ACIDIFICATION COMPOSITIONS FOR IMPROVED FLUID PERFORMANCE

Abstract

A method for stimulating a subsurface carbonate formation includes supplying a composition comprising a hydrophobically modified polymer, a phosphorylated alkyl amino polycarboxylic acid, and a base treatment acid into the subsurface formation; and contacting the subsurface carbonate formation with the composition to form conductive flow pathways within the subsurface carbonate formation. The method may further include producing hydrocarbons from the subsurface carbonate formation. A composition for stimulating a subsurface formation includes a hydrophobically modified polymer, a phosphorylated alkyl amino polycarboxylic acid, and a base treatment acid.

Description

ACIDIFICATION COMPOSITIONS FOR IMPROVED PERFORMANCE zfrocnn / zznz / E / YiAi OF THE FLUID Background of the Invention Operations to extract an underground product from the earth through a well often use treatment fluids to facilitate or enhance the process. Hydrocarbons, such as oil and gas, are underground products commonly extracted from reservoirs—areas of the earth that contain hydrocarbons. A reservoir can be located far below the earth's surface, and the earth may include one or more formations that lie above and / or form the reservoir. A formation is a region of the earth with a distinct lithology that describes the physical characteristics of the rock within the formation, such as its mineral content. To help increase the productivity of a hydrocarbon reservoir, stimulation techniques can be performed using treatment fluids such as stimulation fluids. For example, matrix acidizing and acid fracturing are two stimulation techniques used to increase hydrocarbon production from a well by using acid present in the matrix acidizing and acid fracturing fluids to dissolve the rock. The dissolution of the rock creates or enlarges the conductive pathways of Ref. 333682 permeability to hydrocarbons in an underground formation so that hydrocarbons can flow from the underground formation to the earth's surface through the well. The choice between matrix acidizing and acid fracturing tends to depend on the permeability and porosity of the underground formation. Unconventional hydraulic fracturing is the technique generally used for formations containing harder or very low-permeability rock, such as shale and tight sandstone. Acid fracturing is similar to unconventional fracturing because it uses higher pressures and a reactive fluid to create and enlarge fractures, microfractures, or other natural or generated flow pathways. To create or enlarge fractures or flow pathways, acid fracturing relies on the heterogeneity of the rock, which leads to differential dissolution. Unlike hydraulic fracturing, acid fracturing generally does not involve the placement of proppant in the created or enlarged flow pathways or fractures.Although acid fracturing is used for some formations containing softer rock such as carbonate rock, carbonate rock tends not to lend itself to proppant use. Matrix acidizing is the technique typically used for formations containing softer, permeable rock such as carbonate rock. Matrix acidizing uses an acidizing treatment fluid, introduced at lower pressures below the fracturing gradient, to create and expand conductive flow pathways. The resulting conductive flow pathways may include narrow channels called wormholes. The high solubility of carbonate rock in the acids used for matrix acidizing facilitates the formation of wormholes. A commonly used matrix acidizing composition contains hydrochloric acid (HCl) as its sole acid component. When HCl-based stimulation fluid comes into contact with the formation, it tends to dissolve the carbonate rock near or very near the wellbore and create wide, unbranched perforations without penetrating deeply into the formation. This can limit the effectiveness of common HCl-based matrix acidizing stimulation treatments. Carbonate emulsion acids tend to provide more controlled dissolution than plain HCl. Carbonate emulsion acid is a matrix acidizing or fracturing composition used in emulsion form to deliver acid to a carbonate formation. Carbonate emulsion acid stimulation methods must involve breaking the emulsion to allow for effective backflow, where backflow is the process of allowing fluids to flow from a well after stimulation. Furthermore, the use of carbonate emulsion acid in stimulation methods leads to increased friction during tubing delivery of the composition to the underground formation. This friction may preclude the use of carbonate emulsion acid with coiled tubing, which is used in some wells or when higher flow rates are desired. Brief Description of the Invention The acidizing composition options for improved fluid performance are described with reference to the following figures. The same numbers are used in all figures to refer to similar features and components. The features shown in the figures are not necessarily to scale. Certain features of the options may be exaggerated or somewhat schematically depicted, and some details may be omitted for the sake of clarity and conciseness. Brief Description of the Figures Figure 1 is a schematic view of a delivery system that can be used to introduce a stimulation fluid into an underground formation, according to one or more modalities. Detailed Description of the Invention This description provides a matrix acidizing composition that produces wormholes with deep, branching flow paths. Furthermore, the composition is not an emulsion, thus eliminating the need for breaking agents, and its low viscosity allows for use with coiled tubing. The acidification composition described herein includes a hydrophobically modified polymer, a phosphorylated alkyl amino polycarboxylic acid, and a base treatment acid. The performance of the hydrophobically modified polymer / phosphorylated alkyl amino polycarboxylic acid / HC1 fluid is equal to or exceeds that of the hydrophobically modified polymer / phosphorylated amino polycarboxylic acid / HC1 fluid or plain HC1. The acidification composition described herein can improve acidification performance, as determined by pore volume up to breakthrough measurements, compared to reference compositions containing the base treatment acid and phosphorylated alkyl amino polycarboxylic acid without the hydrophobically modified polymer or the hydrophobically modified polymer without the phosphorylated alkyl amino polycarboxylic acid. An unexpected aspect of the improved performance is that using a smaller amount of the hydrophobically modified polymer in combination with the phosphorylated alkyl amino polycarboxylic acid results in improved performance compared to another composition using a reference amount of the hydrophobically modified polymer in combination with the phosphorylated alkyl amino polycarboxylic acid.The reference and lower amounts of the hydrophobically modified polymer are compared to a reference composition containing the acid and the reference amount of the hydrophobically modified polymer without the phosphorylated alkyl amino polycarboxylic acid. Since the improved yield allows for lower concentrations of both the hydrophobically modified polymer and the phosphorylated alkyl amino polycarboxylic acid, a benefit is the reduced cost. The examples below illustrate this improved performance. By using compositions with low concentrations of hydrophobically modified polymer (e.g., 10 GPT of hydrophobically modified polymer as in Example 3 of the examples), along with phosphorylated alkyl amino polycarboxylic acid in an HCl solution, the pore volume to breakthrough was improved compared to a reference composition with a higher amount of