System and method for remediating pipeline blockage

Abstract

A system and method for reducing fluid pressure in a pipe connecting a well to a remote location, according to which a section of tubing is inserted into the pipe to define a space between the tubing and the pipe. Pressurized fluid is introduced into the pipe in a manner to displace the fluid in the pipe and reduce the fluid pressure in the pipe to prevent the formation of hydrates in the pipe.

1 . A method for reducing fluid pressure in a pipe connecting a well to a remote location, the fluid normally flowing from the well, though the pipe, and to the remote location, the method comprising: 
 terminating the flow of the fluid through the pipe;    inserting a section of tubing into the pipe to define a space between the tubing and the pipe; and    introducing a pressurized gas into the space so that the gas passes through the space and displaces the fluid from the space and through the tubing, to reduce the fluid pressure in the pipe.    
   
   
       2 . The method of  claim 1  wherein the well is formed at a subsea location, wherein the fluid is production fluid, and wherein the remote location is a production facility on the surface of the sea.  
   
   
       3 . The method of  claim 1  wherein the gas is passed from the remote location, through the space in a direction towards the well, and wherein the displaced fluid passes through the tubing towards the remote location.  
   
   
       4 . The method of  claim 1  wherein the fluid in the tubing is also displaced.  
   
   
       5 . The method of  claim 4  wherein the displaced fluid from the space and the tubing are displaced to the remote location.  
   
   
       6 . The method of  claim 1  further comprising terminating the step of introducing, and then reducing the pressure in the space and/or the tubing so that any remaining production fluid in the pipe will be allowed to expand and flow to the remote location.  
   
   
       7 . The method of  claim 1  wherein the reduction of the pressure in the pipe lowers the temperature of the fluid to a value that will cause any hydrates in the pipe to melt.  
   
   
       8 . The method of  claim 1  further comprising removing the tubing from the pipe and starting the flow of the fluid from the well and towards the remote location.  
   
   
       9 . A method for reducing fluid pressure in a pipe connecting a well to a remote location, the fluid normally flowing from the well, though the pipe, and to the remote location, the method comprising: 
 terminating the flow of the fluid through the pipe;    inserting a section of tubing into the pipe to define a space between the tubing and the pipe;    maintaining a fluid pressure on the tubing;    inserting a packer into the space to seal against fluid flow across the packer while maintaining the pressure on the tubing; and    then venting the fluid from the tubing to reduce the fluid pressure in the pipe.    
   
   
       10 . The method of  claim 9  wherein the well is formed at a subsea location, wherein the fluid is production fluid, and wherein the remote location is a production facility on the surface of the sea.  
   
   
       11 . The method of  claim 9  wherein the vented fluid is a gas that passes through the tubing to the remote location.  
   
   
       12 . The method of  claim 9  wherein, after the step of venting, the fluid in the space flows in the tubing and to the remote location.  
   
   
       13 . The method of  claim 12  wherein the vented fluid is a gas and wherein a gas/liquid interface is established in the tubing.  
   
   
       14 . The method of  claim 9  wherein the reduction of the pressure in the pipe lowers the temperature of the fluid to a value that will cause any hydrates in the pipe to melt.  
   
   
       15 . The method of  claim 9  further comprising removing the tubing from the pipe and starting the flow of the fluid from the well and towards the remote location.  
   
   
       16 . The method of  claim 9  wherein the locations of the tubing and the packer in the pipe are selected to ensure that the final equilibrium pressure is low enough to lower the temperature of the fluid in the pipe sufficiently to cause any hydrates in the pipe to melt.  
   
   
       17 . A method for reducing fluid pressure in a pipe connecting a well to a remote location, the fluid normally flowing from the well, though the pipe, and to the remote location, the method comprising: 
 terminating the flow of the fluid through the pipe;    inserting a section of tubing into the pipe to define a space between the tubing and the pipe; and    pumping the fluid from the space and through the tubing to the remote location to reduce the fluid pressure in the pipe.    
   
   
       18 . The method of  claim 17  wherein the well is formed at a subsea location, wherein the fluid is production fluid, and wherein the remote location is a production facility on the surface of the sea.  
   
   
       19 . The method of  claim 17  further comprising inserting a packer into the space to seal against fluid flow across the packer so that the packer prevents the production fluid in the space between the remote location and the packer from being pumped.  
   
   
       20 . The method of  claim 17  wherein the step of pumping comprises providing a pump on the tubing, and activating the pump.  
   
   
       21 . The method of  claim 17  wherein the fluid in the tubing before the step of pumping is also pumped to the remote location.  
   
   
       22 . The method of  claim 17  wherein the reduction of the pressure in the pipe lowers the temperature of the fluid to a value that will cause any hydrates in the pipe to melt.  
   
   
       23 . The method of  claim 17  further comprising removing the tubing from the pipe and starting the flow of the fluid from the well and towards the remote location.  
   
   
       24 . A method for reducing fluid pressure in a pipe connecting a well to a remote location, the fluid normally flowing from the well, though the pipe, and to the remote location, the method comprising: 
 terminating the flow of the fluid through the pipe;    inserting a first tubing into the pipe to define a first space between the tubing and the pipe;    inserting a second tubing into the first tubing to define a second space between the second tubing and the first tubing; and    introducing a pressurized gas into the second space so that the gas passes through the second space and displaces the fluid from the second space and through the tubing, to reduce the fluid pressure in the pipe.    
   
