Abstract: An expander system for radially expanding a tubular element from a first inner diameter to a second inner diameter larger than the first inner diameter, the expander system including an expander movable between a radially retracted mode and a radially expanded mode, wherein the expander includes an expansion surface extending in axial direction of the expander and being operable to expand the tubular element upon movement of the expander from the retracted mode to the expanded mode thereof, the expansion surface being of increasing diameter in axial direction of the expander.

Abstract: A drill bit for drilling a borehole in an object, the drill bit having a central longitudinal axis and comprising a bit body provided with a central shank for connecting the drill bit to a drilling system. The drill bit further comprises at least one cutting arm, each cutting arm being provided with a set of cutters for cutting the object and being coupled to the bit body allowing the cutting arm to pivot between a radially retracted position and a radially expanded position.

Abstract: An expander system for radially expanding a tubular element having an unexpanded portion of a first inner diameter, the expander system including an expander movable between a radially retracted mode and a radially expanded mode, the expander being operable to expand the tubular element from the first inner diameter to a second inner diameter larger than the first inner diameter by movement of the expander from the radially retracted mode to the radially expanded mode thereof, wherein the expander has a contact section of a diameter larger than the first inner diameter when the expander is in the radially retracted mode, and wherein the contact section is arranged to prevent axial movement of the expander through the unexpanded portion of the tubular element when the expander is in the radially retracted mode.

Abstract: An automated method for forge welding tubulars including heating the tubular ends to be joined in a welding chamber while the heated tubular ends are maintained aligned and parallel relative to each other and at a small spacing, whereupon the heated tubular ends are pressed together while a reducing shield gas is injected into the chamber.

Abstract: A method of injecting a stream of treatment fluid into an earth formation in the course of drilling a borehole into the earth formation, using an assembly having a drill string provided with at least one sealing means arranged to selectively isolate a selected part of the borehole from the remainder of the borehole, the drill string further being provided with a fluid passage for the stream of treatment fluid into the selected part of the borehole, the method involving: operating the drill string, and stopping the drilling operation when a zone for which treatment is desired is arranged adjacent to the part of the selected part of the borehole; isolating the selected part of the borehole using the sealing means so as to seal the drill string relative to the borehole wall; and, pumping the stream of treatment fluid via the fluid passage into the selected part of the borehole and from there into the treatment zone.

Abstract: A method of joining expandable tubulars includes joining the tubulars by forge welding and flushing a reducing flushing gas around the heated tubular ends during at least part of the forge welding operation such that oxides are removed from the forge welded tubular ends and the amount of irregularities between the forge welded tubular ends is limited.

Abstract: Device and method for drilling into geological formations. The device comprises: a rotatable body; drilling cutters arranged on an axial end surface of the rotatable body; a percussion part, which is parallel to the rotating axis reciprocatable arranged on said body; and percussion cutters arranged on an axial end surface of the percussion part. The method comprises the steps of: bringing a percussion part with a percussive movement in contact with the formation in order to crack at least a part of the formation, and scraping the cracked parts of the formation with a drilling part.

Abstract: A method of joining heavy duty oilfield, well, or other tubulars includes the step of joining the tubulars by forge welding and flushing a reducing flushing gas around the heated tubular ends during at least part of the forge welding operation such that oxides are removed from the forge welded tubular ends and the amount of oxide inclusions and irregularities between the forge welded tubular ends is limited. The tubular ends may have a teethed sinusoidal or other non-planar shape to inhibit any abrupt variations of the wall strength in the welding area and/or to reduce shear forces to the forge weld when the tubulars are twisted and/or radially expanded.

Abstract: A drill bit for drilling a borehole into an earth formation is provided. The drill bit has a central longitudinal axis and a bottom surface facing the borehole bottom during drilling with the drill bit, and comprises primary fluid injection means arranged at the bottom surface and located at a selected radial distance from the central longitudinal axis, the primary fluid injection means being arranged to eject a primary stream of fluid into the borehole, the primary stream having a component in a transverse plane of the drill bit, directed from the fluid injection means to the central longitudinal axis.

