Synthetic caustic composition

Abstract

An aqueous caustic composition comprising: a caustic component; an amino acid additive adapted to provide an extended buffering effect to the caustic composition when such is exposed to an acid; and water, wherein the caustic component and the amino acid additive are present in a molar ratio ranging from 15:1 to 5:1. Methods of using such compositions are also disclosed.

Claims

1. A method of fracking a hydrocarbon-bearing formation comprising: providing a hydrocarbon-bearing formation; adding a crosslinking activator to a polymer to form a polymer mixture; adding a caustic composition to the polymer mixture to form a crosslinked polymer mixture, the caustic composition comprising: i) a caustic component present in a concentration ranging from 5 wt % to 40 wt % of the caustic composition; ii) an amino acid additive present in a concentration ranging from 2 wt % to 25 wt % of the caustic composition; and iii) water, wherein the amino acid additive is selected from the group consisting of alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine, valine, and salts thereof, adding a proppant to the crosslinked polymer mixture to form a polymer-proppant composition; and injecting the polymer-proppant composition into the hydrocarbon-bearing formation.

2. The method according to claim 1, wherein the crosslinking activator is selected from the group consisting of a borate ion and a zirconate ion.

3. The method according to claim 1, wherein the polymer is a guar gum.

4. The method according to claim 1, wherein the polymer is selected from the group consisting of a guar gum, a carboxymethyl guar gum, a hydroxymethyl guar gum, a hydroxypropylethyl guar gum, an o-carboxymethyl-o-hydroxypropyl guar gum, an ammonium hydroxyl propyl trimethyl chloride of guar gum, an o-carboyxymethyl-o-2 hydroxy-3-(trimethylammonia propyl) guar gum, an acryloyloxy guar gum, a methacryloyl guar gum, a hydroxy propyl guar, a carboxy methyl guar, a carboxy methyl hydroxy propyl guar, and guar.

5. The method according to claim 1, wherein the amino acid additive buffers a pH of the caustic composition between a pH of 8.25 and a pH of 10.

6. The method according to claim 1, wherein a pH of the crosslinked polymer mixture is between a pH of 8.5 and a pH of 9.0.

7. The method according to claim 1, wherein the caustic component is selected from the group consisting of potassium hydroxide, sodium hydroxide, and combinations thereof.

8. The method according to claim 1, wherein the amino acid additive is selected from the group consisting of lysine monohydrochloride, threonine, and methionine.

9. The method according to claim 1, wherein the caustic component is present in a concentration ranging from 10 wt % to 30 wt % of the caustic composition.

10. The method according to claim 1, wherein the caustic component is present in a concentration ranging from 15 wt % to 25 wt % of the caustic composition.

11. The method according to claim 1, wherein the amino acid additive is present in a concentration ranging from 4 wt % to 15 wt % of the caustic composition.

12. The method according to claim 1, where the caustic component and the amino acid additive are present in a molar ratio ranging from 15:1 to 5:1.

13. The method according to claim 1, wherein the caustic composition has a freezing point of less than −18° C.

14. A method of fracking a hydrocarbon-bearing formation comprising: providing a hydrocarbon-bearing formation; adding a cross linking activator to a polymer to form a polymer mixture; adding a caustic composition to the polymer mixture to form a crosslinked polymer mixture, the caustic composition comprising: i) a caustic component present in a concentration ranging from 5 wt % to 40 wt % of the caustic composition; ii) an amino acid additive present in a concentration ranging from 2 wt % to 25 wt % of the caustic composition; and iii) water, wherein the amino acid additive is selected from the group consisting of alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine, valine, and salts thereof, wherein the caustic component and the amino acid additive are present in a molar ratio ranging from 15:1 to 5:1, adding a proppant to the crosslinked polymer mixture to form a polymer-proppant composition; and injecting the polymer-proppant composition into the hydrocarbon-bearing formation.

15. The method of claim 14, where the caustic component and the amino acid additive are present in a molar ratio ranging from 12:1 to 8:1.

16. The method according to claim 14, wherein the crosslinking activator is selected from the group consisting of a borate ion and a zirconate ion.

17. The method according to claim 14, wherein the polymer selected from the group consisting of a guar gum, a carboxymethyl guar gum, a hydroxymethyl guar gum, a hydroxypropylethyl guar gum, an o-carboxymethyl-o-hydroxypropyl guar gum, an ammonium hydroxyl propyl trimethyl chloride of guar gum, an o-carboyxymethyl-o-2 hydroxy-3-(trimethylammonia propyl) guar gum, an acryloyloxy guar gum, a methacryloyl guar gum, a hydroxy propyl guar, a carboxy methyl guar, a carboxy methyl hydroxy propyl guar, and guar.