hydrophobically modified polymer (e.g., 33 GPT as in zfrocnn / zznz / E / YiAi). Comparative Example A of the examples, and without (i.e., excluding) the phosphorylated alkyl amino polycarboxylic acid. In contrast, a composition with an amount equal to the reference amount of hydrophobically modified polymer along with the phosphorylated alkyl amino polycarboxylic acid, for example, 33 GPT of hydrophobically modified polymer as in Example 1 of the examples, did not show improved performance compared to the same reference composition, in examples such as Comparative Example A. The improved performance after lowering the amount of hydrophobically modified polymer, for example, from 33 GPT to 10 GPT, was unexpected. In another example, when comparing a composition with a smaller amount of hydrophobically modified polymer, for example, 10 GPT as in Example 3 of the examples, and a smaller amount of phosphorylated alkyl amino polycarboxylic acid, for example, 2.1 wt% of phosphorylated alkylamino polycarboxylic acid as in Example 3 of the Examples, to a composition with a higher amount of hydrophobically modified polymer, for example, 33% GPT as in Example 1 of the Examples, and a higher amount of phosphorylated alkylamino polycarboxylic acid, for example, 3.5 wt% as in Example 1 of the Examples, the composition with the lower amounts of both hydrophobically modified polymer and phosphorylated alkylamino polycarboxylic acid unexpectedly improved the pore volume to breakthrough. Therefore, while Example 1 illustrates the inventive composition, Examples 2 and 3 illustrate the unexpected improvement in performance by lowering the concentrations of hydrophobically modified polymer and phosphorylated alkylamino polycarboxylic acid. It is understood that concentrations other than those evaluated in the examples are considered. Without intending to be limited to theory, the present inventors believe that the concentration of hydrophobically modified polymer can desirably be set to an amount effective in achieving the lowest pore volume until breakthrough into a calcite-loaded core. The hydrophobically modified polymer is desirably present in an amount to provide the composition with non-Newtonian shear-thickening fluid behavior. For example, the compositions of the present description may include from 0.05 to 15 wt% of hydrophobically modified polymer. Without intending to be limited to theory, the present inventors believe that the concentration of phosphorylated alkylamino polycarboxylic acid can desirably be set to an amount effective in adhering or fixing to a calcite surface at a low pH (below a neutral pH of 7).This creates a molecular film on the calcite surface, thereby inhibiting further reaction by the acid-base treatment. For example, certain compositions may include... 0.25 and 20 wt% of phosphorylated alkyl amino polycarboxylic acid. Without wishing to limit themselves to theory, the present inventors believe that the concentration of base-treatment acid can desirably be set to an amount effective for forming wormholes during matrix acidification treatment. For example, certain embodiments may include between 1.0 and 30 wt% of base-treatment acid. Hydrophobically modified polymer The hydrophobically modified polymer can be a copolymer containing hydrophilic monomers and hydrophobically modified hydrophilic monomers. Suitable hydrophobically modified polymers include an acrylamide / octadecyldimethylammonium methacrylate bromide copolymer, a dimethylaminoethyl methacrylate / hexadecyldimethylammonium methacrylate bromide copolymer, a dimethylaminoethyl methacrylate / vinylpyrrolidone / hexadecyldimethylammonium methacrylate bromide terpolymer, and an acrylamide / 2-acrylamido-2-methyl propanesulfonic acid / 2-ethylhexyl methacrylate terpolymer. The hydrophobically modified polymer is prepared from the polymerization reaction of hydrophilic monomers and hydrophobically modified hydrophilic monomers. Examples of suitable hydrophilic monomers that may be used include acrylamide, 2-acrylamido-2-methyl propanesulfonic acid, N,N-dimethylacrylamide, vinyl pyrrolidone, dimethylaminoethyl methacrylate, acrylic acid, dimethylaminopropyl methacrylamide, vinyl amine, vinyl acetate, trimethylammonium ethyl methacrylate chloride, methacrylamide, and hydroxyethyl acrylate. Of these, acrylamide, 2-acrylamido-2-methyl propanesulfonic acid, acrylic acid, dimethylaminoethyl methacrylate, dimethylaminopropyl methacrylamide, and vinyl pyrrolidone are preferred. An example of a suitable commercially available hydrophobically modified polymer that may be used according to the present description is sold under the trade name HPT-1 through Halliburton Energy Services, Houston, Texas. Examples of particularly suitable hydrophobically modified hydrophilic monomers that can be used include, but are not limited to, alkyl acrylates, alkyl methacrylates, alkyl acrylamides, and alkyl methacrylamides where the alkyl radicals have from about 4 to about 22 carbon atoms, alkyl dimethylammonium ethyl methacrylate bromide, alkyl dimethylammonium ethyl methacrylate chloride, and alkyl dimethylammonium ethyl methacrylate iodide where the alkyl radicals have from about 4 to about 22 carbon atoms, and alkyl dimethylammonium propyl methacrylamide bromide, alkyl dimethylammonium propyl methacrylamide chloride, and alkyl dimethylammonium propyl methacrylamide iodide where the alkyl groups have from about 4 to around 22 carbon atoms. Hydrophobically modified polymers can be prepared by polymerizing any or more hydrophilic monomers with one or more hydrophobically modified hydrophilic monomers. People of intermediate skill are familiar with methods for preparing such polymers. Suitable polymers prepared as described above have estimated molecular weights in the range of about 250,000 to about 3,000,000 and have mole ratios of hydrophilic monomers to hydrophobically modified hydrophilic monomers in the range of about 99.98:0.02 to about 90:10. Phosphorylated alkyl amino polycarboxylic acid Phosphorylated alkyl amino polycarboxylic acids may include at least one polycarboxylic amino functional group and at least one phosphonic acid functional group. Phosphorylated alkyl amino polycarboxylic acids include N-phosphonomethyl iminodiacetic acid (PMIDA), aminotris(methylenephosphonic acid) (ATMP), N,N-bis(phosphonomethyl)glycine (BPMG), N-phosphonomethyl iminodiacetic acid derivatives, aminotris(methylenephosphonic acid) derivatives, and N,N-bis(phosphonomethyl)glycine (BPMG) derivatives. Phosphorylated alkylamino polycarboxylic acid can be supplied as a salt of phosphorylated alkylamino polycarboxylic acid. Suitable salts include those formed with metal cations. The salt can be formed by combining MOH with phosphorylated alkylamino polycarboxylic acid, where M is a metal. The salt form is reprotonated to generate phosphorylated alkylamino polycarboxylic acid when combined with the acid-base treatment. For example, N-phosphonomethyl iminodiacetic acid can be supplied as the tripotassium salt of N-phosphonomethyl iminodiacetic acid. Approximately 3 equivalents of KOH can be combined with 1 equivalent of N-phosphonomethyl iminodiacetic acid to generate the tripotassium salt of N-phosphonomethyl iminodiacetic acid. Acid base treatment The base-treatment acid can be any acid suitable for carbonate acidification. In certain formulations, the base-treatment acid can be a hydrohalic acid or an organic acid. For example, the base-treatment acid can be hydrochloric acid. An advantage of the present composition is that, because it does not contain an inorganic salt, it contains more than 15% by weight of HCl, for example, 28% by weight of HCl. Other suitable base-treatment acids include