Abstract: A hydraulic accumulator for use in a drill string having a fluid passage for supply of fluid to a hydraulic drill string tool is provided. The accumulator comprises a body provided with connecting means for connecting the accumulator to the drill string and an expansion chamber in fluid communication the fluid passage when the accumulator is connected to the drill string by the connecting means. The expansion chamber is expandable between a first volume and a second volume which is larger than the first volume. Further, the expansion chamber is provided with means for moving the expansion chamber from the first to the second volume upon a fluid pressure increase in the fluid passage and for moving the expansion chamber from the second to the first volume upon a pressure decrease in the fluid passage.

Abstract: The invention relates to a device for drilling into geological formations, which device comprises: —a rotatable body; —drilling cutters arranged on an axial end surface of the rotatable body; —a percussion part, which is parallel to the rotating axis reciprocatable arranged on said body; and —percussion cutters arranged on an axial end surface of the percussion part. The invention further relates to a method for drilling into geological formations, which method comprises the steps of: —bringing a percussion part with a percussive movement in contact with the formation in order to crack at least a part of the formation, and scraping the cracked parts of the formation with a drilling part.

Abstract: An automated method for forge welding tubulars including heating the tubular ends to be joined in a welding chamber while the heated tubular ends are maintained aligned and parallel relative to each other and at a small spacing, whereupon the heated tubular ends are pressed together while a reducing shield gas is injected into the chamber.

Abstract: A drill hit for drilling a borehole into an earth formation is provided. The drill bit has a central longitudinal axis and a bottom surface facing the borehole bottom during drilling with the drill bit, and comprises primary fluid injection means (10) arranged at the bottom surface and located at a selected radial distance from the central longitudinal axis, the primary fluid injection means being arranged to eject a primary stream of fluid into the borehole, the primary stream having a component in a transverse plane of the drill bit, directed from the fluid injection means to the central longitudinal axis.

Abstract: A hydraulic accumulator for use in a drill string having a fluid passage for supply of fluid to a hydraulic drill string tool is provided. The accumulator comprises a body provided with connecing means for connecting the accumulator to the drill string and an expansion chamber in fluid communication the fluid passage when the accumulator is connected to the drill string by the connecting means. The expansion chamber is expandable between a first volume and a second volume which is larger than the first volume. Further, the expansion chamber is provided with means for moving the expansion chamber from the first to the second volume upon a fluid pressure increase in the fluid passage and for moving the expansion chambe from the second to the first volume upon a pressure decrease in the fluid passage.

Abstract: The invention relates to a rotary drill bit for drilling a borehole in an earth formation, the drill bit comprising a first and a second disc cutter, each disc cutter being arranged to roll along the borehole bottom during rotation of the drill bit and thereby to cut respective first and second substantially circular, radially spaced cuts in the borehole bottom so that a body of rock material is defined between said cuts. The second disc cutter is arranged to cut into the bottom of the borehole at a selected rotational interval of the drill bit behind the first disc cutter and to shear-off said body of rock material in the direction of the first cut. Each disc cutter includes a set of mutually spaced cutting members arranged to create, during a turn of the drill bit, a corresponding set of cut sections of the cut created by the disc cutter, and wherein the cutting members are arranged so that the sets of cut sections created during subsequent drill bit turns are staggered relative to each other.

Abstract: A method of creating a weld to connect a first element to a second element, said elements being arranged in a wellbore containing a wellbore fluid, is provided. The method comprises selecting a welding path along which the weld is to be created, selecting a volume portion of the wellbore, in which selected volume portion said path is located and sealing said selected volume portion from the remainder of the wellbore volume, and providing pressure control means for controlling the fluid pressure in said selected volume portion. The pressure control means is then operated so as to reduce the fluid pressure in said selected volume portion to a selected pressure at which the weld can be created, and the weld is created along the selected welding path.

Abstract: A method for fracturing an underground formation surrounding an oil and/or gas well comprises positioning a fracturing tool in a selected orientation in the borehole and expanding the tool such that it exerts a circumferentially varying pressure against the borehole wall over a selected period of time thereby initiating in the surrounding formation one or more fractures which each intersect the borehole wall in a selected orientation and simultaneously injecting a proppant into the fracture(s).

Abstract: A device for controlling weight on bit of a drilling assembly for drilling a borehole in an earth formation, is provided. The device includes a fluid passage for the drilling fluid flowing through the drilling assembly, and control means for controlling the flow resistance of drilling fluid in the passage in a manner that the flow resistance increases when the fluid pressure in the passage decreases and that the flow resistance decreases when the fluid pressure in the passage increases.