Abstract: The invention relates to a system and method for radially expanding a tubular element (8). The method comprises the steps of bending the tubular element (8) radially outward and in axially reverse direction so as to form an expanded tubular section (10) extending around an unexpanded tubular section (8) wherein bending occurs in a bending zone (14); and increasing the length of the expanded tubular section (10) by inducing the bending zone (14) to move in axial direction relative to the unexpanded tubular section (8). The method includes the further step of heating the bending zone. Several embodiments to enable heating are described.

Abstract: The invention relates to a system and method for radially expanding a tubular element (8). The method comprises the steps of bending the tubular element (8) radially outward and in axially reverse direction so as to form an expanded tubular section (10) extending around an unexpanded tubular section (8) wherein bending occurs in a bending zone (14); and increasing the length of the expanded tubular section (10) by inducing the bending zone (14) to move in axial direction relative to the unexpanded tubular section (8). The method includes the further step of heating the bending zone. Several embodiments to enable heating are described.

Abstract: A method is provided for determining the rotational stiffness of a drill string for drilling of a borehole in an earth formation, the drill string having a bottom hole assembly (BHA) and an upper end driven by a rotational drive system. The method comprises the steps of determining the time derivative of the drill string torque during drilling of the borehole at a selected time when stick-slip of the BHA occurs, determining the nominal rotational speed of the drill string at an upper part thereof and at said selected time, and determining the rotational stiffness of the drill string from a selected relationship between said time derivative of the drill string torque and said nominal rotational speed at the upper part of the drill string.

Abstract: A system for drilling a borehole in an earth formation is disclosed, the system comprising a first sub-system including a drill string extending into the borehole, and a second sub-system including a drive system for driving the drill string in rotation about the longitudinal axis thereof. Each one of said sub-systems has a rotational resonance frequency, wherein the rotational resonance frequency of the second sub-system is lower than the rotational resonance frequency of the first sub-system.

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.

Abstract: A capacitive electrical connector apparatus for electrical signal or power coupling in a submerged environment. The connector consists of a first member and a second member disposed adjacent one another which are adapted for mechanical mating. Each member comprises an electrode, the electrodes being located opposite to one another and each provided with a dielectric layer at its surface directed to the surface of the other electrode. The electordes are adapted to be connected electrically to respective installation parts to be capacitively coupled. The first and second members mate mechanically in such a way that a cavity remains between the electrodes. When submerged, the cavity is filled with a conductive fluid such as seawater, or, for example, an aqueous drilling fluid.