hydrofluoric acid, phosphoric acid, sulfuric acid, sulfonic acid, nitric acid, acetic acid, acetic anhydride, citric acid, glycolic acid, and formic acid. The base-treatment acid can also be a chelating acid. Suitable chelating acids include methylglycinediacetic acid (MGDA) and glutamic diacetic acid (GLDA). Carrier fluid The compositions described herein also include a carrier fluid. In one or more embodiments, the carrier fluid is aqueous. The carrier fluid provides a medium for transporting the hydrophobically modified polymer, phosphorylated alkylamino polycarboxylic acid, and base treatment acid into the well. The carrier fluid further acts as a solvent for the dissolved components and a suspension medium for the solid components. Typically, the base treatment acid, phosphorylated alkylamino polycarboxylic acid, and hydrophobically modified polymer are dissolved. In one or more embodiments, an aqueous carrier fluid is a brine. In one or more embodiments, the brine includes a salt. For example, the carrier fluid may be an aqueous solution containing KCl, e.g., a 2% aqueous solution of KCl. Other suitable salts include NaCl, NaBr, NH4Cl, and LiCl. The amounts of each of the hydrophobically modified polymer, phosphorylated alkylamino polycarboxylic acid, and base treatment acid in the composition can be expressed as the respective concentrations of the hydrophobically modified polymer, phosphorylated alkylamino polycarboxylic acid, and base treatment acid in the carrier fluid. When the carrier fluid is brine, the amounts of each of the hydrophobically modified polymer, phosphorylated alkylamino polycarboxylic acid, and base treatment acid in the composition can be expressed as the respective concentrations of the hydrophobically modified polymer, phosphorylated alkylamino polycarboxylic acid, and base treatment acid in the brine water. Other components The compositions described herein may also include other components known as acidizing stimulation fluid components. These other components may be matrix acidizing fluid components. They may also be stimulation fluid components that are matrix acidizing fluids for carbonate formations. Supply system No equipment modifications are required compared to zfrocnn / zznz / E / YiAi with conventional acidification stimulation. The compositions described herein are designed for use as an acidification additive and therefore do not require specialized pumping or additional equipment. Figure 1 is a schematic view of a delivery system 100 that can be used to supply or otherwise introduce one or more stimulation fluids into a downhole formation, such as a subsurface formation 104, according to one or more modalities. It should be noted that, although Figure 1 generally represents an onshore system, it should be recognized that similar systems can also be operated in subsea locations. As shown in Figure 1, the delivery system 100 may include a vessel 120 in which one or more stimulation fluids can be performed, agitated, mixed, stored, or a combination thereof.For example, one or more of the polymers, one or more of the particulate additives, and one or more of the organic solvents may be introduced or otherwise added to the vessel and may be mixed or otherwise combined to produce the stimulation fluid. The stimulation fluid may then be stored until ready for use. The vessel 120 may be, among other things, one or more tanks, vessels, columns, or reactors and may include one or more mixing devices and one or more heat control devices. The stimulation fluid can be conveyed or otherwise transported from vessel 120 through line 122 to one or more wellheads 112, where the stimulation fluid can be introduced into one or more lines 128. Line 128 can be extended from wellhead 112 into one or more wells 114 and the underground formation 104, each formed in ground 102. One or more pumps 124 can be coupled to and in fluid communication with line 122, as shown in Figure 1, and / or with line 128, not shown. Pump 124 can be used to transport the stimulation fluid from vessel 120, through lines 122 and 124 and well 114, and into the underground formation 104. Pump 124 can also be used to control the pressure within well 114 and the underground formation 104. One or more of the aqueous downhole fluids may be disposed of or otherwise contained within at least subsurface formation 104. Upon being expelled or otherwise exiting line 128, the stimulation fluid may further penetrate subsurface formation 104 and combine or otherwise mix with the aqueous downhole fluid to produce the additive polymer compound and a fluid mixture within subsurface formation 104. The fluid mixture may contain the combination of the aqueous downhole fluid and one or more organic solvents derived from the stimulation fluid. It should be recognized that the 100 delivery system is merely illustrative, and various additional components may be present that are not necessarily shown in Figure 1 for the sake of clarity. These additional, but not limited to, components may include delivery hoppers, mixing devices, valves, condensers, adapters, gaskets, meters, sensors, pumps, compressors, pressure controllers, pressure sensors, flow rate controllers, flow rate sensors, temperature sensors, or temperature control devices. Method Both the phosphorylated alkylamino polycarboxylic acid and the hydrophobically modified polymer can be supplied as liquid concentrates that can be mixed on-the-fly during delivery or can be batch-mixed. In one or more embodiments, the phosphorylated alkylamino polycarboxylic acid and the hydrophobically modified polymer are batch-mixed and then pumped. In one or more embodiments, the phosphorylated alkylamino polycarboxylic acid and the hydrophobically modified polymer are batch-mixed, stored, and pumped at a later time. Methods for stimulating an underground carbonate formation include supplying a composition comprising a hydrophobically modified polymer, a phosphorylated alkyl amino polycarboxylic acid, and a base treatment acid into the underground formation. The methods may further include mixing the phosphorylated alkyl amino polycarboxylic acid and the hydrophobically modified polymer to form a mixture. The methods may also include adding the mixture to a fluid containing the base treatment acid and / or carrier fluid, and / or other components. The methods may include on-the-fly mixing, which is simultaneous mixing and adding. Alternatively, the method may include batch mixing the phosphorylated alkyl amino polycarboxylic acid and the hydrophobically modified polymer to form a mixture before adding the mixture to a fluid containing the base treatment acid and / or carrier fluid, and / or other components. Methods for stimulating a subsurface carbonate formation also include contacting the subsurface carbonate formation with the composition to form conductive flow pathways within the formation. These flow pathways can form as wormholes within the subsurface carbonate formation. Additionally, methods may include mixing the phosphorylated alkyl amino polycarboxylic acid and the hydrophobically modified polymer to form a slurry and adding the slurry to a fluid containing the base treatment acid and / or carrier fluid, and / or other components, either before or during contact with the subsurface carbonate formation. One or more specific acidizing composition methods have been described for improved fluid performance. In an effort to provide a concise description of these methods, it is possible that not all features of an actual implementation will be described. It should be noted that, in developing any actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific objectives, such as meeting system-related