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.

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.

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 modular reamer shoe for connection to an end of a tubular structure, such as a casing or liner, for deployment in a wellbore includes a body configured for connection to the tubular structure (casing or liner). The body includes a first section and an adjacent second section. The first section is connected to the second section such that torque can be transmitted between the first section and the second section. The first section defines a starter reamer defined by a plurality of first cutting elements and second cutting elements spaced from the first cutting elements. The reamer shoe has a plurality of actuatable blades disposed within the second area of the first section. The plurality of blades moves between extended positions and retracted positions. A nose is connected to the first section of the body. The second section is actuatable and can move in an axial direction so as to move the body, including the nose, in forward/rearward directions.

A release mechanism for a jarring tool is formed by a plurality of segmented release lugs. Each lug includes a plurality of axial spaced projections on an inner surface and a plurality of grooves on an outer surface. The projections have either different widths or are separated by varying distances and releaseably engage corresponding grooves in a mandrel located within a housing of the tool. The release lugs are positioned between a trigger sleeve and the mandrel. The release lugs may be supported by an annular ring member.

A release mechanism for a jarring tool is formed by a plurality of segmented release lugs. Each lug includes a plurality of axial spaced projections on an inner surface and a plurality of grooves on an outer surface. The projections have either different widths or are separated by varying distances and releaseably engage corresponding grooves in a mandrel located within a housing of the tool. The release lugs are positioned between a trigger sleeve and the mandrel. The release lugs may be supported by an annular ring member.

A downhole tool, for removing a restriction in a well tubular metal structure having a wall and an inner diameter, has a tool axis and a tool body having a first part and a second part, an electrical motor arranged in the first part for rotating a rotatable shaft, and a core bit arranged in the second part and having a first end connected with the rotatable shaft and a second end having a cutting edge. The second part of the downhole tool further includes a locator for locating the rim section, the locator being rotable with the core bit until the locator locates the rim section and a threshold value is reached.

A downhole tool, for removing a restriction in a well tubular metal structure having a wall and an inner diameter, has a tool axis and a tool body having a first part and a second part, an electrical motor arranged in the first part for rotating a rotatable shaft, and a core bit arranged in the second part and having a first end connected with the rotatable shaft and a second end having a cutting edge. The second part of the downhole tool further includes a locator for locating the rim section, the locator being rotable with the core bit until the locator locates the rim section and a threshold value is reached.

Methods of preventing stuck pipe include drilling a wellbore with a pipe comprising a multidirectional jarring apparatus. The multidirectional jarring apparatus comprises an internal helical groove that at least partially translates substantially vertical motion to rotational motion. The methods further include measuring a wellbore proximity of the multidirectional jarring apparatus to a sidewall of the wellbore, measuring drilling speed variability, analyzing the wellbore proximity of the multidirectional jarring apparatus to the sidewall of the wellbore and the drilling speed variability, and determining a torque value less than a required operating torque. The methods further include applying a load to the multidirectional jarring apparatus, thereby oscillating the multidirectional jarring apparatus along the internal helical groove to pre-emptively prevent stuck pipe.