Abstract: A vibratory casing recovery bottom hole assembly and a method of recovering casing in a wellbore. The vibratory casing recovery bottom hole assembly includes a casing spear, a flow modifier and a dynamic amplification tool. The flow modifier produces cyclic variations in fluid pressure through the assembly at a first frequency and the bottom hole assembly is configured to have a natural or resonant frequency when vibrated to be near or at the first frequency. The dynamic amplification tool induces vibration in the bottom hole assembly while ensuring the dynamic amplification factor of the system is greater than one so as to transmit maximum vibration to the casing at the casing spear. Embodiments of dynamic amplification tools are described.

Abstract: A method of recovering casing in a wellbore using a vibratory casing recovery bottom hole assembly. In a vibratory casing recovery bottom hole assembly having a casing spear, a flow modifier and one or more further elements including a shock sub. The flow modifier produces cyclic variations in fluid flow through the assembly at a first frequency and at least one of the elements is configured to have a natural or resonant frequency when vibrated to be near or at the first frequency. By tuning elements of the bottom hole assembly to be close or at the frequency of the output of the flow modifier, the dynamic amplification factor of the system is maximised and longer lengths of casing can be recovered. A method of recovering casing using the vibratory casing recovery bottom hole assembly is also described. Further embodiments include a casing cutter and a hydraulic jack.

Abstract: A single trip casing cutting and pulling assembly which includes a casing spear (12), a mud motor (16) and a casing cutter (18), wherein a valve (14) is located between the casing spear (12) and the mud motor (16). The casing spear is operated by fluid flow from surface and the valve (14) prevents operation of the casing cutter (18) until the casing spear (12) is set and casing cutting is required. A method is described for cutting and pulling casing which does not require any rotation of the drill string to operate any part of the casing cutting and pulling assembly. An embodiment is described which includes retrieving the seal assembly (48) on the same trip. Further embodiments describe performing an integrity test and a circulation test on the same trip with the option of making further cuts at shallower depths on the same trip until a section of cut casing can be recovered.

Abstract: A downhole tool which allows the selective operation of a second fluid pressure activated tool below a first fluid pressure activated tool on a tool string in a well. The downhole tool has a piston sleeve moveable inside a cylindrical body between a first position in which a small flow area is provided through the tool and a second position in which a larger flow area is provided. The piston sleeve is held in the first position by a magnet and the first fluid pressure activated tool can be operated by increasing fluid pressure above the tool up to a cracking pressure level which matches the pulling strength of the magnet. Increasing fluid pressure to the cracking pressure therefore selectively moves the piston sleeve to the second position in which the second fluid pressure activated tool can be operated. The downhole tool is resettable.

Abstract: A method and apparatus for casing recovery for well abandonment. A string is run-in, the string including a hydraulic jack (18), an anchor (28), a casing spear (20), a downhole flow pulsing device (22) and a pressure drop sub (24). The casing spear grips an upper end of the length of casing to be pulled. The anchor is set in casing of a greater diameter above the length of cut casing. Fluid pumped through the string and through the pressure drop sub will increase fluid pressure at the hydraulic jack to a first fluid pressure (78). Fluid pumped through the downhole flow pulsing device will vary the fluid flow superimposing a cyclic pressure (82) on the first pressure (78), causing oscillation of an inner mandrel (30) of the hydraulic jack. The jack moves the oscillating inner mandrel upwards relative to the anchor to pull the length of casing.

Abstract: The invention provides a downhole tool for cutting a wellbore casing. The downhole tool comprises a gripping mechanism for gripping a section of wellbore casing and a cutting mechanism configured to cut the casing. The grip mechanism is configured to grip a range of casing diameters.

Abstract: A method of recovering casing in a wellbore using a vibratory casing recover), bottom hole assembly. In a vibratory casing recover), bottom hole assembly having a casing spear, a flow modifier and one or more further elements including a shock sub. The flow modifier produces cyclic variations in fluid flow through the assembly at a first frequency and at least one of the elements is configured to have a natural or resonant frequency when vibrated to be near or at the first frequency. By tuning elements of the bottom hole assembly to be close or at the frequency of the output of the flow modifier, the dynamic amplification factor of the system is maximised and longer lengths of casing can be recovered. A method of recovering casing using the vibratory casing recover), bottom hole assembly is also described. Further embodiments include a casing cutter and a hydraulic jack.

