Abstract: A device for transporting a sensor assembly along a bore comprises an axle extending through a body of the device and mounted to rotate on a rotational axis perpendicular to a central longitudinal axis of the device. A wheel fixed to each end of the axle. The device has a conduit through the body for accommodating an electrical conductor to extend through the device from end-to-end. The conduit comprises a non-linear portion extending around the axle between the ends of the device.

Abstract: Systems and methods for reducing friction between a casing string and a bore of a subterranean well when moving the casing string within the bore of a subterranean well include a roller bearing assembly. The roller bearing assembly has a bearing body and a plurality of spherical bearings spaced around an outer diameter of the bearing body. The bearing body is secured in line with the casing string.

Abstract: Described herein is a perforating assembly and method of use. In one embodiment, the perforating assembly comprising an offset loading tube mounted within a gun carrier. A plurality of shaped charges are mounted within the loading tube and the loading tube is mounted within the gun carrier on one or more swivel mechanisms that enable the loading tube to rotate within the gun carrier.

Abstract: A centralizer includes a centralizer body having a through-bore for receiving a tool. The centralizer includes a centralizer fin radially extending from the centralizer body and longitudinally extending along the centralizer body. The centralizer fin includes a diverter portion. The diverter portion has a front surface at one longitudinal end of the centralizer fin. The centralizer fin includes an engagement portion coupled to the diverter portion distal to the centralizer body. The centralizer fin includes a cladding applied to the front surface of the diverter portion.

Abstract: A downhole device (15) comprising: a body (10) with a bore; at least one wheel (20) or other retained component; an engagement member (40) for engaging the wheel with the body. A retaining member (31) retains the engagement member (40) in place, the retaining member (31) extending along the body (10) and in the line of the main axis of the engagement member (40) so that it abuts. Embodiments allow for more convenient and more reliable retaining of wheels or other components in the device especially reducing the need for using threaded connections, which are prone to failure.

Abstract: A rotating flow coupler that is configured to couple multiple sections of a casing for a horizontal well, wherein the rotating flow coupler is configured to rotate relative to the casing allowing an additional degree of freedom for equipment being lowered into the well. This may allow for equipment such as coil tubing, drilling string, casings strings, etc. to reach a total distance of deeper laterals.

Abstract: A roller coupling apparatus for securing rods and other threaded components together in a pumping system. The roller coupling apparatus can include a body with a plurality of radially-positioned wheels rotatably coupled to the body. The arrangement of the wheels can uniformly spread the rod load within the interior diameter of the tubing. The body can include flat outer surfaces to facilitate increased fluid flow capacity around the apparatus. In operation, the wheels contact and roll along the interior diameter of the tubing, preventing surface-to-surface wear of the coupling body exterior and tubing interior, thereby prolonging coupling and tubing life. In one embodiment, the wheels can include wear grooves that can indicate wear areas in the wellbore. In one embodiment, the body can include grooves to permit retrieval of the apparatus when needed. Multiple apparatuses can be utilized to form rod strings of various lengths.

Abstract: The downhole friction reducing tool of the present invention includes an integral friction coefficient reducer and is configured to reduce friction in all planes, reduce torque and/or drag continually and reduce frictional wear and damage that can result in loss of integrity to surface areas where it travels. The friction coefficient reducer involves a ball transfer unit having a plurality of roller ball units. The roller ball units include a large-diameter load-bearing roller ball unit and a plurality of smaller-diameter supporting roller ball units.

Abstract: A device for transporting a sensor assembly in a bore comprises a plurality of wheels azimuthally spaced apart around a longitudinal axis of the device. Each wheel presents a radial extremity of the device. The wheels are moveably supported to move between a minimum outer diameter of the device and a maximum outer diameter of the device. An adjustable stop mechanism is configured to pre-set the maximum outer diameter of the device within a range of maximum outer diameters so that the device is configurable for use in a pre-determined range of bore diameters. One or more spring elements bias the wheels radially outwards and are preloaded to provide a radial force to the wheels when at the pre-set maximum outer diameter.

Abstract: Apparatus and methods for running casing into a wellbore. An apparatus may be or include a casing collar configured to couple together a first casing joint and a second casing joint. The casing collar may have a body and a plurality of rotatable members connected to the body. The body may have a fluid passage extending axially therethrough, a first coupler configured to couple the casing collar with the first casing joint, and a second coupler configured to couple the casing collar with the second casing joint. At least a portion of each rotatable member may extend from the body in a radially outward direction.

