Patent ID: 7243743

Claim:
A drilling assembly for drilling a borehole into geological formations, said drilling assembly comprising: a drilling shaft placable in the borehole, which shaft comprises a drilling head; a pump device placable in the borehole, wherein the pump device comprises primary sealing means for sealing a first borehole part below the primary sealing means from a second borehole part above the primary sealing means, and wherein the pump device is enabled to pump a fluid from the first borehole part to the second borehole part; a substantially tube shaped casing placable in the borehole, said casing comprising near one end of the casing a secondary sealing means for closing said one end of the casing whereby the first borehole part is divided into lower and upper sections, which secondary sealing means is capable of keeping the pressure in the lower section lower than the pressure in the upper section.