Self-propelled swabbing device and method

Abstract

A self-propelled swabbing device and method for use in removing liquid to surface from within an installed wellbore casing. The device includes a longitudinally extending plunger sized to fit within the wellbore casing, and includes an internal surface defining an internal flow passage extending longitudinally therethrough. The device further includes a seal between the plunger and the casing and a valve stem having a valve operative to be shuttled between an opened position and a closed position to seal the internal flow passage. The stem extends longitudinally through the plunger to form a piston and sealed chamber maintained at a pressure below that desired for closing the valve. A biaser is further provided for biasing the valve in the opened position until a set pressure is reached, at which point the valve, is shuttled to the closed position and flow through the internal flow passage is stopped. The device may include snap-closed and snap-open magnetic devices for ensuring that the valve remains either fully closed or fully open.

1 . A self-propelled swabbing device for use in removing liquid to surface from within an installed wellbore casing, said device comprising: 
 a longitudinally extending plunger sized to fit within said wellbore casing, and having an internal surface defining an internal flow passage extending longitudinally therethrough;    a seal between said plunger and said wellbore casing;    a valve stem including a valve operative to be shuttled between an opened position and a closed position to seal said internal flow passage, said valve stem extending longitudinally through said plunger to form a piston and sealed chamber maintained at a pressure below that desired for closing said valve; and    a biaser for biasing said valve in said opened position until a set pressure is reached,    whereby said valve is shuttled to said closed position and flow through said internal flow passage is stopped.    
   
   
       2 . The device according to  claim 1 , further including a snap-closed device and a snap-open device for ensuring that said valve within said internal flow passage is either fully opened or fully closed until a set pressure is reached.  
   
   
       3 . The device according to  claim 2 , wherein one or both of said snap-closed device and said snap-open device includes magnetic properties.  
   
   
       4 . The device according to  claim 1 , wherein said biaser is located within said sealed chamber.  
   
   
       5 . The device according to  claim 4 , wherein said biaser forms one or more surfaces defining said sealed chamber.  
   
   
       6 . The device according to  claim 4 , wherein said biaser is a spring.  
   
   
       7 . The device according to  claim 5 , wherein said spring is a coil spring.  
   
   
       8 . The device according to  claim 1 , wherein said valve opens automatically upon removal of trapped liquids, thereby allowing said plunger to fall back to bottom.  
   
   
       9 . The device according to  claim 8 , wherein said valve stem extends beyond a surface end of said plunger for striking a strike plate once said plunger delivers accumulated liquids to surface to forcibly push said valve to said opened position and equalize pressure across said device, thereby allowing said plunger to fall back to bottom.  
   
   
       10 . A self-propelled swabbing method for removing liquid to surface from within an installed wellbore casing, said method comprising the steps of: 
 sealing spacing between said wellbore casing and a swabbing device having a valve;    biasing said valve in an opened position until a set pressure is reached;    allowing liquid to flow from below, through and above said swabbing device while said valve is opened;    allowing said valve to close upon achieving said set pressure created by said liquid accumulating above said swabbing device;    allowing pressure from liquids and/or gases within said wellbore and below said swabbing device to build below said swabbing device until combined weight of said swabbing device and accumulated liquid are overcome by said building pressure and begin to rise to surface;    releasing said trapped liquid at surface; and    allowing said valve to open upon a set pressure once said trapped liquid is released, enabling said swabbing device to fall back to bottom.    
   
   
       11 . The method according to  claim 10  further including the step of magnetically snapping open and/or closed said valve to avoid partial opening and/or closing of said valve.