Method and apparatus for pumping liquid from wells

Abstract

An improved, unattended, liquid pumping device for oil and gas wells featuring a bellows controlled flow valve that opens and closes at preset pressures. The liquid pumping device may operate within a liner suspended into the well. The liquid pumping device may also include sealing elements configured to deform radially to allow the pumping device to pass through restrictions in the well or liner.

1 . A method for pumping fluid from a well having a casing, comprising the steps of: 
 suspending a liner through the casing and into liquid in the well;    placing a pump in the liner such that the pump descends through the liner into the liquid;    automatically closing the pump such that the pump forms a fluid seal to substantially impede fluid flow around the pump in the liner;    raising the pump with a column of fluid in the liner in response to a build up of fluid pressure from closing the pump; and    automatically opening the pump in response to a decrease in the difference between the fluid pressure above the pump and the fluid pressure below the pump.    
   
   
       2 . The method of  claim 1  comprising the step of forming a fluid-tight seal between the liner and the casing to substantially impede the flow of fluid from the well between the liner and the casing.  
   
   
       3 . The method of  claim 1  wherein the liner is a hollow tubing.  
   
   
       4 . The method of  claim 3  wherein the step of suspending a liner comprises the steps of: 
 inserting a first length of tubing into the well;    connecting a second length of tubing to the first length of tubing; and    inserting the second length of tubing into the well.    
   
   
       5 . The method of  claim 1  wherein the step of suspending a liner comprises the step of unwinding the liner from a spool and inserting the liner into the well.  
   
   
       6 . The method of  claim 1  comprising the step of attaching a cap to the bottom end of the liner, wherein the cap is operable to impede the displacement of the pump to prevent the pump from descending out of the bottom of the liner.  
   
   
       7 . The method of  claim 6  comprising the step of cushioning impact between the pump and the cap.  
   
   
       8 . The method of  claim 1  comprising the steps of: 
 attaching upper and lower discharge lines to the well; and    suspending the pump between upper and lower discharge lines after the step of raising the pump and before the step of automatically opening the pump.    
   
   
       9 . The method of  claim 1  comprising the step of selecting a liner having a diameter of approximately 3″ or greater.  
   
   
       10 . A system for pumping fluid from a well having a casing, comprising: 
 an elongated hollow tubing insertable into the casing of a well, wherein the hollow tubing has an interior surface;    a casing plunger, comprising: 
 a housing having an upper end and a lower end;  
 a seal disposed intermediate the upper end and lower end, forming a fluid-tight seal between the housing and the interior surface of the tubing;  
 a fluid passage extending through the case, having an inlet port below the seal and a discharge port above the seal; and  
 a pressure sensitive valve system disposed within the fluid passage, such that the valve system automatically closes when a pressure on the valve system is greater than a closing pressure, and opens when the pressure on the valve system is less than an opening pressure; and  
   a seal forming a fluid tight seal between the liner and the casing of the well.    
   
   
       11 . The device of  claim 10  wherein the valve system seals the fluid passage when the valve system is closed, thereby substantially impeding fluid flow through device when the valve system is closed.  
   
   
       12 . The device of  claim 10  wherein the tubing is spooled onto a reel.  
   
   
       13 . The device of  claim 10  wherein the tubing comprises a plurality of separate sections and each section comprises a connector for connecting the sections.  
   
   
       14 . The device of  claim 10  comprising a stop operable to impede displacement of the casing plunger beyond a bottom edge of the tubing.  
   
   
       15 . The device of  claim 14  comprising a cushioning element operable to cushion the casing plunger as the casing plunger contacts the stop.  
   
   
       16 . The device of  claim 14  wherein the stop comprises a cap enclosing the bottom edge, wherein the cap comprises a plurality of orifices.  
   
   
       17 . A pump for pumping fluid from a well having a generally cylindrical tube having an internal surface, wherein the pump comprises: 
 a housing having an upper end and a lower end;    a seal disposed intermediate the upper end and lower end, forming 
 a fluid-tight seal between the housing and the internal surface of the cylindrical tube, wherein the seal comprises:  
 a body;  
 a first seal element projecting radially outwardly away from the body; and  
 a second seal element projecting radially outwardly from the body, axially spaced from the first seal element;  
   a fluid passage extending through the housing, having an inlet port below the seal and a discharge port above the seal; and    a pressure sensitive valve system disposed within the fluid passage, such that the valve system automatically closes when a pressure on the valve system is greater than a closing pressure, and opens when the pressure on the valve system is less than an opening pressure.    
   
   
       18 . The pump of  claim 17  wherein the seal is configured to maintain a sealing relationship with the internal surface as the seal passes through a restriction in the tube of 5-20% of the diameter of the tube.  
   
   
       19 . The pump of  claim 17  wherein the tube has a portion having a cross section that is out of round, and wherein the seal is configured to maintain a sealing relationship with the internal surface of the tube when the pump passes through the out of round portion.  
   
   
       20 . The pump of  claim 17  wherein the first and second seal elements each have an axial length and a radial thickness, wherein the radial thickness is greater than the axial length.  
   
   
       21 . The pump of  claim 17  wherein the pump comprises a second seal configured similarly to the seal, axially spaced apart from the seal.  
   
   
       22 . The pump of  claim 17  wherein the first and second sealing elements are configured to deform radially and axially.  
   
   
       23 . The pump of  claim 17  wherein the first sealing element is operable to deform axially an amount greater than the axial thickness of the first sealing element.  
   
   
       24 . The pump of  claim 17  wherein the first sealing element is a circumferential flange projecting outwardly from the body and the second sealing element is a circumferential flange projecting outwardly from the body.