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.

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.

A mechanically locking hydraulic jar device includes an outer sleeve, an inner sleeve partially disposed in an inner bore of the outer sleeve, and a mechanical lock engaging the outer sleeve and the inner sleeve in a default position to axially secure the inner sleeve to the outer sleeve. Activation of the hydraulic jar disables the mechanical lock to allow axial movement of the inner sleeve relative to the outer sleeve, which generates an impact force when the inner sleeve reaches an activated position. The hydraulic jar device also includes an upward block and a downward block configured to limit the upward and downward axial movement, respectively, of the inner sleeve relative to the outer sleeve when the mechanical lock is disabled.

A mechanically locking hydraulic jar device includes an outer sleeve, an inner sleeve partially disposed in an inner bore of the outer sleeve, and a mechanical lock engaging the outer sleeve and the inner sleeve in a default position to axially secure the inner sleeve to the outer sleeve. Activation of the hydraulic jar disables the mechanical lock to allow axial movement of the inner sleeve relative to the outer sleeve, which generates an impact force when the inner sleeve reaches an activated position. The hydraulic jar device also includes an upward block and a downward block configured to limit the upward and downward axial movement, respectively, of the inner sleeve relative to the outer sleeve when the mechanical lock is disabled.

A downhole impact apparatus operable to impart an impact to an object within a wellbore. The impact apparatus may include a housing, a first chamber within the housing, a second chamber within the housing, and a piston assembly slidably disposed within the housing. The piston assembly may include a first piston slidably disposed within the first chamber and dividing the first chamber into a first volume and a second volume, a second piston slidably disposed within the second chamber, and a shaft connecting the first and second pistons. The first volume may be open to a space external to the housing and the second volume may be fluidly isolated from the space external to the housing. Relative movement between the piston assembly and the housing ends with the impact. The second chamber may be configured to contain a fluid to prevent relative movement between the piston assembly and the housing.

A mechanical jar including a housing, a piston disposed in the housing and responsive to applied fluid pressure to move in a first direction relative to the housing, a biasing arrangement disposed in the housing and configured to bias the piston in a second direction opposite the first direction, and a restraint configured to prevent movement of the piston in the second direction until a threshold force is applied to the restraint by the piston, whereafter the piston suddenly moves in the second direction.

A mechanical jar including a housing, a piston disposed in the housing and responsive to applied fluid pressure to move in a first direction relative to the housing, a biasing arrangement disposed in the housing and configured to bias the piston in a second direction opposite the first direction, and a restraint configured to prevent movement of the piston in the second direction until a threshold force is applied to the restraint by the piston, whereafter the piston suddenly moves in the second direction.

Systems and methods for moving a tubular string within a subterranean well include a downhole assembly. The downhole assembly includes a torque disconnecting member and a shock generating member. During normal drilling activities, both components are inactive. When a stuck pipe event occurs, first the torque disconnecting member is activated while the shock generating member is still inactive. Once the torque disconnecting member is activated, then the shock generating member is activated. A laterally-protruding shock pad of the activated shock generating member produces shocks against the proximate side of a wellbore wall while the shock generating member is rotating. Systems and methods for moving a tubular string within a subterranean well include a fishing assembly. The fishing assembly includes a fishing member, a swivel member, and an imbalanced member. The imbalanced member has a cross-sectional center of gravity off-centered relative to the longitudinal axis to produce shocks against the proximate side of the wellbore wall while the imbalanced member is rotating.

Systems and methods for moving a tubular string within a subterranean well include a downhole assembly. The downhole assembly includes a torque disconnecting member and a shock generating member. During normal drilling activities, both components are inactive. When a stuck pipe event occurs, first the torque disconnecting member is activated while the shock generating member is still inactive. Once the torque disconnecting member is activated, then the shock generating member is activated. A laterally-protruding shock pad of the activated shock generating member produces shocks against the proximate side of a wellbore wall while the shock generating member is rotating. Systems and methods for moving a tubular string within a subterranean well include a fishing assembly. The fishing assembly includes a fishing member, a swivel member, and an imbalanced member. The imbalanced member has a cross-sectional center of gravity off-centered relative to the longitudinal axis to produce shocks against the proximate side of the wellbore wall while the imbalanced member is rotating.

A pulsating hammer tool providing longer, stronger and frequent shock waves is disclosed. Selective closure of a poppet valve and interruptions of fluid flow through sliding valve assemblies and a flow regulator valve, generates shock waves and induces opening of the poppet valve. Shock waves generated by the sliding valve assemblies and the flow regulator valve combine with those generated by opening/closing of the poppet valve resulting in waves with increased amplitude. Shape, dimensions and orientations of flow paths through flow regulator valve are chosen to impart desired frequency and magnitude to generated shock waves. Similarly, the frequency of shock waves generated by the valve assemblies can be controlled by varying lengths of the valve mid-sections and/or wash pipes, or by adjusting fluid pressure or the number and size of vents.