Abstract: A downhole releasable swivel joint comprises a mandrel and a housing. A resilently deformable retaining device maintains the components in the illustrated first relative axial position until downward movement of the housing is stopped and a sufficient load is applied to the mandrel to overcome the retaining force of the retaining device whereupon the mandrel is able to move downwardly relative to the housing to adopt a second relative axial position. Apertures are provided in the wall of the mandrel and apertures are provided in the wall of the housing. When the mandrel is in the illustrated first relative axial position the apertures and are isolated from each other by a seal. When the mandrel is in the second relative axial position the apertures communicate with each other to permit flow from the interior of the mandrel to the exterior of the housing.

Abstract: A casing scraper comprises a plurality of blade modules mounted on a mandrel. The blade modules are identical to each other and have castellated ends which are engaged with the couplers to prevent relative rotation between the modules. By manipulation of a thread protector the modules can be operated in a configuration in which they are free to rotate relative to the mandrel or in a configuration in which they are rotationally fast with the mandrel. Each module comprises a housing in which a plurality of scraper blades are mounted. The scraper blades include shoulders which prevent the blades passing completely through mounting windows provided in the housing and are biased radially outwardly relative to the housing by compression springs.

Abstract: A downhole swivel joint assembly comprising an upper component and a lower component. The components may assume either of two stable positions relative to each other, namely an unactivated configuration in which the components are rotationally fast with each other by virtue of the inter-engagement of splines of the lower component with splines of the upper component and an activated configuration in which the respective splines are disengaged so that the upper and lower components can rotate relative to each other. In the activated configuration the upper component is supported relative to the lower component on a ball bearing pack. Movement of the components between the activated and unactivated configurations is controlled by a resiliently deformable latch member which is C-shaped in transverse cross-section.

Abstract: A casing brush assembly comprises a mandrel, upper and lower stabilisers, a brush and a magnet assembly. The magnet assembly comprises a plurality of helically extending brush elements each of which is spaced from the underlying mandrel so that it can flex inwardly to accommodate variations in casing diameter. The thickness of the brush elements is relatively thin in the portions which connect the central regions to the ends of the brush with the result that the deflection of the brush elements is largely accommodated by the relatively thin regions. The magnet assembly includes three rings of magnets held in a non-magnetic cage and located beneath a thin cover of non-magnetic material. The assembly can be used in a non-rotating mode (in which the brush is free to rotate relative to the mandrel) or in a rotating mode in which the brush is rotationally fast with the mandrel.

Abstract: The invention relates to apparatus for use in wellbores and particularly, but not exclusively, to circulating subs used during downhole drilling operations. The apparatus includes a control groove and a pin received within the control groove for determining whether or not a longitudinal movement of a piston in a given direction relative to the apparatus body will move the apparatus between open and closed configurations. The apparatus further includes a control member located between and movable relative to the body and the piston. The control groove is defined in one of the piston and control member, and the pin is provided on the other of the piston and control member. Means are also provided for constraining movement of the piston relative to the body to longitudinal movement only. The invention thus provides an apparatus which has improved reliability in moving between open and closed configurations.

Abstract: The present invention relates to downhole apparatus and particularly, but not exclusively, to multi-cycle circulating subs used during downhole drilling operations. Apparatus is provided comprising a piston (242) slidably mounted in a body between positions in which at least one aperture in the body is opened and closed. Movement of the piston (242) is controlled by a pin (86), secured to one of the body and a control member, and a control groove (52) formed in the other of the body and control member for receiving a portion of the pin. An arrangement of elements (232, 276) respectively connected to the control member and body is such as to normally resist axial movement of the control member from a first axial position to a second axial position. A spring (44) is located in a chamber for biasing the piston (242). The chamber is vented by an opening in the body.

Abstract: A casing brush assembly (1) comprises a mandrel (2), upper and lower stabilisers (5,6), a brush (9) and a magnet assembly (10). The magnet assembly comprises a plurality of helically extending brush elements each of which is spaced from the underlying mandrel so that it can flex inwardly to accommodate variations in casing diameter. The thickness of the brush elements is relatively thin in the portions which connect the central regions to the ends of the brush with the result that the deflection of the brush elements is largely accommodated by the relatively thin regions. The magnet assembly (10) includes three rings of magnets held in a non-magnetic cage and located beneath a thin cover of non-magnetic material. The assembly can be used in a non-rotating mode (in which the brush is free to rotate relative to the mandrel) or in a rotating mode in which the brush is rotationally fast with the mandrel.

Abstract: A casing scraper comprises a plurality of blade modules (5,6,7) mounted on a mandrel (2). The blade modules (5,6,7) are identical to each other and have castellated ends which are engaged with the couplers (16,18) to prevent relative rotation between the modules. By manipulation of a thread protector (10) the modules can be operated in a configuration in which they are free to rotate relative to the mandrel or in a configuration in which they are rotationally fast with the mandrel. Each module comprises a housing in which a plurality of scraper blades are mounted. The scraper blades include shoulders which prevent the blades passing completely through mounting windows provided in the housing and are biased radially outwardly relative to the housing by compression springs.

Abstract: A stabilizer sleeve (7) for a drill string, adapted to fit about a down hole motor (1) or a drill string member, is formed with an internally threaded coupling at a lower end for releasable coupling to complimentary threads (8) formed on an upwardly extending intermediate coupling portion (15) of a bottom coupling-nut (3). The coupling-nut (3) is provided with a lower end portion (14) of larger diameter and an upper coupling portion (16) of reduced diameter. The upper coupling portion (16) is conventionally formed with an upwardly tapering form and right-hand thread whereas the intermediate coupling portion (15) is formed with a left-hand thread. The stabilizer sleeve (7) fits about the motor (1) or other body member and above the coupling-nut (3) so that the sleeve (7) may be removed upwardly from the coupling-nut (3).

Abstract: A drop-ball sub-assembly comprises a tubular casing (4) defining a flushing fluid flow passage adapted for coupling at one end (3) to an inlet pipe (1) and at the other end (23) to an outlet pipe (24). A drop-ball (17) supporting member (8) is secured within the casing (4) in the flow passage. Apertures (21) are arranged to allow fluid flow past the supporting member (8), and a further aperture (9) supports a blow-out device (13) supporting a drop-ball (17) on a side distal from the end (23). The blow-out device (13) and the apertures (21,9) are such that at a first, lower fluid rate from the inlet (3) to the outlet (23) end, fluid flows through said aperture (21) and the blow-out device is retained, and that at a second, higher flow rate the blow-out device (13) is blown out of the further aperture to release the ball (17) through the further aperture (9). The blow-out device suitably comprises a frangible disc.

Abstract: A downhole motor (19) is mounted in a drill pipe (13) above a hole enlarger (14) intermediate ends of the pipe (13). The motor drives a lower pilot bit (28). A split flow bypass device (24) above the motor (19) allows part of the flow to drive the motor and the remainder to bypass through a central passage, the divided flows rejoining below the motor (19) with a restricted flow through jet nozzles (32) to the hole enlarger cutter (15). Flow passes centrally of the output shaft (26), past a bleed valve (34) bleeding up to 5% to an outer shaft space for lubricating bearings (30), to flow restrictor jet nozzles (33) of the pilot bit (28).