Breakers for gelled fracturing fluids

Abstract

A fracturing fluid for a downhole environment is disclosed, comprising a water-sensitive gel; and a hydrated breaker. A fracturing fluid for a downhole environment is also disclosed, the fracturing fluid comprising a water-sensitive carrier and a breaker, the breaker comprising one or more hydrates, and wherein water of the one or more hydrates is releasable so as to act with the water-sensitive carrier to reduce the viscosity of the fluid. A method of treating a downhole environment with a fracturing fluid is also disclosed, the method comprising: providing to the downhole environment a fluid comprising a water-sensitive carrier and a breaker, the breaker comprising one or more hydrates; and allowing water from the one or more hydrates to release so as to act with the carrier to reduce the viscosity of the fluid.

1 . A fracturing fluid for a downhole environment, the fracturing fluid comprising:
 a water-sensitive gel; and   a hydrated breaker having a crystalline framework containing water that is bound within the crystalline framework and releasable into the fracturing fluid to act on the water-sensitive gel to reduce the viscosity of the fracturing fluid.   
     
     
         2 . The fracturing fluid of  claim 1  in which the water is bound within the crystalline framework by forces that are sufficient to bind the water under a first set of conditions and insufficient to bind the water under a second set of conditions. 
     
     
         3 . The fracturing fluid of  claim 2  in which the first set of conditions comprise ambient surface temperature. 
     
     
         4 . The fracturing fluid of  claim 2  in which the second set of conditions correspond to the conditions of a selected downhole environment. 
     
     
         5 . The fracturing fluid of  claim 1  in which the hydrated breaker is selected to release water bound within the crystalline framework at a delayed rate under a set of conditions. 
     
     
         6 . The fracturing fluid of  claim 5  in which the set of conditions comprise temperatures at or above 40° Celsius. 
     
     
         7 . The fracturing fluid of  claim 6  in which the set of conditions comprise temperatures at or above 60° Celsius. 
     
     
         8 . The fracturing fluid of  claim 7  in which the set of conditions comprise temperatures at or above 100° Celsius. 
     
     
         9 . The fracturing fluid of  claim 1  in which the crystalline framework is saturated with water bound within the crystalline framework. 
     
     
         10 . The fracturing fluid of  claim 1  in which the water bound within the crystalline framework is present in an amount of 0.01-0.5% by volume of the fracturing fluid. 
     
     
         11 . The fracturing fluid of  claim 1  in which the hydrated breaker comprises a hydrated ionic salt breaker. 
     
     
         12 . The fracturing fluid of  claim 11  in which the hydrated ionic salt breaker comprises one or more of a sulfate and a chloride. 
     
     
         13 . The fracturing fluid of  claim 12  in which the hydrated ionic salt breaker comprises one or more of magnesium chloride, sodium sulfate, calcium sulfate, barium chloride, calcium chloride, aluminum sulfate, aluminum potassium sulfate, magnesium sulphate, and zinc sulphate. 
     
     
         14 . The fracturing fluid of  claim 13  in which the hydrated ionic salt breaker comprises aluminum potassium sulfate. 
     
     
         15 . The fracturing fluid of  claim 14  in which the hydrated ionic salt breaker comprises AlK(SO 4 ) 2 (12H 2 O). 
     
     
         16 . The fracturing fluid of  claim 13  in which the hydrated ionic salt breaker comprises one or more of magnesium chloride, sodium sulfate, barium chloride, calcium chloride, magnesium sulphate, zinc sulfate, calcium sulphate, and aluminum sulphate. 
     
     
         17 . The fracturing fluid of  claim 16  in which the hydrated ionic salt breaker comprises one or more of MgCl 2 (6H 2 O), Na 2 SO 4 (10H 2 O), BaCl 2 (2H 2 O), CaCl 2 (6H 2 O, MgSO 4 (7H 2 O), ZnSO 4 (7H 2 O), CaSO 4 (2H 2 O), Al 2 (SO 4 ) 3 (16H 2 O). 
     
     
         18 . The fracturing fluid of  claim 1  further comprising hydrocarbon fluid. 
     
     
         19 . The fracturing fluid of  claim 18  in which the hydrocarbon fluid comprises liquefied petroleum gas. 
     
