Oil fields do not quite work that way. An oil well is not like a fuel tank that can be drained freely at will
Obviously, as smaller fields become depleted, more pressure will be put on the remining ones.
But there are technical limits on how much and how quickly oil can be extracted.
Historically, most oil fields were considered commercially exhausted at a point where around 2/3 of the oil in the ground was still there (This figure has improved in recent years, with developments in drilling etc but not by a huge amount) More can be extracted but it rapidly becomes very expensive. Not only in cash terms, but also in terms of EROI (Energy return on investment)
There may well come a time, and possibly fairly soon (Relatively speaking) when oil is no longer used primarily as an energy source, but there will still be both demand and production as a feedstock for making the other things that we make from oil. And there is sufficient oil in the ground to meet that demand for centuries if not millennia to come.