A downhole apparatus comprises a casing string with a frangible disk positioned therein. A flow barrier is connected in the casing string and spaced downwardly from the frangible disk. The frangible disk and the flow barrier define a buoyancy chamber. The sliding sleeve will impact and shatter the frangible disk into a plurality of pieces that will pass downwardly in the casing after the casing has been lowered to a desired depth.

An inflatable multifunctional downhole tool includes a body having an outer shell and a threaded connection at an axial end of the body, at least one pressurized container disposed inside the outer shell, the pressurized container containing compressed gas, a plurality of floatation chambers fluidly connected through connection lines to the at least one pressurized container, a dissolvable plug positioned along each of the connection lines between the floatation chambers and the at least one pressurized container, and a tool sub threadably connected to the threaded connection of the body.

A completion assembly includes an upper liner and a lower liner, a wellbore completion component that interposes the upper and lower liners, a dissolvable pipe plug secured within an aperture defined in the wellbore completion component, and a dissolvable projectile seat arranged adjacent the wellbore completion component.

A method of deploying a plug in a subterranean well can include positioning a tool string in the well, the tool string including a plug release tool and a well tool, then releasing the plug from the plug release tool, and then operating the well tool in response to the releasing the plug. A plug release tool for use in a subterranean well can include an outer housing, and an insert secured in the outer housing, the insert including multiple longitudinally extending flow passages formed through the insert.

A valve housing has a first flapper moveable from an open position in the housing in which two-way flow is allowed to a closed position in which only one-way flow is permitted. A first collet sleeve is moveable from a first position to a second position in the valve housing. The first collet sleeve in the first position retains the flapper valve in the open position. The collet sleeve is moveable from a first position to a second position which allows the flapper to move to a closed position.

Geologic material in a borehole is weakened by accelerating a projectile into contact with the material. A drill bit is then used to bore through the weakened material. To accelerate the projectile, an endcap is placed in a conduit using a source of gas. The endcap isolates the conduit from the external environment. A projectile is then positioned in the conduit above the endcap. Movable members within the conduit are operated in sequence to enable single endcaps and projectiles to be moved into the conduit. Gas from the conduit is evacuated into an annulus between the conduit and a surrounding conduit, and a propellant material is provided into the conduit. The propellant material applies a force to the projectile to accelerate the projectile into contact with the geologic material. A fluid is circulated down a second annulus outside of the surrounding conduit to contact the drill bit and remove debris.

A completion assembly includes an upper liner and a lower liner, a wellbore completion component that interposes the upper and lower liners, a dissolvable pipe plug threaded into the wellbore completion component, and a dissolvable projectile seat arranged adjacent the wellbore completion component.

A plug assembly includes an expandable assembly and a locking ring. The expandable assembly is adapted to be deformed radially over the locking ring. The locking ring has a stopping inner surface. The plug assembly is used with an untethered object, which has an outer surface adapted to couple with the stopping inner surface of the locking ring. The untethered object is also adapted to contact an inner surface of the plug assembly and, using well fluid pressure, to apply forces to the plug assembly. The forces cause the longitudinal movement of the untethered object while contacting the inner surface of the plug assembly until the untethered object contacts the stopping inner surface of the locking ring.

Embodiments described herein provide systems and methods for minimizing deceleration of downhole tools when the downhole tools are pumped down into wellbores through drill pipe in an untethered manner. For example, embodiments described herein include a hydraulic downhole tool deceleration system that includes a hydraulic decelerator configured to be affixed to a downhole tool string pumped down through drill pipe during operation. The hydraulic decelerator is configured to contact a hard shoulder while traveling through the drill pipe, and to limit an initial magnitude of deceleration of the downhole tool string caused at the initial moment of contact of the hydraulic decelerator against the hard shoulder.

A wellbore tubular flotation device comprises a housing having a locking element disposed thereon. The housing is shaped to move through an interior of a wellbore tubular segment. The locking element is shaped to engage the interior of the wellbore tubular segment. The locking element comprises a locking mechanism configured to urge the locking element into contact with the interior of the wellbore tubular. A burst disk is engaged with the housing and is shaped to close the tubular segment to fluid flow. A release mechanism is configured to reverse the urging of the locking mechanism when a release tool is moved through the housing.