Abstract: Embodiments provide a method for centralizing a coiled tubing in a wellbore. The method includes the step of supplying a roller set to a roller set assembly system located at a surface. The roller set includes a first half and a second half. The roller set assembly system includes a first guide cable and a second guide cable. The method includes the step of installing the first half to the first guide cable and the second half to the second guide cable. The method includes the step of securing the first half and the second half to the coiled tubing such that the roller set is fixed to the coiled tubing. The method includes the step of injecting the coiled tubing into the wellbore.

Abstract: A roller coupling apparatus for securing rods and other threaded components together in a pumping system. The roller coupling apparatus can include a body with a plurality of radially-positioned wheels rotatably coupled to the body. The arrangement of the wheels can uniformly spread the rod load within the interior diameter of the tubing. In operation, the wheels contact and roll along the interior diameter of the tubing, preventing surface-to-surface wear of the coupling body exterior and tubing interior, thereby prolonging coupling and tubing life. In one embodiment, the wheels can include wear grooves that can indicate wear areas in the wellbore. Multiple apparatuses can be utilized to form rod strings of various lengths.

Abstract: A rod guide is provided for use on a rod string extending through a bore of a wellbore tubular. The rod guide has an elongate, generally cylindrical body configured to be connected in-line with a rod string, and a plurality of wheels rotatably fastened to the outside of the cylindrical body and configured to roll along the wellbore tubular. The plurality of wheels are angularly offset from each other to provide multiple rolling planes upon which the rod guide my roll, and can be arranged in series or in opposing pairs. The wheels also assist in centralizing the rod guide in the wellbore tubular. When arranged in a helical pattern, the wheels also facilitate rotation of the rod string.

Abstract: A downhole tool and method for orienting a tool string within a passage, such as a wellbore or a tubular disposed in the wellbore. The downhole tool may be operable for detachably connecting with the tool string and orienting the tool string within the passage. The downhole tool may include a frame comprising a first frame portion and a second frame portion, wherein the first and second frame portions may be detachably connectable with each other around the tool string to detachably connect the frame with the tool string. The downhole tool may further include a first orienting feature rotatably connected with the first frame portion along a first axis of rotation and a second orienting feature rotatably connected with the second frame portion along a second axis of rotation. The first and second axes of rotation may be radially offset from a central axis of the tool string.

Abstract: A molded rod guide for guiding and protecting a sucker rod in a fluid mineral extraction setting. Said molded rod guide comprising a two mating portions and a center channel. Said two mating portions comprise a first mating portion and a second mating portion. Said two mating portions are configured to selectively mate with one another and form said center channel. Said two mating portions comprise an assembled configuration and a separated configuration. With said two mating portions in said assembled configuration, said molded rod guide comprises a plurality of flutes, a body portion, a width and a height. Said body portion wraps around said center channel. Said center channel comprises a center axis. Said molded rod guide is configured to selectively surround a portion of a rod by wrapping said center channel around a portion of said rod.

Abstract: Systems and methods for moving a tubular string within a subterranean well include a structural ring sized with a ring inner diameter to circumscribe the tubular string and a ring outer diameter to fit within a bore of the subterranean well. A plurality of individual openings are spaced around an outer diameter surface of the structural ring, each individual opening associated with an inflatable member. The inflatable member is operable to vibrationally impact an internal surface of the subterranean well with repeated inflating and deflating the inflatable member. Wheels are spaced around an inner diameter surface of the structural ring.

Abstract: A multi-phase power cable includes: a plurality of phase cores, each including an insulated electric conductor; a screen assembly including a metallic screen rod; a moisture barrier metallic sheet enclosing the plurality of phase cores and the screen rod; an outer jacket radially outer to the moisture barrier metallic sheet; and a multilayer arrangement including a first, second and third semiconducting water swellable layer surrounding the phase cores and in radial internal position with respect to the moisture barrier metallic sheet and in electric contact therewith, the screen assembly being arranged between the second and third semiconducting water swellable layers.

