Method of Using Water-in-Oil Emulsion to Remove Oil Base or Synthetic Oil Base Filter Cake

Abstract

Fluid producing or injecting wells may be treated with a water-in-oil emulsion for the removal or inhibition of unwanted particulates, including pipe dope, asphaltenes and paraffins. In addition, such emulsions are effective in the displacement of oil base drilling muds and/or residues from such muds from wells. The emulsion may also be used to break the interfacial and/or rheological properties of oil base mud and synthetic oil base mud filter cakes, and act as a demulsifier to break the water-in-oil emulsion present in such oil base and synthetic oil base muds. The water-in-oil emulsions may optionally contain a dispersing agent as well as a surfactant.

1 . A method of removing an oil base or synthetic oil base filter cake from a wellbore and/or subterranean formation which comprises introducing a composition comprising a water-in-oil emulsion into the wellbore, wherein solids from the filter cake are dispersed into the aqueous phase of the emulsion and further wherein at least a portion of the filter cake is removed from the wellbore. 
     
     
         2 . The method of  claim 1 , wherein the composition further comprises a dispersing agent. 
     
     
         3 . The method of  claim 1 , wherein the outer phase of the water-in-oil emulsion is an organic solvent. 
     
     
         4 . The method of  claim 2 , wherein the dispersing agent is a pH adjusting agent. 
     
     
         5 . The method of  claim 1 , wherein the inner phase of the water-in-oil emulsion further comprises a pH adjusting agent. 
     
     
         6 . The method of  claim 1 , wherein the inner phase of the water-in-oil emulsion is an aqueous salt solution. 
     
     
         7 . The method of  claim 6 , wherein the aqueous salt solution is selected from the group consisting of sodium formate brine, potassium formate brine, cesium formate brine, sodium bromide brine, potassium bromide brine, cesium bromide brine, calcium bromide brine, zinc bromide brine, sodium chloride brine, potassium chloride brine, cesium chloride brine, calcium chloride brine, zinc chloride brine, seawater and mixtures thereof. 
     
     
         8 . The method of  claim 3 , wherein the organic solvent is selected from the group consisting of aromatic petroleum cuts, mono-, di- and tri-glycerides of saturated or unsaturated fatty acids, esters, minerals oils, chlorinated hydrocarbons, deodorized kerosene, naphtha, paraffins, isoparaffins, olefins, aliphatic hydrocarbons, aromatic hydrocarbons, long chain alcohols, ketones, nitrites, amides, amines, cyclic ethers, branched ethers, linear ethers, aliphatic ethers of glycols, pyrrolidones, N-alkyl piperidones, N,N-dialkyl alkanolamides, N,N,N′,N′-tetra alkyl ureas, dialkylsulfoxides, pyridines, hexaalkylphosphoric triamides, 1,3-dimethyl-2-imidazolidinone, nitroalkanes, nitro-compounds of aromatic hydrocarbons, sulfolanes, butyrolactones, alkylene carbonates, alkyl carbonates, tetrahydrofuran, dioxane, dioxolane, methyltetrahydrofuran, dimethylsulfone, tetramethylene sulfone, thiophene, polyalkylene glycols, polyalkylene glycols ethers, polyalkylene glycols esters and mixtures thereof. 
     
     
         9 . A method of removing an oil base or synthetic oil base filter cake containing drilled and/or deposited solids from a wellbore and/or subterranean formation comprising:
 (a) introducing into the wellbore a composition comprising a water-in-oil emulsion;   (b) digesting at least a portion of the filter cake with the composition wherein at least a portion of the solids are dispersed in the aqueous phase of the emulsion and further wherein at least a portion of the solids separate from the filter cake; and   (c) removing the aqueous phase containing at least a portion of the solids and at least a portion of the filter cake from the wellbore.   
     
     
         10 . The method of  claim 9 , wherein the composition further comprises a dispersing agent. 
     
