Abstract: A method and system for introducing a fluid into a borehole, in which there is arranged a tubular drill string including a drill bit, wherein the drill bit is provided with a passageway between the interior of the drill string and the borehole, and with a removable closure element for selectively closing the passageway in a closing position, and wherein there is further provided a fluid injection tool comprising a tool inlet and a tool outlet, the method comprising passing the fluid injection tool through the drill string to the closure element, and using it to remove the closure element from the closing position, passing the fluid injection tool outlet through the passageway, and introducing the fluid into the borehole from the interior of the drill string through fluid injection tool into the borehole.

Abstract: A rotary drill bit assembly suitable for directionally drilling a borehole into an underground formation, the drill bit assembly having a bit body extending along a central longitudinal bit-body axis, and having a bit-body face at its front end, wherein an annular portion of the bit-body face is provided with one or more chip-making elements; a pilot bit extending along a central longitudinal pilot-bit axis, the pilot bit being partly arranged within the bit body and projecting out of the central portion of the bit-body face, the pilot bit having a pilot-bit face provided with one or more chip-making elements at its front end; a joint means arranged to pivotably connect the pilot bit to the bit body so that the bit-body axis and the pilot-bit axis can form a variable diversion angle; and a steering means arranged to pivot the pilot bit in order to steer the direction of drilling.

Abstract: A method and system for introducing a fluid into a borehole, in which there is arranged a tubular drill string including a drill bit, wherein the drill bit is provided with a passageway between the interior of the drill string and the borehole, and with a removable closure element for selectively closing the passageway in a closing position, and wherein there is further provided a fluid injection tool comprising a tool inlet and a tool outlet, the method comprising passing the fluid injection tool through the drill string to the closure element, and using it to remove the closure element from the closing position; passing the fluid injection tool outlet through the passageway, and introducing the fluid into the borehole from the interior of the drill string through fluid injection tool into the borehole.

Abstract: A rotary drill bit assembly suitable for directionally drilling a borehole into an underground formation, the drill bit assembly having a bit body extending along a central longitudinal bit-body axis, and having a bit-body face at its front end, wherein an annular portion of the bit-body face is provided with one or more chip-making elements; a pilot bit extending along a central longitudinal pilot-bit axis, the pilot bit being partly arranged within the bit body and projecting out of the central portion of the bit-body face, the pilot bit having a pilot-bit face provided with one or more chip-making elements at its front end; a joint means arranged to pivotably connect the pilot bit to the bit body so that the bit-body axis and the pilot-bit axis can form a variable diversion angle; and a steering means arranged to pivot the pilot bit in order to steer the direction of drilling.