Abstract: The low friction wireline standoff improves wireline cable performance during borehole logging operations. The use of low friction wireline standoffs ameliorates the effects of wireline cable differential sticking, wireline cable key-seating, and high wireline cable drags, by reducing or eliminating contact of the wireline cable with the borehole wall during the logging operation. The low friction wireline standoff comprises external wheels mounted on two finned half shells that clamp onto the wireline with precision cable inserts which are manufactured to fit a wide range of logging cables. The wheels reduce the cable drag down-hole resulting in lower surface logging tensions, aiding conveyance in deep and deviated wells.

Abstract: A centralizer includes a centralizer body to be situated at the outer surface of a pipe string in the form of casing, liner, or the like used while drilling, the centralizer body being formed with a plurality of outer centralizer blades arranged in an inclined manner to the longitudinal axis thereof, wherein the centralizer body has an separate split inner tube secured to the pipe string by means of a press fit, and low friction inner surface of the centralizer body and separate center tube facing each other are made from low friction material.

Abstract: A downhole tool, for selectively reaming a wellbore or stabilizing drill string components within a wellbore, includes an elongate tool body adapted to receive reamer cartridges or stabilizer cartridges depending on the function desired. The reamer cartridges are radially insertable into corresponding pockets in the tool body, with each reamer cartridge having a reamer insert with an array of cutting elements. The reamer insert is disposed within a bushing and is rotatable relative thereto, about a rotational axis transverse to the longitudinal axis of the tool. However, the rotational axis is offset from the tool body axis, resulting in eccentric contact of the cutting elements with the wall of the wellbore, which in turn imparts rotation to the reamer insert when the tool is being moved axially through a wellbore without rotation.

Abstract: A multi-tasking downhole rod guide for centralizing a downhole pump rod within a production tubing string, while simultaneously reducing abrasion and deterioration of the production tubing and affording a built-in backflow preventer. The rod guide is configured with an elongate helix having a continuous trough-like channel through which hydrocarbons flow upwardly under high pressure. As the pressurized hydrocarbons flow through a succession of plates at each equidistant helical level, the elongate helix rotates synchronously with the upwardly flowing hydrocarbons within the production tubing string. Integrated bearing assembly and backflow An integrated bearings assembly and backflow restrictor accommodate hydrocarbons flow perturbations and sustain continuous fluid flow uphole.

Abstract: A towing string useful for positioning a towed assembly into a horizontal well bore includes a towed assembly coupled to a tractor assembly. The tractor assembly is operable to convert introduced energy into a pulling force that is directed downhole. The tractor assembly includes a disposable motor and a coupled rotary tractor. The rotary tractor has a rotating portion that is operable to rotate around a central axis of the rotary tractor and a rotary element that is operable to frictionally engage the well bore wall. A method for using the towing string for positioning the towed assembly in the horizontal section includes introducing the towing string into the horizontal well bore, operating the towing string such that the rotary element frictionally engages the well bore wall, and introducing energy to the towing string such that the tractor assembly provides a pulling force directed downhole.

Abstract: A multi-tasking downhole rod guide for centralizing a downhole pump rod production tubing within production tubing, while simultaneously reducing abrasion and deterioration of the production tubing and engendering auxiliary pump-boosting functions. The rod guide is configured with an elongate helix having a continuous trough-like channel through which hydrocarbons flow upwardly under high pressure. As the pressurized hydrocarbons flow through a succession of plates at each equidistant helical level, the elongate helix rotates synchronously with the upwardly flowing hydrocarbons within the production tubing string.

Abstract: A drill pipe protector assembly comprising at least one protector sleeve (23) adapted to be mounted to the drill pipe string (7) through a fluid bearing (25) so as to be co-axially rotatable with respect to the drill pipe string (7). A retainer arrangement (21, 35) axially fixes the protector sleeve (23) with respect to the drill pipe string (7). The fluid bearing (25) is constructed according to the principles of a hydrostatic fluid bearing. At least one fluid channel (53) connects the fluid bearing (25) to a fluid path of pressurized drilling fluid flowing within an inner space (51) of the drill pipe string (7).

Abstract: In one embodiment, a wear band comprises a rotating element having a bore receivable on a tubular, the bore comprising first and second bore portions slidably receiving first and second sleeve bearings. Outer surfaces of the sleeve bearings slidably engage the bore portions and the bores of the sleeve bearings slidably engage the tubular. A first stop collar and a second stop collar may be received on the tubular to together straddle the rotating element and sleeve bearings to longitudinally secure the rotating element in a position on the tubular. The tubular may be included within a tubular string run into a borehole or into the bore of an installed casing, such as in casing while drilling. The rotating element provides stand-off between a tubular and the wall of a bore, reduces frictional resistance to longitudinal sliding and also to rotation of the tubular string within the bore.