and business-related constraints, which may vary from implementation to implementation. Furthermore, it should be appreciated that such a development effort could be complex and time-consuming, but it would nevertheless be a routine design, fabrication, and manufacturing task for mid-level tradespeople who benefit from this description. Certain terms are used throughout the description and claims to refer to particular features or components. As someone of average skill will appreciate, different people may refer to the same feature or component by different names. This document does not purport to distinguish between components or features that differ in name but not in function. Unless otherwise stated, a numerical parameter n expressing quantities used in the present description and associated claims means approximately n. Accordingly, unless otherwise stated, reference to a numerical parameter in the description and appended claims is an approximation that may vary depending on the property the numerical parameter represents and the measurement method used to determine that property. For example, the approximation may be at least that of significant digits, with each numerical parameter provided to no more than n significant digits. For example, the appropriate number of significant digits associated with a measurement method is a reference to the degree of approximation. Simple rounding techniques apply to numerical parameters reported in alternative units.For example, °C and °F are alternative units and kilogram (kg) and pound (Ib) are zfrocnn / zznz / E / YiAi alternative units. Whenever a numerical interval is described with a lower and an upper bound, any number and any interval included within the interval are specifically described. In particular, it should be understood that each interval of values ​​defines every number and interval encompassed within the larger interval of values. The reference to 'n' indicates a closed interval [n,m]. The reference to 'n' less than m indicates a half-open interval [n,m]. The reference to 'n' greater than 'n' up to 'm' indicates another half-open interval (n,m). The reference to 'n' greater than 'a' and 'a' less than 'b' indicates an open interval (n,m). References throughout this description to include mean to include, among others. References in this description to a modality, modalities, some modalities, certain modalities, or similar expressions mean that a particular feature or structure described in relation to that modality may be included in at least one modality of this description. Therefore, these phrases or similar expressions throughout this description may, but do not necessarily, refer to the same modality. SPECIFIC MODALITIES Methods for stimulating an underground carbonate formation may include supplying a composition comprising a hydrophobically modified polymer, a phosphorylated alkyl amino polycarboxylic acid, and a base treatment acid within the underground carbonate formation; and contacting the underground carbonate formation with the composition to form conductive flow pathways in the underground carbonate formation. The methods may include the modalities in accordance with any of the preceding paragraphs or a combination thereof and further include where the composition comprises between 0.05 and 15% by weight of hydrophobically modified polymer. The methods may include the modalities in accordance with any of the preceding paragraphs or a combination thereof and further include where the composition comprises between 0.25 and 20% by weight of phosphorylated alkyl amino polycarboxylic acid. The methods may include the modalities in accordance with any of the preceding paragraphs or a combination thereof and further include where the composition comprises between 1.0 and 30% by weight of acid-base treatment. The methods may include the modalities in accordance with any of the preceding paragraphs or a combination thereof and further include where the phosphorylated alkyl amino polycarboxylic acid zfrocnn / zznz / E / YiAi is selected from the group consisting of N-phosphonomethyliminodiacetic acid (PMIDA), the phosphorylated alkyl amino polycarboxylic acid is aminotris(methylenephosphonic acid) (ATMP), the phosphorylated alkyl amino polycarboxylic acid is N,N-bis(phosphonomethyl)glycine (BPMG) and derivatives thereof. The methods may include the modes according to any of the preceding paragraphs or a combination thereof and further include where the hydrophobically modified polymer is selected from the group consisting of acrylamide / octadecyldimethylammoniumethyl methacrylate bromide copolymers, dimethylaminoethyl methacrylate / hexadecyldimethylammoniumethyl methacrylate bromide copolymers, dimethylaminoethyl methacrylate / vinylpyrrolidone / hexadecyldimethylammoniumethyl methacrylate bromide terpolymers, and acrylamide / 2-acrylamido-2-methyl propanesulfonic acid / 2-ethylhexyl methacrylate terpolymers. The methods may include the modalities in accordance with any of the preceding paragraphs or a combination thereof and further include where the base treatment acid is selected from the group consisting of hydrochloric acid, hydrofluoric acid, phosphoric acid, sulfuric acid, sulfonic acid, nitric acid, acetic acid, acetic anhydride, citric acid, glycolic acid and formic acid, methylglycinediacetic acid (MGDA) and glutamic diacetic acid (GLDA). For example, methods for stimulating an underground carbonate formation may include supplying a composition comprising a hydrophobically modified polymer, a phosphorylated alkyl amino polycarboxylic acid, and a base treatment acid within the underground carbonate formation; and contacting the underground carbonate formation with the composition to form conductive flow pathways in the underground carbonate formation, wherein the composition comprises between 0.05 and 15 wt% of hydrophobically modified polymer, wherein the composition comprises between 0.25 and 20 wt% of phosphorylated alkyl amino polycarboxylic acid, wherein the composition comprises between 1.0 and 30% by weight of base treatment acid, wherein the phosphorylated alkyl amino polycarboxylic acid is phosphonomethyliminodiacetic acid, wherein the hydrophobically modified polymer is selected from the group consisting of acrylamide / octadecyldimethylammoniumethyl methacrylate bromide copolymer, a dimethylaminoethyl methacrylate / hexadecyldimethylammoniumethyl methacrylate bromide copolymer, a dimethylaminoethyl methacrylate / vinylpyrrolidone / hexadecyldimethylammoniumethyl methacrylate bromide terpolymer, and an acrylamide / 2-acrylamide-2zfrocnn / zznz / E / YiAi methyl / 2-ethylhexyl methacrylate terpolymer, and wherein the base treatment acid comprises hydrochloric acid. Compositions to stimulate an underground formation may include a hydrophobically modified polymer, a phosphorylated alkyl amino polycarboxylic acid, and a base treatment acid. The compositions may include the modalities according to any of the preceding paragraphs or a combination thereof and further include where the composition comprises between 0.05 and 15% by weight of hydrophobically modified polymer. The compositions may include the forms in accordance with any of the preceding paragraphs or a combination thereof and further include where the composition comprises between 0.25 and 20% by weight of phosphorylated alkyl amino polycarboxylic acid. The compositions may include the modalities in accordance with any of the preceding paragraphs or a combination thereof and further include where the composition comprises between 1.0 and 30% by weight of acid-base treatment. The compositions may include the forms in accordance with any of the preceding paragraphs or