Abstract: Wellbore isolation is used for a tubing string in a well. A first plug is held by a first temporary retention in a bore of a housing disposed on the tubing string and is sealed in the bore with a first seal. A second plug is also held in the bore by a second temporary retention and is sealed in the bore with a second seal. The first and second seals seal a space in the bore between the plugs. Both plugs can be of a dissolvable material. An uphole end of the first plug facing away from the space can have a non-dissolvable coating, while a downhole end of the second plug facing away from the space can have a non-dissolvable coating. The first plug releases in the bore when an uphole pressure is applied in the tubing string, and the second plug then releases after the first plug.

Abstract: Wellbore isolation is used for a tubing string in a well. A first plug is held by a first temporary retention in a bore of a housing disposed on the tubing string and is sealed in the bore with a first seal. A second plug is also held in the bore by a second temporary retention and is sealed in the bore with a second seal. The first and second seals seal a space in the bore between the plugs. Both plugs can be of a dissolvable material. An uphole end of the first plug facing away from the space can have a non-dissolvable coating, while a downhole end of the second plug facing away from the space can have a non-dissolvable coating. The first plug releases in the bore when an uphole pressure is applied in the tubing string, and the second plug then releases after the first plug.

Abstract: A downhole sleeve has an insert movable in the sleeve's bore from a closed condition to an opened condition when a ball dropped in the bore engages an indexing seat in the sliding sleeve. In the closed condition, the insert prevents communication between the bore and the sleeve's port, while the insert in the opened condition permits communication between the bore and port. Keys of a seat extend into the bore to engage the ball and to move the insert open. After opening, the keys retract so the ball can pass through the sleeve to another cluster sleeve or to an isolation sleeve of an assembly. Insets or buttons disposed in the sleeve's port temporarily maintain fluid pressure in the sleeve's bore so that a cluster of sleeves can be opened before treatment fluid dislodges the button to treat the surrounding formation through the open port.

Abstract: A downhole sleeve has an insert movable in the sleeve's bore from a closed condition to an opened condition when a ball dropped in the bore engages an indexing seat in the sliding sleeve. In the closed condition, the insert prevents communication between the bore and the sleeve's port, while the insert in the opened condition permits communication between the bore and port. Keys of a seat extend into the bore to engage the ball and to move the insert open. After opening, the keys retract so the ball can pass through the sleeve to another cluster sleeve or to an isolation sleeve of an assembly. Insets or buttons disposed in the sleeve's port temporarily maintain fluid pressure in the sleeve's bore so that a cluster of sleeves can be opened before treatment fluid dislodges the button to treat the surrounding formation through the open port.

Abstract: A downhole sleeve has an insert movable in the sleeve's bore from a closed condition to an opened condition when a ball dropped in the bore engages an indexing seat in the sliding sleeve. In the closed condition, the insert prevents communication between the bore and the sleeve's port, while the insert in the opened condition permits communication between the bore and port. Keys of a seat extend into the bore to engage the ball and to move the insert open. After opening, the keys retract so the ball can pass through the sleeve to another cluster sleeve or to an isolation sleeve of an assembly. Insets or buttons disposed in the sleeve's port temporarily maintain fluid pressure in the sleeve's bore so that a cluster of sleeves can be opened before treatment fluid dislodges the button to treat the surrounding formation through the open port.

Abstract: A downhole sleeve has an insert movable in the sleeve's bore from a closed condition to an opened condition when a ball dropped in the bore engages an indexing seat in the sliding sleeve. In the closed condition, the insert prevents communication between the bore and the sleeve's port, while the insert in the opened condition permits communication between the bore and port. Keys of a seat extend into the bore to engage the ball and to move the insert open. After opening, the keys retract so the ball can pass through the sleeve to another cluster sleeve or to an isolation sleeve of an assembly. Insets or buttons disposed in the sleeve's port temporarily maintain fluid pressure in the sleeve's bore so that a cluster of sleeves can be opened before treatment fluid dislodges the button to treat the surrounding formation through the open port.

Abstract: A downhole sleeve has a sliding sleeve movable in a bore of the sleeve's housing. The sliding sleeve is movable from a closed condition to an opened condition when a ball is dropped in the sleeve's bore and engages an indexing seat in the sliding sleeve. The sliding sleeve in the closed condition prevents communication between the bore and the port, and the sleeve in the opened condition permits communication between the bore and the port. In the closed condition, keys of the seat extend into the bore to engage the ball and to move the sliding sleeve open. In the opened condition, the keys of the seat retract from the bore so the ball can pass through the sleeve to another cluster sleeve or to another isolation sleeve of an assembly.