Scale inhibitor fluids and methods for inhibiting fouling

Abstract

A scale inhibitor fluid includes from 0.001 ppm to 100 ppm of a phosphonate compound, from 20 ppm to 400 ppm of a cationic-containing surfactant, and an aqueous fluid. The cationic surface active agent comprises at least one of a cationic surface active agent with single positive charges, a cationic surface active agent with double positive charges and a zwitterionic cationic surface active agent. A method for inhibiting fouling in a wellbore includes introducing a phosphonate compound, a cationic-containing surfactant, and an aqueous fluid into the wellbore to produce a scale inhibitor fluid.

Description

Background Art

[0001] In oil and gas extraction operations, scaling occurs when various fluids, including hydrocarbon mixtures, fluids in underground formations ("formation fluids"), and fluids used in drilling and extraction operations ("drilling fluids", "injection fluids"), come into contact with each other during operations and some of the compounds contained in the fluids react to form insoluble precipitates. Commonly formed scales include, but are not limited to, calcium carbonate, magnesium carbonate, and calcium sulfate. Such scaling may reduce the permeability of the formation, restrict fluid flow through the oil and gas wellbore ("wellbore") and various parts of the oil and gas extraction system (such as drill pipe), and cause problems with production equipment, negatively affecting well productivity and associated production costs. The severity of scaling depends in part on wellbore and reservoir conditions (including temperature, pressure, and the types and concentrations of dissolved ions in the fluids).

[0002] Traditionally, scaling is controlled by the use of antiscalants, and a variety of antiscalants have been developed and commercialized. Antiscalants generally prevent or slow the scaling process by chelating scaling cations or by threshold inhibition, nucleation inhibition, crystal deformation and / or dispersion mechanisms. Conventional antiscalants may include polyphosphonates, phosphonates, polycarboxylic acids, and polyelectrolytes. However, conventional antiscalants are often not effective in preventing scaling in the required or desired manner in extraction operations, particularly in high temperature, high salinity environments, and at low antiscalant dosages. Therefore, there is a need for continued improvement in antiscalants for oil and gas extraction operations. Summary of the invention

[0003] This Summary is provided to introduce a selection of concepts that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended as an aid in limiting the scope of the claimed subject matter.

[0004] In one aspect, embodiments disclosed herein generally relate to antiscalant fluids. The antiscalant fluid may include 0.001ppm to 100ppm of a phosphonate compound, 20ppm to 400ppm of a cation-containing surfactant, and an aqueous fluid. The cation-containing surfactant may include at least one of a single positively charged cation-containing surfactant, a double positively charged cation-containing surfactant, and a zwitterionic cation-containing surfactant.

[0005] On the other hand, embodiments disclosed herein generally relate to a method for inhibiting scaling in a wellbore. The method may include introducing a phosphonate compound, a cationic surfactant, and an aqueous fluid into the wellbore to produce an antiscalant fluid. The concentration range of the phosphonate compound in the antiscalant fluid may be 0.001ppm to 100ppm, and the concentration range of the cationic surfactant in the antiscalant fluid may be 20ppm to 400ppm. The cationic surfactant may include at least one of a single positively charged cationic surfactant, a double positively charged cationic surfactant, and a zwitterionic cationic surfactant.

[0006] Other aspects and advantages of the claimed subject matter will be apparent from the following description and the appended claims. DETAILED DESCRIPTION

[0007] The present disclosure generally relates to antiscalant fluids for underground oil and gas extraction operations, and methods for inhibiting scaling. The antiscalant fluids provide improved antiscalant performance in environments including high temperature and high salinity conditions. The antiscalant fluids also provide this improved performance while maintaining substantially lower phosphonate concentrations, thereby contributing to the overall cost benefits provided by the antiscalant fluids. The antiscalant fluids can provide effective antiscalant performance in continuous injection and extrusion processing operations.

[0008] In one aspect, embodiments herein relate to an antiscalant fluid comprising 100 ppm or less of a phosphonate compound, 20 ppm to 400 ppm of a cationic-containing surfactant, and an aqueous fluid.

