A settable down hole tool is of increased drillability and/or of increased expansibility. The improvement in drillability can be caused by fracturing cast iron slips into a large number of small pieces that can be circulated out of a well without further reduction in size. The improvement in expansibility can be partially caused by providing an expander cone of increased hardness thereby allowing an increased angle on the expander cone and slips. The improvement in expansibility can be partially caused by increasing the thickness of the slips.

A method for enhanced oil recovery from a hydrocarbon bearing subterranean formation includes withdrawing hydrocarbons from a production well extending into the formation, identifying a high permeability streak in the formation, and injecting a dense CO.sub.2 composition from an injection well into the high permeability streak. The dense CO.sub.2 composition includes dense CO.sub.2 and a thickener soluble in the dense CO.sub.2. The thickener includes copolymer. The method includes, after injecting the dense carbon dioxide composition into the high permeability streak, injecting an aqueous treatment fluid into the formation. The dense CO.sub.2 composition blocks the high permeability streak to divert at least a portion of the aqueous treatment fluid into bypassed regions of the formation during the injecting of the aqueous treatment fluid, and the injecting of the aqueous treatment fluid into the hydrocarbon bearing subterranean formation drives hydrocarbons in the hydrocarbon bearing subterranean formation towards the production well.

A method for enhanced oil recovery from a hydrocarbon bearing subterranean formation includes withdrawing hydrocarbons from a production well extending into the formation, identifying a high permeability streak in the formation, and injecting a dense CO.sub.2 composition from an injection well into the high permeability streak. The dense CO.sub.2 composition includes dense CO.sub.2 and a thickener soluble in the dense CO.sub.2. The thickener includes copolymer. The method includes, after injecting the dense carbon dioxide composition into the high permeability streak, injecting an aqueous treatment fluid into the formation. The dense CO.sub.2 composition blocks the high permeability streak to divert at least a portion of the aqueous treatment fluid into bypassed regions of the formation during the injecting of the aqueous treatment fluid, and the injecting of the aqueous treatment fluid into the hydrocarbon bearing subterranean formation drives hydrocarbons in the hydrocarbon bearing subterranean formation towards the production well.

A plugging assembly includes a plug and a setting tool attached directly to the plug, wherein the plug includes an elongate core with an uphole end and a downhole end opposite the uphole end, and a sealing element disposed fully around the core to seal against the casing. The plug additionally includes an anchoring system for anchoring the plug to the casing in a fixed position, a compression fitting disposed around the core at or near the uphole end of the core, and a nose at the downhole end of the core. The setting tool includes an elongate housing extending between an uphole end and a downhole end opposite the uphole end, an open passageway extending from the uphole end to the downhole end of the housing, and the downhole end of the housing is aligned to directly engage the compression fitting of the plug.

A plugging assembly includes a plug and a setting tool attached directly to the plug, wherein the plug includes an elongate core with an uphole end and a downhole end opposite the uphole end, and a sealing element disposed fully around the core to seal against the casing. The plug additionally includes an anchoring system for anchoring the plug to the casing in a fixed position, a compression fitting disposed around the core at or near the uphole end of the core, and a nose at the downhole end of the core. The setting tool includes an elongate housing extending between an uphole end and a downhole end opposite the uphole end, an open passageway extending from the uphole end to the downhole end of the housing, and the downhole end of the housing is aligned to directly engage the compression fitting of the plug.

A system includes a first instrumented bridge plug positionable in a downhole wellbore environment. The first instrumented bridge plug includes an acoustic source for transmitting an acoustic signal. The system also includes a second instrumented bridge plug positionable in the downhole wellbore environment. The second instrumented bridge plug includes an acoustic sensor for receiving a reflected acoustic signal originating from the acoustic signal. The reflected acoustic signal being usable to interpret wellbore formation characteristics of the downhole wellbore environment.

A system includes a first instrumented bridge plug positionable in a downhole wellbore environment. The first instrumented bridge plug includes an acoustic source for transmitting an acoustic signal. The system also includes a second instrumented bridge plug positionable in the downhole wellbore environment. The second instrumented bridge plug includes an acoustic sensor for receiving a reflected acoustic signal originating from the acoustic signal. The reflected acoustic signal being usable to interpret wellbore formation characteristics of the downhole wellbore environment.

Methods of capturing carbon dioxide in a wellbore can include installing a sealing element in the wellbore. The sealing element swells in the presence of carbon dioxide and can be used for capturing the carbon. The sealing element can include a carbon-swelling material, such as a carbon-swelling polymers, metal-based materials, or combinations of elastomeric polymers and metal-based materials. The sealing element can also include combinations of different carbon-swelling materials, fillers or other compounds, and materials that are not carbon swellable. The sealing element can create a seal, form an anchor, or create a seal and form an anchor in the wellbore after swelling.

Methods of capturing carbon dioxide in a wellbore can include installing a sealing element in the wellbore. The sealing element swells in the presence of carbon dioxide and can be used for capturing the carbon. The sealing element can include a carbon-swelling material, such as a carbon-swelling polymers, metal-based materials, or combinations of elastomeric polymers and metal-based materials. The sealing element can also include combinations of different carbon-swelling materials, fillers or other compounds, and materials that are not carbon swellable. The sealing element can create a seal, form an anchor, or create a seal and form an anchor in the wellbore after swelling.

There is provided a method for preparing a wellbore for insertion of a barrier, the method comprising: providing a section of tubing or formation within the wellbore having a modified internal surface that is shaped such that a region adjacent the modified internal surface can be filled with barrier material and the barrier material can solidify to interlock with and be anchored by the modified internal surface.