Abstract: A method for modelling a drillstring in a wellbore, the method comprising providing a model of the drillstring, the model representing the drillstring by a sequence of alternating springs and elements, where each element describes the mass and/or the moment of inertia of a corresponding part of the drillstring and each spring represents at least one of: axial, torsional and/or bending stiffnesses of one of the corresponding parts of the drillstring, wherein the model describes one or more forces on each element by one or more systems of ordinary equations of first or second order, where each equation comprise a linear part that comprises constant coefficients and a non-linear part that includes one or more of: one or more non-linear terms, one or more non-smooth terms, one or more time dependent terms and/or one or more coupled terms; and the method comprises recalculating the model for a plurality of time steps, wherein recalculating the model for the respective time step comprises calculating one, two or th

Abstract: A drill string (2) for a floating drill rig, the drill string (2) comprising: a bore (4) running the length of the drill string (2) and configured to receive a drilling fluid; and a controllable dynamic flow restriction (14) in the bore, wherein the controllable dynamic flow restriction (14) is operable to restrict flow of the drilling fluid through the bore (4) and thereby generate excess pressure in the drill string when the drill string (2) moves down, and to allow additional drilling fluid to be pushed through the bore (4) and out of the fluid connection under the excess pressure generated when the drill string (2) moves upward.

Abstract: A drill string (2) for a floating drill rig, the drill string (2) comprising: a bore (4) running the length of the drill string (2) and configured to receive a drilling fluid; and a controllable dynamic flow restriction (14) in the bore, wherein the controllable dynamic flow restriction (14) is operable to restrict flow of the drilling fluid through the bore (4) and thereby generate excess pressure in the drill string when the drill string (2) moves down, and to allow additional drilling fluid to be pushed through the bore (4) and out of the fluid connection under the excess pressure generated when the drill string (2) moves upward.

Abstract: A method of locating a drilling apparatus and/or a borehole in a subterranean region. The method may include the steps of transmitting seismic waves into the subterranean region during a subterranean drilling operation, the seismic waves being transmitted from a location remote from the drilling apparatus, detecting a seismic response from the drilling apparatus or borehole, and comparing the detected response with predetermined seismic survey data of the subterranean region to determine the location of the apparatus or borehole.

Abstract: A subsea mud pump can be used to return heavy drilling fluid to the surface. In order to provide a less stringent requirement for such a pump and to better manage the bottom hole pressure in the case of a gas kick or well control event, the gas should be separated from the drilling fluid before the drilling fluid enters the subsea mud pump and the pressure within the separating chamber. The mud pump suction should be controlled and kept equal or lower than the ambient seawater pressure. This can be achieved within the cavities of the subsea BOP by a system arrangement and methods explained. This function can be used with or without a drilling riser connecting the subsea BOP to a drilling unit above the body of water.

Abstract: A subsea mud pump can be used to return heavy drilling fluid to the surface. In order to provide a less stringent requirement for such a pump and to better manage the bottom hole pressure in the case of a gas kick or well control event, the gas should be separated from the drilling fluid before the drilling fluid enters the subsea mud pump and the pressure within the separating chamber. The mud pump suction should be controlled and kept equal or lower than the ambient seawater pressure. This can be achieved within the cavities of the subsea BOP by a system arrangement and methods explained. This function can be used with or without a drilling riser connecting the subsea BOP to a drilling unit above the body of water.

Abstract: Method for drilling and lining a well wherein at least one liner (1, 2, 32) with a larger external diameter than the substantial part of a drilling riser (10) is pre-installed at a point below the substantial part of the drilling riser (10). A bore hole section (21) is drilled after the drilling riser (10) has been installed, the bore hole section having a larger diameter than the at least one pre-installed liner (1, 2, 32). The at least one pre-installed liner (1, 2, 32) is subsequently lowered into the bore hole section (21, 22). A drilling and liner system for implementing the method is also described.

