Patent attributes
A method for stabilising an unconsolidated zone (18) of a borehole, by forming a region of the borehole having enlarged diameter (22) in the unconsolidated zone; positioning a fluid-filled casing (26) in the borehole the liner having a pipe (28) extending therethrough into a lower portion; pumping cement from the surface inside the pipe so as to exit the liner at the lower portion and flow upwards to fill the annulus (44) formed between the outside of the liner and the borehole in the unconsolidated zone; withdrawing the pipe (28) from the casing while pumping fluid therethrough so as to maintain the liner substantially fluid-filled and to displace cement above the liner in the adjacent region; drilling through the cement and liner in the unconsolidated zone after the cement has set.