Abstract: A vibratory casing recovery bottom hole assembly and a method of recovering casing in a wellbore. The vibratory casing recovery bottom hole assembly includes a casing spear, a flow modifier and a dynamic amplification tool. The flow modifier produces cyclic variations in fluid pressure through the assembly at a first frequency and the bottom hole assembly is configured to have a natural or resonant frequency when vibrated to be near or at the first frequency. The dynamic amplification tool induces vibration in the bottom hole assembly while ensuring the dynamic amplification factor of the system is greater than one so as to transmit maximum vibration to the casing at the casing spear. Embodiments of dynamic amplification tools are described.

Abstract: Apparatus (10) and method for removing a section of well tubing. A work string including a hydraulic tensioning device (14) and a section mill (12) a run in a rigless arrangement to provide continuous upward milling of the tubing (24) by raising the work string at a desired rate of progress. The hydraulic tensioning device (14) has a lower end (34) moveable longitudinally relative to the work string by application of fluid pressure in the work string to apply a weight on the section mill. The hydraulic tensioning device includes a self-correcting mechanism (30) to maintain the lower end at a position between a fully extended position and a fully retracted position to provide continuous milling of the tubing by the section mill at a milling rate matching the rate at which the work string is lifted. Embodiments are described for use in a rigless well abandonment procedure.

Abstract: A resettable mechanism and a method of controlled actuation of a hydraulically operated downhole tool to allow selective operation of the downhole tool in a wellbore. The resettable mechanism provides an inner sleeve member which is longitudinally moveable between a first and second position which opens and closes a fluid pathway to at least one actuation port on the downhole tool. Movement of the inner sleeve member is controlled via an indexing mechanism operated by drop balls. An embodiment of a casing recovery system is described mechanism operated wherein a downhole pulling tool is selectively actuated so as to prevent operation of the pulling tool while a hydraulically operated casing cutter is cutting casing.

Abstract: Method and apparatus for removing a section of well tubing. The well tubing (24) is milled in an upward direction on a hydraulic tensioning device (14) which maintains a constant load on the section mill so that long sections of tubing can be removed in a near continuous procedure on a single trip into the well. The hydraulic device includes an indicator (30) to provide a signal as the device nears each end of a stroke to inform a user that: the section mill is about to bottom out and the work string needs to be raised to extend the device; and the device is fully extended and can begin another stroke. Embodiments are described for use in a rigless well abandonment procedure.

Abstract: A downhole tool which allows the selective operation of a second fluid pressure activated tool below a first fluid pressure activated tool on a tool string in a well. The downhole tool has a piston sleeve moveable inside a cylindrical body between a first position in which a small flow area is provided through the tool and a second position in which a larger flow area is provided. The piston sleeve is held in the first position by a magnet and the first fluid pressure activated tool can be operated by increasing fluid pressure above the tool up to a cracking pressure level which matches the pulling strength of the magnet. Increasing fluid pressure to the cracking pressure therefore selectively moves the piston sleeve to the second position in which the second fluid pressure activated tool can be operated. The downhole tool is resettable.

Abstract: A downhole anchor mechanism (110) which can be set on at least two successive standard diameters of casing (232). The tool body has a recess into which a split cone (70) is located. The increased thickness of the split cone (70) provides for a greater thickness of slip (90), giving increased radial travel of the slips 90 when moved axially over the split cone (70). The cone (70) and slips (90) are profiled to provide two ramps/slopes for increased structural integrity and a greater ramp angle to reduce the axial travel of the slips to achieve the increased radial travel. The downhole anchor mechanism (110) provides anchoring of a work string on two standard diameters of casing in a single trip in a wellbore.

