Wellbore plug

Abstract

A wellbore plug comprises a body received within a tubular in an oil or gas well, and engaging a seat to seal an annulus. A sealing member occludes the bore in a first configuration. A spring urges the sealing member towards one end of the body in the first configuration. A locking member locks the sealing member in the first configuration, and can be unlocked in response to pressure within the bore above a pressure threshold, which permits movement of the sealing member to a second configuration. The spring expands when pressure within the bore is reduced below the threshold to push the sealing member into a third configuration, which permits fluid passage through the bore. A method of pressure testing and a method of injecting fluid into a well is also disclosed, using the wellbore plug.

1 . A wellbore plug comprising:
 a body having an axis and a bore adapted to transmit fluid between a first end of the body and a second end of the body, the body being adapted to be received within a tubular in an oil or gas well, and being adapted to engage a seat within the oil or gas well tubular to seal an annulus between the outer surface of the body and an inner surface of the tubular;   a sealing member adapted to occlude the bore through the body to resist fluid flow through the bore of the body when the wellbore plug is in a first configuration;   a resilient device adapted to urge the sealing member towards one end of the body when the wellbore plug is in the first configuration;   a locking member adapted to lock the sealing member in the first configuration, and adapted to be unlocked in response to pressure within the bore above a pressure threshold;   wherein unlocking of the locking member permits movement of the sealing member within the bore to shift the wellbore plug from the first configuration to a second configuration;   wherein movement of the sealing member in response to expansion of the resilient device when pressure within the bore is reduced below the threshold shifts the wellbore plug from the second configuration to a third configuration; and   wherein in the third configuration, the sealing member permits fluid passage through the bore between the first and second ends of the body.   
     
     
         2 . (canceled) 
     
     
         3 . A wellbore plug as claimed in  claim 1 , wherein the sealing member is restrained against axial movement within the bore by the locking member. 
     
     
         4 . A wellbore plug as claimed in  claim 1 , wherein the sealing member moves in one direction when the wellbore plug shifts from the first to the second configuration, and in the opposite direction when the wellbore plug shifts from the second configuration to the third configuration. 
     
     
         5 . (canceled) 
     
     
         6 . A wellbore plug as claimed in  claim 1 , wherein the bore has a catching chamber having an inner diameter that is larger than the outer diameter of the sealing member, and wherein the catching chamber provides a clearance permitting fluid flow between the inner surface of the bore of the body and the outer surface of the sealing member when the sealing member is in the third configuration. 
     
     
         7 . A wellbore plug as claimed in  claim 6 , wherein the second end of the body incorporates a seal adapted to engage the seat within the oil or gas well tubular to seal the annulus between the outer surface of the body and the inner surface of the tubular, and wherein the catching chamber is disposed between the first end of the body and the sealing member when the sealing member is in the first configuration. 
     
     
         8 . (canceled) 
     
     
         9 . A wellbore plug as claimed in  claim 6 , wherein the catching chamber retains the sealing member in the third configuration and permits fluid flow around the sealing member within the catching chamber. 
     
     
         10 . A wellbore plug as claimed in  claim 1 , wherein the bore comprises a seal housing having an inner diameter in which the sealing device is received in a sliding fit, and wherein a resilient seal is compressed between the outer surface of the sealing device and the inner surface of the seal housing. 
     
     
         11 . A wellbore plug as claimed in  claim 10 , wherein the seal housing incorporates a first shoulder facing the first end of the body, and adapted to limit axial movement of the sealing member in a direction from the first end of the body to the second end within the seal housing by abutting a shoulder facing the second end of the body on the sealing member. 
     
     
         12 . A wellbore plug as claimed in  claim 10 , wherein the seal housing is radially stepped, with a larger diameter portion closer to the first end than to the second end, and a smaller diameter portion closer to the second end than to the first end. 
     
     
         13 . A wellbore plug as claimed in  claim 1 , wherein the sealing member prevents fluid flow within the bore in the first and second configurations. 
     
     
         14 . A wellbore plug as claimed in  claim 1 , wherein the resilient device is maintained in compression between the sealing member and a shoulder in the body in the first and second configurations, and wherein the shoulder is disposed between the second end of the body and the sealing member. 
     
     
         15 . A wellbore plug as claimed in  claim 1 , wherein the movement of the sealing member as the wellbore plug shifts from the first to the second configuration from compresses the resilient device. 
     
     
         16 . A wellbore plug as claimed in  claim 1 , wherein the resilient device is held in compression in the first and second configurations, and expands when the wellbore plug shifts from the second configuration to the third configuration. 
     
     
         17 . A wellbore plug as claimed in  claim 1 , wherein the sealing member and the body are separate. 
     