[0009] Phosphate compounds

[0010] In one or more embodiments, the antiscalant fluid may include a phosphonate compound. The phosphonate compound forms a complex of the phosphonate compound and the scaling cation in the fluid by combining with the scaling cation (such as calcium ion) in the fluid, reducing the amount of the scaling cation in the fluid, thereby playing the role of an antiscalant. In addition, the phosphonate compound can prevent or delay the further growth of the crystallites by static adsorption on the surface of the crystallites of the formed fouling.

[0011] In one or more embodiments, the antiscalant fluid can include an amount of phosphonate compound in the range of about 0.001 to 100 ppm, such as a lower limit selected from any one of 0.001, 0.01, 0.05, 0.1, 0.5, 1, 2, 3, 4, 5, 10, 20, 30 ppm to an upper limit selected from any one of 50, 60, 70, 80, 90, 100 ppm, wherein any lower limit can be paired with any upper limit.

[0012] In one or more embodiments, the phosphonate compound can be any conventionally available phosphonate compound including phosphonate scale inhibitors. In one or more embodiments, the phosphonate compound can be a nitrogen-containing phosphonate compound. In one or more embodiments, the nitrogen-containing phosphonate compound can be, but is not limited to, aminotrimethylenephosphonic acid (ATMP), diethylenetriamine penta(methylenephosphonic acid) (DETPMP), bis(hexamethylene)triamine penta(methylenephosphonic acid) (BHMT, bis(hexamethylene triamine penta(methylene phosphonic acid)), or bis(hexamethylene)triamine penta(methylenephosphonic acid)) and hydroxyethylamino-bis(methylenephosphonic acid) (MEA), similar nitrogen-containing phosphonates and combinations thereof.

[0013] In one or more embodiments, the phosphonate compound may be a compound containing C-PO(OH) 2 and C-PO(OR) 2 The phosphonate compound may be a phosphonate, which includes but is not limited to a phosphonate having one of the following structures: C-PO(OH)(ONa), C-PO(ONa) 2 , C-PO(OH)(OK) and C-PO(OK) 2 In one or more embodiments, the phosphonate compound can be a combination of any of the phosphonate compounds described above.

[0014] Contains cationic surfactant

[0015] In one or more embodiments, the antiscalant fluid can include a cationic surfactant. A cationic surfactant refers to a quaternary ammonium compound having a positively charged portion and an alkyl hydrophobic chain. A cationic surfactant may be able to form micelles at very low concentrations in a fluid with high salinity. The total dissolved salt of such a high salinity fluid can be in the range of 50,000 ppm to 200,000 ppm. A cationic surfactant can increase the solubility of the crystallites of the fouling formed, thereby preventing or reducing the growth of the crystallites.

[0016] In one or more embodiments, the cation-containing surfactant may include at least one of a singly positively charged cation-containing surfactant, a doubly positively charged cation-containing surfactant, and a zwitterionic cation-containing surfactant. A singly positively charged cation-containing surfactant refers to a cation-containing surfactant containing one positively charged portion. An example of a singly positively charged cation-containing surfactant may be represented by the following formula:

[0017] RN + (CH3 ) 3 ·X -

[0018] RN + (CH 2 CH 3 ) 3 ·X -

[0019] RN + (CH 2 CH 3 ) 2 (CH 3 )·X -

[0020] RN + (CH 2 CH 3 )(CH 3 ) 2 ·X -

[0021] wherein R is a straight or branched alkyl hydrocarbon including 6 to 18 carbons and may contain no or one carbon double bond (C=C), and X is a halogen ion including Cl, Br and I.

[0022] In one or more embodiments, the single positively charged cation-containing surfactant may include a surfactant having the formula: 12 N + (CH 3 ) 3 ·Br - ) represented by dodecyltrimethylammonium bromide ("DTAB") and represented by the formula: 16 N + (CH 3 ) 3 ·Br - It stands for cetyltrimethylammonium bromide ("CTAB").