a combination thereof and further include wherein the phosphorylated alkyl amino polycarboxylic acid is selected from the group consisting of N-phosphonomethyliminodiacetic acid (PMIDA), the phosphorylated alkyl amino polycarboxylic acid is aminotris(methylenephosphonic acid) (ATMP), the phosphorylated alkyl amino polycarboxylic acid is N,N-bis(phosphonomethyl)glycine (BPMG) and derivatives thereof. The compositions may include the embodiments in accordance with any of the preceding paragraphs or a combination thereof and further include wherein the hydrophobically modified polymer is selected from the group consisting of an acrylamide / octadecyldimethylammoniumethyl methacrylate bromide copolymer, a dimethylaminoethyl methacrylate / hexadecyldimethylammoniumethyl methacrylate bromide copolymer, a dimethylaminoethyl methacrylate / vinylpyrrolidone / hexadecyldimethylammoniumethyl methacrylate bromide terpolymer, and an acrylamide / 2-acrylamide-2-methyl propanesulfonic acid / 2-ethylhexyl methacrylate terpolymer. The compositions may include the modalities according to any of the preceding paragraphs or a combination thereof and further include where the base treatment acid is selected from the group consisting of hydrochloric acid, hydrofluoric acid, phosphoric acid, sulfuric acid, sulfonic acid, nitric acid, acetic acid, acetic anhydride, citric acid, glycolic acid and formic acid, methylglycinediacetic acid (MGDA) and glutamic diacetic acid (GLDA). For example, compositions for stimulating a subsurface formation may include a hydrophobically modified polymer; a phosphorylated alkyl amino polycarboxylic acid and a base treatment acid, wherein the composition comprises between 0.05 and 15% by weight of hydrophobically modified polymer, wherein the composition comprises between 0.25 and 20% by weight of phosphorylated alkyl amino polycarboxylic acid, between 1.0 and 30% by weight of base treatment acid, wherein the phosphorylated alkyl amino polycarboxylic acid is phosphonomethyliminodiacetic acid, wherein the hydrophobically modified polymer is selected from the group consisting of acrylamide / octadecyldimethylammoniumethyl methacrylate bromide copolymer, a dimethylaminoethyl methacrylate / hexadecyldimethylammoniumethyl methacrylate bromide copolymer, a dimethylaminoethyl methacrylate / vinylpyrrolidone / hexadecyldimethylammoniumethyl methacrylate bromide terpolymer, and an acrylamide / 2-acrylamido-2-methyl propanesulfonic acid / 2-ethylhexyl methacrylate terpolymer, and wherein the base treatment acid comprises hydrochloric acid. Methods for extracting hydrocarbons may include supplying a composition comprising a hydrophobically modified polymer, a phosphorylated alkyl amino polycarboxylic acid, and a base treatment acid into the underground formation through a well; contacting the underground carbonate formation with the composition to form conductive flow pathways in the underground carbonate formation; and producing hydrocarbons from the underground formation through the well. The methods may include the modalities in accordance with any of the preceding paragraphs or a combination thereof and further include where the composition comprises between 0.05 and 15% by weight of hydrophobically modified polymer. The methods may include the modalities in accordance with any of the preceding paragraphs or a combination thereof and further include where the composition comprises between 0.25 and 20% by weight of phosphorylated alkyl amino polycarboxylic acid. The methods may include the modalities in accordance with any of the preceding paragraphs or a combination thereof and further include where the composition comprises between 1.0 and 30% by weight of acid-base treatment. The methods may include the modalities in accordance with any of the preceding paragraphs or a combination thereof and further include wherein the phosphorylated alkyl amino polycarboxylic acid is selected from the group consisting of N-phosphonomethyliminodiacetic acid (PMIDA), the phosphorylated alkyl amino polycarboxylic acid is aminotris(methylenephosphonic acid) (ATMP), the phosphorylated alkyl amino polycarboxylic acid is N,N-bis(phosphonomethyl)glycine (BPMG) and derivatives thereof. zfrocnn / zznz / E / YiAi The methods may include the modes according to any of the preceding paragraphs or a combination thereof and further include where the hydrophobically modified polymer is selected from the group consisting of acrylamide / octadecyldimethylammoniumethyl methacrylate bromide copolymers, dimethylaminoethyl methacrylate / hexadecyldimethylammoniumethyl methacrylate bromide copolymers, dimethylaminoethyl methacrylate / vinylpyrrolidone / hexadecyldimethylammoniumethyl methacrylate bromide terpolymers, and acrylamide / 2-acrylamido-2-methyl propanesulfonic acid / 2-ethylhexyl methacrylate terpolymers. The methods may include the modalities in accordance with any of the preceding paragraphs or a combination thereof and further include where the base treatment acid is selected from the group consisting of hydrochloric acid, hydrofluoric acid, phosphoric acid, sulfuric acid, sulfonic acid, nitric acid, acetic acid, acetic anhydride, citric acid, glycolic acid and formic acid, methylglycinediacetic acid (MGDA) and glutamic diacetic acid (GLDA). For example, hydrocarbon extraction may include supplying a composition comprising a hydrophobically modified polymer, a phosphorylated alkyl amino polycarboxylic acid, and a base treatment acid into the underground formation through a well; contacting the underground carbonate formation with the composition to form conductive flow pathways in the underground carbonate formation; and producing hydrocarbons from the underground formation through the well, wherein the composition comprises between 0.05 and 15 wt% of hydrophobically modified polymer, wherein the composition comprises between 0.25 and 20 wt% of phosphorylated alkyl amino polycarboxylic acid, wherein the composition comprises between 1.0 and 30% by weight of base treatment acid, wherein the phosphorylated alkyl amino polycarboxylic acid is phosphonomethyliminodiacetic acid, wherein the hydrophobically modified polymer is selected from the group consisting of acrylamide / octadecyldimethylammoniumethyl methacrylate bromide copolymer, a dimethylaminoethyl methacrylate / hexadecyldimethylammoniumethyl methacrylate bromide copolymer, a dimethylaminoethyl methacrylate / vinyl pyrrolidone / hexadecyldimethylammoniumethyl methacrylate bromide terpolymer, and an acrylamide / 2-acrylamide-2-methyl propanesulfonic acid / 2-ethylhexyl methacrylate terpolymer, and wherein the base treatment acid comprises hydrochloric acid. To facilitate a better understanding of the description, the following non-limiting examples are provided. The following examples are not the only examples that could be provided and are not intended to limit the scope of the description, including the claims. EXAMPLES The examples illustrate the improved performance of the compositions described herein. In particular, the improved performance is demonstrated through the enhanced pore volume to breakthrough results shown in the core flooding test. In the examples, for each concentration specified as a percentage, the % is % by weight, also referred to as % w / w. For each concentration specified in GPT, GPT represents gallons per thousand gallons. The core flooding test in the following examples used a conventional core testing process. Core samples were obtained from an outlying formation. The carbonate rock in the core samples contained porosity, and the cumulative porosity volume provided the pore volume (PV) of the representative core. The connections between the pores provided