     
         18 . A wellbore plug as claimed in  claim 1 , wherein the body contains at least one port permitting fluid communication between the bore of the body and an outer surface of the body between the sealing member and the second end of the body, and wherein the port is adapted to be closed by a sleeve that slides axially within the bore. 
     
     
         19 . (canceled) 
     
     
         20 . A wellbore plug as claimed in  claim 1 , wherein the sealing member is separate from the body, and wherein the body is adapted to be latched into the tubular, between a first section of the tubular and a second section of the tubular and installed with the tubular during deployment of the tubular, and wherein the body incorporates a seat adapted to seat the sealing member when the sealing member lands on the latched body, and wherein the body is adapted to be unlatched from the tubular by a pressure differential applied across the seated sealing member on the latched body to permit the body to travel axially along the second section of the tubular. 
     
     
         21 . A wellbore plug as claimed in  claim 1 , wherein the sealing member incorporates a channel permitting selective fluid communication across the sealing member when seated in the body, and wherein the channel incorporates a seal preventing fluid communication through the channel below a pressure differential above a burst pressure, and wherein the seal is adapted to be disrupted by a pressure differential above the burst pressure to permit fluid communication through the channel. 
     
     
         22 - 33 . (canceled) 
     
     
         34 . A wellbore plug comprising:
 a body having an axis and a bore adapted to transmit fluid between a first end of the body and a second end of the body, the body being adapted to be received within a tubular in an oil or gas well, and being adapted to engage a seat within the oil or gas well tubular to seal an annulus between the outer surface of the body and an inner surface of the tubular;   a sealing member adapted to occlude the bore through the body to resist fluid flow through the bore of the body when the wellbore plug is in a first configuration;   a resilient device adapted to urge the sealing member towards one end of the body when the wellbore plug is in the first configuration;   a locking member adapted to lock the sealing member against axial movement in the bore in the first configuration, and adapted to be unlocked in response to pressure within the bore above a pressure threshold;   wherein unlocking of the locking member permits movement of the sealing member within the bore to shift the wellbore plug from the first configuration to a second configuration;   wherein movement of the sealing member in response to expansion of the resilient device when pressure within the bore is reduced below the threshold shifts the wellbore plug from the second configuration to a third configuration; and   wherein in the third configuration, the sealing member permits fluid passage through the bore between the first and second ends of the body;   wherein the sealing member moves in one direction when the wellbore plug shifts from the first to the second configuration, and in the opposite direction when the wellbore plug shifts from the second configuration to the third configuration;   wherein the bore has a catching chamber having an inner diameter that is larger than the outer diameter of the sealing member, and wherein the catching chamber provides a clearance permitting fluid flow between the inner surface of the bore of the body and the outer surface of the sealing member when the sealing member is in the third configuration.   
     
     
         35 . A wellbore plug comprising:
 a body having an axis and a bore adapted to transmit fluid between a first end of the body and a second end of the body, the body being adapted to be received within a tubular in an oil or gas well, and being adapted to engage a seat within the oil or gas well tubular to seal an annulus between the outer surface of the body and an inner surface of the tubular;   a sealing member adapted to occlude the bore through the body to resist fluid flow through the bore of the body when the wellbore plug is in a first configuration;   a resilient device adapted to urge the sealing member towards one end of the body when the wellbore plug is in the first configuration;   a locking member adapted to lock the sealing member against axial movement in the bore in the first configuration, and adapted to be unlocked in response to pressure within the bore above a pressure threshold;   wherein unlocking of the locking member permits movement of the sealing member within the bore to shift the wellbore plug from the first configuration to a second configuration;   wherein movement of the sealing member in response to expansion of the resilient device when pressure within the bore is reduced below the threshold shifts the wellbore plug from the second configuration to a third configuration;   wherein in the third configuration, the sealing member permits fluid passage through the bore between the first and second ends of the body;   wherein the resilient device is maintained in compression between the sealing member and a shoulder in the body in the first and second configurations, and wherein the shoulder is disposed between the second end of the body and the sealing member; and   wherein the resilient device is held in compression in the first and second configurations, and expands when the wellbore plug shifts from the second configuration to the third configuration.   
     
     
         36 . A wellbore plug as claimed in  claim 35 , wherein the bore has a catching chamber having an inner diameter that is larger than the outer diameter of the sealing member, and wherein the catching chamber provides a clearance permitting fluid flow between the inner surface of the bore of the body and the outer surface of the sealing member when the sealing member is in the third configuration, wherein the second end of the body incorporates a seal adapted to engage the seat within the oil or gas well tubular to seal the annulus between the outer surface of the body and the inner surface of the tubular, and wherein the catching chamber is disposed between the first end of the body and the sealing member when the sealing member is in the first configuration.