A complete trip from the bottom of the wellbore to the top
Pertaining to the mud and cuttings that are calculated or measured to come from the bottom of the hole since the start of circulation.
Circulation may be initiated after a static period, such as a trip, or from a given depth while drilling.
This latter type is particularly useful to mud loggers and others trying to discern the lithology being drilled, so mud loggers or mud engineers often retrieve what is referred to as a “bottoms-up sample” of the cuttings or the drilling fluid.
The sample obtained at the bottoms-up time or a volume of fluid to pump, as in “pump bottoms-up before drilling ahead.”