High pressure tie back receptacle and seal assembly

Abstract

A tie back assembly and method of use is presented. In one method, a tie back seal mandrel is inserted into a tie back receptacle. Both the inner surface of the tie back receptacle and the outer surface of the seal mandrel are tapered to cooperate when mated. A seal assembly forms an annular seal between the tapered surfaces when the mandrel is inserted into the receptacle. Preferably the seal assembly has a burst seal and a collapse seal carried on one of the tapered surfaces, where the seals are spaced apart longitudinally. The seals are positioned at locations along the tapered surfaces to provide adequate wall thickness for support at pressure. Hydrostatic fluid in the wellbore increases the force necessary to withdraw the seal mandrel dues to creation of a lower pressure zone between the spaced apart seals.

1 - 3 . (canceled) 
     
     
         4 . A method of assembling together a tie back receptacle member and a tie back seal member in a wellbore extending through a subterranean formation, the method comprising the steps of:
 positioning the tie back receptacle member in the wellbore at a downhole location where the wellbore comprises a casing;   hanging the tie back receptacle member in the wellbore and supported by the casing;   running the tie back seal member into the wellbore, the tie back seal member having a seal mandrel at its lower end, the seal mandrel having a tapered outer surface;   positioning the seal mandrel into the tie back receptacle member, the tie back receptacle member defining a tie back receptacle having a tapered inner surface; and   sealing the tapered surfaces against one another by moving at least a burst seal and a collapse seal carried on one of the tapered surfaces into sealing engagement with the other tapered surface; and   wherein the burst and collapse seals are spaced apart from one another.   
     
     
         5 . The method according to  claim 4 , further comprising the step of moving the burst seal into sealing engagement between the tapered surfaces and moving the collapse seal into sealing engagement between the tapered surfaces. 
     
     
         6 . The method according to  claim 5 , wherein an annular space is defined between the burst and collapse seals and the tapered surfaces, and further comprising the step of flowing wellbore fluid out of the annular space. 
     
     
         7 . The method according to  claim 6 , wherein the step of flowing wellbore fluid out of the annular space further comprises flowing wellbore fluid over at least one of the collapse and burst seals. 
     
     
         8 . The method according to  claim 6 , further comprising the step of creating a lower pressure in the annular space than the hydrostatic pressure in the wellbore. 
     
     
         9 . The method according to  claim 6 , wherein the step of flowing wellbore fluid out of the annular space further comprises, flowing wellbore fluid out of the annular space after the seal mandrel is positioned in sealing engagement with the tie back receptacle. 
     
     
         10 . The method according to  claim 8 , wherein the lower pressure in the annular space is created during a further step of withdrawing the seal mandrel from the tie back receptacle. 
     
     
         11 . The method according to  claim 10 , further comprising the step of expanding the seal mandrel in response to creating the lower pressure in the annular space. 
     
     
         12 . The method according to  claim 11 , further comprising the step of contracting the tie back receptacle in response to creating the lower pressure in the annular space. 
     
     
         13 . The method according to  claim 4 , further comprising the step of fastening the tie back receptacle member and the seal member together. 
     
     
         14 . The method according  13 , further comprising the step of interlocking coordinating grooves and ridges on the tapered surfaces of the seal mandrel and tie back receptacle. 
     
     
         15 . The method according to  claim 14 , wherein the grooves and ridges are positioned between the burst and collapse seals. 
     
     
         16 . (canceled) 
     
     
         17 . A tie back assembly for use in a subterranean wellbore, the assembly comprising:
 a seal mandrel having a tapered outer surface;   a tie back receptacle of a size to receive the seal mandrel therein, the tie back receptacle having a tapered inner surface corresponding to the tapered surface of the seal mandrel; and   an annular seal assembly positioned between the outer surface of the seal mandrel and the inner surface of the tie back receptacle; and   wherein the seal assembly comprises two longitudinally spaced apart, annular seals.   
     
     
         18 . The assembly according to  claim 17 , wherein an annular space is defined between the annular seals, the inner surface of the tie back receptacle and the outer surface of the seal mandrel, the seals designed to hold against less pressure from fluid trapped in the annular space than pressure from fluid exterior to the annular space. 
     
     
         19 . The assembly according to  claim 17 , further comprising a plurality of surface structures formed on the outer surface of the seal mandrel and a corresponding plurality of surface structures formed on the inner surface of the tie back receptacle, the surface structures cooperating to produce an increase in drag force when the seal mandrel is removed from the tie back receptacle. 
     
     
         20 . The method according to  claim 17 , wherein the two longitudinally spaced apart seals act to produce a relatively lower pressure area defined by the annular space when the seal mandrel is removed from the tie back receptacle.