     
         20 . The fracturing fluid of  claim 1  in which the water-sensitive gel is made from a gelling agent that comprises a combination of an alkoxide of a group IIIA element and an alkoxide of an alkali metal. 
     
     
         21 . The fracturing fluid of  claim 20  in which the group IIIA element comprises one or more of boron and aluminum. 
     
     
         22 . The fracturing fluid of  claim 20  in which the alkoxide of a group IIIA element further comprises:
   M 1 (OR 1 )(OR 2 )(OR 3 ) 
 in which M 1 =the group IIIA element, and R 1 , R 2 , and R 3  are organic groups. 
 
     
     
         23 . The fracturing fluid of  claim 22  in which the organic group of one or more of R 1 , R 2 , and R 3  comprises 2-10 carbon atoms. 
     
     
         24 . The fracturing fluid of  claim 22  in which the organic group of one or more of R 1 , R 2 , and R 3  comprises an alkyl group. 
     
     
         25 . The fracturing fluid of  claim 22  in which M 1 =boron, and R 1 , R 2 , and R 3  comprise 2-10 carbon atoms. 
     
     
         26 . The fracturing fluid of  claim 20  in which the alkali metal comprises one or more of lithium, sodium, and potassium. 
     
     
         27 . The fracturing fluid of  claim 20  in which the alkoxide of an alkali metal further comprises:
   M 2 (OR 4 ) 
 in which M 2 =the alkali metal, and R 4  comprises an organic group. 
 
     
     
         28 . The fracturing fluid of  claim 27  in which the organic group of R 4  comprises 2-24 carbon atoms. 
     
     
         29 . The fracturing fluid of  claim 28  in which the organic group of R 4  comprises 12 carbon atoms. 
     
     
         30 . The fracturing fluid of  claim 29  in which M 2 =lithium and the organic group of R 4  comprises 2-24 carbon atoms. 
     
     
         31 . The fracturing fluid of  claim 1  in which the water is bound within the crystalline framework by forces that are variable with temperature and range from forces that, when the hydrated breaker is added to the fracturing fluid at surface the water is not released into the fracturing fluid, and when the fracturing fluid is within the downhole environment to be fractured, the water undergoes a controlled release into the fracturing fluid at a rate that is dependent on the temperature of the fracturing fluid within the downhole environment. 
     
     
         32 . A fracturing fluid comprising:
 liquefied petroleum gas;   a water-sensitive gel; and   a hydrated breaker having a crystalline framework containing water that is bound within the crystalline framework and releasable into the fracturing fluid to act on the water-sensitive gel to reduce the viscosity of the fracturing fluid.   
     
     
         33 . A method of treating downhole environment, the method comprising:
 adding a gelling agent and a hydrated breaker to a fracturing fluid to produce a water-sensitive gel, the hydrated breaker having a crystalline framework containing water that is bound within the crystalline framework and releasable into the fracturing fluid to act on the water-sensitive gel to reduce the viscosity of the fracturing fluid; and   treating a downhole environment with the water-sensitive gel.   
     
     
         34 . The method of  claim 33  in which the hydrated breaker is selected to release water bound within the crystalline framework at a delayed rate while treating the downhole environment. 
     
     
         35 . A fracturing fluid for a downhole environment, the fluid comprising:
 a water-sensitive gel; and   a hydrated breaker.   
     
     
         36 . Fracturing fluid for a downhole environment, the fluid comprising:
 a water-sensitive carrier and a breaker, the breaker comprising one or more hydrates, and wherein water of the one or more hydrates is releasable so as to act with the water-sensitive carrier to reduce the viscosity of the fluid.   
     
     
         37 . Fluid according to  claim 36  wherein the one or more hydrates are configured to release water over one or both of:
 a particular period of time; and 
 a particular range of temperature. 
 
     
     
         38 . Fluid according to  claim 36  wherein the water-sensitive carrier is formed from a fluid and one or more gelling agent. 
     
     
         39 . A method of treating a downhole environment with a fracturing fluid, the method comprising:
 providing to the downhole environment a fluid comprising a water-sensitive carrier and a breaker, the breaker comprising one or more hydrates; and   allowing water from the one or more hydrates to release so as to act with the carrier to reduce the viscosity of the fluid.   
     
     
         40 . The method according to  claim 39 , comprising removing from the downhole environment the fluid of reduced viscosity.