Downhole plug assemblies with collet adapters and methods thereof

Abstract

Downhole plug assemblies comprising plug, release sleeve and collet adapter and methods thereof are disclosed. The plug comprises of a mandrel with a bore and an outer subassembly comprising a top element, anchoring system, sealing system and a nose element. The release sleeve is engaged and secured within the bore at a proximal portion by a plurality of shearable fastening members. The collet adapter comprises of a plurality of fingers with each finger ending in a head at the tip. The collet head is engaged with a slanting face of the release sleeve at a lower end and is configured to be engaged with a setting tool at an upper end. During the release process, the fingers expand to prevent disengaging from the face thus transferring the load to the release sleeve and causing the fastening members to shear off and the release sleeve to release from the mandrel.

We claim: 
     
         1 . A downhole plug assembly comprising:
 a plug comprising a substantially cylindrical central mandrel and a substantially cylindrical hollow outer subassembly, the outer subassembly thereof being disposed circumferentially around the mandrel, the mandrel thereof having a proximal portion and a distal portion and a substantially longitudinal bore, the proximal portion thereof being configured to be oriented up hole and the distal portion thereof being configured to be oriented downhole, the proximal portion thereof having a plurality of apertures disposed circumferentially, the aperture thereof extending therethrough perpendicular to the longitudinal axis of the bore and being engaged with a shearable fastening member, the outer subassembly thereof comprising an annular top element disposed circumferentially around the proximal portion, at least one of an anchoring system disposed circumferentially around the mandrel for securely engaging the plug with a casing in a well bore, an expandable sealing system disposed circumferentially around the mandrel for sealing the gap between an outer surface of the plug and the casing and an annular nose element disposed circumferentially around the distal portion;   an annular release sleeve having a first end and a second end, the first end thereof being configured to be oriented up hole and the second end thereof being configured to be oriented downhole, the release sleeve thereof having an outer diameter and a progressively tapering inner diameter, the inner diameter at the second end thereof being lesser than the inner diameter at the first end thereof, the release sleeve thereof further having an external surface and an internal surface, each of the external surface and the internal surface having a length associated therewith, the length of the external surface being lesser than the length of the internal surface, the second end thereof having a slanting face sloping towards the first end, the release sleeve thereof further having at least one of a receiving member, the receiving member being configured for receiving and engaging a plurality of the shearable fastening members, the release sleeve thereof being releasably engaged and secured within the bore at the proximal portion by a plurality of the shearable fastening members, the release sleeve engaged with the plug forming a plug subassembly; and   a collet adapter having an upper end and a lower end, the upper end thereof being configured to be oriented up hole and the lower end thereof being configured to be oriented downhole, the collet adapter being configured to be an adapter between a setting tool and the plug subassembly, the upper end thereof being configured to be engaged with the setting tool, the lower end thereof having a plurality of fingers separated by slots, each finger thereof ending in a head at the tip, the collet adapter being slidable through the progressively tapering inner diameter of the release sleeve to compress and then snap into an engaging position wherein a lower surface of each of the head engages the face, the fingers thereof configured to be radially expandable to securely engage the face upon application of a load greater than a setting load thereby transferring the load to the release sleeve and then to the shearable fastening members causing the fastening members thereof to shear off and the release sleeve thereof to release from the mandrel.   
     
     
         2 . The downhole plug assembly as claimed in  claim 1 , wherein the receiving member is a hole, the hole thereof extending therethrough perpendicular to the longitudinal axis of the bore. 
     
     
         3 . The downhole plug assembly as claimed in  claim 1 , wherein the receiving member is a circumferential groove on the external surface. 
     
     
         4 . The downhole plug assembly as claimed in  claim 1 , wherein the plug is a frac plug. 
     
     
         5 . The downhole plug assembly as claimed in  claim 4 , wherein the bore has a conical feature defined for seating a frac ball. 
     
     
         6 . The downhole plug assembly as claimed in  claim 1 , wherein the plug further comprises of a bridge plug adapter seated within the bore thus converting the plug into a bridge plug. 
     
     
         7 . The downhole plug assembly as claimed in  claim 6 , wherein the bridge plug adapter is threadably engaged with an inner surface of the mandrel. 
     
     
         8 . The downhole plug assembly as claimed in  claim 1 , wherein the plug is substantially made of composite material. 
     
     
         9 . The downhole plug assembly as claimed in  claim 1 , wherein the shearable fastening members engaging the mandrel with the release sleeve shear off without leaving any debris within the bore of the mandrel. 
     
