Abstract: A disconnect device for use as part of a tubing string downhole in an oil or gas well and which comprises a tubular body, at least one slip held within the tubular body, and a sleeve housed within the tubular body to hold the at least one slip in coupling engagement with at least one of a coupling component of an upper sub and a coupling component of a lower sub, in use, the sleeve being selectively moveable relative to the at least one slip to release the slip and thereby release the coupling, wherein the slip cooperatively engages with at least one of the coupling component of the upper sub and the coupling component of the lower sub by means of at least one localized protrusion on the slip or on the coupling component extending into a corresponding shaped local depression or hole in the other of the at least one slip and the coupling component whereby tensile load and torque may be transmitted by the coupling, that part of the device which is to be released and left downhole by releasing the coupling engag

Abstract: The present invention provides a roller sub for use downhole in oil or gas wells as part of a toolstring or drill string to reduce friction between the string and wellbore. The roller sub is a modular assembly of parts which assemble together to trap the roller wheels in place between them, avoiding need for grub screws to fasten the individual wheels and rendering the roller sub very compact.

Abstract: A disconnect device for use as part of a tubing string downhole in an oil or gas well and which comprises a tubular body (2), at least one slip (8) held within the tubular body (2), and a sleeve (10) housed within the tubular body (2) to hold the at least one slip (8) in coupling engagement with at least one of a coupling component of an upper sub (1) and a coupling component of a lower sub (3), in use, the sleeve (10) being selectively moveable relative to the at least one slip (8) to release the slip and thereby release the coupling, wherein the slip (8) cooperatively engages with at least one of the coupling component of the upper sub (1) and the coupling component of the lower sub (3) by means of at least one localised protrusion (18) on the slip (8) or on the coupling component extending into a correspondingly shaped local depression or hole (19) in the other of the at least one slip and the coupling component whereby tensile load and torque may be transmitted by the coupling, that part of the device whi

Abstract: The present invention provides a roller sub for use downhole in oil or gas wells as part of a toolstring or drill string to reduce friction between the string and wellbore. The roller sub is a modular assembly of parts which assemble together to trap the roller wheels in place between them, avoiding need for grub screws to fasten the individual wheels and rendering the roller sub very compact.

Abstract: A tubing connector non-releasably connected to a tube of tubing string for use downhole in oil and gas well operations, the connector comprising connector body (1) with an end portion fitted concentrically within or over a corresponding end of the tube (2), the end portion having a plurality of depressions (12) coinciding with corresponding depressions (10) on the corresponding end of the tube (2) whereby the connector body (1) and tube (2) are connected together, the depressions (10) and the tube (2) having been formed by localized plastic deformation of the walls of the tube (2).