Convertible downhole isolation plug

Abstract

A downhole tool that is capable of isolating communication pressure from below the set downhole tool, and is capable of being converted to a frac plug is provided. The downhole tool includes a packer with a ball seat defined therein. A plug is disposed at a lower end of the downhole tool to isolate the upper well from the lower well. A sealing ball is carried with the packer into the well by a setting tool. The movement of the sealing ball away from the ball seat is limited by isolation of the sealing ball from the lower well. A rod is disposed through the downhole tool contacting the plug. The rod is partially disposed in the ball seat, preventing the sealing ball from sealing. When the packer is set, flow within the well is isolated, thereby allowing treatment of the well above the packer. With the application of sufficient pressure, the sealing ball applies force to the rod which shears the plug from within the tool. The tool is converted to a standard frac plug.

1 . A downhole tool for use in a well comprising:
 a mandrel defining a central flow passage and a ball seat;   a sealing element disposed about the mandrel and movable from an unset to a set position in the well;   a plug detachably disposed in the mandrel for completely preventing flow through the central flow passage; and   a sealing ball longitudinally spaced from the ball seat, wherein application of a predetermined pressure in the well will detach the plug from the mandrel and move the sealing ball into engagement with the ball seat.   
     
     
         2 . The downhole tool of  claim 1 , further comprising a rod disposed in the mandrel, wherein the rod engages the sealing ball to space the sealing ball from the ball seat until the plug is detached. 
     
     
         3 . The downhole tool of  claim 1 , the plug having a rod extending therefrom to engage the sealing ball and space the sealing ball from the ball seat. 
     
     
         4 . The downhole tool of  claim 1 , wherein the tool comprises a bridge plug prior to detachment of the plug from the mandrel, and a frac plug after detachment. 
     
     
         5 . A downhole tool for use in a well, the tool comprising:
 a mandrel having an upper and a lower end, the mandrel defining a longitudinal central flow passage therethrough, wherein the mandrel defines a ball seat on the upper end thereof;   a sealing element disposed about the mandrel for sealingly engaging the well;   a plug detachably retained in the mandrel; and   a rod disposed in the longitudinal central flow passage, the rod having first and second ends, the first end contacting the plug and extending therefrom in the longitudinal flow passage.   
     
     
         6 . The downhole tool of  claim 5 , further comprising a sealing ball spaced apart from the ball seat. 
     
     
         7 . The downhole tool of  claim 6 , wherein a second end of the rod engages the sealing ball to space the sealing ball from the ball seat and to prevent the sealing ball from engaging the ball seat until a pressure of a predetermined amount is applied in the well. 
     
     
         8 . The downhole tool of  claim 7 , wherein the predetermined pressure is sufficient to detach the plug from the mandrel. 
     
     
         9 . The downhole tool of  claim 7 , wherein the plug is detached and removed from the mandrel and the ball moved into engagement with the ball seat upon the application of the predetermined pressure in the well. 
     
     
         10 . The downhole tool of  claim 7 , wherein the tool converts from a bridge plug to a frac plug in the well upon detachment of the plug from the mandrel. 
     
     
         11 . The downhole tool of  claim 5 , wherein the downhole tool is movable from an unset to a set position in the well. 
     
     
         12 . A method for converting a downhole tool from a bridge plug to a frac plug comprising:
 lowering the downhole tool into the well, the downhole tool defining a longitudinal central flow passage therethrough;   blocking flow in both an upward and a downward direction through the longitudinal central flow passage with a solid plug disposed therein;   setting the downhole tool in the well so that the downhole tool sealingly engages the well;   positioning a sealing ball in the well above the longitudinal central flow passage;   increasing a pressure in the well to a predetermined pressure to remove the solid plug; and   contacting a ball seat on the downhole tool with the sealing ball, the sealing ball preventing flow in the downward direction through the longitudinal central flow passage.   
     
     
         13 . The method of  claim 12 , further comprising the step of perforating the well above the tool prior to the step of increasing the pressure in the well to the predetermined pressure. 
     
     
         14 . The method of  claim 12 , further comprising the step of fracturing a zone above the tool after the step of contacting the ball seat with the sealing ball. 
     
     
         15 . The method of  claim 12 , further comprising spacing the ball from the ball seat with a rod that engages the solid plug. 
     
     
         16 . A method of fracturing a plurality of zones in a well comprising:
 (a) fracturing a first zone in the well;   (b) lowering a bridge plug into the well, the bridge plug comprising a mandrel with a sealing element disposed thereabout and a solid plug disposed therein, the mandrel defining a longitudinal flow passage therethrough;   (c) placing a sealing ball in the well prior to setting the bridge plug in the well;   (d) spacing the sealing ball from the longitudinal flow passage;   (e) setting the bridge plug in the well above the first fractured zone;   (f) simultaneously detaching the solid plug and moving the sealing ball into engagement with the ball seat to convert the bridge plug to a frac plug; and   (g) fracturing a second zone above the tool.   
     
     
         17 . The method of  claim 16 , where the simultaneous detaching and moving step comprises increasing pressure in the well above the bridge plug. 
     
     
         18 . The method of  claim 16 , further comprising decreasing pressure in the well to allow fluid from the first zone to pass upwardly through the longitudinal flow passage. 
     
     
         19 . The method of  claim 16 , further comprising:
 repeating steps (a)-(e) above the second fractured zone with a second bridge plug;   simultaneously detaching the solid plug and moving the sealing ball of the second bridge plug into engagement with the ball seat of the second bridge plug to convert the second bridge plug to a second frac plug; and   fracturing a third zone above the second frac plug.   
     
     
         20 . The method of  claim 19 , further comprising decreasing pressure in the well after fracturing the third zone so that fluid from the first, second and third fractured zones may pass upwardly in the well. 
     
     
         21 . A method of converting a downhole tool from a bridge plug to a frac plug in the well comprising:
 lowering a mandrel having an upper and lower end into the well, the mandrel defining a longitudinal central flow passage therethrough and a ball seat on the upper end thereof, the mandrel having a solid plug connected therein for blocking flow therethrough;   positioning a frac ball in the well spaced from the ball seat; and   simultaneously detaching the solid plug from the mandrel and moving the sealing ball into engagement with the seat, so that flow downwardly through the longitudinal central passage is prevented and upward flow therethrough is allowed.   
     
     
         22 . The method of  claim 21 , further comprising:
 positioning a rod in the longitudinal flow passage; and   spacing the sealing ball from the seat with the rod prior to detaching the plug from the mandrel.   
     
     
         23 . The mandrel of  claim 22 , wherein the rod engages the solid plug and the sealing ball.