In situ microemulsions used as spacer fluids

Abstract

Nanoemulsions, miniemulsions, microemulsion systems with excess oil or water or both (Winsor III) or single phase microemulsions (Winsor IV) may be formed in situ during hydrocarbon recovery operations after drilling with OBM or SBM using one or more fluid pills. The nanoemulsions, miniemulsions, microemulsion systems with excess oil or water or both or single phase microemulsions remove oil and solids from the well and wellbore surfaces. In one non-limiting embodiment, a single phase microemulsion (SPME) or other in situ-formed fluid may be created from a polar phase, a nonpolar phase, at least one viscosifier, and at least one surfactant.

What is claimed is: 
     
         1 . A thermodynamically stable, single phase microemulsion (SPME) comprising a polar phase, a nonpolar phase, a polyglycerol ester surfactant and at least one viscosifier. 
     
     
         2 . The SPME of  claim 1  where the polar phase is water or brine. 
     
     
         3 . The SPME of  claim 1  where the polar phase is brine selected from the group consisting of halide brines and formate brines. 
     
     
         4 . The SPME of  claim 1  where the nonpolar phase is selected from the group consisting of oil-based mud, synthetic-based mud, residual oily debris, and combinations thereof. 
     
     
         5 . The SPME of  claim 1  further comprising a second surfactant selected from the group consisting of:
 nonionic surfactants selected from the group consisting of alkyl polyglycosides, sorbitan esters, methyl glucoside esters, alcohol ethoxylates, and mixtures thereof; 
 anionic surfactants selected from the group consisting of alkali metal alkyl sulfates, alkyl or alkylaryl sulfonates, linear or branched alkyl ether sulfates and sulfonates, alcohol polypropoxylated and/or polyethoxylated sulfates, alkyl or alkylaryl disulfonates, alkyl disulfates, alkyl sulphosuccinates, alkyl ether sulfates, linear and branched ether sulfates and mixtures thereof; and 
 cationic surfactants selected from the group consisting of arginine methyl esters, alkanolamines, and alkylenediamides, and mixtures thereof. 
 
     
     
         6 . The SPME of  claim 5  where the second surfactant is an alkoxylated alcohol. 
     
     
         7 . A thermodynamically stable, Winsor IV single phase microemulsion (SPME) comprising a polar phase selected from the group consisting of water and brine, a nonpolar phase, a polyglycerol ester surfactant and at least one viscosifier. 
     
     
         8 . The Winsor IV SPME of  claim 7  where the polar phase is brine selected from the group consisting of halide brines and formate brines. 
     
     
         9 . The Winsor IV SPME of  claim 7  where the nonpolar phase is selected from the group consisting of oil-based mud, synthetic-based mud, residual oily debris, and combinations thereof. 
     
     
         10 . The Winsor IV SPME of  claim 7  further comprising a second surfactant selected from the group consisting of:
 nonionic surfactants selected from the group consisting of alkyl polyglycosides, sorbitan esters, methyl glucoside esters, alcohol ethoxylates, and mixtures thereof; 
 anionic surfactants selected from the group consisting of alkali metal alkyl sulfates, alkyl or alkylaryl sulfonates, linear or branched alkyl ether sulfates and sulfonates, alcohol polypropoxylated and/or polyethoxylated sulfates, alkyl or alkylaryl disulfonates, alkyl disulfates, alkyl sulphosuccinates, alkyl ether sulfates, linear and branched ether sulfates and mixtures thereof; and 
 cationic surfactants selected from the group consisting of arginine methyl esters, alkanolamines, and alkylenediamides, and mixtures thereof. 
 
     
     
         11 . The Winsor IV SPME of  claim 10  where the second surfactant is an alkoxylated alcohol. 
     
     
         12 . A thermodynamically stable, Winsor IV single phase microemulsion (SPME) comprising:
 a polar phase is brine selected from the group consisting of halide brines and formate brines,   a nonpolar phase selected from the group consisting of oil-based mud, synthetic-based mud, residual oily debris, and combinations thereof,   a polyglycerol ester surfactant, and   at least one viscosifier.   
     
     
         13 . The Winsor IV SPME of  claim 12  further comprising a second surfactant selected from the group consisting of:
 nonionic surfactants selected from the group consisting of alkyl polyglycosides, sorbitan esters, methyl glucoside esters, alcohol ethoxylates, and mixtures thereof; 
 anionic surfactants selected from the group consisting of alkali metal alkyl sulfates, alkyl or alkylaryl sulfonates, linear or branched alkyl ether sulfates and sulfonates, alcohol polypropoxylated and/or polyethoxylated sulfates, alkyl or alkylaryl disulfonates, alkyl disulfates, alkyl sulphosuccinates, alkyl ether sulfates, linear and branched ether sulfates and mixtures thereof; and 
 cationic surfactants selected from the group consisting of arginine methyl esters, alkanolamines, and alkylenediamides, and mixtures thereof. 
 
     
     
         14 . The Winsor IV SPME of  claim 12  where the second surfactant is an alkoxylated alcohol.