Method for Reducing Aqueous Content of Oil-Based Fluids

Abstract

A method for reducing the aqueous content of oil-based drilling fluid includes contacting an invert emulsion wellbore fluid with a water absorbing polymer, interacting the water absorbing polymer with the wellbore fluid for a sufficient period of time so that the water absorbing polymer absorbs at least a portion of the aqueous fluid form the wellbore fluid; and separating the water absorbing polymer containing the absorbed water from the wellbore fluid.

1 . A method for removing aqueous fluid from a wellbore fluid, comprising:
 contacting the wellbore fluid with a water absorbing polymer, the wellbore fluid comprising:
 an invert emulsion; 
   interacting the water absorbing polymer with the wellbore fluid so that the water absorbing polymer absorbs at least a portion of the aqueous fluid from the wellbore fluid; and   separating the water absorbing polymer containing the absorbed aqueous fluid from the wellbore fluid.   
   
   
       2 . The method of  claim 1 , wherein the invert emulsion is comprised of an oleaginous continuous phase and an aqueous discontinuous phase. 
   
   
       3 . The method of  claim 2 , wherein the oleaginous continuous phase is selected from at least one of mineral oil, synthetic oil, diesel, crude oil, and mixtures thereof. 
   
   
       4 . The method of  claim 2 , wherein the aqueous discontinuous phase is selected from at least one of fresh water, sea water, brine, mixture of water and water soluble organic compounds, and mixtures thereof. 
   
   
       5 . The method of  claim 1 , wherein the water absorbing polymer is a water absorbing crystalline polymer capable of absorbing at least ten times its own weight in fresh water. 
   
   
       6 . The method of  claim 5 , wherein the water absorbing polymer is selected from at least one of acrylamide based polymers and copolymers, starch derivatives, and combinations thereof. 
   
   
       7 . The method of  claim 1 , wherein the sufficient period of time is one to three hours. 
   
   
       8 . The method of  claim 1 , wherein the separating step further comprises passing the wellbore fluid over a shaker screen. 
   
   
       9 . A method for removing non-emulsified aqueous content from a wellbore fluid in situ, comprising:
 determining a design limit of the oil-to-water ratio for the wellbore fluid;   feeding the wellbore fluid to the borehole, the wellbore fluid comprising:   an invert emulsion;   monitoring the oil-to-water ratio of the wellbore fluid;   adding a water absorbing polymer when the oil/water ratio decreases below the design limit;   allowing the water absorbing polymer to interact with the wellbore fluid so that the water absorbing polymer absorbs sufficient aqueous content to return the oil/water ratio above the design limit; and   separating the water absorbing polymer containing the absorbed water from the wellbore fluid.   
   
   
       10 . The method of  claim 9 , where the oil-to-water ratio of the wellbore fluid is intermittently monitored. 
   
   
       11 . The method of  claim 9 , where the oil-to-water ratio of the wellbore fluid is continually monitored. 
   
   
       12 . The method of  claim 9 , where the water absorbing polymer is added directly to an active bore hole pit. 
   
   
       13 . The method of  claim 9 , where the water absorbing polymer is added through a flow line carrying the wellbore fluid. 
   
   
       14 . The method of  claim 9 , where the water absorbing polymer is selected from at least one of acrylamide based polymers and copolymers, starch derivatives, and combinations thereof. 
   
   
       15 . The method of  claim 14 , where the water absorbing polymer is 0.3-1.0 millimeter polymer polymer granules. 
   
   
       16 . The method of  claim 9 , where the separating step further comprises passing the wellbore fluid over a shaker screen. 
   
   
       17 . A method for removing emulsified aqueous content from an existing invert emulsion wellbore fluid, where the existing invert emulsion wellbore fluid comprises an existing oil-to-water ratio, comprising:
 determining a desired oil-to-water ratio for the existing invert emulsion wellbore fluid;   adding a sufficient amount of water absorbing polymer to the existing wellbore fluid to adjust the existing oil-to-water ratio to the desired oil-to-water ratio;   allowing the water absorbing polymer to interact with the existing wellbore fluid for a sufficient period of time so that the water absorbing polymer absorbs sufficient aqueous content to adjust the existing wellbore fluid to the desired oil-to-water ratio, thereby yielding an adjusted wellbore fluid; and   separating the water absorbing polymer containing the absorbed aqueous content from the adjusted wellbore fluid.   
   
   
       18 . The method of  claim 17 , where the water absorbing polymer is selected from at least one of acrylamide based polymers and copolymers, starch derivatives, and combinations thereof. 
   
   
       19 . The method of  claim 17 , where the water absorbing polymer is 0.3-1.0 millimeter polymer granules. 
   
   
       20 . The method of  claim 17 , where the separating step further comprises passing the wellbore fluid over a shaker screen.