Abstract: A method for the manufacture of a pipe (1) for use in petroleum exploitation, the manufacturing process comprising roll-forming of a steel plate (11) to form a hollow (0?) with a longitudinal gap for being welded to form said pipe (1), the method characterized by the following steps: said steel plate (11) having lateral edge surfaces (221, 222), in which along on or more of said lateral edge surfaces (221, 222) are formed longitudinal grooves (22, 22?) thus forming first bridge parts (23, 23?) comprising a first lateral edge surface (221i, 222i) along a first side of said groove (22, 22?), and thus forming a second lateral edge surface (221y, 222y) on a second side of said groove (22, 22?); welding of said first bridge parts' (23, 23?) first lateral edge surfaces (221i, 222i), thereby joining said grooves (22, 22?) joining said second lateral edge surfaces (221y, 222y) to form a lid (3) to cover said grooves (22, 22?) to form a canal (2) in the wall of said pipe (1).

Abstract: Method for drilling and lining a well wherein at least one liner (1, 2, 32) with a larger external diameter than the substantial part of a drilling riser (10) is pre-installed at a point below the substantial part of the drilling riser (10). A bore hole section (21) is drilled after the drilling riser (10) has been installed, the bore hole section having a larger diameter than the at least one pre-installed liner (1, 2, 32). The at least one pre-installed liner (1, 2, 32) is subsequently lowered into the bore hole section (21, 22). A drilling and liner system for implementing the method is also described.

Abstract: The invention relates to a method and a device for determining the thickness and topography of buoyant objects, especially ship's hulls (1), by means of a beam (2, 17) carrying an array of ultrasound sensors (3). The object (1) and the beam (2) are moved relative to each other in the object's longitudinal direction while the distance between the object and the beam are automatically adjusted by raising/lowering the beam (2) by means of lifting means (6) and/or distance elements secured by floating bodies (4). The invention also relates to a device for implementing the method.

Abstract: A drilling riser for use at great sea depths for drilling of wells in the seabed using a drill string, with the drilling riser arranged to be connected between a wellhead at the seabed and a vessel, and arranged for use with a drilling fluid with sufficiently high density to balance the fluid pressure from the geological formations, with a sensor arranged to detect the level of the drilling fluid's level in the drilling riser, and a return riser pipe with an adjustable return riser pump. The return riser pipe extends up to the vessel, from an outlet on the riser, from a depth which is substantially below the sea surface, and at the same time at a height substantially above the seabed.

Abstract: A blow-out prevention device shuts off an annulus between a drill column and a well wall by means of an expandable sealing device when an unwanted blow-out of fluid and/or gas takes place from an unstable geological well formation when drilling for oil or gas.When a blow-out takes place, a compressive-pulse code is activated in the inlet of the drill column and is transmitted through the drilling fluid to a pressure sensor which transmits the compressive-pulse code on to a microprocessor (37) which is preprogrammed with the pressure code. If the pressure codes coincide, an electric motor is activated, which, via a set of gears and a nut-and-bolt device, displaces a valve plate axially towards a valve seat. The drilling fluid then flows out through nozzles and causes a large pressure drop which is used to expand the sealing device so that the annulus is shut.

Abstract: An under-reaming tool for use in preferably horizontal and extended reach bore holes includes a succession of stabilizers, under-reamers and expandable stabilizers. A common drilling mud activator is provided for the expandable elements of under-reamers and expandable stabilizers. A preferred under-reaming device comprises a main body with a number of guiding surfaces distributed over the circumference thereof which have a pitch increasing radially in an axial direction and with a ring collar formed as a piston in a surrounding cylinder housing having a small and a large radial annular surface, and having reaming pads/wings and/or stabilizer pads/wings in sliding contact with a respective guiding surface, the pads being taken up in ports in a jacket surrounding the main body, in such a way that the pads can only be moved radially relative to the jacket, the jacket being attached to or formed as a part of the cylinder housing.