Crosslinker composition including synthetic layered silicate
Disclosed herein are crosslinker compositions for aqueous hydroxyl functional polymers. The compositions include at least one borate species, about 0.05 wt % to 10 wt % of a synthetic layered silicate, and a water source. The compositions are characterized by shelf stability, wherein the sparingly soluble borate does not undergo sedimentation. The crosslinker compositions are usefully added to aqueous polymer solutions of hydroxyl functional polymers to form injectable compositions for hydraulic fracturing.
1. A crosslinker composition consisting essentially of
about 5 wt % to 65 wt % of a borate species;
about 0.05 wt % to 10 wt % of a synthetic layered silicate; and
a water source.
2. The composition of claim 1 wherein borate species comprises Na 2 [B 4 O 5 (OH) 4 ].8H 2 O.
3. The composition of claim 2 wherein the composition comprises about 0.5 wt % to 30 wt % Na 2 [B 4 O 5 (OH) 4 ].8H 2 O.
4. The composition of claim 1 wherein the borate species comprises a sparingly soluble borate having the chemical formula
(AM) a (AEM) b B c O d .x H 2 O
wherein a, b, c and d are integers, 0≤a≤2, 1≤b≤4, 2≤c≤14, d=[0.5a+b+1.5c], 0<x<20, AM is an alkali metal, and AEM is an alkaline earth metal.
5. The composition of claim 4 wherein the composition comprises about 30 wt % to 50 wt % of the sparingly soluble borate.
6. The composition of claim 4 wherein the sparingly soluble borate is Ulexite.
7. The composition of claim 1 wherein the borate species comprises a combination of Na 2 [B 4 O 5 (OH) 4 ].8H 2 O and a sparingly soluble borate.
8. The composition of claim 7 comprising about 0.5 wt % to 30 wt % Na 2 [B 4 O 5 (OH) 4 ].8H 2 O and about 30 wt % to 50 wt % of the sparingly soluble borate.
9. The composition of claim 1 wherein the composition comprises about 0.5 wt % to 2 wt % of the synthetic layered silicate.
10. The composition of claim 1 wherein the synthetic layered silicate is a lithium-magnesium-sodium silicate.
11. The composition of claim 1 wherein the synthetic layered silicate is characterized as having the chemical formula Na 0.3 (Mg,Li) 3 Si 4 O 10 (OH) 2 .
12. The composition of claim 1 wherein the particle size of the synthetic layered silicate is about 5 nm to to 100 nm in the longest direction.
13. The composition of claim 1 wherein the water source is present at about 30 wt % to 80 wt %.
14. The composition of claim 1 wherein the water source has a density of about 998 kg/m 3 to 1050 kg/m 3 .
15. An injectable composition comprising the crosslinker composition of claim 1 and an hydroxyl functional polymer.
16. The injectable composition of claim 15 further comprising a proppant.
17. A method of forming an injectable composition, the method comprising
forming a crosslinker composition of claim 1 ,
forming an aqueous polymer solution comprising about 0.01 wt % to 5 wt % of an hydroxyl functional polymer; and
combining the crosslinker composition with the aqueous polymer solution at a ratio of about 1:100 to 1:5000 vol:vol crosslinker composition:aqueous polymer solution to form an injectable composition having a pH of about 8 to 14.
18. The method of claim 17 wherein the aqueous polymer solution comprises about 0.5 wt % to 2 wt % of an hydroxyl functional polymer.
19. The method of claim 17 wherein the hydroxyl functional polymer is guar gum, carboxyl functionalized guar, or a combination thereof.
20. The method of claim 17 wherein the ratio is about 1:200 to 1:2000.
21. A method of recovering hydrocarbon compounds, the method comprising
forming a crosslinker composition of claim 1 ,
forming an aqueous polymer solution comprising about 0.01 wt % to 5 wt % of an hydroxyl functional polymer,
combining the crosslinker composition with the aqueous polymer solution at a ratio of about 1:100 to 1:5000 vol:vol crosslinker composition:aqueous polymer solution to form an injectable composition having a pH of about 8 to 14,
injecting the injectable composition into one or more subterranean hydrocarbon-containing reservoirs; and
recovering hydrocarbon compounds from the one or more reservoirs.
22. The method of claim 21 further comprising adding about 0.01 kg to 1.5 kg of a proppant per liter of the injectable composition.
23. The method of claim 22 wherein the proppant comprises natural sand, silica, bauxite, a ceramic, a resin-coated sand, or a combination of two or more thereof.