Intervention blowout preventer and well intervention tool

Abstract

The present invention relates to an intervention blowout preventer ( 1 ) for being mounted on a well head ( 2 ) or a Christmas tree, comprising a plurality of valves ( 3, 4 ) arranged in fluid communication with each other, connected and forming a tubular pipe ( 5 ) enclosing a cavity being in fluid communication with the well head when the intervention blowout preventer is mounted onto the well head and at least one plug ( 37 ) in the well head has been removed, wherein the intervention blowout preventer further comprises a pressure reducing system ( 1 ) comprising a chamber ( 6 ) and a piston ( 7 ) arranged inside the chamber dividing the chamber into a first chamber part ( 8 ) and a second chamber part ( 9 ), the first chamber part being in fluid communication with the cavity and the second chamber part being filled with a compressible fluid, such as gas. Furthermore, the invention relates to a well intervention tool ( 100 ), a well intervention system ( 200 ) and a well intervention method.

1 . An intervention blowout preventer ( 1 ) for being mounted on a well head ( 2 ) or a Christmas tree, comprising:
 a plurality of valves ( 3 ,  4 ) arranged in fluid communication with each other, connected and forming a tubular pipe ( 5 ) enclosing a cavity ( 10 ) being in fluid communication with the well head when the intervention blowout preventer is mounted onto the well head and at least one plug  37  in the well head has been removed, wherein the intervention blowout preventer further comprises a pressure reducing system ( 120 ) comprising a chamber ( 6 ) and a piston ( 7 ) arranged inside the chamber dividing the chamber into a first chamber part ( 8 ) and a second chamber part ( 9 ), the first chamber part being in fluid communication with the cavity and the second chamber part being filled with a compressible fluid, such as gas.   
     
     
         2 . An intervention blowout preventer according to  claim 1 , wherein the cavity has a first pressure and the intervention blowout preventer further comprises a control device ( 11 ), such as a valve, for controlling the pressure in the cavity by letting fluid in the cavity into the first chamber part. 
     
     
         3 . An intervention blowout preventer according to  claim 1 , wherein the piston is slidably arranged on a shaft ( 12 ) arranged inside the chamber. 
     
     
         4 . An intervention blowout preventer according to  claim 1 , wherein the first chamber part is connected with the cavity by means of a flow channel ( 15 ). 
     
     
         5 . An intervention blowout preventer according to  claim 1 , further comprising a control unit ( 38 ) comprising a storage device, and a communication unit for communicating with the control device. 
     
     
         6 . An intervention blowout preventer according to  claim 1 , further comprising a sensor for sensing a pressure in the cavity. 
     
     
         7 . An intervention blowout preventer according to  claim 1 , wherein the pressure reducing system further comprises a pump ( 60 ) for pumping fluid from the cavity into the first chamber part. 
     
     
         8 . An intervention blowout preventer according to  claim 1 , wherein the chamber is an accumulator. 
     
     
         9 . An intervention blowout preventer according to  claim 1 , wherein the pressure reducing system further comprises an accumulator. 
     
     
         10 . An intervention blowout preventer according to  claim 8 , wherein the accumulator comprises the piston, a bladder or a diaphragm. 
     
     
         11 . A well intervention tool ( 100 ) intended to be arranged in a lubricator for pulling a plug ( 37 ) in a top part ( 23 ) of a well head ( 2 ) or a Christmas tree of a well for entering the well, the well head having an axial extension, comprising:
 a connection pulling unit ( 50 ) having a connection unit ( 51 ) for connection to the plug,   a stroking tool ( 52 ) having a tool housing ( 53 ) and being connected to the connection pulling unit and providing an axial movement along the axial extension, and   a fixation unit ( 54 ) for fixating the stroking tool in relation to the well head so that the axial movement of the stroking tool pulls the plug out of the well head,   
       wherein the stroking tool comprises a chamber ( 106 ) and a piston ( 107 ) arranged inside the chamber dividing the chamber into a first chamber part ( 108 ) and a second chamber part ( 109 ), the first chamber part being in fluid communication with an opening ( 113 ) in the tool housing and the second chamber part being filled with a compressible fluid, such as gas. 
     
     
         12 . A well intervention tool ( 100 ) according to  claim 11 , wherein the stroking tool further comprises a control device ( 11 ), such as a valve, for letting fluid in through the opening of the housing into the first chamber part. 
     
     
         13 . A well intervention tool ( 100 ) according to  claim 11  wherein the connection pulling unit is a GS pulling tool. 
     
     
         14 . A well intervention tool ( 100 ) according to  claim 11 , wherein the piston is slidably arranged on a shaft ( 112 ) arranged inside the chamber. 
     
     
         15 . A well intervention tool ( 100 ) according to  claim 11 , wherein the control device is arranged in the opening. 
     
     
         16 . A well intervention tool ( 100 ) according to  claim 11 , wherein the stroking tool is connected with the connection pulling unit by means of a stroker shaft ( 55 ). 
     
     
         17 . A well intervention tool ( 100 ) according to  claim 11 , wherein the fixating unit comprises an anchoring section having anchors moving radially from the tool towards an inside wall of the lubricator. 
     
     
         18 . A well intervention system ( 200 ) comprising:
 an intervention blowout preventer according to  claim 1  for connection onto a well head,   a lubricator ( 20 ) connectable to the intervention blowout preventer, and   an intervention tool ( 100 ) arranged inside the lubricator for pulling the plug ( 37 ) in a top part ( 23 ) of a well head ( 2 ) or a Christmas tree of a well for entering the well.   
     
     
         19 . A well intervention method comprising the steps of:
 arranging the well intervention tool ( 100 ) according to inside a lubricator,   connecting the lubricator on the intervention blowout preventer,   connecting the well intervention tool to the plug ( 37 ),   equalising a pressure inside the cavity of the intervention blowout preventer with a pressure in the well below the plug, and   pulling the plug ( 37 ) in a top part ( 23 ) of a well head ( 2 ) or a Christmas tree of a well.