permeability. With some permeability, flow through the core was possible. Fluid was pumped into a core sample. The amounts of fluid that passed through the core sample were measured in pore volume units. During the injection pumping of the fluid into the core, a differential pressure was measured along the core. Once the reactive fluid created a hole through the core, the differential pressure decreased, indicating breakthrough.The volume of treatment fluid pumped compared to the core pore volume provides pore volume to breakthrough (PVbt). For Comparative Examples 1-3 and Examples 4-6, core samples were obtained from the same carbonate rock, and the carrier, pre-wash, and post-wash fluids were a brine containing 2% KCl. For each example, the HCl concentration was 15%, the flow rate was 1 mL / minute, and the temperature was 200°F. For each example, permeability was measured in millidarcy (mD) units as calculated for laminar flow through a porous medium according to Darcy's law. Table 1 shows the pore volume up to breakthrough test results, i.e., the results for PVbt, where PVbt is in pore volume units, as described in the preceding paragraph. In Table 1, the phosphorylated alkyl amino polycarboxylic acid is listed as component A. Component A included N-phosphonomethyl iminodiacetic acid in the form of the tripotassium salt. That is, component A was the tripotassium salt of N-phosphonomethyl iminodiacetic acid. The tripotassium salt of N-phosphonomethyl iminodiacetic acid was reprotonated when placed in the acid-base treatment. Approximately 3 equivalents of KOH were combined with one equivalent of N-phosphonomethyl iminodiacetic acid to generate the tripotassium salt of N-phosphonomethyl iminodiacetic acid. In Table 1, the hydrophobically modified polymer is listed as component B.Component B was a commercially available hydrophobically modified polymer form sold under the trade name HPT-1 through Halliburton Energy Services, Inc. zfrocnn / zznz / E / YiAi Table 1. Core flooding test results Example Component A (% by weight) Component B (GPT) Estimated cost (nominal unit) Initial permeability (mD) PVbt 1 0.0 33.0 0.12 0.68 3.87 2 7.0 0.0 1.0 0.57 1.54 3 2.1 0.0 0.3 0.70 4.69 4 3.5 33.0 0.62 0.77 4.17 5 2.1 16.5 0.36 0.64 1.54 6 2.1 10.0 0.33 0.71 1.50 As a baseline reference, when evaluating the results in Table 1, a known PVbt value for 15% HC1 in water is 11, and the initial permeability for this test is similar to the results shown in Table 1. The current PVbt value for 15% HC1 is illustrative of the performance of simple HC1 fluids in forming flow paths. All the results in Table 1 show better performance than the baseline reference. That is, all the results in the Table 1 shows PVbt less than 11. Example 1 is a comparative example showing that component B used at a concentration of 33 GPT in 15% HCI provided better results than 15% plain HCI, but not the efficacy indicated in Example 2 with 7% of component A in 15% HCI. Example 2 is a comparative example showing that component A in 15% HCl provided high performance (low PVbt) when used at an appropriate concentration. Example 2 shows that 7% of component A in 15% HCl provides better efficacy than 33% of component B in 15% HCl. Example 3 is a comparative example showing that a reduced amount of component A in 15% HCI in an amount to provide approximately one-third of the amount that for Example B reduced the yield (raised the PVbt) to worse than the yield for Example 1. Example 4 compared to Example 1 shows that surprisingly, adding 3.5% of component A to 33 GPT in 15% HCI provided a slightly worse performance. Example 5, compared to Example 3, shows improved performance from the addition of component B to component A. Example 5, compared to Example 4, shows that surprisingly decreasing the concentrations of both component A and component B, specifically to 2.1% component A with 16.5% GPT of component B in 15% HCl, significantly improved performance. The performance was the same as that of Example 2. Example 6 shows that combining 2.1% of component A with 10 GPT of component B in 15% HCl also provides improved yield. It is noted that Examples 2 (PVbt = 1.54) and 3 (PVbt = 1.50) show essentially the same result for PVbt within the experimental error. Example 6, compared to Example 4, shows that by surprisingly decreasing the concentrations of both component A and component B, specifically to 2.1% of component A with 10 GPT of component B in 15% HCl, the yield was significantly improved. The yield was the same as the yield in Example 2. The compositions in Examples 5 and 6 are illustrative of compositions that provided improved performance. In particular, the results shown in Examples 5 and 6, compared with comparative Examples 1 and 3, show that compositions with both the hydrophobically modified polymer and the phosphorylated alkylamino polycarboxylic acid (e.g., either Example 5 or Example 6) are capable of better performance than a composition with a hydrophobically modified polymer and no phosphorylated alkylamino polycarboxylic acid (e.g., Example A) or phosphorylated alkylamino polycarboxylic acid and no hydrophobically modified polymer (e.g., Example 3).A comparison of the results shown in Examples 5 and 6 with those of Example 2 shows that both compositions with the hydrophobically modified polymer and phosphorylated alkyl amino polycarboxylic acid have comparable performance to an optimized composition with phosphorylated alkyl amino polycarboxylic acid and no hydrophobically modified polymer, Example 2. The compositions in Examples 5 and 6 illustrate compositions with low concentrations that unexpectedly provide improved performance. In particular, the results shown illustrate a composition (e.g., Example 5 or Example 6) where a non-zero, minor amount of the hydrophobically modified polymer in combination with a non-zero, minor amount of phosphorylated alkyl amino polycarboxylic acid is more effective at forming flow pathways in the underground formation compared to a composition (e.g., Example 4) comprising a non-zero reference amount of the hydrophobically modified polymer and a non-zero reference amount of phosphorylated alkyl amino polycarboxylic acid. The cores in Examples 1–6 were visually inspected after testing. Each core was cylindrical, with the cylinder extending between two ends: an injection end and a production end. A hole extended from the injection face of each core. For Examples 1–4, the hole was larger than for Examples 5 and 6. Additionally, Examples 1–4 exhibited some facial dissolution. Facial dissolution is a region of dissolution on the surface of the core face that has a crater-like appearance. In each case, the facial dissolution was contiguous with the hole, extending through the core. The lack of facial dissolution for the holes in Examples 5 and 6 illustrates holes that are narrow passageways, i.e., wormholes. The described methods, including the examples, should not be interpreted or otherwise used as limiting the scope of the description, including the claims. It should be fully recognized that the different teachings of the methods discussed can be employed separately or in any combination suitable for producing the desired results. Furthermore, a person of average skill will understand that the description has broad application, and the discussion of any method is intended only as an example of that method and is not intended to suggest that the scope of the description, including the claims, is limited to that method. It is hereby stated that, as of this date, the best method known to the applicant for putting the aforementioned invention into practice is the one that is clear from the present description of the invention.

