The present invention relates to a tubular oil separator providing separation of respective fluid components mixed in fluids from oil wells, wherein the tubular oil separator A is arranged to mitigate problems related to turbulence and possible non-Newtonian fluid behaviors of fluid components mixed in the fluids from the oil wells in the oil separator. The invention further relates to a method of operating a separator. Moreover the invention relates to a system of multiple separators. Inventive aspects of the separator comprises an elongated outer, closed tubular section and an elongated, inner tubular section, which is closed in one end and open in another end, —where the inner tubular section is arranged inside the outer tubular section, —and where oil well substances are introduced into the open end of the inner tubular section via a tube feed section passing through the outer tubular section and into the inner tubular section, —and where the inner tubular section comprises multiple, elongated and p
