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: Re-treatment of a formation having a wellbore, which can be an open hole or a cased hole lined with casing, involves deploying a tubing string in the casing having tools disposed at intervals thereon. The tools position on the tubing string, and the tubing string with the tools thereon is inserted into the casing. Biasing rings of the tools passively engage with the casing. The annulus is accessed between the tubing string and the casing at the intervals between the tools. For example, sliding sleeves on the tubing string can be opened (selectively), or new plug and perforation operations can be used to create perforations in the tubing string at desired intervals between the tools. With access achieved, retreatment is pumped down the tubing string, out the access to the annulus, and at least partially sealed by the engaged rings in the intervals between the tools.

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: Re-treatment of a formation having a wellbore, which can be an open hole or a cased hole lined with casing, involves deploying a tubing string in the casing having tools disposed at intervals thereon. The tools position on the tubing string, and the tubing string with the tools thereon is inserted into the casing. Biasing rings of the tools passively engage with the casing. The annulus is accessed between the tubing string and the casing at the intervals between the tools. For example, sliding sleeves on the tubing string can be opened (selectively), or new plug and perforation operations can be used to create perforations in the tubing string at desired intervals between the tools. With access achieved, retreatment is pumped down the tubing string, out the access to the annulus, and at least partially sealed by the engaged rings in the intervals between the tools.