System and method for de-watering of hydrocarbon production wells using electrolysis

Abstract

Systems and methods for de-watering of hydrocarbon production wells which uses electrolysis of a water fraction in downhole fluids and a reaction chamber at a distal end of a hydrocarbon production well to generate hydrogen and oxygen gases, to improve hydrocarbon inflow into the production well. The produced hydrogen and/or oxygen gases may be used in combination with hydrocarbons produced by the production well to fuel a gas turbine at surface to generate electrical power for the electrolysis, or such gases may be recombined at surface to provide purified water. A first gas collection means surrounds a region above or proximate an anode for collecting the oxygen gas, and a first production tubing extends therefrom to surface. Means are further provided for collecting and producing hydrogen gas at a cathode, either in combination with produced hydrocarbons from the production well, or separately therefrom.

We claim: 
     
         1 . A system for de-watering a hydrocarbon production well via electrolysis of water to reduce hydrostatic backpressure of said water at a distal end of said hydrocarbon production well so as to thereby improve flow of hydrocarbon fluids into said production well, comprising:
 a source of DC electric current;   a reaction chamber situated proximate a distal end of said production well, having a port or aperture therein which allows ingress of fluids from a hydrocarbon-containing formation, said fluids comprising liquid water and liquid and/or gaseous hydrocarbons from said hydrocarbon-containing formation;   said reaction chamber comprising:
 (i) a pair of electrodes suspended in said fluids, a first of said pair of electrodes coupled to a negative polarity output from said source of DC electrical current source and forming a cathode, and a second of said pair of electrodes coupled to a positive polarity output from said source of DC electrical current source and forming an anode; 
 (ii) a semi-permeable membrane interposed between said anode and said cathode and substantially submersed in said fluids, which is permeable to ions in said fluids but impermeable to hydrogen gas and oxygen gas and thereby prevents oxygen gas produced at said anode from flowing to or coming into contact with said cathode and said hydrogen gas, and likewise prevents hydrogen gas produced at said cathode flowing to or coming into contact with said anode and said oxygen gas produced at said anode; 
   said reaction chamber configured, using said source of electrical DC current supplied thereto and said pair of electrodes, to convert liquid water in said fluid to its constituent components hydrogen gas and oxygen gas via electrolysis and via the chemical reaction:   
       
         
           
           
               
               
           
         
         a first gas collection means surrounding a region above or proximate said anode for collecting said oxygen gas produced at said anode; 
         first production tubing, extending from said first gas collection means to surface for transporting said oxygen gas from said first gas collection means uphole in said production well to surface; and 
         means for collecting said hydrogen gas produced at said cathode and hydrocarbon liquids and/or gases flowing into said production well. 
       
     
     
         2 . The system for de-watering a hydrocarbon production well as claimed in  claim 1 , wherein:
 said means for collecting comprises:
 (i) a second gas collection means surrounding a region above or proximate said cathode for collecting said hydrogen gas produced at said cathode; 
 (ii) a second production tubing, extending from said second gas collection means to surface for transporting said hydrogen gas uphole in said production well to surface. 
   
     
     
         3 . The system for de-watering a hydrocarbon production well as claimed in  claim 1 , wherein
 said means for collecting comprises:
 (i) production tubing for together conveying a mixture of the hydrogen gas produced at the cathode and remaining fluids after the water component there has been converted to hydrogen gas and oxygen gas, to surface. 
   
     
     
         4 . The system for de-watering a hydrocarbon production well as claimed in  claim 1 , wherein the system further comprises:
 means to permit the addition, from surface, of an electrolyzer to said reaction chamber to aid or facilitate the electrolytic reaction recited in  claim 1 .   
     
     
         5 . The system as claimed in  claim 1 , further comprising:
 means to measure ionic concentration, electrical conductivity, or pH of the fluids in said reaction chamber; and   means to permit, in response to measured ionic concentration, electrical conductivity, or pH of the fluids in the reaction chamber, the addition, from surface, of an electrolyzer to fluids in the reaction chamber to aid or facilitate the electrolytic reaction recited in  claim 1  in the reaction chamber.   
     
     
         6 . The system as claimed in  claim 1 , further comprising;
 liquid level detection means for detecting the level or hydrostatic pressure of water-containing fluids at a distal end of said hydrocarbon production well, and   means for actuating said electrodes to effect electrolysis of water in said reaction chamber when said level or hydrostatic pressure of said water-containing fluids are at or above a given level.   
     
     
         7 . The system for de-watering a hydrocarbon production well as claimed in  claim 1 , wherein said source of DC electrical current comprises a source of AC electrical current at surface of the hydrocarbon production well, which source of AC electrical current is rectified into said source of DC electrical current by a downhole AC-DC rectifier situated downhole in the hydrocarbon production well proximate said reaction chamber, which rectifier rectifies the AC electrical current downhole into the DC electrical current. 
     