[0023] A double positively charged cation-containing surfactant refers to a cation-containing surfactant containing two positively charged moieties. An example of a double positively charged cation-containing surfactant can be represented by the following formula:

[0024] RN + (CH 3 ) 2 -R 1 -N + (CH 3 ) 3 2X -

[0025] RN +(CH 3 ) 2 -R 1 -N + (CH 2 CH 3 ) 3 2X -

[0026] RN + (CH 3 ) 2 -R 1 -N + (CH 2 CH 3 )(CH 3 ) 2 2X -

[0027] RN + (CH 3 ) 2 -R 1 -N + (CH 2 CH 3 ) 2 (CH 3 )·2X -

[0028] wherein R is a straight or branched alkyl hydrocarbon containing 6 to 18 carbon atoms and may contain no or one carbon double bond, 1 is a linear alkyl hydrocarbon comprising 2 to 5 carbons, which may be optionally linked to a hydroxyl group, and X - is a halogen ion including Cl, Br or I.

[0029] In one or more embodiments, the dipositively charged cation-containing surfactant may include a compound represented by the formula: 18 N + (CH 3 ) 2 -CH 2 -CH(OH)-CH 2 -N + (CH 3 ) 2 2Cl - (“BCS”).

[0030] Zwitterionic cation-containing surfactants refer to cation-containing surfactants containing both positively charged moieties and negatively charged moieties. The negatively charged moieties of zwitterionic cation-containing surfactants may include, but are not limited to, carboxyl groups and sulfonate groups. Examples of zwitterionic cation-containing surfactants may be represented by the following formula:

[0031] RN + (CH 3 ) 2 -R 1 -SO 3 -

[0032] RN + (CH 3 ) 2 -R 1 -COO -

[0033] wherein R is a straight or branched alkyl hydrocarbon comprising 6 to 18 carbons and may contain no or one carbon double bond, and R 1 is a straight chain alkyl hydrocarbon comprising 2 to 5 carbons, which may be optionally linked to a hydroxyl group.

[0034] In one or more embodiments, the zwitterionic cation-containing surfactant may include 3-(N,N-dimethylmyristyl ammonium) propanesulfonate ("SB3-14") represented by the formula: 14 N + (CH 3 ) 2 -CH 2 -CH 2 -SO 3 - .

[0035] In one or more embodiments, the antiscalant fluid can include one or more cation-containing surfactants. In the case where the antiscalant fluid contains multiple cation-containing surfactants, the multiple cation-containing surfactants can be a combination of any of the cation-containing surfactants described above.

[0036] In one or more embodiments, the antiscalant fluid can include an amount of cationic surfactant ranging from about 20 ppm to 400 ppm, such as a lower limit selected from any one of 20, 25, and 30 ppm to an upper limit selected from any one of 40, 50, 60, 70, 80, 90, 100, 150, 200, 250, 300, 350, and 400 ppm, wherein any lower limit can be paired with any upper limit.

[0037] In one or more embodiments, the antiscalant fluid can include a phosphonate compound and a cation-containing surfactant such that the ratio of the cation-containing surfactant to the phosphonate compound is in the range of about 0.5 to 100, such as a lower limit selected from any one of 0.5, 1, 2, 3, and 4 to an upper limit selected from any one of 6, 7, 8, 9, 10, 25, 50, and 100, on a ppm basis, wherein any lower limit can be paired with any upper limit.

[0038] Water-based fluid

[0039] In one or more embodiments, the scale inhibitor fluid may include an aqueous fluid. The aqueous fluid may be any fluid that is aqueous and can be mixed with a phosphonate compound and a cationic surfactant. In one or more embodiments, the aqueous fluid may be a reservoir fluid or a formation fluid, or a fluid in a formation, which may contain ions (such as calcium, magnesium, carbonate and sulfate ions) that may form a precipitate. The aqueous fluid may also contain other common materials in sodium chloride and a reservoir fluid.

[0040] In one or more embodiments, the aqueous fluid can be a fluid introduced into the wellbore during oil and gas extraction operations, such as a drilling fluid or an injection fluid. Such a fluid introduced into the wellbore can contain ions (such as sulfate ions) capable of forming precipitates, sodium chloride, and other additives conventionally used in oil and gas extraction operations, such as the additives described in the following section.

[0041] In one or more embodiments, the aqueous fluid may be a mixture of the reservoir fluid and the fluid introduced into the wellbore. In such a mixture, various ions from different fluids may react when mixed, thereby increasing the possibility of scaling.

[0042] In one or more embodiments, the aqueous fluid can contain calcium ions in an amount of about 2000 ppm or more, such as at least 2000, 4000, 6000, 8000, and 10000 ppm.

