Wellhead connection device and method for reducing axial stresses in a pipe run

Abstract

The invention relates to a wellhead connection device ( 10 ) for the top-side connection of a pipe run of a deep well. A wellhead connection device ( 10 ) according to the invention has a housing ( 12 ), which comprises a through opening ( 14 ), and a pipe connection element ( 36 ) arranged inside the through opening ( 14 ) in the housing ( 12 ). The pipe connection element ( 36 ) is arranged to be axially displaceable in the housing ( 12 ) in order to compensate for axial stresses during normal operation. The invention moreover relates to a method for reducing axial stresses in a pipe run which is firmly connected to a pipe connection element ( 36 ) of a wellhead connection device ( 10 ).

1 . A wellhead connection device ( 10 ) for the top-side connection of a pipe run of a deep well, having a housing ( 12 ), which comprises a through opening ( 14 ), and a pipe connection element ( 36 ) arranged inside the through opening ( 14 ) in the housing ( 12 ), wherein the pipe connection element ( 36 ) is arranged to be axially displaceable in the housing ( 12 ) in order to compensate for axial stresses during normal operation,
 characterized in that   a fluid space ( 46 ) is provided in the housing ( 12 ), functionally interacting with the pipe connection element ( 36 ), and is arranged such that the axial position of the pipe connection element ( 36 ) during normal operation stands in functional connection with the fluid quantity and/or the fluid pressure in the fluid space ( 46 ).   
     
     
         2 . The wellhead connection device ( 10 ) according to  claim 1 , characterized in that a housing cover ( 56 ) is arranged at one axial end of the housing ( 12 ). 
     
     
         3 . The wellhead connection device ( 10 ) according to  claim 1 , characterized in that the pipe connection element ( 36 ) comprises at least one guide section formed radially on the outside and the at least one guide section is surrounded by a bearing element on the outside. 
     
     
         4 . The wellhead connection device ( 10 ), characterized in that at least one guide section of the pipe connection element ( 36 ) is formed as a radially protruding collar ( 38 ) along a portion of the axial length of the pipe connection element ( 36 ). 
     
     
         5 . The wellhead connection device ( 10 ) according to  claim 4 , characterized in that the fluid space ( 46 ) directly borders on the collar ( 38 ) and a shoulder surface ( 42 ) bordering on the collar and having a radially oriented direction of extension serves as an active surface for the pressure in the fluid space ( 46 ) acting on the pipe connection element ( 36 ). 
     
     
         6 . The wellhead connection device ( 10 ) according to  claim 2 , characterized in that
 a) the housing ( 12 ) and/or the housing cover ( 56 ) is formed as a bearing element on the inside
 and/or 
   b) at least one bearing sleeve ( 64 ) serving as a bearing element is arranged in the housing ( 12 ) and/or in the housing cover ( 56 ) and fixed to the housing.   
     
     
         7 . The wellhead connection device ( 10 ) having a one-piece or multi-piece bearing sleeve ( 64 ) arranged in the housing ( 12 ) according to  claim 6 , characterized in that the position of the bearing sleeve ( 64 ) in the housing is dictated in the axial direction by landing bolts ( 32 ) and/or by retaining screws ( 34 ). 
     
     
         8 . The wellhead connection device ( 10 ) according to  claim 1 , characterized in that there are provided
 a) means of measuring the hydrostatic pressure ( 72 ) in the fluid space ( 46 ) and/or   b) means of detecting the axial position of the pipe connection element ( 36 ) within the housing ( 12 ) and/or   c) means of passive dampening of the pipe connection element displacement.   
     
     
         9 . A method for reducing axial stresses in the pipe run which is firmly connected to the pipe connection element ( 36 ) of the wellhead connection device ( 10 ) according to  claim 1 , characterized by the following steps:
 a) positioning of the pipe connection element ( 36 ) in the housing ( 12 ) such that the pipe connection element ( 36 ) is situated in a middle position and the fluid pressure is within a target region;   b) continuous or at least regular measuring of the hydrostatic pressure of the fluid; and   c) as soon as the pressure leaves the target region or threatens to do so by reaching a margin region, increasing or reducing the quantity of fluid present in the fluid space ( 46 ) in order to maintain the hydrostatic pressure as much as possible within the target region or to bring the hydrostatic pressure back to the target region by axial displacement of the pipe connection element ( 36 ).