2.
adj. [Drilling]
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.