Abstract: This invention relates to a steerable drill bit arrangement, in particular for the use in drilling boreholes for oil and gas extraction. According to the invention there is provided a steerable drill bit arrangement comprising a drill bit, a steering component and a stabilizer, the steering component being adapted to provide a steering force which in use can drive the drill bit along a non-linear path, the stabilizer being located between the drill bit and the steering component and in use providing a fulcrum for the steering force provided by the steering component, the position of the fulcrum provided by the stabilizer being adjustable relative to the drill bit and the steering component. In use, the position of the fulcrum can be adjusted to vary the maximum curvature of the borehole and to suit the rock type(s) being drilled.

Abstract: This invention relates to a downhole assembly and to a cutter assembly, and in particular to a downhole assembly including an apparatus for breaking up large-scale material which is present behind a drill bit, and to a cutter assembly for use in such a downhole assembly. The downhole assembly is suitably for use in a drillstring, the downhole assembly comprising a drill bit, a sensitive component, and at least one rotatable set of cutter blades located between the drill bit and the sensitive component.

Abstract: This invention relates to a downhole assembly and to a cutter assembly, and in particular to a downhole assembly including an apparatus for breaking up large-scale material which is present behind a drill bit, and to a cutter assembly for use in such a downhole assembly. The downhole assembly is suitably for use in a drillstring, the downhole assembly comprising a drill bit, a sensitive component, and at least one rotatable set of cutter blades located between the drill bit and the sensitive component.

Abstract: This invention relates to a downhole assembly and to a cutter assembly, and in particular to a downhole assembly including an apparatus for breaking up large-scale material which is present behind a drill bit, and to a cutter assembly for use in such a downhole assembly. The downhole assembly is suitably for use in a drillstring, the downhole assembly comprising a drill bit, a sensitive component, and at least one rotatable set of cutter blades located between the drill bit and the sensitive component.

Abstract: This invention relates to a steerable drill bit arrangement, in particular for the use in drilling boreholes for oil and gas extraction. According to the invention there is provided a steerable drill bit arrangement comprising a drill bit, a steering component and a stabilizer, the steering component being adapted to provide a steering force which in use can drive the drill bit along a non-linear path, the stabilizer being located between the drill bit and the steering component and in use providing a fulcrum for the steering force provided by the steering component, the position of the fulcrum provided by the stabilizer being adjustable relative to the drill bit and the steering component. In use, the position of the fulcrum can be adjusted to vary the maximum curvature of the borehole and to suit the rock type(s) being drilled.

Abstract: This invention relates to a steerable drill bit arrangement, in particular for the use in drilling boreholes for oil and gas extraction. There is provided a steerable drill bit arrangement in which the drill bit is connected to a drill string including a steering component and a stabiliser, the stabiliser being located between the steering component and the drill bit, the steering component being adapted to move the drill string transversely relative to a borehole in which it is located, the stabiliser having an inner part adapted to rotate with the drill string and an outer part adapted to engage the borehole wall, the outer part being rotatable relative to the inner part so that the outer part can remain substantially stationary as the remainder of the stabiliser rotates with the drill string.

Abstract: This invention relates to a downhole assembly and to a cutter assembly, and in particular to a downhole assembly including an apparatus for breaking up large-scale material which is present behind a drill bit, and to a cutter assembly for use in such a downhole assembly. The downhole assembly is suitably for use in a drillstring, the downhole assembly comprising a drill bit, a sensitive component, and at least one rotatable set of cutter blades located between the drill bit and the sensitive component.

Abstract: This invention relates to a steerable drill bit arrangement, in particular for the use in drilling boreholes for oil and gas extraction. There is provided a steerable drill bit arrangement in which the drill bit (20) is connected to a drill string (16) including a steering component (12) and a stabiliser (14), the stabiliser (14) being located between the steering component (12) and the drill bit (20), the steering component (12) being adapted to move the drill string (16) transversely relative to a borehole in which it is located, the stabiliser (14) having an inner part (32) adapted to rotate with the drill string (16) and an outer part (34) adapted to engage the borehole wall, the outer part (34) being rotatable relative to the inner part so that the outer part (34) can remain substantially stationary as the remainder of the stabiliser (14) rotates with the drill string (16).