Petroleum produciton is going to end in the next 20 years??? Gosh!!! I suppose we'd better start re-designing our entire way of life then!!
The oil & gas industry will see me to retirement in 30 years and it will see BabyDriller to retirement too (and he's only 4).... unless there's some incredible new free source of energy about to be patented somewhere.
You might find your career changes from drilling for oil to drilling for gas to driling for gas shale to drilling for Coal Bed Methane; or, the career becomes exclusively international in a National Oil Co, but there's still a lot of oil & gas to be found and produced, and it's going to be needed for some time.
The best advice thought, as the Oil Industry is notoriously boom & bust is 1) make sure you have a permanaent house soemwhere, even if you haven't leved there for years and 2) make sure you always have 3 months salary saved up in the bank... 6 months if you think you might need longer to get the next job.