Wellbore subassemblies and methods for creating a flowpath
Wellbore subassemblies usable to create a flowpath between a formation and a wellbore can include an inner sleeve and an outer sleeve positioned internal to and external of a core, the core having sockets containing charge assemblies. Upon actuation of the charge assemblies, the inner and outer sleeves are both simultaneously penetrated to form a fluid flowpath between the interior of the subassembly and the formation exterior to the subassembly. The structure of the subassembly can enable it to be lowed and used as part of a tubular conduit string both before and after perforation, the charge assemblies being unobtrusively embedded within the wall of the subassembly.
1. A wellbore subassembly comprising:
a tubular core defining a core axial bore in the interior of the core, and an exterior space outside the core, said core comprising a tubular wall with one or more cavities therein configured to hold one or more charge assemblies, and a first end and a second end wherein the first end and second end are configured to connect the core to a tubular drill string such that the core axial bore provides a substantially continuous fluid channel from a drill string connected to said first end, through the core and into a drill string connected to said second end, a first tubular sleeve forming an outer sleeve axial bore and positioned over the core to contain at least a portion of the core inside the outer sleeve axial bore, and one or more charge assemblies in the one or more cavities configured to discharge into the core axial bore and into the exterior space outside the core for creating a flowpath between the core axial bore and the exterior space outside the core.
2. The subassembly of claim 1 , further comprising a second tubular sleeve defining a second sleeve axial bore positioned within the core axial bore.
3. The subassembly of claim 2 , wherein the charge assembly is configured to discharge into the core axial bore and to penetrate through the second tubular sleeve.
4. The subassembly of claim 1 , wherein the charge assembly is configured to discharge into the exterior space and penetrate through the first tubular sleeve.
5. The subassembly of claim 1 , wherein the charge assembly comprises a first charge configured to discharge into the core axial bore and a second charge configured to discharge into the exterior space outside the core.
6. The subassembly of claim 5 , wherein the first charge and the second charge are configured to discharge simultaneously.
7. The wellbore subassembly of claim 1 , wherein the core further comprises a first end piece and a second end piece with threaded connectors connecting the first and second ends of the core to the tubular drill string.
8. A method for creating a flowpath between a wellbore and a formation, the method comprising the steps of engaging a wellbore subassembly with a tubular string, wherein the wellbore subassembly comprises a tubular core defining a core axial bore in the interior of the core, and an exterior space outside the core, said core comprising a tubular wall with one or more cavities therein configured to hold one or more charge assemblies, and a first end and a second end wherein the first end and second end are configured to connect the core to a tubular drill string such that the core axial bore provides a continuous fluid channel from a drill string connected to said first end, through the core and into a drill string connected to said second end, and a charge assembly in the cavity configured to discharge into the interior space and into the exterior space; lowering the wellbore subassembly to a selected position in the wellbore; and actuating the charge assembly such that the charge assembly discharges into the interior space and into the exterior space to create a flowpath between the interior space and the exterior space,
wherein the tubular core comprises a channel for accommodating a detonation cord that extends between the charge assembly and a firing assembly, and wherein actuating the charge assembly comprises actuating the firing assembly to ignite the detonation cord, thereby causing the charge assembly to discharge into the core axial bore and into the exterior space outside the core.
9. The method of claim 8 , wherein the tubular body comprises an outer sleeve between the cavity and the exterior space, an inner sleeve between the cavity and the interior space, or both of said outer sleeve and said inner sleeve, and wherein actuating the charge assembly causes the charge assembly to penetrate through the outer sleeve, the inner sleeve, or combinations thereof.
10. The method of claim 8 , wherein the charge assembly comprises a first charge configured to discharge into the interior space and a second charge configured to discharge into the exterior space, wherein the first charge and the second charge engage a single portion of the detonation cord, and wherein actuating the charge assembly causes the first charge and the second charge to discharge simultaneously.
11. The method of claim 8 , wherein the core further comprises a first end piece and a second end piece with threaded connectors connecting the first and second ends of the core to the tubular drill string.