Royal Dutch Shell sees deep-water oil drilling continuing in the future and as of next year will produce more gas than oil, its chief executive was quoted as saying by a Swiss newspaper on Sunday.

Asked how high the price of oil needed to be for Shell to profit from its investment of $30 billion in 2011, Peter Voser said: If the price of oil is between $50 and $90 a barrel, the investment's are worth it.

Following the rig explosion and oil spill in the Gulf of Mexico last year that prompted calls for a cessation of deepwater oil drilling, Shell has received permission to drill in the region and has been there since April.

You can like it or not: Deep-water drilling will be part of extracting oil in the future, Voser said in an interview with the NZZ am Sonntag.

Voser said if Shell's total reserves, including those it was not yet working with, were taken into account it had enough for the next 50 or 60 years.

This figure may rather rise than fall, he said. A big part of these reserves is natural gas.

(Reporting by Catherine Bosley; Editing by Dan Lalor)