Claims

1. A method for stimulating an underground carbonate formation, characterized in that it comprises: supplying a composition comprising a hydrophobically modified polymer, a phosphorylated alkyl amino polycarboxylic acid, and a base treatment acid within the underground carbonate formation; and contacting the underground carbonate formation with the composition to form conductive flow pathways in the underground carbonate formation.

2. The method according to claim 1, characterized in that the composition comprises between 0.05 and 15% by weight of hydrophobically modified polymer.

3. The method according to claim 1, characterized in that the composition comprises between 0.25 and 20% by weight of phosphorylated alkyl amino polycarboxylic acid.

4. The method according to claim 1, characterized in that the composition comprises between 1.0 and 30% by weight of base treatment acid.

5. The method according to claim 1, zfrocnn / zznz / E / YiAi characterized in that the phosphorylated alkyl amino polycarboxylic acid is selected from the group consisting of N-phosphonomethyliminodiacetic acid (PMIDA), the phosphorylated alkyl amino polycarboxylic acid is aminotris(methylenephosphonic acid) (ATMP), the phosphorylated alkyl amino polycarboxylic acid is N,N-bis(phosphonomethyl)glycine (BPMG) and derivatives thereof.

6. The method according to claim 5, characterized in that the hydrophobically modified polymer is selected from the group consisting of acrylamide / octadecyldimethylammoniumethyl methacrylate bromide copolymers, dimethylaminoethyl methacrylate / hexadecyldimethylammoniumethyl methacrylate bromide copolymers, dimethylaminoethyl methacrylate / vinylpyrrolidone / hexadecyldimethylammoniumethyl methacrylate bromide terpolymers, and acrylamide / 2-acrylamido-2-methyl propanesulfonic acid / 2-ethylhexyl methacrylate terpolymers.

7. The method according to claim 1, characterized in that the hydrophobically modified polymer is selected from the group consisting of acrylamide / octadecyldimethylammoniumethyl methacrylate bromide copolymers, dimethylaminoethyl methacrylate / hexadecyldimethylammoniumethyl methacrylate bromide copolymers, dimethylaminoethyl methacrylate / vinylpyrrolidone / hexadecyldimethylammoniumethyl methacrylate bromide terpolymers, and acrylamide / 2-acrylamido-2methyl propanesulfonic acid / 2-ethylhexyl methacrylate terpolymers.

8. The method according to claim 1, characterized in that the base treatment acid is selected from the group consisting of hydrochloric acid, hydrofluoric acid, phosphoric acid, sulfuric acid, sulfonic acid, nitric acid, acetic acid, acetic anhydride, citric acid, glycolic acid and formic acid, methylglycinediacetic acid (MGDA) and glutamic diacetic acid (GLDA).

