Systems And Methods For Flow-Activated Initiation Of Plug Assembly Flow Seats

Abstract

The present disclosure describes systems and methods for flow-activated plug assembly flow seat initiation, which in some aspects may comprise sealing a plug within a downhole bore, and may include a plug assembly comprising a frustoconical tube; a tubular mandrel positioned longitudinally through the frustoconical tube and having port(s) fluidly connecting a mandrel bore with the bore of the frustoconical tube, and having a shear member extending from the mandrel; and a ball configured to fluidly seal the proximal end of the tubular mandrel; wherein the tubular mandrel is configured to move between a first position having a fluid passageway through the ports and a second position wherein the shear member has been sheared away when a predetermined fluid pressure is applied to the plug assembly and the tubular mandrel is positioned relative to the frustoconical tube such that the port(s) are blocked, closing the fluid passageway.

What is claimed is: 
     
         1 . A plug assembly, comprising:
 (a) a frustoconical tube having a first end, a second end, an exterior surface, and an interior surface, the interior surface defining a tube bore extending longitudinally through the frustoconical tube through the first end and the second end, the first end having a first inner diameter and the second end having a second inner diameter smaller than the first inner diameter, the interior surface having a first step circumferentially between the first end and the second end;   (b) a tubular mandrel positioned longitudinally through the tube bore of the frustoconical tube, the tubular mandrel having a proximal end proximate to the first end of the frustoconical tube, a distal end extending through the second end of the frustoconical tube, an exterior surface, an interior surface defining a mandrel bore longitudinally through the tubular mandrel through the proximal end and the distal end, one or more ports between the proximal end and the distal end fluidly connecting the mandrel bore with the exterior surface;   (c) a shear member engaging the mandrel with the frustoconical tube;   (d) a ball positionable at least partially in the mandrel bore of the tubular mandrel at the proximal end and configured to fluidly seal the proximal end of the tubular mandrel,
 wherein the tubular mandrel is configured to move between a first position and a second position in the frustoconical tube; wherein in the first position the tubular mandrel is positioned relative to the frustoconical tube such that the shear member contacts the frustoconical tube between the first step of the frustoconical tube and the first end of the frustoconical tube, and such that a fluid passageway is formed between the exterior surface of the mandrel and the tube bore of the frustoconical tube, through the one or more ports of the tubular mandrel, and through the distal end of the tubular mandrel; and wherein in the second position the shear member has been sheared away by the first step of the frustoconical tube when a predetermined fluid pressure is applied to the plug assembly, and wherein the tubular mandrel is positioned relative to the frustoconical tube such that the interior surface of the frustoconical tube blocks the one or more ports, thereby closing the fluid passageway. 
   
     
     
         2 . The plug assembly of  claim 1 , wherein the interior surface of the frustoconical tube has a second step between the first step and the first end of the frustoconical tube, and wherein in the second position the second step blocks fluid flow from the one or more ports of the tubular mandrel. 
     
     
         3 . The plug assembly of  claim 2 , wherein the exterior surface of the tubular mandrel has a mandrel step between the one or more ports and the proximal end, and wherein in the second position, the mandrel step of the exterior surface of the tubular mandrel is seated against the second step of the frustoconical tube such that the fluid passageway through the one or more ports is closed. 
     
     
         4 . The plug assembly of  claim 3 , wherein the second step of the interior surface of the frustoconical tube is sloped and the mandrel step of the exterior surface of the mandrel is sloped such that the first step seated against the mandrel step creates a fluid impervious seal. 
     
     
         5 . The plug assembly of  claim 2 , wherein the interior surface of the frustoconical tube is at least partially sloped between the first end and the second step of the frustoconical tube. 
     
     
         6 . The plug assembly of  claim 1 , wherein the interior surface of the frustoconical tube is at least partially sloped between the first end and the first step. 
     
     
         7 . The plug assembly of  claim 1 , wherein the first step is proximate to the second end of the frustoconical tube. 
     
     
         8 . The plug assembly of  claim 1 , wherein the predetermined fluid pressure creates a pressure differential between the proximal end and the distal end of the tubular mandrel, forcing the shear member against the first step, the fluid pressure resulting in a shear force sufficient to shear off the shear member, thereby allowing the fluid pressure to move the tubular mandrel to the second position. 
     
     
         9 . The plug assembly of  claim 1 , further comprising a slip member having one or more slip segments, the slip member positioned at least partially circumferentially about the second end of the frustoconical tube such that the slip segments are pushed outwardly when the second end of the frustoconical tube moves longitudinally, the slip member having a sloped interior surface configured to engage the second end of the exterior surface of the frustoconical tube. 
     
     
         10 . The plug assembly of  claim 1 , further comprising an end cap in contact with the second end of the tubular mandrel. 
     
     
         11 . The plug assembly of  claim 1 , the shear member selected from a shear ring, a shear pin, a friction fit section, and a collet system. 
     