Abstract: A backspin retarder for a progressive cavity pump deploys on the drive string uphole from a pump unit. The backspin retarder has a shaft that connects to portions of the drive string. An impeller disposes on the shaft and can move axially and radially. In an unengaged condition, the impeller and shaft can rotate relative to one another so the drive string can rotate in a drive direction without impediment from the impeller. In an engaged condition, the impeller rotates with the shaft in a backspin direction. In this way, vanes on the impeller can retard the backspin of the shaft and drive string by attempting to force the lifted fluid column flowing downhole past the impeller back uphole. The retarder can use a pin and slot arrangement or an arrangement of engageable teeth to engage the impeller to the rotation of the shaft.

Abstract: A downhole system includes a downhole string insertable within a subterranean wellbore and a roller assembly coupled with the string. The roller assembly includes rollers mounted on lateral sides of the downhole string for reducing the resistance of deploying the string within the wellbore. The string is rotatable about its axis with respect to the roller assembly; bearing surfaces, or low torque surfaces, are included in the roller assembly to further reduce rotational friction so the string precisely positions itself to a designated orientation.

Abstract: The invention relates to a centralization and running tool (CTR) in a subsea installation in connection with offshore related oil and gas exploration, where the subsea installation (SCM) is arranged to be placed on the ocean bottom or a drilling template and comprises a pipe-formed body (10), at least partially open at the top and extended, arranged to receive and carry through a drill stem (12) from a drilling rig or a drilling vessel. The centralization and running tool (20) is arranged to surround the drill stem (12) and to be placed in the pipe-formed body (10), and the centralization and running tool (20) comprises, together with the drill stem (12), a rotary packing housing (22) with a number of seals (24,26) that lie against the drill stem (12), and the packing housing (22), in accordance with the movements of the drill stem (12), is arranged for radial movement to take up angular deviations of the drill stem (12).

Abstract: A method to select, evaluate and recommend optimal rod pumping system design for a downhole well. The method includes the steps of selecting at least one downhole rod type as a setup preference, selecting at least one pumping unit type as a setup preference, and selecting at least one motor power meter type as a setup preference. Well information, including depth of a pump and run time, is entered as a case input. Additionally, a target production for the well is entered. Records are retrieved from a database wherein the records contain input data on each downhole rod type, each pumping unit type, and each pump motor type. Data is merged from all the case inputs, all of the setup preferences, and from the database records. Scores of gearbox loading, structure loading, system efficiency, rod loading, minimum polished rod loading and bottom minimum stress are calculated and then combined to determine a calculated percentage score for each pumping unit type for the downhole well.

Abstract: A transport assembly configured to be attached to downhole apparatus has a support assembly configured to be attached to the downhole apparatus and a ground engaging assembly, which may be a roller wheel configured to contact with and move in relation to a surface of a wellbore. The roller wheel may engage with the support assembly so as to provide for their relative rotation. The transport assembly also includes a retaining member disposed between the roller wheel and the support assembly, and the retaining member is operable to resist separation of the roller wheel from the support assembly. The transport assembly is further configured such that, when the transport assembly is in use moving along a wellbore, the roller wheel bears against the retaining member, which in turn bears against the support assembly. The retaining member is a ball-bearing.

Abstract: The invention relates to a downhole device for incorporation into a downhole string and movement in a wellbore. The device comprises a body member, at least one roller arranged on the device to engage the inner surface of the wellbore and means to orient the device in the wellbore. The means to orient the device are provided on the or each roller. Preferably the means to orient the device comprise a projecting portion provided on the or each roller which projects radially outwardly from the body member. The projecting portion can be an eccentrically-shaped portion of the or each roller.

