초록 ▼

Single-phase microemulsions (SPMEs) and in situ-formed microemulsions in water-wetting pills may be used to reverse the wettability of subterranean rock previously drilled with an oil-based mud or synthetic-based mud before pumping a high fluid loss squeeze pill or crosslink pill or other water-base

Single-phase microemulsions (SPMEs) and in situ-formed microemulsions in water-wetting pills may be used to reverse the wettability of subterranean rock previously drilled with an oil-based mud or synthetic-based mud before pumping a high fluid loss squeeze pill or crosslink pill or other water-based pill. This wettability reversal occurs by solubilization of the non-polar material into the microemulsion when the water-wetting pill contacts the non-polar material. An in situ microemulsion may be formed when one or more surfactant and a polar phase (e.g. water or brine), and eventually some amount of organic phase, contacts the reservoir formation and reverses the wettability encountered in the porous media. The microemulsions are effective for reversing the wettability that occurs from non-polar materials which include, but are not necessarily limited to, oil-based mud, synthetic-based mud, paraffins, asphaltenes, emulsions, slugs, and combinations thereof.

대표청구항 ▼

1. A method of changing the wettability of a rock formation previously contacted with an oil-based mud (OBM) comprising a non-polar fluid, the method comprising: pumping a water-wetting pill into the rock formation, where the water-wetting pill comprises in situ emulsion-forming components comprisin