     
         10 . The downhole plug assembly as claimed in  claim 1 , wherein the shearable fastening members are shearable screws. 
     
     
         11 . A method for installing, setting and releasing a plug for isolation in a well bore, the method comprising the steps of:
 a) providing a plug subassembly, the plug subassembly thereof comprising a plug and an annular release sleeve,   the plug thereof comprising a substantially cylindrical central mandrel and a substantially cylindrical hollow outer subassembly, the outer subassembly thereof being disposed circumferentially around the mandrel, the mandrel thereof having a proximal portion and a distal portion and a substantially longitudinal bore, the proximal portion thereof being configured to be oriented up hole and the distal portion thereof being configured to be oriented downhole, the proximal portion thereof having a plurality of apertures disposed circumferentially, the aperture thereof extending therethrough perpendicular to the longitudinal axis of the bore and being engaged with a shearable fastening member, the outer subassembly thereof comprising an annular top element disposed circumferentially around the proximal portion, at least one of an anchoring system disposed circumferentially around the mandrel for securely engaging the plug with a casing in a well bore, an expandable sealing system disposed circumferentially around the mandrel for sealing the gap between an outer surface of the plug and the casing and an annular nose element disposed circumferentially around the distal portion,   the release sleeve thereof having a first end and a second end, the first end thereof being configured to be oriented up hole and the second end thereof being configured to be oriented downhole, the release sleeve thereof having an outer diameter and a progressively tapering inner diameter, the inner diameter at the second end thereof being lesser than the inner diameter at the first end thereof, the release sleeve thereof further having an external surface and an internal surface, each of the external surface and the internal surface having a length associated therewith, the length of the external surface being lesser than the length of the internal surface, the second end thereof having a slanting face sloping towards the first end, the release sleeve further having at least one of a receiving member, the receiving member being configured for receiving and engaging a plurality of the shearable fastening members, the release sleeve thereof being releasably engaged and secured within the bore at the proximal portion by a plurality of the shearable fastening members;   b) providing a collet adapter, the collet adapter thereof having an upper end configured to be oriented up hole and a lower end configured to be oriented downhole, the collet adapter thereof being configured to be an adapter between a setting tool and the plug subassembly, the upper end thereof being engaged with the setting tool, the lower end thereof having a plurality of fingers separated by slots, each finger thereof ending in a head at the tip, each head thereof being configured to engage the face of the release sleeve;   c) installing the plug subassembly onto the setting tool by sliding the collet adapter through the progressively tapering inner diameter of the release sleeve thereby compressing and snapping the collet adapter thereof into an engaging position wherein a lower surface of each of the head engages the face, the plug subassembly and the collet adaptor together forming a downhole plug assembly;   d) deploying the downhole plug assembly engaged with the setting tool downhole to a predetermined location;   e) actuating a setting sleeve with a setting load, the sleeve thereof contacting the top element at a bottom end, thereby pushing the top element and setting the plug, wherein the anchoring system engages the plug with the casing and the sealing system seals the gap between the outer surface of the plug and the casing; and   f) applying a load greater than the setting load thereby pulling the collet adapter, the fingers thereof radially expanding to securely engage the face thereby transferring the load to the release sleeve and then to the shearable fastening members causing the fastening members to shear off and the release sleeve thereof to release from the mandrel.   
     
     
         12 . The method as claimed in  claim 11 , wherein the receiving member is a hole, the hole thereof extending therethrough perpendicular to the longitudinal axis of the bore. 
     
     
         13 . The method as claimed in  claim 11 , wherein the receiving member is a circumferential groove on the external surface. 
     
     
         14 . The method as claimed in  claim 11 , wherein the plug is a frac plug. 
     
     
         15 . The method as claimed in  claim 14 , wherein the bore has a conical feature defined for seating a frac ball. 
     
     
         16 . The method as claimed in  claim 11 , wherein the plug further comprises of a bridge plug adapter seated within the bore thus converting the plug into a bridge plug. 
     
     
         17 . The method as claimed in  claim 16 , wherein the bridge plug adapter is threadably engaged with an inner surface of the mandrel. 
     
     
         18 . The method as claimed in  claim 11 , wherein the plug is made of composite material. 
     
     
         19 . The method as claimed in  claim 11 , wherein the shearable fastening members engaging the mandrel with the release sleeve shear off without leaving any debris within the bore of the mandrel. 
     
     
         20 . The method as claimed in  claim 11 , wherein the shearable fastening members are shearable screws.