[0043] In one or more embodiments, the aqueous fluid contains primarily sulfate ions in an amount of about 2000 ppm or more, such as at least 2000, 4000, 6000, 8000, and 10000 ppm.

[0044] In one or more embodiments, the aqueous fluid may contain additives, which may include, but are not limited to, barium sulfate, calcium carbonate, thickeners, viscosity modifiers, lubricants, shale inhibitors, weighting agents, deflocculants, emulsifiers, and the like.

[0045] Scale inhibition rate

[0046] In one or more embodiments, the antiscalant fluid provides improved antiscaling performance when compared to a fluid containing a conventional antiscalant. This improvement in antiscaling performance can be characterized by the % antiscaling rate and the % increase in antiscaling rate.

[0047] The scale inhibition rate % represents the ratio of the amount of scale-forming ions retained in ionic form in a fluid stored under specific conditions to the total amount of scale-forming ions in the fluid.

[0048] In particular, by introducing 4000 ppm of calcium ions and 4000 ppm of sulfate ions into the fluid, storing the fluid at 105°C in a sealed state for 24 hours to heat-treat the fluid, obtaining the amount of calcium ions in the fluid after heat treatment, and calculating the ratio of the amount of calcium ions in the fluid before and after heat treatment, the scale inhibition rate % of the fluid is determined. The amount of calcium ions in the fluid can be obtained by using a device such as an inductively coupled plasma mass spectrometer (ICP-MS). The scale inhibition rate % can be expressed by the following formula:

[0049]

[0050] Where m f represents the concentration of calcium ions in the fluid after heat treatment, and m i Indicates the concentration of calcium ions in the fluid before heat treatment. The scale inhibition increase rate % of the antiscalant fluid is the difference between the scale inhibition rate % of the antiscalant fluid and the scale inhibition rate % of the reference fluid. The reference fluid is defined as a fluid that is the same as the antiscalant fluid, except that the fluid does not contain a cationic surfactant.

[0051] In one or more embodiments, the scale inhibition increase rate % of the antiscalant fluid can be about 5% or more, such as at least 5%, at least 10%, at least 15%, at least 20%, at least 24%, at least 25%, or at least 30%. In one or more embodiments, when the cationic surfactant is a double positively charged cationic surfactant, the scale inhibition increase rate % of the antiscalant fluid can be at least 20%, at least 24%, or at least 25%. In one or more embodiments, when the cationic surfactant is a zwitterionic cationic surfactant, the scale inhibition increase rate % of the antiscalant fluid can be at least 25%, or at least 30%.

[0052] Methods for inhibiting scaling

[0053] In one aspect, embodiments herein relate to a method for inhibiting scaling in a wellbore. In one or more embodiments, the method may include introducing a phosphonate compound, a cationic surfactant, and an aqueous fluid into the wellbore to produce an antiscalant fluid. The antiscalant fluid is produced when the phosphonate compound, the cationic surfactant, and the aqueous fluid are combined before or in the wellbore.

[0054] In one or more embodiments, the phosphonate compound, the cation-containing surfactant, and the aqueous fluid can be introduced into the wellbore separately. In one or more embodiments, the aqueous fluid can be introduced into the wellbore, followed by the phosphonate compound, and finally the cation-containing surfactant. In one or more embodiments, the aqueous fluid can be introduced into the wellbore, followed by the cation-containing surfactant, and finally the phosphonate compound.

[0055] In one or more embodiments, the aqueous fluid and the phosphonate compound can be mixed before being introduced into the wellbore. Then, the mixture of the aqueous fluid and the phosphonate compound can be introduced into the wellbore, followed by the introduction of the cationic surfactant. In one or more embodiments, the aqueous fluid and the cationic surfactant can be mixed before being introduced into the wellbore. Then, the mixture of the aqueous fluid and the cationic surfactant can be introduced into the wellbore, followed by the introduction of the phosphonate compound. In one or more embodiments, the aqueous fluid can be introduced into the wellbore, and then the phosphonate compound and the cationic surfactant are introduced into the wellbore simultaneously.

