Abstract: A well barrier can include an inner mandrel, a flow passage, and a releasably secured plug. The plug blocks fluid flow through the flow passage, and includes a shoulder that prevents the plug from displacing completely through the inner mandrel. A method of treating a subterranean well can include treating a deeper zone, setting a well barrier in the well between the deeper zone and a shallower zone, then treating the shallower zone, and then applying a pressure differential from the deeper to the shallower zone, thereby displacing a plug out of the well barrier. A well treatment system can include a well barrier with a plug releasably secured to an inner mandrel. The plug is released by application of a pressure differential in a longitudinal direction, and fluid communication is unblocked by application of a pressure differential in an opposite longitudinal direction.

Abstract: A pressure isolation assembly can include multiple pressure isolation modules arranged in series and isolating a pressure actuated downhole tool from a downhole fluid pressure. Each of the modules may be configured to open in response to a single pressure cycle comprising an increase in the downhole fluid pressure followed by a decrease in the downhole fluid pressure. A method can include determining a number of fluid pressure cycles to apply to enable actuation of a downhole tool; installing a number of pressure isolation modules in a pressure isolation assembly, the number corresponding to the number of pressure cycles; deploying the downhole tool and the pressure isolation assembly while the pressure isolation assembly isolates a fluid passage of the downhole tool from downhole fluid pressure; and applying the number of pressure cycles, thereby permitting communication of at least a fraction of the downhole fluid pressure to the fluid passage.

Abstract: A well barrier can include an inner mandrel, a flow passage, and a releasably secured plug. The plug blocks fluid flow through the flow passage, and includes a shoulder that prevents the plug from displacing completely through the inner mandrel. A method of treating a subterranean well can include treating a deeper zone, setting a well barrier in the well between the deeper zone and a shallower zone, then treating the shallower zone, and then applying a pressure differential from the deeper to the shallower zone, thereby displacing a plug out of the well barrier. A well treatment system can include a well barrier with a plug releasably secured to an inner mandrel. The plug is released by application of a pressure differential in a longitudinal direction, and fluid communication is unblocked by application of a pressure differential in an opposite longitudinal direction.

Abstract: A well barrier can include an inner mandrel, a flow passage, and a releasably secured plug. The plug blocks fluid flow through the flow passage, and includes a shoulder that prevents the plug from displacing completely through the inner mandrel. A method of treating a subterranean well can include treating a deeper zone, setting a well barrier in the well between the deeper zone and a shallower zone, then treating the shallower zone, and then applying a pressure differential from the deeper to the shallower zone, thereby displacing a plug out of the well barrier. A well treatment system can include a well barrier with a plug releasably secured to an inner mandrel. The plug is released by application of a pressure differential in a longitudinal direction, and fluid communication is unblocked by application of a pressure differential in an opposite longitudinal direction.

Abstract: A well barrier can include an inner mandrel, a flow passage, and a releasably secured plug. The plug blocks fluid flow through the flow passage, and includes a shoulder that prevents the plug from displacing completely through the inner mandrel. A method of treating a subterranean well can include treating a deeper zone, setting a well barrier in the well between the deeper zone and a shallower zone, then treating the shallower zone, and then applying a pressure differential from the deeper to the shallower zone, thereby displacing a plug out of the well barrier. A well treatment system can include a well barrier with a plug releasably secured to an inner mandrel. The plug is released by application of a pressure differential in a longitudinal direction, and fluid communication is unblocked by application of a pressure differential in an opposite longitudinal direction.

Abstract: A completion apparatus for a wellbore includes several flow tools and an actuation mechanism. The flow tools have a piston defining first and second chambers with a housing. The chambers communicate with hydraulics so the piston are movable in response to the communicated hydraulics. A sleeve disposed in the housing is movable with the piston between first, second, and third positions. The sleeve can have a seat movable between two conditions for passing/engaging plugs. The sleeve in the first position closes off communication through the first and second ports, and the sleeve in the second position permits communication through the first port and closes off communication through the second port. The sleeve in the third position closes off communication through the first port and permits communication through the second port. The actuation mechanism is operable to communicate the hydraulics respectively with the chambers of the flow tools.

Abstract: A downhole tool has a housing with a communication path extending from a first to a second part of a bore. An indexer disposed in the communication path is movably responsive to applied pressure at the first part. The indexer counts a number of applications of the applied pressure and permits fluid communication of the applied pressure from the first part to the second part in response to the counted number. An insert in the housing bore sealably encloses the second part of the communication path and is movable from a first position covering to a second position uncovering a port in the housing. At least a portion of the insert acted upon by the applied fluid pressure in the second part initiates movement of the insert from the first to the second position. A kit having a modular housing portion and the indexer can adapt the downhole tool for use.

