Self-destructive barite filter cake in water-based and oil-based drilling fluids

Abstract

Drilling fluid compositions may include a weighting agent, a nitrite-containing compound, and an ammonium-containing compound, where the nitrite-containing compound and the ammonium-containing compound may be encapsulated together in copolymer micro-particles forming encapsulated thermochemical compounds, and where at least one property selected from the group consisting of the density, the plastic viscosity, the yield point, the gel strength, and the pH, of the drilling fluid composition may be substantially similar to the at least one property of a comparable drilling fluid composition devoid of the encapsulated thermochemical compounds. Methods for reducing a filter cake from a wellbore surface in a subterranean formation are also provided. The methods may include introducing into the wellbore the drilling fluid compositions, allowing the drilling fluid composition to reach a temperature in the wellbore sufficient for the encapsulated thermochemical compounds to react, where the reaction of the encapsulated thermochemical compounds generates heat and nitrogen gas.

1 . A drilling fluid composition comprising:
 a weighting agent;   a nitrite-containing compound; and   an ammonium-containing compound;   where the nitrite-containing compound and the ammonium-containing compound are encapsulated together in copolymer micro-particles forming encapsulated thermochemical compounds,   where the copolymer micro-particles are stable for at least 48 hours, and   where at least one property selected from the group consisting of the density, the plastic viscosity, the yield point, the gel strength, and the pH of the drilling fluid composition is substantially similar to the at least one property of a comparable drilling fluid composition devoid of the encapsulated thermochemical compounds.   
     
     
         2 . The drilling fluid of  claim 1 , where the weighting agent is barium sulfate. 
     
     
         3 . The drilling fluid of  claim 2 , where the barium sulfate comprises barium sulfate particles having a size in a range of about 40 microns to about 60 microns. 
     
     
         4 . The drilling fluid of  claim 1 , where the nitrite-containing compound is sodium nitrite. 
     
     
         5 . The drilling fluid of  claim 1 , where the ammonium-containing compound is ammonium chloride. 
     
     
         6 . The drilling fluid of  claim 1 , where the ammonium-containing compound is ammonium sulfate. 
     
     
         7 . The drilling fluid of  claim 1 , where the drilling fluid composition is a water-based drilling fluid. 
     
     
         8 . The drilling fluid of  claim 1 , where the drilling fluid composition is an oil-based drilling fluid. 
     
     
         9 . The drilling fluid of  claim 1 , further comprising one or more additives selected from the group consisting of rheology modifiers, pH-adjusters, clay stabilizers, bridging agents, fluid loss control agents, and emulsifiers. 
     
     
         10 . The drilling fluid of  claim 1 , where the copolymer micro-particles have a size in a range of about 25 to about 50 microns. 
     
     
         11 . The drilling fluid of  claim 1 , where the encapsulated thermochemical compounds are present in the drilling fluid in an amount of about 1 wt % to about 15 wt % based on the total weight of the drilling fluid. 
     
     
         12 . A method for reducing a filter cake from a wellbore surface in a subterranean formation, the method comprising:
 introducing into the wellbore a drilling fluid composition comprising a weighting agent, a nitrite-containing compound, and an ammonium-containing compound,   where nitrite-containing compound and the ammonium-containing compound are encapsulated together in copolymer micro-particles forming encapsulated thermochemical compounds; and   allowing the drilling fluid composition to reach a temperature in the wellbore sufficient for the encapsulated thermochemical compounds to react,   where the reaction of the encapsulated thermochemical compounds generates heat and nitrogen gas; and   where at least a portion of the formed filter cake is removed using the heat and nitrogen gas released from the reaction of the thermochemical compounds.   
     
     
         13 . The method of  claim 12 , where at least 70 vol % of the formed filter cake is removed. 
     
     
         14 . The method of  claim 12 , further comprising forming the drilling fluid composition before introducing it into the wellbore. 
     
     
         15 . The method of  claim 12 , further comprising cementing the wellbore after the step of removing at least a portion of the formed filer cake. 
     
     
         16 . The method of  claim 12 , further comprising producing hydrocarbons after the step of removing at least a portion of the formed filer cake.