1. A method of changing the wettability of a rock formation previously contacted with an oil-based mud (OBM) comprising a non-polar fluid, the method comprising: pumping a water-wetting pill into the rock formation, where the water-wetting pill comprises in situ emulsion-forming components comprising: at least one surfactant; andat least one polar fluid;thereby contacting the rock formation with the water-wetting pill;forming in situ an in situ-formed emulsion from the in situ emulsion-forming components and at least some of the non-polar fluid of the OBM where the in situ-formed emulsion is a thermodynamically stable, macroscopically homogeneous mixture of at least three components, where the three components comprise a polar phase from the polar fluid, a non-polar phase at least partially from the non-polar fluid of the OBM, and the at least one surfactant, where the water-wetting pill further comprises an acid selected from the group consisting of mineral acids, acetic acid, formic acid, polyamino carboxylic acids, salts of these acids and mixtures thereof;changing the wettability of at least part of the rock formation to water-wet; andsubsequently pumping a second pill into the rock formation where the subsequent pill comprises water. 2. The method of claim 1 where the second pill is selected from the group consisting of fluid loss pills, crosslink pills, reservoir rock cleaning pills, horizontal healing pills and combinations thereof. 3. The method of claim 1 where the at least one surfactant is selected from the group consisting of non-ionic surfactants, anionic surfactants, cationic surfactants, amphoteric surfactants, flurocarbon surfactants, silicon surfactants, cleavable, gemini surfactants, and extended surfactants containing a non-ionic spacer-arm central extension and an ionic or nonionic polar group, and mixtures thereof. 4. The method of claim 3 where in the surfactants: the nonionic surfactants are selected from the group consisting of alkyl polyglycosides, sorbitan esters, methyl glucoside esters, polyglycol esters, and alcohol ethoxylates;the anionic surfactants are selected from the group consisting of alkali metal alkyl sulfates, alkyl or alkylaryl sulfonates, linear or branched alkyl ether sulfates and sulfonates, alcohol polypropoxylated sulfates, alcohol polyethoxylated sulfates, alkyl or alkylaryl disulfonates, alkyl disulfates, alkyl sulphosuccinates, alkyl ether sulfates, linear and branched ether sulfates;the cationic surfactants are selected from the group consisting of arginine methyl esters, alkanolamines, and alkylenediamides; andthe extended chain surfactants comprise propoxylated spacer arms, ethoxylated spacer arms, propoxylated and ethoxylated spacer arms, and mixtures thereof. 5. The method of claim 1 where at least one polar fluid further comprises brine. 6. The method of claim 1 where the in situ emulsion-forming components further comprise a fluid selected from the group consisting of a non-polar fluid, a fluid of intermediate polarity and mixtures thereof. 7. The method of claim 1 where the surfactant in the water-wetting pill is an ionic surfactant and the water-wetting pill further comprises a co-surfactant. 8. The method of claim 7 where the co-surfactant is a surface active substance selected from the group consisting of mono or poly-alcohols, organic acids or amines, polyethylene glycol, ethoxylation solvents and mixtures thereof. 9. A method of changing the wettability of a rock formation previously contacted with an oil-based mud (OBM) comprising a non-polar fluid, the method comprising: pumping a water-wetting pill into the rock formation, where the water-wetting pill comprises in situ emulsion-forming components comprising: at least one surfactant; andat least one polar brine fluid;thereby contacting the rock formation with the water-wetting pill;forming in situ an in situ-formed emulsion from the in situ-emulsion-forming components and at least some of the non-polar fluid of the OBM where the in situ-formed emulsion is a thermodynamically stable, macroscopically homogeneous mixture of at least three components, where the three components comprise a polar phase from the polar brine fluid, a non-polar phase at least partially from the non-polar fluid of the OBM, and the at least one surfactant, where the water-wetting pill further comprises an acid selected from the group consisting of mineral acids, acetic acid, formic acid, polyamino carboxylic acids, salts of these acids and mixtures thereof;changing the wettability of at least part of the rock formation to water-wet; andsubsequently pumping a second pill into the rock formation where the subsequent pill comprises water. 10. The method of claim 9 where the second pill is selected from the group consisting of fluid loss pills, crosslink pills, horizontal healer pills, reservoir rock cleaning pills and combinations thereof. 11. The method of claim 9 where the at least one surfactant is selected from the group consisting of non-ionic surfactants, anionic surfactants, cationic surfactants, amphoteric surfactants, flurocarbon surfactants, silicon surfactants, cleavable, gemini surfactants, and extended surfactants containing a non-ionic spacer-arm central extension and an ionic or nonionic polar group, and mixtures thereof. 12. The method of claim 11 where in the surfactants: the nonionic surfactants are selected from the group consisting of alkyl polyglycosides, sorbitan esters, methyl glucoside esters, polyglycol esters, and alcohol ethoxylates;the anionic surfactants are selected from the group consisting of alkali metal alkyl sulfates, alkyl or alkylaryl sulfonates, linear or branched alkyl ether sulfates and sulfonates, alcohol polypropoxylated sulfates, alcohol polyethoxylated sulfates, alkyl or alkylaryl disulfonates, alkyl disulfates, alkyl sulphosuccinates, alkyl ether sulfates, linear and branched ether sulfates;the cationic surfactants are selected from the group consisting of arginine methyl esters, alkanolamines, and alkylenediamides; andthe extended chain surfactants comprise propoxylated spacer arms, ethoxylated spacer arms, propoxylated and ethoxylated spacer arms, and mixtures thereof. 13. The method of claim 9 where the in situ emulsion-forming components further comprise a fluid selected from the group consisting of a non-polar fluid, a fluid of intermediate polarity and mixtures thereof. 14. The method of claim 9 where the surfactant in the water-wetting pill is an ionic surfactant and the water-wetting pill further comprises a co-surfactant. 15. The method of claim 14 where the co-surfactant is a surface active substance selected from the group consisting of mono or poly-alcohols, organic acids or amines, polyethylene glycol, ethoxylation solvents and mixtures thereof. 16. A method of changing the wettability of a rock formation previously contacted with an oil-based mud (OBM) comprising a non-polar fluid, the method comprising: pumping a water-wetting pill into the rock formation, where the water-wetting pill comprises in situ emulsion-forming components comprising: at least one surfactant; andat least one polar fluid;thereby contacting the rock formation with the water-wetting pill;forming in situ an in situ-formed emulsion from the in situ emulsion-forming components and at least some of the non-polar fluid of the OBM where the in situ-formed emulsion is a thermodynamically stable, macroscopically homogeneous mixture of at least three components, where the three components comprise a polar phase from the polar fluid, a non-polar phase at least partially from the non-polar fluid of the OBM, and the at least one surfactant, where the water-wetting pill further comprises an acid selected from the group consisting of mineral acids, acetic acid, formic acid, polyamino carboxylic acids, salts of these acids and mixtures thereof;changing the wettability of at least part of the rock formation to water-wet; andsubsequently pumping a second pill into the rock formation where the subsequent pill comprises water, the second pill being selected from the group consisting of fluid loss pills, crosslink pills, reservoir rock cleaning pills, horizontal healing pills and combinations thereof; where the at least one surfactant is selected from the group consisting of non-ionic surfactants, anionic surfactants, cationic surfactants, amphoteric surfactants, flurocarbon surfactants, silicon surfactants, cleavable, gemini surfactants, and extended surfactants containing a non-ionic spacer-arm central extension and an ionic or nonionic polar group, and mixtures thereof. 17. The method of claim 16 where in the surfactants: the nonionic surfactants are selected from the group consisting of alkyl polyglycosides, sorbitan esters, methyl glucoside esters, polyglycol esters, and alcohol ethoxylates;the anionic surfactants are selected from the group consisting of alkali metal alkyl sulfates, alkyl or alkylaryl sulfonates, linear or branched alkyl ether sulfates and sulfonates, alcohol polypropoxylated sulfates, alcohol polyethoxylated sulfates, alkyl or alkylaryl disulfonates, alkyl disulfates, alkyl sulphosuccinates, alkyl ether sulfates, linear and branched ether sulfates;the cationic surfactants are selected from the group consisting of arginine methyl esters, alkanolamines, and alkylenediamides; andthe extended chain surfactants comprise propoxylated spacer arms, ethoxylated spacer arms, propoxylated and ethoxylated spacer arms, and mixtures thereof. 18. The method of claim 16 where the in situ emulsion-forming components further comprise a fluid selected from the group consisting of a non-polar fluid, a fluid of intermediate polarity and mixtures thereof. 19. The method of claim 16 where the surfactant in the water-wetting pill is an ionic surfactant and the water-wetting pill further comprises a co-surfactant.