9. The method according to claim 1, characterized in that the composition comprises between 0.05 and 15% by weight of hydrophobically modified polymer, wherein the composition comprises between 0.25 and 20% by weight of phosphorylated alkyl amino polycarboxylic acid, wherein the composition comprises between 1.0 and 30% by weight of base treatment acid, wherein the phosphorylated alkyl amino polycarboxylic acid is phosphonomethyliminodiacetic acid, wherein the hydrophobically modified polymer is selected from the group consisting of acrylamide / octadecyldimethylammoniumethyl methacrylate bromide copolymer, a dimethylaminoethyl methacrylate / hexadecyldimethylammoniumethyl methacrylate bromide copolymer, a dimethylaminoethyl methacrylate / vinylpyrrolidone / hexadecyldimethylammoniumethyl methacrylate bromide terpolymer, and an acrylamide / 2-acrylamido-2-methyl propanesulfonic acid / 2-ethylhexyl methacrylate terpolymer, and wherein the base treatment acid comprises hydrochloric acid.

10. A composition for stimulating an underground formation, characterized in that it comprises: a hydrophobically modified polymer; a phosphorylated alkyl amino polycarboxylic acid; and a base treatment acid.

11. The composition according to claim 10, characterized in that it comprises between 0.05 and 15% by weight of hydrophobically modified polymer.

12. The composition according to claim 10, characterized in that it comprises between 0.25 and 20% by weight of phosphorylated alkyl amino polycarboxylic acid.

13. The composition according to claim 10, characterized in that it comprises between 1.0 and 30% by weight of base treatment acid.

14. The composition according to claim 10, characterized in that the phosphorylated alkyl amino polycarboxylic acid is selected from the group consisting of N-phosphonomethyliminodiacetic acid (PMIDA), the phosphorylated alkyl amino polycarboxylic acid is aminotris(methylenephosphonic acid) (ATMP), the phosphorylated alkyl amino polycarboxylic acid is N,N-bis(phosphonomethyl)glycine (BPMG) and derivatives thereof.

15. The composition according to claim 14, characterized in that the hydrophobically modified polymer is selected from the group consisting of acrylamide / octadecyldimethylammoniumethyl methacrylate bromide copolymer, dimethylaminoethyl methacrylate / hexadecyldimethylammoniumethyl methacrylate bromide copolymer, a dimethylaminoethyl methacrylate / vinylpyrrolidone / hexadecyldimethylammoniumethyl methacrylate bromide terpolymer, and an acrylamide / 2-acrylamide-2-methyl propanesulfonic acid / 2-ethylhexyl methacrylate terpolymer.

16. The composition according to claim 10, characterized in that the hydrophobically modified polymer is selected from the group consisting of acrylamide / octadecyldimethylammoniumethyl methacrylate bromide copolymer, dimethylaminoethyl methacrylate / hexadecyldimethylammoniumethyl methacrylate bromide copolymer, dimethylaminoethyl methacrylate / vinylpyrrolidone / hexadecyldimethylammoniumethyl methacrylate bromide terpolymer, and acrylamide / 2-acrylamide-2-methyl propanesulfonic acid / 2-ethylhexyl methacrylate terpolymer.

17. The composition according to claim zfrocnn / zznz / E / YiAi 10, characterized in that the base treatment acid is selected from the group consisting of hydrochloric acid, hydrofluoric acid, phosphoric acid, sulfuric acid, sulfonic acid, nitric acid, acetic acid, acetic anhydride, citric acid, glycolic acid and formic acid, methylglycinediacetic acid (MGDA) and glutamic diacetic acid (GLDA).

18. The composition according to claim 10, characterized in that the composition comprises between 0.05 and 15% by weight of hydrophobically modified polymer, wherein the composition comprises between 0.25 and 20% by weight of phosphorylated alkyl amino polycarboxylic acid, between 1.0 and 30 wt% of base treatment acid, wherein the phosphorylated alkyl amino polycarboxylic acid is phosphonomethyliminodiacetic acid, wherein the hydrophobically modified polymer is selected from the group consisting of acrylamide / octadecyldimethylammonium ethyl methacrylate bromide copolymer, dimethylaminoethyl methacrylate / hexadecyldimethylammonium ethyl methacrylate bromide copolymer, dimethylaminoethyl methacrylate / vinylpyrrolidone / hexadecyldimethylammonium ethyl methacrylate bromide terpolymer, and acrylamide / 2-acrylamido-2-methyl propanesulfonic acid / 2-ethylhexyl methacrylate terpolymer, and wherein the base treatment acid comprises hydrochloric acid. zfrocnn / zznz / E / YiAi.

19. A method for extracting hydrocarbons, characterized in that it comprises: supplying a composition comprising a hydrophobically modified polymer, a phosphorylated alkyl amino polycarboxylic acid, and a base treatment acid into the underground formation through a well; contacting the underground carbonate formation with the composition to form conductive flow pathways in the underground carbonate formation; and producing hydrocarbons from the underground formation through the well.

20. The method according to claim 19, characterized in that the phosphorylated alkyl amino polycarboxylic acid is selected from the group consisting of N-phosphonomethyliminodiacetic acid (PMIDA), the phosphorylated alkyl amino polycarboxylic acid is aminotris(methylenephosphonic acid) (ATMP), the phosphorylated alkyl amino polycarboxylic acid is N,N-bis(phosphonomethyl)glycine (BPMG), and derivatives thereof; and the hydrophobically modified polymer is selected from the group consisting of acrylamide / octadecyldimethylammonium ethyl methacrylate bromide copolymer, dimethylaminoethyl methacrylate / hexadecyldimethylammonium ethyl methacrylate bromide copolymer, dimethylaminoethyl methacrylate / vinyl pyrrolidone / hexadecyldimethylammonium ethyl methacrylate bromide terpolymer, and acrylamide / methyl propane sulfonic acid / 2-ethylhexyl methacrylate terpolymer.