Clay control additive for wellbore fluids
View Patent ↗A clay stabilizer which is capable of inhibiting swelling in a wide variety of clay types and is also capable of restoring permeability in formations which have previously been damaged by clay swelling. Amine salts of differing molecular weights configurations and ionic strength are combined to provide transport into micropores, mesopores and macropores in the formation and to effect cationic change therein. A poly quaternary amine having a high to very high charge density is added along with lower molecular weight amine salts to substantially permanently exchange cations with the clay in the formation.
1. A clay stabilizer for use in a formation having a mixture of two or more clay types comprising:
two or more amine salts capable of cation exchange with the two or more clay types within the formation, each of the two or more amine salts having a different molecular weight and charge density relative to each of the other of the two or more amine salts so as to permit transport into different sized pore spaces within the formation for reducing clay swelling therein.
wherein one of the two or more amine salts is a protonated amine in a range of C 1 to about C 18 having from one to about seven available amine groups; and
wherein one of the two or more amine salts is a long chain poly quaternary amine having a molecular weight less than about 5000 atomic mass units and having greater than about 200 quaternized nitrogen atoms; and
the balance being water.
2. The clay stabilizer of claim 1 wherein the two or more amine salts further comprise:
a cationic amine in a range of C 1 to about C 18 or mixtures thereof so as to provide migration and cation exchange in small pore spaces in the formation; and
the long chain poly quaternary amine having a molecular weight less than about 5000 atomic mass units and having greater than about 200 quaternized nitrogen atoms.
3. The clay stabilizer of claim 1 further comprising:
a cationic amine or mixtures thereof so as to provide migration and cation exchange in small pore spaces in the formation;
the protonated amine so as to provide migration and cation exchange within intermediate pore spaces in the formation; and
the long chain poly quaternary amine having a molecular weight less than about 5000 atomic mass units and having greater than about 200 quaternized nitrogen atoms.
4. The clay stabilizer of claim 3 wherein:
the protonated amine has a molecular weight at least one order of magnitude greater than the cationic amine; and
the long chain poly quaternary amine has a molecular weight at least 1 to 3 orders of magnitude greater than the cationic amine.
5. The clay stabilizer of claim 4 wherein the long chain poly quaternary amine is polydimethyldiallylammonium chloride.
6. The clay stabilizer of claim 2 wherein the cationic amine is a saturated quaternary amine.
7. The clay stabilizer of claim 6 wherein the saturated quaternary amine is choline bicarbonate.
8. The clay stabilizer of claim 2 wherein the long chain poly quaternary amine is polydimethyldiallylammonium chloride.
9. The clay stabilizer of claim 1 wherein the pH is adjusted so as to maintain the protonated amine in the protonated state.
10. The clay stabilizer of claim 9 wherein the pH is adjusted using an organic acid.
11. The clay stabilizer of claim 1 wherein the two or more amine salts further comprise:
one or more amine salts in the range of C 1 to about C 18 .
12. The clay stabilizer of claim 1 wherein the protonated amine is an alkylamine.
13. The clay stabilizer of claim 1 wherein the protonated amine is an alkylpolyamine.
14. The clay stabilizer of claim 1 wherein the protonated amine is hexamethylenediamine.
15. The clay stabilizer of claim 1 wherein the long chain poly quaternary amine is polydimethyldiallylammonium chloride.
16. A clay stabilizer for use in a formation having a mixture of two or more clay types comprising:
two or more amine salts capable of cation exchange with the two or more clay types within the formation, each of the two or more amine salts having a different molecular weight and charge density relative to each of the other of the two or more amine salts so as to permit transport into different sized pore spaces within the formation for reducing clay swelling therein,
wherein one of the two or more amine salts is a protonated amine having a molecular weight sufficient to permit transport into mesopores in the formation; and
wherein one of the two or more amine salts is a long chain poly quaternary amine having a molecular weight less than about 5000 atomic mass units and having greater than about 200 quaternized nitrogen atoms so as to provide transport into the large pore spaces in the formation and cation exchange therein; and
the balance being water.
17. The clay stabilizer of claim 16 wherein the two or more amine salts comprise:
a cationic amine or mixtures thereof in a range from about C 1 to about C 18 so as to provide transport into micropores in the formation and cation exchange therein;
the protonated amine in a range from about C 1 to about C 18 so as to provide transport into the mesopores in the formation and cation exchange therein; and
the long chain polyquaternary amine having greater than about 200 quaternized nitrogen atoms so as to provide transport into the large pore spaces in the formation and cation exchange therein.
18. The clay stabilizer of claim 17 wherein,
the protonated amine has a molecular weight at least one order of magnitude greater than the cationic amine; and
the long chain polyamine has a molecular weight at least 1 to 3 orders of magnitude greater than the cationic amine.