On the oil drillings, the technician fluids flushings (or muddy ) is the person who supervises and adjusts the parameters of the mud of the well to guarantee an effective work of the tools and a good safety of the well.

To go up the " cuttings" (cuts of drillings), to maintain the well opened, and to protect themselves from the increase of gas or various fluids (water, oil…) mud is injected by the circulating head in top of the axis of the drill rod made up of tubes and is recovered from the annular zone between the well and the train of stems. Mud is stored in basins. These basins must have a level varying only volume corresponding to the deepening of the hole, or the addition or removal of elements of drill rod in the well. If their level varies in another manner, that can be the sign of the loss of mud in the ground, or the presence of gas pushing back mud. In these cases, the muddy one must make readjustments of the composition of mud. To schematize, a reduction in the Densité of mud is obtained by adding water, and an increase, by adding Baryte.