7000psi mud pressures at 4.5km..., page-9

Hi guys

I don't know much about drilling but I understand hydraulics and pressure.

First thing to create pressure,you need a restriction.No restriction,no pressure.The restriction in this case is the drilling mud traverling down the centre? of the drill string and arriving at cutting head against the rock.

Once the mud has pass the cutting head and carried away the drilling chips then the pressure falls "away"

Therefore, the 7000psi mud pressure is not acting on the well wall,only at the drill tip

I may well be wrong here,cause I do not understand how the drilliing mud works.