Delays could mean French oil giant Total SA's (TOT) capital expenditure will fall short of $18 billion this year, Chief Executive Christophe de Margerie said Thursday.

While Total is maintaining a capex program of $18 billion for 2009, de Margerie said he doesn't know if the company will spend the full amount, adding that there might be delays.

"It's a huge amount $18 billion," de Margerie said, adding: "Will it be this at the end of the year? I don't know."

"I have a feeling that, for different reasons, there might be delays," he said, without elaborating.

De Margerie also reiterated that more expensive oil projects, such as extra-heavy crude, will "definitely need higher prices" than the current level. A price of $75 to $80 a barrel might be the right level, he said.

De Margerie spoke at an oil conference in Paris.

Total's CEO also emphasized the need to keep investing in research and development. R&D "cannot be cut in this time of crisis," he told delegates.

He went on to speak about renewable energy.

"Yes there is a future for solar," de Margerie said, emphasizing the need to invest in research to make it viable without subsidies. He added he doesn't expect "major progress" in that regard until around 2020.

-By Adam Mitchell, Dow Jones Newswires; +33 1 40171756; adam.mitchell@dowjones.com