Bubble enhanced downhole oil water separation

Abstract

Use of a bubble-generating mechanism in a production environment is described, The bubble generating mechanism may be used to facilitate the separation of a target fluid from a non-target fluid in the production environment, such as by creating a gradient of the fluids or creating separate and distinct zones of the fluids to be separated. The target fluid can then be preferentially recovered from the production environment based on the gradient or distinct zones.

1 . A downhole tool assembly, comprising:
 at least one pump configured to pump a target fluid from a target-fluid rich zone of a production environment, wherein the production environment contain both the target fluid and a non-target fluid;   a bubble generator configured to inject gas bubbles into the production environment, wherein the gas bubbles are sized so as to associate with droplets of the target fluid to decrease the apparent density of the target fluid relative to the non-target fluid.   
     
     
         2 . The downhole tool assembly of  claim 1 , wherein the target fluid is a hydrocarbon fluid and the non-target fluid is water. 
     
     
         3 . The downhole tool assembly of  claim 1 , wherein the production environment is a wellbore. 
     
     
         4 . The downhole tool assembly of  claim 1 , wherein the at least one pump or a second pump are configured to pump the non-target fluid to a subterranean reservoir. 
     
     
         5 . The downhole tool assembly of  claim 1 , wherein the gas bubbles generated by the bubble generator are nanobubbles having a diameter equal to or less than 500 μm. 
     
     
         6 . The downhole tool assembly of  claim 1 , wherein the at least one pump comprises an electrical submersible pump, a progressive cavity pump, a rod pump, or a turbine pump. 
     
     
         7 . The downhole tool assembly of  claim 1 , wherein the gas bubbles are formed from in situ well gas, atmospheric gas, O 2 , CO 2 , or N 2 . 
     
     
         8 . The downhole tool assembly of  claim 1 , wherein the bubble generator comprises:
 a pump configured to move a gas from the surface to the production environment;   gas tubing through which the gas flows to the production environment; and   a nozzle comprising a plurality of apertures, wherein the nozzle receives the pressurized gas from the compressor and injects bubbles into the production environment when the pressurized gas passes through the apertures.   
     
     
         9 . The downhole tool assembly of  claim 8 , wherein the nozzle comprises a ceramic nozzle. 
     
     
         10 . The downhole tool assembly of  claim 1 , wherein the bubble generator is configured to inject gas bubbles into the production environment either continuously during operation or intermittently during operation. 
     
     
         11 . The downhole tool assembly of  claim 1 , wherein the bubble generator is configured to generate bubbles sized to correspond to or be distributed around an average size or a median size of the droplets of the target fluid in the production environment. 
     
     
         12 . A method for separating a target fluid from water in a downhole environment, comprising:
 generating a plurality of bubbles in a mixture of a target fluid and water present in a production environment, wherein the bubbles bond with droplets of the target fluid to decrease the apparent density of the droplets;   pumping target fluid to the surface from a first zone of the production environment having an increased concentration of the target fluid due to the decreased apparent density of the droplets.   
     
     
         13 . The method of  claim 12 , wherein the target fluid is a hydrocarbon fluid. 
     
     
         14 . The method of  claim 12 , further comprising:
 pumping water to a subterranean reservoir from a second zone of the production environment having an decreased concentration of the target fluid due to the decreased density of the droplets.   
     
     
         15 . The method of  claim 14 , wherein pumping target fluid and pumping water are performed in alternation. 
     
     
         16 . The method of  claim 12 , wherein generating the plurality of bubbles comprises generating nanobubbles having a diameter equal to or less than 500 μm. 
     
     
         17 . The method of  claim 12 , wherein generating the plurality of bubbles comprises generating the plurality of bubbles from one or more of in situ well gas, atmospheric gas, O 2 , CO 2 , or N 2 . 
     
     
         18 . The method of  claim 12 , wherein generating the plurality of bubbles comprises:
 pumping a gas from a surface pump to a bubble emitter; and   forcing the gas through a nozzle of the bubble emitter positioned in the production environment, wherein the nozzle comprises apertures configured to generate the plurality of bubbles when the compressed gas passes through.   
     
     
         19 . The method of  claim 12 , wherein the plurality of bubbles are generated continuously or intermittently during operation. 
     
     
         20 . A method for purging settled fines in a downhole environment, comprising:
 operating a first pump configured to inject water into a downhole formation to instead agitate fines within the downhole environment so as to raise at least a portion of the fines to the level of an inlet to a second pump; and   operating the second pump so as to intake the agitated fines and to lift the fines form the downhole environment with a produced fluid.