Method and system for regeneration of a membrane used to separate fluids in a wellbore

Abstract

A system is provided which has a downhole membrane separator, including a membrane, which separates hydrocarbons, such as methane and oil, from other contaminants, such as CO 2 and water. After the membrane becomes fouled with contaminants after separating a sufficient quantity of a feedstock, the membrane is backflushed or chemically treated, in place to assist in the removal of contaminants from the membrane. An explosive may be used to create the a pressure wave which backflushes the membrane. Or else, the pressure differential across the membrane may be reversed to create the backflushing action. Chemicals may be used to assist in removing foulants. Or else, a spray or bubbler system may be used to create turbulence to assist in the removal of a foulant. Methods of unfouling the membrane are also taught including backflushing and chemical treatment of the membranes to removed unwanted contaminants from the membrane.

What is claimed:  
     
         1 . A method of regenerating a membrane in a wellbore which is used to separate contaminants from a fluid mixture, comprising the steps of: 
 backflushing the membrane with a fluid passing from a permeate side to a retentate side to dislodge contaminants from the membrane thereby regenerating the membrane.    
     
     
         2 . The method of  claim 1  wherein: 
 the step of backflushing includes increasing the fluid pressure on the permeate side over that on the retentate side to induce fluid to flow from permeate side to the retentate side with contaminants be removed from the membrane.  
 
     
     
         3 . The method of  claim 1  wherein: 
 the step of backflushing includes detonating an explosive to create a relative high pressure wave which causes fluid to backflush through the membrane.  
 
     
     
         4 . The method of  claim 1  wherein: 
 a mechanical device is actuated to create a high pressure wave which causes fluid to backflush through the membrane.  
 
     
     
         5 . The method of  claim 1  wherein: fluid pressure on the permeate side of the membrane is gradually increased over the fluid pressure on the retentate side to cause fluid to backflush through the membrane.  
     
     
         6 . The method of  claim 1  further including: 
 adding a chemical to a fluid in the wellbore which contacts the membrane to at least partially release the contaminants on the membrane.  
 
     
     
         7 . The method of  claim 1  wherein: 
 bubbles of gas are introduced to the retentate side of the membrane to reduce fluid pressure thereon thereby causing fluid to backflush through the membrane.  
 
     
     
         8 . The method of  claim 1  wherein: 
 the wellbore includes a fluid tubing passing a fluid there down to introduce fluid into the wellbore at or below the location of the membrane.  
 the fluid tubing is attached outside a production string.  
 
     
     
         9 . The method of  claim 8  wherein: 
 a nozzle is attached to the fluid string and the nozzle sprays fluid on to the membrane.  
 
     
     
         10 . The method of  claim 8  wherein: 
 gas bubbles are created by an aerator which is in communication with the fluid tubing.  
 
     
     
         11 . A method for regenerating a membrane which separates first and second fluid components from a fluid mixture in a wellbore, the method comprising the steps of: 
 positioning a membrane having a first retentate side and a second permeate side in a wellbore, the membrane being selectively permeable to more readily allow a first fluid component to pass there through than a second fluid component;    introducing a fluid mixture, comprising the first and second fluid components and contaminants therein, to the permeate side of the membrane with the fluid pressure on the retentate side being at a higher pressure than on the permeate side;    allowing the first and second fluid components to partially pass through the membrane with the permeate side of the membrane being enriched in the first fluid component and the retentate side becoming enriched in the second fluid component and with a contaminants from the fluid mixture forming on the retentate side of the membrane;    increasing the pressure on permeate side of the membrane to dislodge the contaminants from the membrane thereby regenerating the membrane.    
     
     
         12 . A regenerative membrane system for separating fluid components and contaminants of a fluid mixture in a wellbore to produce a desired fluid component to the surface of a well, the system comprising: 
 a wellbore which receives a fluid mixture from a subterranean formation, the fluid mixture including a first fluid component and a second fluid component;    a membrane separator positioned within the wellbore to receive the fluid mixture, the membrane separator including a membrane having a first retentate side and a second permeate side and the membrane being selectively permeable to more readily allow the first fluid component to pass there through than the second fluid component;    a tubing located within the wellbore and in fluid communication with one of the retentate side and the permeate side of the membrane and in fluid communication with the surface of the well;    a casing located within the wellbore and in fluid communication with the other of the retentate side and permeate side of the membrane;    at least one of the casing and the tubing being in fluid communication with the surface of the well to deliver one of the first and the second fluid components to the surface of the well;    a pressure actuation device which may be actuated to increase the fluid pressure on the permeate side of the membrane to be greater than the retentate side of the membrane;    wherein under normal operating conditions the fluid mixture may be introduced to the retentate side with the first fluid component becoming enriched in one of the tubing and the casing and the permeate side being enriched in the second fluid component and the other of the tubing and the casing with contaminants being formed on the permeate side of the membrane; and    wherein the pressure actuation device may be actuated to increase the fluid pressure on the permeate side to be greater than on the retentate side such that the contaminants are is at least partially dislodged from the membrane thereby regenerating the membrane.