Techniques for removing a tubular from a wellbore include running a downhole tool on a downhole conveyance into a wellbore formed from a terranean surface into a subterranean formation; activating a piston sub-assembly to repeatedly move pistons to contact a portion of a casing installed in the wellbore to at least de-bond a cement layer installed between the portion of the casing and the subterranean formation from the portion of the casing; activating a cutting sub-assembly to move a cutting blade to cut through the portion of the casing adjacent the de-bonded portion of the cement layer; activating a hanger sub-assembly to move a set of slips into contacting engagement with the cut portion of the casing; and running the downhole tool on the downhole conveyance out of the wellbore with the cut portion of the casing engaged with the set of slips.

A buoyancy assist tool and a fluid barrier in a casing string define a buoyancy chamber therebetween. The buoyancy assist tool has a housing connected in the casing string with a retaining sleeve detachably connected in the housing. The retaining sleeve is movable from a first to a second position in the housing. A flapper disk is positioned in the housing and covers an upper end of the retaining sleeve in the first position of the retaining sleeve. In the second position of the retaining sleeve the flapper disk is in a retracted position out of the flow path through the housing.

A method for dissipating force within a tubing string including providing a severing device to a desired location within a tubing string; a cut zone along the length of the tubing, and a housing disposed along the length of tubing and sized to enclose the cut zone therein, wherein the housing includes a first end and a second end each forming a housing shoulder, severing the tubing at the cut zone using the severing device creating a first tubing section and a second tubing section; wherein the first tubing section and the second tubing section slide apart within the housing.

A method for dissipating force within a tubing string including providing a severing device to a desired location within a tubing string; a cut zone along the length of the tubing, and a housing disposed along the length of tubing and sized to enclose the cut zone therein, wherein the housing includes a first end and a second end each forming a housing shoulder, severing the tubing at the cut zone using the severing device creating a first tubing section and a second tubing section; wherein the first tubing section and the second tubing section slide apart within the housing.

An assembly disposed within a subterranean wellbore can include a first dislodging tool coupled to a bottom end of a tubing string, wherein the first dislodging tool, when enabled at a first time, performs a first action to free at least one service tool, disposed below the first dislodging tool in the subterranean wellbore, from being stuck.

An assembly disposed within a subterranean wellbore can include a first dislodging tool coupled to a bottom end of a tubing string, wherein the first dislodging tool, when enabled at a first time, performs a first action to free at least one service tool, disposed below the first dislodging tool in the subterranean wellbore, from being stuck.

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.

A method and apparatus for casing recovery in which a clean-up of the inside of the outer casing above the inner casing is performed on the same trip in the wellbore as cutting and pulling a section of the inner casing. A bottom hole assembly including a spear, a casing cutter and at least one clean-up tool is described. An embodiment of a clean-up tool being a jetting sub which can jet fluid radially to wash the outer casing and selectively allow fluid to pass through the sub at different pressures is described. The jetting sub can be used to control operation of other tools in the bottom hole assembly such as the casing cutter and a hydraulic jack.

A method and apparatus for casing recovery in which a clean-up of the inside of the outer casing above the inner casing is performed on the same trip in the wellbore as cutting and pulling a section of the inner casing. A bottom hole assembly including a spear, a casing cutter and at least one clean-up tool is described. An embodiment of a clean-up tool being a jetting sub which can jet fluid radially to wash the outer casing and selectively allow fluid to pass through the sub at different pressures is described. The jetting sub can be used to control operation of other tools in the bottom hole assembly such as the casing cutter and a hydraulic jack.

A downhole apparatus including a sleeve, a tool string, a plug, a means for setting the plug wherein an upper portion of the sleeve is connectable to a lower portion of the tool string, and a lower portion of the sleeve is arranged to receive the plug and the means for setting the plug. A method for using the downhole apparatus (1) is disclosed.