Patent ID: 7231975
Filing Date: 2007-06-19
Classification: E21B

Abstract:
1. A method of stabilising a zone of interest of a borehole surrounding a formation, comprising: (i) forming a region of the borehole having enlarged diameter in the zone of interest when compared to the adjacent zone above; (ii) positioning a drillable liner in the borehole extending across the zone of interest and into the adjacent zone above, said drillable liner forming an annulus between the outside of the liner and the borehole in the zone of interest, the drillable liner having a drill pipe connected with a setting tool, wherein the drill pipe: extends therethrough to a lower portion, is connected to a float shoe at the lower portion which has side ports for communication with the annulus and cross webs to engage in the formation at the lower portion, and is connected to a cement supply at the surface; (iii) pumping cement from the surface inside the drill pipe so as to exit the drillable liner at the lower portion and flow upwards to fill the annulus and to extend into the adjacent zone above; (iv) withdrawing the drill pipe from the drillable liner; and (v) drilling through the cement and drillable liner in the zone of interest after the cement has set to form a borehole of substantially similar diameter to that of the adjacent zone above.