Downhole plug assembly

Abstract

An apparatus includes a body member and a ring member. The body member has a through passageway, and the body member includes an outer engagement surface. The ring member has a contracted state and an expanded state, and the ring member includes an inner engagement surface and an outer surface. The seal member is adapted to axially move with respect to the body member in response to the application of an axial force such that the outer engagement surface of the body member physically engages the inner engagement surface of the ring member to radially expand the ring member to transition the ring member to the expanded state and cause the outer surface of the ring member to contact an inner wall of a tubing string. The physical engagement of the inner engagement surface of the ring member with the outer engagement surface of the body member forms a seal between the ring member and the body member. The contact of the outer surface of the ring member with the tubing string forms a seal between the ring member and the tubing string and secures the ring member to the tubing string. The inner engagement surface and the outer engagement surface are adapted to physically interact to retain the ring member in the expanded state when the axial force is removed.

What is claimed is: 
     
         1 . A method comprising:
 running a plug assembly inside a tubing string of a well; and   setting the plug assembly, wherein setting the plug assembly comprises:
 axially, moving a seal member of the plug assembly with respect to a body member of the plug assembly to cause an outer engagement surface of the body member to physically engage an inner engagement surface of a ring member of the plug assembly to radially expand the ring member to transition the ring member to an expanded state and cause an outer surface of the ring member to contact an inner wall of the tubing string; 
   using the physical engagement of the inner engagement surface of the ring member with the outer engagement surface of the body member to form a seal between the ring member and the body member;   using contact of the outer surface of the ring member with the tubing string to form a seal between the ring member and the tubing string and secure the ring member to the tubing string; and   using a physical interaction between the inner engagement surface and the outer engagement surface to retain the ring member in the expanded state when the axial force is removed.   
     
     
         2 . The method of  claim 1 , wherein using the physical engagement of the inner engagement surface of the ring member with the outer engagement surface of the body member to form the seal comprises forming the seal between tapered surfaces. 
     
     
         3 . The method of  claim 1 , wherein using the inner engagement surface and the outer engagement surface to retain the ring member in the expanded state comprises using the physical interaction of tapered surfaces. 
     
     
         4 . The method of  claim 1 , wherein using the physical interaction of the inner engagement surface and the outer engagement surface to retain the ring member in the expanded state comprises engaging ratchet teeth of the ring member and the body member. 
     
     
         5 . A system usable with a well comprising:
 a tubing string; and   an untethered object; and   a plug assembly, comprising:
 a body member having a through passageway, the body member comprising an outer engagement surface and a seat adapted to catch the untethered object to form a fluid barrier in the tubing string; and 
 a ring member having a contracted state and an expanded state, the ring member comprising an inner engagement surface and an outer surface, 
   wherein:
 the seal member is adapted to axially move with respect to the body member in response to the application of an axial force such that the outer engagement surface of the body member physically engages the inner engagement surface of the ring member to radially expand the ring member to transition the ring member to the expanded state and cause the outer surface of the ring member to contact an inner wall of the tubing string; 
 the physical engagement of the inner engagement surface of the ring member with the outer engagement surface of the body member forms a seal between the ring member and the body member; 
 the contact of the outer surface of the ring member with the tubing string forms a seal between the ring member and the tubing string and secures the ring member to the tubing string; and 
 the inner engagement surface and the outer engagement surface are adapted to physically interact to retain the ring member in the expanded state when the axial force is removed. 
   
     
     
         6 . The system of  claim 5 , wherein the inner engagement surface of the ring member comprises a tapered surface, the ring circumscribes a longitudinal axis, and the tapered surface is inclined with respect to the axis by an angle between 5 and 10 degrees. 
     
     
         7 . The system of  claim 5 , wherein the inner engagement surface of the ring member comprises a ratchet profile. 
     
     
         8 . The system of  claim 5 , wherein:
 the inner engagement surface of the ring member comprises a first tapered surface;   the outer engagement surface of the body member comprises a second tapered surface; and   the first and second tapered surfaces are adapted to form the seal between the ring member and the body member.   
     
