Historically, in the USA, some oil fields existed where the oil rose naturally to the surface, but most of these fields have long since been used up, except in certain pnope wovfehe same reservoir, to ensure that the extraction rate will be economically viable.
Historically some oil fields existed. This was in the USA. The oil rose naturally to the surface. Most of these fields have long since been used up to ensure that the extraction rate will be economically viable. This was except in certain pnope wovfehe same reservoir.