Abstract: In completing a well bore in a underground formation, the well bore being closed off by a closing structure for blocking flow of pressurized fluid through the well bore, a substantially tubular element having a tube wall surrounding an axial bore is passed through the closing structure. The tube wall having passed the closing structure is processed along at least a portion of its axial dimension from a first condition into a second, processed condition. In the first condition, the tube wall is substantially impermeable in radial direction to pressurized fluid for precluding a flow of pressurized fluid from passing the penetrated closing structure. In the second condition the tube wall is radially permeable to pressurized fluid along at least a processed portion of its axial dimension. A tubular element to be used in such an application is described as well.

Abstract: For making of breaking a coupling between a pipe section (1) and a pipe string (2) projecting from a rotary drilling rig into a bore in the lithosphere, the pipe section (1) is rotated relative to the pipe string (2) by applying a torque up to a make-up or breaking torque. Exertion of said torque generates a reactive torque in an opposite sense of rotation. Rotation induced by a motor (17; 50) is transferred to the pipe string (2) so that said pipe string (2) is rotated as well. The reactive torque is transferred to the pipe string (2) along a path bypassing the motor (17; 50). Thus, the make-up or breaking torque can be exerted without requiring a substantial change of the torque exerted to rotate the pipe string (2) at a constant rotational velocity in order to avoid changes of the rotational velocity of the pipe string (2). A pipe coupling device and a pipe handler for carrying out this method are described as well.

Abstract: A pipe coupling has coupling members provided with a pin and a box. The outer surface of the pin is provided with axially extending columns of teeth, separated by free slots, and the inner surface of the box is provided with axially extending columns of counter teeth, also separated by free slots. To connect the coupling, the pin is axially inserted into the box and rotated over a fraction of a full turn to make the engagement surfaces of the teeth engage with the corresponding engagement surfaces of the counter teeth, thereby creating an axial pre-tension between the pin and the box. The design of the teeth is differentiated over the length of the pin and the box to be adapted to differences in loads during make-up and in use and the coupling is protected against release and overturning.