     
         11 . The method of  claim 9 , wherein the outer phase of the water-in-oil emulsion is an organic solvent. 
     
     
         12 . The method of  claim 10 , wherein the dispersing agent is a pH adjusting agent. 
     
     
         13 . The method of  claim 9 , wherein the inner phase of the water-in-oil emulsion further comprises a pH adjusting agent. 
     
     
         14 . The method of  claim 9 , wherein the inner phase of the water-in-oil emulsion is an aqueous salt solution. 
     
     
         15 . The method of  claim 11 , wherein the organic solvent is selected from the group consisting of aromatic petroleum cuts, mono-, di- and tri-glycerides of saturated or unsaturated fatty acids, esters, minerals oils, chlorinated hydrocarbons, deodorized kerosene, naphtha, paraffins, isoparaffins, olefins, aliphatic hydrocarbons, aromatic hydrocarbons, long chain alcohols, ketones, nitrites, amides, amines, cyclic ethers, branched ethers, linear ethers, aliphatic ethers of glycols, pyrrolidones, N-alkyl piperidones, N,N-dialkyl alkanolamides, N,N,N′,N′-tetra alkyl ureas, dialkylsulfoxides, pyridines, hexaalkylphosphoric triamides, 1,3-dimethyl-2-imidazolidinone, nitroalkanes, nitro-compounds of aromatic hydrocarbons, sulfolanes, butyrolactones, alkylene carbonates, alkyl carbonates, tetrahydrofuran, dioxane, dioxolane, methyltetrahydrofuran, dimethylsulfone, tetramethylene sulfone, thiophene, polyalkylene glycols, polyalkylene glycols ethers, polyalkylene glycols esters and mixtures thereof. 
     
     
         16 . A method of removing an oil base or synthetic oil base filter cake from a wellbore and/or subterranean formation which comprises introducing a composition comprising a dispersing agent and a water-in-oil emulsion into the wellbore, wherein the outer phase of the water-in-oil emulsion is an organic solvent. 
     
     
         17 . The method of  claim 16 , wherein the dispersing agent is a pH adjusting agent. 
     
     
         18 . The method of  claim 16 , wherein the inner phase of the water-in-oil emulsion is an aqueous salt solution. 
     
     
         19 . The method of  claim 16 , wherein the organic solvent is selected from the group consisting of aromatic petroleum cuts, mono-, di- and tri-glycerides of saturated or unsaturated fatty acids, esters, minerals oils, chlorinated hydrocarbons, deodorized kerosene, naphtha, paraffins, isoparaffins, olefins, aliphatic hydrocarbons, aromatic hydrocarbons, long chain alcohols, ketones, nitrites, amides, amines, cyclic ethers, branched ethers, linear ethers, aliphatic ethers of glycols, pyrrolidones, N-alkyl piperidones, N,N-dialkyl alkanolamides, N,N,N′,N′-tetra alkyl ureas, dialkylsulfoxides, pyridines, hexaalkylphosphoric triamides, 1,3-dimethyl-2-imidazolidinone, nitroalkanes, nitro-compounds of aromatic hydrocarbons, sulfolanes, butyrolactones, alkylene carbonates, alkyl carbonates, tetrahydrofuran, dioxane, dioxolane, methyltetrahydrofuran, dimethylsulfone, tetramethylene sulfone, thiophene, polyalkylene glycols, polyalkylene glycols ethers, polyalkylene glycols esters and mixtures thereof. 
     
     
         20 . A method of removing an oil base or synthetic oil base filter cake containing drilled and/or deposited solids from a wellbore and/or subterranean formation comprising introducing into the wellbore a composition comprising a water-in-oil emulsion, wherein the organic phase of the water-in-oil emulsion dissolves at least a portion of the oil in the oil base or synthetic oil base filter cake and further wherein at least a portion of the solids are dispersed in the aqueous phase of the emulsion.