Patent ID: 7252162
Filing Date: 2007-08-07
Classification: E21B

Abstract:
1. A method of injecting a stream of treatment fluid into an earth formation in the course of drilling a borehole into the earth formation, so as to suppress fluid communication between the borehole and a fracture or a highly permeable region in the earth formation, using an assembly comprising a drill string extending into the borehole, the drill string being provided with at least one sealing means arranged to isolate a selected part of the borehole from the remainder of the borehole, each sealing means being rotatable relative to the drill string and being movable between a radially retracted mode in which the sealing means is radially displaced from the borehole wall and a radially expanded mode in which the sealing means is biased against the borehole wall so as to seal the drill string relative to the borehole wall, the drill string further being provided with a fluid passage for the stream of treatment fluid, the fluid passage having an outlet debouching into the selected part of the borehole, which method comprises the steps of: operating the drill string so as to progress the borehole until a treatment zone in the earth formation is reached, which treatment zone includes the fracture or the highly permeable region, for which treatment is desired; stopping the drilling operation when the treatment zone is arranged adjacent to the part of the borehole which is selected by the arrangement of the sealing means on the drill string; moving the sealing means from the retracted mode to the expanded mode thereof so as to seal the drill string relative to the borehole wall; and pumping the stream of treatment fluid via the fluid passage and the outlet into the selected part of the borehole and from there into the treatment zone, wherein the drill string is rotated during pumping and/or during a curing period of the treatment fluid after pumping.