18. The method according to claim 14, wherein a pH of the crosslinked polymer mixture is between a pH of 8.5 and a pH of 9.0.

19. The method according to claim 14, wherein the caustic component is selected from the group consisting of potassium hydroxide, sodium hydroxide, and combinations thereof.

20. The method according to claim 14, wherein the amino acid additive is selected from the group consisting of lysine monohydrochloride, threonine, and methionine.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) The invention may be more completely understood in consideration of the following description of various embodiments of the invention in connection with the accompanying figures, in which:

(2) FIG. 1 depicts a titration curve of a composition of NaOH (25 wt %);

(3) FIG. 2 depicts a titration curve of a composition according to a preferred embodiment of the present invention, said composition comprising NaOH (25 wt %) with 4 wt % lysine monohydrochloride;

(4) FIG. 3 depicts a titration curve of a composition according to a preferred embodiment of the present invention, said composition comprising NaOH (25 wt %) and 5 wt % methionine;

(5) FIG. 4 depicts a titration curve of a composition according to a preferred embodiment of the present invention, said composition comprising NaOH (25 wt %) and 5 wt % tryptophan;

(6) FIG. 5 depicts a titration curve of a composition according to a preferred embodiment of the present invention, said composition comprising NaOH (25 wt %) and 5 wt % glutamic acid;

(7) FIG. 6 depicts a titration curve of a composition comprising NaOH (25 wt %) and 5 wt % threonine;

(8) FIG. 7 depicts a titration curve of a composition according to a preferred embodiment of the present invention, said composition comprising NaOH (25 wt %) and 5 wt % lysine;

(9) FIG. 8 depicts a titration curve of a composition according to a preferred embodiment of the present invention, said composition comprising NaOH (25 wt %) and 5 wt % lysine monohydrochloride;

(10) FIG. 9 depicts a titration curve of a composition according to a preferred embodiment of the present invention, said composition comprising NaOH (25 wt %) and 5 wt % lysine monohydrochloride;

(11) FIG. 10 depicts a titration curve of a composition according to a preferred embodiment of the present invention, said composition comprising NaOH (25 wt %) and 4 wt % lysine monohydrochloride USP; and

(12) FIG. 11 depicts a titration curve of a composition according to a preferred embodiment of the present invention, said composition comprising NaOH (25 wt %) and 5 wt % monosodium glutamate.

DESCRIPTION OF AN EMBODIMENT OF THE PRESENT INVENTION

(13) Borate crosslinked gel fracturing fluids utilize borate ions to crosslink the hydrated polymers and provide increased viscosity. The polymers most often used in these fluids are guar and HPG. The crosslink obtained by using borate is reversible and is triggered by altering the pH of the fluid system (increasing the pH generates the crosslink function, decreasing the pH eliminates the crosslink). The reversible characteristic of the crosslink in borate fluids helps them clean up more effectively, resulting in good regained permeability and conductivity. The present invention can be utilized in this type of situation all the while having a minimal negative effect on polymer chains. The latter is yet another advantage of a preferred embodiment of the present invention. Borate crosslinked fluids have proved to be highly effective in both low and high permeability formations.

(14) To achieve an optimal crosslinking of borate crosslinked guar gel, a pH between 8.5 and 9.0 is necessary. This is a very narrow pH window. A common drawback of using neat caustic is that, as a strong base, a pH in that range can be quite difficult to adjust. A slight difference in dosage can result in a high pH shift, this results in the breakdown of the crosslinking in the gel.

(15) In an attempt to overcome the drawback of using strong caustic agents in the presence of crosslinked gels, or at least to compensate and create a buffer which allows some flexibility in the dosage, a crosslinker and guar gum is added on location on the fly with special equipment.

(16) According to a preferred embodiment of the present invention, it is desirable to have a buffered caustic solution, which enables one to adjust the pH more precisely in a desired range (in other words it is more forgivable in terms of overdosage). Such a buffer provides a substantial advantage over the use of a neat caustic composition.

(17) According to another preferred embodiment of the present invention, it is desirable to have a buffered caustic solution in water treatment. Caustics such as sodium hydroxide can be used to raise the pH of water supplies. Increased pH renders the water less susceptible to corrode pipes and reduces the amount of free metals including copper and other metals which can be found in drinking water.

(18) According to a preferred embodiment of the present invention, there is provided a method to treat water, wherein said method comprises the steps of:

(19) providing an aqueous caustic composition comprising: a caustic component; an amino acid additive adapted to provide an extended buffering effect to the caustic composition when such is exposed to an acid; and water; wherein the amino acid additive is selected from the group consisting of: alanine; arginine; asparagine; aspartic acid; cysteine; glutamic acid; glutamine; histidine; isoleucine; leucine; lysine; methionine; phenylalanine; proline; serine; threonine; tryptophan; tyrosine; valine and salts thereof, and wherein the caustic component is present in a concentration of up to 40 wt % of the composition and the caustic component and the amino acid additive are present in a molar ratio ranging from 15:1 to 5:1; and

(20) exposing a water requiring treatment to a pre-determined amount of said caustic composition for a period of time sufficient to effect the treatment intended.