     
         8 . The system for de-watering a hydrocarbon production well as claimed in  claim 1 , further comprising:
 a burner for heating water to produce steam;   a steam turbine;   an electrical generator coupled to said steam turbine;   wherein said electrical source of DC power is provided by said generator, or by an inverter coupled to said generator which converts AC power from said generator to DC power.   
     
     
         9 . The system for de-watering a hydrocarbon production well as claimed in  claim 8 , wherein said burner is fueled by hydrocarbon gases produced by said production well. 
     
     
         10 . The system for de-watering a hydrocarbon production well as claimed in  claim 8 , wherein said burner is fueled by said hydrogen gas produced at said cathode. 
     
     
         11 . The system for de-watering a hydrocarbon production well as claimed in  claim 1 , further comprising:
 a gas turbine;   an electrical generator coupled to said gas turbine;   wherein said electrical source of DC power is provided by said generator or by an inverter coupled to said generator which converts AC power from said generator to DC power.   
     
     
         12 . The system for de-watering a hydrocarbon production well as claimed in  claim 11 , wherein said gas turbine is fueled by hydrocarbon gases flowing into said production well and produced to surface from said production well. 
     
     
         13 . The system for de-watering a hydrocarbon production well as claimed in  claim 11 , wherein said gas turbine is fueled by said hydrogen gas produced at said cathode. 
     
     
         14 . The system for de-watering a hydrocarbon production well as claimed in  claim 1 , wherein said source of electrical DC power is provided by a wind turbine and/or a solar panel array, or by a wind turbine and/or solar panel array in combination with a rectifier to convert AC power to DC electrical power. 
     
     
         15 . The system for de-watering a hydrocarbon production well as claimed in  claim 1 , wherein said system further comprises an oxygen sensor configured to sense levels of oxygen in said production well. 
     
     
         16 . The system for de-watering a hydrocarbon production well as claimed in  claim 15 , wherein said oxygen sensor is configured to sense and warn of presence of oxygen gas in the means for collecting. 
     
     
         17 . The system for de-watering a hydrocarbon production well as claimed in  claim 16 , wherein said system is further configured to stop supply of electrical current to said electrodes in the event that presence of oxygen gas is detected by said oxygen sensor in said means for collecting. 
     
     
         18 . A method for de-watering a hydrocarbon production well via electrolysis to reduce water content in hydrocarbon fluids being produced to surface from said hydrocarbon production well, comprising the steps of:
 (i) placing a reaction chamber proximate a distal end of said hydrocarbon production well;   (ii) providing a means for ingress of a fluid mixture comprising liquid water and hydrocarbons from said production well into said reaction chamber;   (iii) providing a pair of electrodes in said reaction chamber and suspending them in said fluid mixture in said reaction chamber;   (iv) providing a semi-permeable membrane between said pair of electrodes which is permeable to ions in said fluid mixture but impermeable to hydrogen gas and oxygen gas;   (v) coupling a first of said pair of electrodes to a negative DC electric current source and forming a cathode, and coupling a second of said pair of electrodes to a positive DC electrical current source and forming an anode;   (vi) collecting oxygen gas formed at said anode and sending said oxygen gas to surface via dedicated tubing;   (vii) transporting said fluid mixture containing hydrocarbons from said reaction chamber having reduced water content due to said water having been decomposed in said reaction chamber to hydrogen and oxygen, to surface via production tubing in said production well.   
     
     
         19 . The method for de-watering a hydrocarbon production well as claimed in  claim 18 , further comprising the steps of:
 collecting hydrogen gas formed at said cathode; and   directing said hydrogen gas to surface via dedicated tubing.   
     
     
         20 . The method for de-watering a hydrocarbon production well as claimed in  claim 19 , further comprising the step, at surface, of combusting or combining said hydrogen gas which has been collected with said oxygen gas which has been collected to produce water vapour and condensing said water vapour to obtain purified liquid water. 
     
     
         21 . The method for de-watering a hydrocarbon production well as claimed in  claim 18 , further comprising the steps of:
 collecting hydrogen gas formed at said cathode; and   directing said hydrogen gas to surface via said production tubing and mixed with said hydrocarbon fluids or gases being produced to surface.   
     
     
         22 . The method for de-watering a hydrocarbon production well as claimed in  claim 18  further comprising the steps of:
 directing an electrolyzer in the form of an acid or a base downhole into said fluid mixture in said reaction chamber to aid or assist in the electrolysis of water in said fluids.