Above it the Q4000 rig and three attendant vessels have 50, 000 barrels of peculiarly heavy drilling mud and pumps capable of providing 30, 000 horsepower with which to muscle that mud into the well.
At that point the fluid-dynamics equivalent of a titanic arm-wrestling match will get under way, with the surface vessels' pumps trying to push the mud down the well while the rising oil tries to push it out.