven by China and emerging countries. Rural migration into cities is of paramount importance, cities will be congested."

Cadu's energy resourcing theme was echoed by Shell France president and general manager lubricants Europe, Patrick Romeo, at the conference.

"Energy is life," he said. "It is a real challenge in the 21st century to deliver energy for 9bn people in the world and at the same time having to face challenges such as global warming.

"Shell is spending money to make sure there is enough energy tomorrow. Being innovative means investing a lot of time in new ideas, in R&D, take industrial risks and invest in units such as Pearl GTL in Qatar."