It has been predicted that oil reserves will only last for 40-50 years. It is now more than 50 years since the first oil was discovered and oil & gas production is still rising. What has not been included in the prediction was the invention of new technology to discover new oil reserves and the methodology to extract it. A good example is fracking. It was not in the picture then when the prediction was said.
Definitely, oil reserves is not infinite. There will still be a little bit to squeeze out of the reserves but it will be more difficult and more expensive.
I kept asking myself, than when people knew that oil reserves will run out, why were there no more emphasis on discovering other energy sources than in hydrocarbon? Of course, there is nuclear and renewable energy. For nuclear energy, due to the issue of nuclear being used in purposes other than energy production, there has been resistance in developing it further. For renewable energy sources, only a few like hydro and geothermal can actually support based loads continuously. Wind and solar are not available at their full capacity 24 hours a day.
The inefficiency of oil & gas production is affecting the wages of workers in the industry. With oil prices going down and and higher production cost, the first move to cut cost is reduction of wages. Worse, job cuts.