Abstract: A rod guide is provided for use in a rotating rod string (12) for powering a progressive cavity pump (14) for pumping downhole fluids through tubing (16) to the surface. The rod guide includes a rotor sleeve (20) secured to the rod string. The rotor sleeve includes a plurality of axially spaced reduced diameter body portions 22, and a plurality of axially spaced enlarged diameter ridge portions 24. Upper and lower stop surfaces 26, 28 on the ridge portions permit axial movement of the stator sleeve with respect to the rotor sleeve. A stator sleeve (40) positioned over the rotor sleeve, and has a sleeve body (42) with a generally circular configuration with opposing circumferential ends (44, 46) spreadable to position the stator sleeve about the rotor sleeve. A plurality of ribs (48) extend outward from the stator sleeve body.

Abstract: A centralizing device (1) for an elongated body (16) which is located in a mousehole machine (2), the centralizing device (1) being at the upper portion of the mousehole machine (2), and the centralizing device (1) being supported and rotatable around a substantially horizontal axis of rotation (22) extending through the opening (10) of the mousehole machine, and the centralizing device (1) including two centralizing bows (24) located on radially opposite sides of the axis of rotation (22).

Abstract: A wellbore pressure isolation apparatus is deployed in a wellbore and has a sealing element that can be activated to seal against an interior surface of a surrounding tubular. Once set, a ball valve in the apparatus restricts upward fluid communication through the apparatus, and another ball valve in the apparatus can restrict downward fluid communication through the apparatus. These ball valve can have disintegratable balls intended to disintegrate in wellbore conditions after different periods of time. To facilitate deployment of the apparatus in a horizontal section of the well bore, the apparatus has a plurality of rollers positioned on a distal end. In addition, the apparatus has a ring disposed about the body between the distal body portion and an adjacent body portion. The ring has an outside diameter at least greater than that of the adjacent body portion to facilitate pumping of the apparatus in the wellbore.

Abstract: A centralizer for tubular elements is provided which includes an inner part formed by a first material having high mechanical performance and chemical stability and an outer part arranged on said inner part, formed by a second material. The second material may be an autolubricating material. The second material may further possess a low coefficient of friction. The second material may additionally possess lower mechanical performance and chemical stability than the first material. A method of manufacturing the centralizer is also provided, including steps of injecting the first material on a tubular element to form the inner part on the tubular element and injecting the second material to form the outer part on the formed inner part.

Abstract: A rod guide is provided for use in a rotating rod string (12) for powering a progressive cavity pump (14) for pumping downhole fluids through tubing string (16) to the surface. The rod guide includes a rotor sleeve (20) secured to the rod string. A stator sleeve (40) is positioned over the rotor sleeve, and has a sleeve body (42) with a generally circular configuration with opposing circumferential ends (44, 46) spreadable to position the stator sleeve about the rotor sleeve. A plurality of ribs (48) extend outward from the stator sleeve body. One circumferential end of the stator sleeve has a catch member (52), and an opposing circumferential end of the stator sleeve has a receiving cavity (54) for receiving at least a portion of the catch member. The circumferential ends of the stator sleeve are connected by the catch member and the receiving cavity.

Abstract: A rod guide is provided for use in a rotating rod string (12) for powering a progressive cavity pump (14) for pumping downhole fluids through tubing (16) to the surface. The rod guide includes a rotor sleeve (20) secured to the rod string. The rotor sleeve includes a plurality of axially spaced reduced diameter body portions 22, and a plurality of axially spaced enlarged diameter ridge portions 24. Upper and lower stop surfaces 26, 28 on the ridge portions permit axial movement of the stator sleeve with respect to the rotor sleeve. A stator sleeve (40) positioned over the rotor sleeve, and has a sleeve body (42) with a generally circular configuration with opposing circumferential ends (44, 46) spreadable to position the stator sleeve about the rotor sleeve. A plurality of ribs (48) extend outward from the stator sleeve body.

Abstract: A rod guide is provided for use in a rotating rod string (12) for powering a progressive cavity pump (14) for pumping downhole fluids through tubing (16) to the surface. The rod guide includes a rotor sleeve (20) secured to the rod string and having a plurality of circumferentially spaced exterior surfaces (22) each positioned substantially along an exterior of a cylinder. The rotor sleeve also includes one or more stop surfaces (24) for limiting axial movement of a stator sleeve (40) with respect to the rotor sleeve, and two or more axially extending cavities (26) each extending from a bottommost surface to an opposing uppermost surface of the rotor sleeve and passing through the one or more stop surfaces. Stator sleeve (40) surrounds the rotor sleeve and has an interior surface (42) for engaging the plurality of circumferentially spaced exterior surfaces of the rotor sleeve, and a plurality of ribs (44) extending outward from two or more outer cylindrical surface portions (44) of the stator sleeve.

