| 摘要 |
A drilling system (10) comprising a drive shaft (32) having a fluid flow conduit (34) extending therethrough; a drill bit (36) mounted for rotation by the drive shaft and having a bit face (40) which, in use, contacts a formation to be drilled, and including a fluid flow passage (42) with an outlet (44) near the centre of the bit face, a first fluid flow line (48) extending from the outside of the drive shaft to the flow passage in the drill bit; and a second fluid flow line (54) extending from the outside of the drive shaft to the flow conduit. A method of drilling a well using such a system comprise positioning the system in a borehole; rotating the drive shaft to rotate the bit; urging the bit against the formation to be drilled; and pumping drilling fluid down the borehole so as to pass though the first flow line and to exit the fluid flow passage in the drill bit via the outlet, flow over the bit face and pass into the fluid low conduit via the second fluid flow line. |