EXAMPLE 1

Preparation of a Caustic Composition According to a Preferred Embodiment

(21) A composition according to a preferred embodiment of the present invention was prepared by providing 100 ml of 25 wt % NaOH solution. The NaOH solution is then mixed with the appropriate weight of additive, in this case, lysine to be present in an amount of 5 wt %, to obtain the desired weight % concentration. The resulting composition is mixed until one visually determines that solubilization is completed.

Titration of the Composition

(22) The titration of the composition of Example 1 was performed in order to assess its buffering ability. In order to do so, 1 ml of the buffer (composition of Example 1) was drawn and placed in a flask, the buffer was then diluted in 100 ml of distilled water. The resulting solution was titrated with 1 N HCl standard. The pH was continuously recorded with a pH meter. The solution was gently stirred with a magnetic stir bar during the measurements. Prior to recording the pH after each addition of HCl, sufficient time was given to allow for the pH to stabilize. The resulting titration curve associated with Example 1 is found in FIG. 7.

(23) As can be seen by referring to FIGS. 1 to 11, preferred embodiments of the present invention (set out in FIGS. 2 to 11) displayed an extended/linear buffering effect when exposed to acid addition as compared to caustic composition free of additive. This advantageous buffering effect translates into an increased ability to control the pH of crosslinked gels during fracking operations. This is even more advantageous when the pH adjustment is done on the fly. Preferred compositions of the present invention display a strong caustic character, extended linear buffering effect (compared to neat caustic), greatly reduced freeze point and minimized dermal damage upon direct contact with human skin.

(24) According to a preferred embodiment of the present invention, certain additives such as lysine monohydrochloride, and threonine can buffer the pH drop of a 25 wt % caustic solution in the pH range of 8.25 to 10. Such a buffering effect is desirable in fracking operations to maintain the integrity of a guar gel based polymeric system.

(25) According to a preferred embodiment of the present invention, a caustic composition comprising lysine-HCl as additive can have a freezing point as low as −45° C. This is a substantial decrease in the freeze point compared to −18° C. for 25 wt % NaOH. This proves to be highly desirable for winter operations in the oil and gas industry.

Dermal Test

(26) Human dermal tests were performed to assess the safety of inadvertent exposure to a composition according to a preferred embodiment of the present invention.

(27) The tests have determined that human skin having an extended exposure time between 20 to 30 minutes showed minimal signs of damage (i.e. skin irritation) from direct exposure of the composition. This stands in stark contrast with pure NaOH (25%) which, when dropped on the skin causes immediate burning of the skin, followed with scarring.

(28) According to a preferred embodiment, it is desirable to use REACH-ECHA approved products such as lysine and methionine. To have REACH-ECHA approved components provides more opportunities to apply the present technology all the while improving recovery and minimizing environmental damage.

(29) According to another application of the composition according to the preferred embodiment of the present invention, a hot solution of the caustic composition according to a preferred embodiment of the present invention can be used to dissolve aluminium-containing minerals in the bauxite. This, as a result, forms a supersaturated solution of sodium aluminate. When the solution is cooled it will yield a solid form of sodium aluminate. This sodium aluminate can be employed in water treatment, in construction to accelerate the solidification of concrete, in the paper industry, to make fire bricks production, to manufacture alumina.

(30) According to another preferred embodiment of the present invention, it is desirable to have a buffered caustic solution in water treatment. Caustics such as sodium hydroxide can be used to raise the pH of water supplies. Increased pH renders the water less susceptible to corrode pipes and reduces the amount of free metals including copper and other metals which can be found in drinking water.

(31) According to a preferred embodiment of the present invention, there is provided a method of fracking a hydrocarbon-bearing formation using a cross-linked polymer gel, said method comprising the steps of:

(32) providing a hydrocarbon-bearing formation;

(33) providing a polymer;

(34) providing a cross-linking activator and adding such to the polymer;

(35) adding to the polymer mixture a caustic composition comprising: a caustic component; an amino acid additive adapted to provide an extended buffering effect to the caustic composition when such is exposed to an acid; and water; wherein the amino acid additive is selected from the group consisting of: alanine; arginine; asparagine; aspartic acid; cysteine; glutamic acid; glutamine; histidine; isoleucine; leucine; lysine; methionine; phenylalanine; proline; serine; threonine; tryptophan; tyrosine; valine and salts thereof,

(36) adding a proppant to the resulting polymer mixture; and

(37) injecting said resulting polymer-proppant composition into the formation. Preferably, the caustic component is present in amount of up to 40 wt % of the composition. Preferably, the crosslinking component is selected from the group consisting of: a borate ion and a zirconate ion. Preferably also, the polymer is a guar gum.