Abstract: The present invention generally relates to an apparatus and methods for improving the stability of a wellbore during drilling operations using a rotary drill string. More specifically, embodiments of the present invention provide systems and methods for enhancing the performance of the filter or mud cake layer on the wall of the wellbore as a protective and isolating layer.

Abstract: In accordance with the teachings of the present invention, a method is provided for preventing formation of sludge in a subsurface cavity having particulate laden fluid disposed therein. The method includes positioning a downhole device having a fluid agitator into the fluid of the subsurface cavity and agitating the fluid using the fluid agitator.

Abstract: A roller sub system for reducing friction between a tool string and a wall in a well bore for use in the oil and gas industry. The apparatus has a roller body and wheel sub system, which is configured to have removably mounted wheels of variable diameters. A plurality of different diameter wheel sets are described for mounting on the roller sub axles and orientating the system in the well bore. The wheels are fixed to the roller sub axles through a quick-release mechanism. A single apparatus can thus be employed with different diameter wheels to operate in well bores of variable diameters.

Abstract: A field-installable rod guide for a rod moveable within an oilfield tubular having an interior tubular surface for driving a downhole pump to pump liquids to the surface through the oilfield tubular. The rod guide comprises a body including interfitting body members. An outer tapered surface on one body member is engaged by an inner taper-engagement surface on the other body member, to urge the body members toward a rod gripping position about the rod. The mechanism disclosed provides a particularly strong engagement with the rod, so that the rod guide may be used for either reciprocating or rotating rods. For rotating type rod guides, an outer sleeve may be included about the body.

Abstract: In accordance with the teachings of the present invention, a method is provided for preventing formation of sludge in a subsurface cavity having particulate laden fluid disposed therein. The method includes positioning a downhole device having a fluid agitator into the fluid of the subsurface cavity and agitating the fluid using the fluid agitator.

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 drill pipe protector having a tubular sleeve that is attached to a section of drill pipe and resides over the outer diameter of the drill pipe while moving within an associated well casing or well hole. The sleeve has low-friction end pads positioned on the ends of the sleeve to reduce friction between the ends of the sleeve and the end of an adjacent thrust bearing collar used to hold the sleeve in place on the drill pipe.

Abstract: A method and apparatus for advancing a rotating motorized downhole tool for operations in oil/gas wells. The apparatus is adapted for drilling and milling away of casing sections in the wells, as preparation for plugging the same. The appraratus includes a rotating tool and a driving motor indirectly suspended on coiled tubing. The apparatus also includes a carriage connected to the motor adapted to absorb torques that occur during use. The carriage is connected to the coiled tubing via a swivel coupling such that a tensile force on the coiled tubing provides an advancing force for the tool and motor.

Abstract: An apparatus for propulsion inside an oblong cavity, such as pipes or the like, is disclosed.

Abstract: A method and apparatus for advancing a rotating motorized downhole tool for operations in oil/gas wells. The apparatus is adapted for drilling and milling away of casing sections in the wells, as preparation for plugging the same. The apparatus includes a rotating tool and a driving motor indirectly suspended on coiled tubing. The apparatus also includes a carriage connected to the motor adapted to absorb torques that occur during use. The carriage is connected to the coiled tubing via a swivel coupling such that a tensile force on the coiled tubing provides an advancing force for the tool and motor.

Abstract: A centralizer apparatus for centralizing tubular casing in a borehole having two stop collars for securing to the casing in a spaced apart relationship and two moving collars, one slidably and rotatably coupled to each stop collar, a plurality of bow springs, each bow spring having a first end spaced apart from a second end, each bow spring biased outwardly from the center axis, the first ends connected to the first moving collar, the second ends connected to the second moving collar.

Abstract: Apparatus which can collect loose debris, particularly ferrous debris, has a body 2 with upper 3 and lower 4 stabiliser sleeve. The body 2 has a one or more integral magnets or magnetic areas 5. In one embodiment the magnets are located in a first and second row on a split sleeve 6 and are covered by a protective stainless steel sleeve7. The apparatus may alternatively comprise magnetic scraper blades or a magnetic sub. The magnets are selectively activated. There is also described a method of trapping or retaining debris in a well bore.