Drilling Mud

Drilling mud is the liquid that circulates from top to bottom inside drill pipes and back from bottom to top in the space between the wellbore and the drill string (known as the annulus) when oil wells are drilled. The drilling mud: lifts the cuttings to the surface, ensures borehole stability by containing formation pressures thanks to its density, protects reservoir formations from drilling fluid invasion by building a mud cake, and helps break apart rock as it is expelled from the drill bit at high pressure.