     
         9 . The system of  claim 5 , wherein:
 the inner engagement surface of the ring member comprises a first tapered surface;   the outer engagement surface of the body member comprises a second tapered surface; and   the first and second tapered surfaces are adapted to produce a friction force to retain the ring member in the expanded state when the axial force is removed.   
     
     
         10 . The system of  claim 5 , wherein:
 the inner engagement surface of the ring member comprises a first tapered surface and first ratchet teeth;   the outer engagement surface of the body member comprises a second tapered surface and second ratchet teeth;   the first and second tapered surfaces are adapted to form the seal between the ring member and the body member; and   the first and second ratchet teeth are adapted to lock an axial position of the seal member relative to the body member to retain the ring member in the expanded state when the axial force is removed.   
     
     
         11 . An apparatus comprising:
 a body member having a through passageway, the body member comprising an outer engagement surface; and   a ring member having a contracted state and an expanded state, the ring member comprising an inner engagement surface and an outer surface,   wherein:
 the seal member is adapted to axially move with respect to the body member in response to the application of an axial force such that the outer engagement surface of the body member physically engages the inner engagement surface of the ring member to radially expand the ring member to transition the ring member to the expanded state and cause the outer surface of the ring member to contact an inner wall of a tubing string; 
 the physical engagement of the inner engagement surface of the ring member with the outer engagement surface of the body member forms a seal between the ring member and the body member; 
 the contact of the outer surface of the ring member with the tubing string forms a seal between the ring member and the tubing string and secures the ring member to the tubing string; and 
 the inner engagement surface and the outer engagement surface are adapted to physically interact to retain the ring member in the expanded state when the axial force is removed. 
   
     
     
         12 . The apparatus of  claim 11 , wherein the body member comprises a slotted metal ring. 
     
     
         13 . The apparatus of  claim 11 , wherein the inner engagement surface of the ring member comprises a tapered surface. 
     
     
         14 . The apparatus of  claim 13 , wherein the ring member circumscribes a longitudinal axis and the tapered surface is inclined with respect to the axis by an angle between 5 and 10 degrees. 
     
     
         15 . The apparatus of  claim 11 , wherein the inner engagement surface of the ring member comprises a ratchet profile. 
     
     
         16 . The apparatus of  claim 11 , wherein:
 the inner engagement surface of the ring member comprises a first tapered surface;   the outer engagement surface of the body member comprises a second tapered surface; and   the first and second tapered surfaces are adapted to form the seal between the ring member and the body member.   
     
     
         17 . The apparatus of  claim 11 , wherein:
 the inner engagement surface of the ring member comprises a first tapered surface;   the outer engagement surface of the body member comprises a second tapered surface; and   the first and second tapered surfaces are adapted to produce a friction force to retain the ring member in the expanded state when the axial force is removed.   
     
     
         18 . The apparatus of  claim 11 , wherein:
 the inner engagement surface of the ring member comprises a first tapered surface and first ratchet teeth;   the outer engagement surface of the body member comprises a second tapered surface and second ratchet teeth;   the first and second tapered surfaces are adapted to form the seal between the ring member and the body member; and   the first and second ratchet teeth are adapted to lock an axial position of the seal member relative to the body member to retain the ring member in the expanded state when the axial force is removed.   
     
     
         19 . The apparatus of  claim 18 , wherein:
 the first ratchet teeth of the inner engagement surface of the ring member is associated with a first range of inner diameters of the ring member;   the first tapered surface of the inner engagement surface of the ring member is associated with a second range of inner diameters of the ring member; and   the diameters of the first range of inner diameters are larger than the diameters of the second range of inner diameters.   
     
     
         20 . The apparatus of  claim 11 , wherein the body member comprises a seat to circumscribe the through passageway, and the seat is adapted to catch an object to form a fluid barrier in the well. 
     
     
         21 . The apparatus of  claim 11 , wherein the at least one of the seal members or the body member comprises a degradable material constructed to degrade in a time interval less than one month in a downhole environment of the well.