(38) According to a preferred embodiment of the present invention, there is provided a method of removing impurities present in petroleum during the refining thereof, said method comprising the steps of:

(39) providing a petroleum product to be refined;

(40) providing a caustic composition comprising: a caustic component; an amino acid additive adapted to provide an extended buffering effect to the caustic composition when such is exposed to an acid; and water; wherein the amino acid additive is selected from the group consisting of: alanine; arginine; asparagine; aspartic acid; cysteine; glutamic acid; glutamine; histidine; isoleucine; leucine; lysine; methionine; phenylalanine; proline; serine; threonine; tryptophan; tyrosine; valine and salts thereof,

(41) adding said caustic composition to said petroleum product to be refined; and

(42) allowing said caustic composition and petroleum product to be refined to remain in contact with one another for a period of time determine to be sufficient for the sufficient removal of at least one of carbon dioxide and sulfur-containing compounds.

(43) According to a preferred embodiment of the present invention, there is provided a use of the caustic composition for the control of pH of drilling fluids.

(44) According to a preferred embodiment of the present invention, there is provided a use of the caustic composition for the breaking down of organic matter present in petroleum during the refining thereof.

(45) According to a preferred embodiment of the present invention, there is provided a use of the caustic composition for the removal of various impurities during the refining stage of petroleum production. Preferably, the impurities are selected from the group consisting of: include: carbon dioxide and sulfur-containing compounds.

(46) According to a preferred embodiment of the present invention, there is provided an aqueous caustic composition comprising:

(47) a caustic component;

(48) an amino acid additive adapted to provide an extended buffering effect to the caustic composition when such is exposed to an acid; and

(49) water;

(50) wherein the amino acid additive is selected from the group consisting of: alanine; arginine; asparagine; aspartic acid; cysteine; glutamic acid; glutamine; histidine; isoleucine; leucine; lysine; methionine; phenylalanine; proline; serine; threonine; tryptophan; tyrosine; valine and salts thereof, and wherein the caustic component is present in a concentration of up to 40 wt % of the composition and the caustic component and the additive are present in a molar ratio ranging from 15:1 to 5:1. Preferably, the caustic component and the additive are present in a molar ratio ranging from 12:1 to 8:1. Preferably, the caustic component comprises an hydroxide anion and a monovalent cation.

(51) According to a preferred embodiment of the present invention, there is provided a use of a buffered caustic solution in water treatment, wherein said buffered caustic solution comprising: a caustic component; an additive adapted to provide an extended buffering effect to the caustic composition when such is exposed to acid; and water;

(52) wherein the caustic component is present in a concentration of up to 40 wt % of the composition and the caustic component and the additive are present in a molar ratio ranging from 15:1 to 5:1.

(53) According to a preferred embodiment of the present invention, there is provided a method to treat water, wherein said method comprises the steps of:

(54) providing an aqueous caustic composition comprising: a caustic component; an amino acid additive adapted to provide an extended buffering effect to the caustic composition when such is exposed to an acid; and water; wherein the amino acid additive is selected from the group consisting of: alanine; arginine; asparagine; aspartic acid; cysteine; glutamic acid; glutamine; histidine; isoleucine; leucine; lysine; methionine; phenylalanine; proline; serine; threonine; tryptophan; tyrosine; valine and salts thereof;

(55) wherein the caustic component is present in a concentration of up to 40 wt % of the composition and the caustic component and the additive are present in a molar ratio ranging from 15:1 to 5:1; and

(56) exposing a water requiring treatment to a pre-determined amount of said caustic composition for a period of time sufficient to effect the treatment intended.

(57) According to a preferred embodiment of the present invention, there is provided a method for treating mine water from an ore deposit, wherein the mine water contains sodium carbonate and sodium bicarbonate, the method comprising:

(58) pumping the mine water from the ore deposit;

(59) introducing a tailings stream comprising an amount of the composition according to the present invention into the mine water to form a reaction solution;

(60) maintaining a pH of between about 11.5 and about 13 in the reaction solution;

(61) separating a treated mine water from the reaction solution to form a concentrate;

(62) introducing the treated mine water into an alkali production process.

(63) Although a few embodiments have been shown and described, it will be appreciated to those skilled in the art that various changes and modifications can be made to the embodiments described herein. The terms and expressions used in the above description have been used herein as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding equivalents of the features shown and described or portions thereof, it being recognized that the invention is defined and limited only by the claims that follow.