   
       25 . The method of  claim 24  wherein the well is formed at a subsea location, wherein the fluid is production fluid, and wherein the remote location is a production facility on the surface of the sea.  
   
   
       26 . The method of  claim 24  wherein the gas is passed from the remote location, through the second space in a direction towards the well, and wherein the displaced fluid passes through the tubing to the remote location.  
   
   
       27 . The method of  claim 24  wherein the fluid in the tubing is also displaced.  
   
   
       28 . The method of  claim 27  wherein the displaced fluid from the second space and the tubing are displaced to the remote location.  
   
   
       29 . The method of  claim 24  further comprising terminating the step of introducing, and then reducing the pressure in the second space and/or the tubing so that any remaining production fluid in the pipe will be allowed to expand and flow to the remote location.  
   
   
       30 . The method of  claim 24  wherein the reduction of the pressure in the pipe lowers the temperature of the fluid to a value that will cause any hydrates in the pipe to melt.  
   
   
       31 . The method of  claim 24  further comprising removing the tubings from the pipe and starting the flow of the fluid from the well and towards the remote location.  
   
   
       32 . A method for reducing fluid pressure in a pipe connecting a well to a remote location, the fluid normally flowing from the well, though the pipe, and to the remote location, the method comprising: 
 terminating the flow of the fluid through the pipe;    inserting a section of tubing into the pipe to define a space between the tubing and the pipe;    inserting at least one pigging device into the space, the pigging device normally permitting the flow of fluid across the device and adapted to be expanded to create a seal across the space;    expanding the pigging device to create the seal; and    introducing gas into the tubing so that it flows through the tubing and into the space to displace fluid from the tubing into the space and displace the fluid and the expanded pigging device in the space in a direction towards the remote location to reduce the fluid pressure in the pipe.    
   
   
       33 . The method of  claim 32  wherein the well is formed at a subsea location, wherein the fluid is production fluid, and wherein the remote location is a production facility on the surface of the sea.  
   
   
       34 . The method of  claim 32  wherein the displacement of the pigging device sweeps out the fluid that is in the space between the pigging device and the remote location.  
   
   
       35 . The method of  claim 32  wherein, upon the displacement of the pigging device, the gas displaces fluid in the tubing to the space.  
   
   
       36 . The method of  claim 35  wherein the displacement of the pigging device in the space causes fluid in the space between the pigging device and the well to be displaced in a direction towards the remote location.  
   
   
       37 . The method of  claim 32  wherein a plurality of pigging devices are inserted into the space, and are selectively expanded and displaced to remove fluid from the pipe.  
   
   
       38 . The method of  claim 32  wherein the reduction of the pressure in the pipe lowers the temperature of the fluid to a value that will cause any hydrates in the pipe to melt.  
   
   
       39 . The method of  claim 32  further comprising removing the tubing and the pigging device from the pipe and starting the flow of the fluid from the well and towards the remote location.  
   
   
       40 . A system for reducing fluid pressure in a pipe connecting a well to a remote location, the fluid normally flowing from the well, through the pipe, and to the remote location, the system comprising: 
 a tubing disposed in the pipe to define a space between the tubing and the pipe; and    a packer disposed in the space to seal against fluid flow across the packer while maintaining a gas pressure on the tubing; and    means for venting the gas from the tubing to reduce the fluid pressure in the pipe.    
   
   
       41 . The system of  claim 40  wherein the well is formed at a subsea location, wherein the fluid is production fluid, and wherein the remote location is a production facility on the surface of the sea.  
   
   
       42 . The system of  claim 40  wherein the vented gas passes through the tubing to the remote location.  
   
   
       43 . The system of  claim 40  wherein, after the gas is vented, the fluid in the space flows in the tubing and to the remote location.  
   
   
       44 . A system for reducing fluid pressure in a pipe connecting a well to a remote location, the fluid normally flowing from the well, through the pipe, and to the remote location, the system comprising: 
 a tubing disposed in the pipe to define a space between the tubing and the pipe; and    at least one pigging device disposed in the space and establishing a seal across the space; and    means for introducing gas into the tubing so that it flows through the tubing and into the space to displace the pigging device in the space in a direction towards the remote location to reduce the fluid pressure in the pipe.    
   
   
       45 . The system of  claim 44  wherein the well is formed at a subsea location, wherein the fluid is production fluid, and wherein the remote location is a production facility on the surface of the sea.  
   
   
       46 . The system of  claim 44  wherein the displacement of the pigging device sweeps out the fluid that is in the space between the pigging device and the remote location.  
   
   
       47 . The system of  claim 44  wherein the gas displaces fluid in the tubing to the space.  
   
   
       48 . The system of  claim 47  wherein the displacement of the pigging device in the space causes fluid in the space between the pigging device and the well to be displaced in a direction towards the remote location.  
   
   
       49 . The system of  claim 44  wherein the pigging device is adapted to allow fluid to pass through it.  
   
   
       50 . The system of  claim 44  wherein a plurality of pigging devices are inserted into the space, and are selectively displaced to remove fluid from the pipe.