Abstract: A downhole tool has a housing with a communication path extending from a first to a second part of a bore. An indexer disposed in the communication path is movably responsive to applied pressure at the first part. The indexer counts a number of applications of the applied pressure and permits fluid communication of the applied pressure from the first part to the second part in response to the counted number. An insert in the housing bore sealably encloses the second part of the communication path and is movable from a first position covering to a second position uncovering a port in the housing. At least a portion of the insert acted upon by the applied fluid pressure in the second part initiates movement of the insert from the first to the second position. A kit having a modular housing portion and the indexer can adapt the downhole tool for use.

Abstract: A completion apparatus for a wellbore includes several flow tools and an actuation mechanism. The flow tools have a piston defining first and second chambers with a housing. The chambers communicate with hydraulics so the piston are movable in response to the communicated hydraulics. A sleeve disposed in the housing is movable with the piston between first, second, and third positions. The sleeve can have a seat movable between two conditions for passing/engaging plugs. The sleeve in the first position closes off communication through the first and second ports, and the sleeve in the second position permits communication through the first port and closes off communication through the second port. The sleeve in the third position closes off communication through the first port and permits communication through the second port. The actuation mechanism is operable to communicate the hydraulics respectively with the chambers of the flow tools.

Abstract: A completion apparatus for a wellbore includes several flow tools and an actuation mechanism. The flow tools have a piston defining first and second chambers with a housing. The chambers communicates with hydraulics so the piston are movable in response to the communicated hydraulics. A sleeve disposed in the housing is movable with the piston between first, second, and third positions. The sleeve can have a seat movable between two conditions for passing/engaging plugs. The sleeve in the first position closes off communication through the first and second ports, and the sleeve in the second position permits communication through the first port and closes off communication through the second port. The sleeve in the third position closes off communication through the first port and permits communication through the second port. The actuation mechanism is operable to communicate the hydraulics respectively with the chambers of the flow tools.

Abstract: A downhole tool, such as a toe sleeve, has an insert movably disposed in the housing's bore and sealably enclosing a second part of the communication path from a first port. A barrier disposed between the first and second parts of the communication path is breachable in response to a level of the applied pressure in the housing's bore. At least one retainer is engaged between the insert and the housing and at least temporarily retains the insert toward a closed position. The at least one retainer is at least partially composed of a dissolvable material and at least partially dissolves in response to the applied pressure communicated through the communication path to the second part. The at least one retainer when at least partially dissolved permits the applied pressure to initiate movement of the insert, such as from a closed position toward an opened position.

Abstract: A completion apparatus for a wellbore includes several flow tools and an actuation mechanism. The flow tools have a piston defining first and second chambers with a housing. The chambers communicates with hydraulics so the piston are movable in response to the communicated hydraulics. A sleeve disposed in the housing is movable with the piston between first, second, and third positions. The sleeve can have a seat movable between two conditions for passing/engaging plugs. The sleeve in the first position closes off communication through the first and second ports, and the sleeve in the second position permits communication through the first port and closes off communication through the second port. The sleeve in the third position closes off communication through the first port and permits communication through the second port. The actuation mechanism is operable to communicate the hydraulics respectively with the chambers of the flow tools.

Abstract: A downhole tool, such as a toe sleeve, has an insert movably disposed in the housing's bore and sealably enclosing a second part of the communication path from a first port. A barrier disposed between the first and second parts of the communication path is breachable in response to a level of the applied pressure in the housing's bore. At least one retainer is engaged between the insert and the housing and at least temporarily retains the insert toward a closed position. The at least one retainer is at least partially composed of a dissolvable material and at least partially dissolves in response to the applied pressure communicated through the communication path to the second part. The at least one retainer when at least partially dissolved permits the applied pressure to initiate movement of the insert, such as from a closed position toward an opened position.

Abstract: A downhole tool has a housing with a communication path extending from a first to a second part of a bore. An indexer disposed in the communication path is movably responsive to applied pressure at the first part. The indexer counts a number of applications of the applied pressure and permits fluid communication of the applied pressure from the first part to the second part in response to the counted number. An insert in the housing bore sealably encloses the second part of the communication path and is movable from a first position covering to a second position uncovering a port in the housing. At least a portion of the insert acted upon by the applied fluid pressure in the second part initiates movement of the insert from the first to the second position. A kit having a modular housing portion and the indexer can adapt the downhole tool for use.