Abstract: A well bore integrity test tool (10) and method of pressure integrity testing a well bore by performing positive and negative pressure tests in a well bore in multiple locations in the well and on the same trip as other operations in the well bore. The tool includes a resettable anchor mechanism (20) and a tension set packer assembly (22). An embodiment of performing a dress-off, integrity testing, casing cutting and pulling in a single trip for well abandonment is described.

Abstract: A single trip casing cutting and pulling assembly which includes a casing spear (12), a mud motor (16) and a casing cutter (18), wherein a valve (14) is located between the casing spear (12) and the mud motor (16). The casing spear is operated by fluid flow from surface and the valve (14) prevents operation of the casing cutter (18) until the casing spear (12) is set and casing cutting is required. A method is described for cutting and pulling casing which does not require any rotation of the drill string to operate any part of the casing cutting and pulling assembly. An embodiment is described which includes retrieving the seal assembly (48) on the same trip. Further embodiments describe performing an integrity test and a circulation test on the same trip with the option of making further cuts at shallower depths on the same trip until a section of cut casing can be recovered.

Abstract: Apparatus (10) and method for removing a section of well tubing. A work string including a hydraulic tensioning device (14) and a section mill (12) a run in a rigless arrangement to provide continuous upward milling of the tubing (24) by raising the work string at a desired rate of progress. The hydraulic tensioning device (14) has a lower end (34) moveable longitudinally relative to the work string by application of fluid pressure in the work string to apply a weight on the section mill. The hydraulic tensioning device includes a self-correcting mechanism (30) to maintain the lower end at a position between a fully extended position and a fully retracted position to provide continuous milling of the tubing by the section mill at a milling rate matching the rate at which the work string is lifted. Embodiments are described for use in a rigless well abandonment procedure.

Abstract: A resettable mechanism for preventing the accidental actuation of a load set downhole tool and method of use. The resettable mechanism provides a collet (52) and a detent (56) with a collet ring arranged to ride over the detent under a load in excess of the operating load of the downhole tool and the collet load. Reversing the loading resets the mechanism and the downhole tool. A disengagement assembly (66) is described to disenable the detent (56) and operate the downhole tool at the operating load. Embodiments to a retrievable mechanical tension-set packer and a casing cutting and removal system are described which prevent premature actuation of the packer when run from floating structures.

Abstract: The invention provides a method of determining the condition of a cement bond of a casing in a wellbore. The method comprises perforating a tubing in the wellbore at a zone of interest and displacing a settable composition through the perforations into the annulus between the casing and tubing to secure the tubing. The method also comprises cutting the tubing and assessing the status of the cement bond of the casing.

Abstract: A method for removing one or more control lines (15) in a well (1), the control lines (15) running in an annulus behind a tubular (7) in the wellbore, during a well abandonment procedure comprising the steps: perforating the tubular (7) at a location adjacent the one or more control lines (15); displacing a self-supporting settable composition (21) through the perforations (20) into the annulus (18) to secure the one or more control lines (15) in place; cutting the tubular (7) and the one or more control lines (15) at the location of the self-supporting settable composition (21); washing away the self-supporting settable composition (21); and removing at least a portion of the one or more control lines from the wellbore. Embodiments are described for control lines (15) run in an annulus (18) between production tubing (7) and casing, pulling the production tubing (7) with the control lines (15), and milling the production tubing and control lines in a rigless method for well abandonment.

Abstract: A rigless method for abandoning a well in which the production tubing (7) and control lines (15) are left in place. The production tubing (7) is perforated at a zone of interest at any position in the well. A settable composition (21) which is dissolvable in acid is injected through the perforations (20a, 20b) into the annulus between the casing (5) and the production tubing (7) over the zone of interest and allowed to set. The composition supports the tubing (7) and secures the control lines (15) so that they can be cut and milled away to expose the casing. An acid wash is performed to remove all the settable composition and clean the casing (5) in preparation for a cement bond log to be performed. If the quality of the cement bond is acceptable a cement plug (28) is deployed. Further cuts in the production tubing (7) can be made to expose further sections of casing (5) in the event that the cement bond log is unacceptable.