     
         12 . A method for sealing a plug assembly in a wellbore, comprising:
 a) deploying a plug assembly and a setting tool into a casing within a drilled wellbore, the plug assembly comprising:
 i) a frustoconical tube having first end, a second end, an exterior surface, and an interior surface, the interior surface defining a tube bore extending longitudinally through the frustoconical tube through the first end and the second end, the first end having a first inner diameter and the second end having a second inner diameter smaller than the first inner diameter, the interior surface having a first step circumferentially between the first end and the second end, 
 ii) a tubular mandrel positioned longitudinally through the tube bore of the frustoconical tube, the tubular mandrel having a proximal end proximate to the first end of the frustoconical tube, a distal end extending through the second end of the frustoconical tube, an exterior surface, an interior surface defining a mandrel bore longitudinally through the tubular mandrel through the proximal end and the distal end, one or more ports between the proximal end and the distal end fluidly connecting the mandrel bore with the exterior surface, 
 iii) a shear member engaging the mandrel with the frustoconical tube, 
 iv) a ball positionable at least partially in the mandrel bore of the tubular mandrel at the proximal end and configured to fluidly seal the proximal end of the tubular mandrel, and 
 v) a slip member having one or more slip segments, the slip member positioned at least partially around the second end of the frustoconical tube such that the slip segments are pushed outwardly when the second end of the frustoconical tube moves longitudinally, the slip member having a sloped interior surface configured to engage the second end of the exterior surface of the frustoconical tube; 
   b) securing the plug assembly in the casing by introducing fluid flow into the casing to longitudinally move the frustoconical tube with the setting tool, thereby expanding the slip segments of the slip member and coupling the plug assembly to the casing with the slip segments;   wherein the tubular mandrel of the plug assembly is in a first position relative to the frustoconical tube such that the shear member holds the position between the first step of the frustoconical tube and the first end of the frustoconical tube, and such that a fluid passageway is formed between the exterior surface of the mandrel and the tube bore of the frustoconical tube, through the one or more ports of the tubular mandrel, and through the distal end of the tubular mandrel; and   c) increasing the fluid flow above a predetermined flow rate to shear the shear member, causing the tubular mandrel to move to a second position relative to the frustoconical tube, in which the interior surface of the frustoconical tube blocks the one or more ports and closes the fluid passageway.   
     
     
         13 . The method of  claim 12 , wherein the predetermined flow rate is 15 barrels/minute or more. 
     
     
         14 . The method of  claim 13 , wherein the predetermined flow rate creates a pressure differential between pressure on the proximate end and the distal end of the tubular mandrel. 
     
     
         15 . The method of  claim 14 , wherein a magnitude of the pressure differential is proportional to the square of the magnitude of a flow rate passing through the fluid passageway. 
     
     
         16 . The method of  claim 12 , wherein the first step of the frustoconical tube is proximate to the second end of the frustoconical tube. 
     
     
         17 . The method of  claim 12 , wherein the interior surface of the frustoconical tube has a second step between the first step and the first end of the frustoconical tube, and wherein in the second position the second step blocks fluid flow from the one or more ports of the tubular mandrel. 
     
     
         18 . The method of  claim 17 , wherein the exterior surface of the tubular mandrel has a mandrel step between the one or more ports and the proximal end, and wherein in the second position, the mandrel step of the exterior surface of the tubular mandrel is seated against the second step of the frustoconical tube such that the fluid passageway through the one or more ports is closed. 
     
     
         19 . The method of  claim 12 , wherein the interior surface of the tubular mandrel has a circumferential ball seat step between the one or more ports and the proximal end of the tubular mandrel. 
     
     
         20 . The method of  claim 19 , wherein the ball seat step is sealingly engageable with the ball. 
     
     
         21 . The method of  claim 12 , the shear member selected from a shear ring, a shear pin, a friction fit section, and a collet system. 
     
     
         22 . A tubular modular plug for a frac plug assembly, the tubular modular plug comprising:
 a) a body defining a counterbore therethrough with a first section and second section,   b) the first section comprising—
 i) a tip, 
 ii) at least one aperture arranged on the body, 
 iii) a shear member connected to the body, and 
 iv) a first inner diameter; 
   c) the second section comprising—
 i) a ball located within the second section with a diameter larger than the first inner diameter, 
 ii) a ball seat step, 
 iii) a ball stop connected to the second section opposite the first section, and 
 iv) a second inner diameter larger than the first inner diameter. 
   
     
     
         23 . The tubular modular plug of  claim 22 , wherein the tip defines a collet. 
     
     
         24 . The tubular modular plug of  claim 22 , wherein each aperture is radially spaced about a central axis. 
     
     
         25 . The tubular modular plug of  claim 22 , wherein the shear member comprises a shear ring with an outer diameter larger than a first outer diameter of the body. 
     
     
         26 . The tubular modular plug of  claim 22 , wherein the ball seat step is circumferentially chamfered.