[0056] In one or more embodiments, the aqueous fluid, phosphonate compound, and cation-containing surfactant can be mixed prior to being introduced into the wellbore. In one or more embodiments, the aqueous fluid, phosphonate compound, and cation-containing surfactant are not mixed prior to being introduced into the wellbore, but can be introduced into the wellbore simultaneously.

[0057] In one or more embodiments, the method can include introducing a phosphonate compound, a cationic surfactant, and an aqueous fluid into the wellbore in amounts such that the concentration of the phosphonate compound in the antiscalant fluid is in the range of 0.001 ppm to 100 ppm and the concentration of the cationic surfactant in the antiscalant fluid is in the range of 20 ppm to 400 ppm.

[0058] In one or more embodiments, the method may further include maintaining the concentration of the phosphonate compound in the scale inhibitor fluid within the range of 0.001 ppm to 100 ppm and maintaining the concentration of the cationic surfactant within the range of 20 ppm to 400 ppm throughout the duration of the oil and gas extraction operation. The concentrations of the phosphonate compound and the cationic surfactant may be maintained by additionally introducing the phosphonate compound and / or the cationic surfactant into the wellbore. The additional introduction of the phosphonate compound and / or the cationic surfactant may be performed continuously or intermittently. There is no limitation on the amount or frequency of the additional introduction, provided that the above concentrations of the phosphonate compound and the cationic surfactant are maintained.

[0059] Example

[0060] The following examples are provided to illustrate embodiments of the present disclosure. The examples are not intended to limit the scope of the invention, nor should they be so interpreted.

[0061] Example 1

[0062] An exemplary antiscalant fluid was prepared by first mixing equal amounts of a 4% NaCl solution containing 8000 ppm calcium ions and a 4% NaCl solution containing 8000 ppm sulfate solution, and then adding appropriate amounts of aminotrimethylenephosphonic acid (ATMP) and dodecyltrimethylammonium bromide (DTAB, C 12 N + (CH 3 ) 3 ·Br - ), so that the concentrations of calcium ions, sulfate ions, ATMP and DTAB in the exemplary antiscalant fluid are 4000ppm, 4000ppm, 40ppm and 20ppm respectively. The antiscalant fluid is placed in a sealed bottle and stored at 105°C for 24 hours. The calcium ion concentration of the sample is then analyzed using an inductively coupled plasma mass spectrometer (ICP-MS), and the scale inhibition rate of calcium sulfate is calculated based on the measured calcium ion concentration and the equation provided in the previous section.

[0063] Example 2

[0064] An antiscalant fluid was prepared according to Example 1, except that the amount of DTAB added was changed so that the DTAB concentration was 40 ppm.

[0065] Example 3

[0066] An antiscalant fluid was prepared according to Example 1, except that the amount of DTAB added was changed so that the DTAB concentration was 80 ppm.

[0067] Example 4

[0068] An antiscalant fluid was prepared according to Example 1, except that the amount of DTAB added was changed so that the DTAB concentration was 200 ppm.

[0069] Example 5

[0070] An antiscalant fluid was prepared according to Example 1, except that the amount of DTAB added was changed so that the DTAB concentration was 400 ppm.

[0071] Example 6

[0072] In addition to DTAB being replaced by cetyltrimethylammonium bromide (CTAB, C 16 N + (CH 3 ) 3 ·Br - ) was replaced by an antiscalant fluid according to Example 1. The concentration of CTAB in the fluid was adjusted to 40 ppm.

[0073] Example 7

[0074] In addition to DTAB having structure C 18 N+(CH 3 ) 2 -CH 2 -CH(OH)-CH 2 -N + (CH 3 ) 2 The antiscalant fluid was prepared according to Example 1, except that the bi-positively charged cationic surfactant of 2Cl(BCS) was replaced. The concentration of BCS in the fluid was adjusted to 40 ppm.

[0075] Example 8

[0076] An antiscalant fluid was prepared according to Example 1, except that DTAB was replaced by SB3-14. The concentration of SB3-14 in the fluid was adjusted to 40 ppm.

[0077] Example 9

[0078] An antiscalant fluid was prepared according to Example 1, except that DTAB was replaced by SB3-14. The concentration of SB3-14 in the fluid was adjusted to 80 ppm.

[0079] Example 10

[0080] An antiscalant fluid was prepared according to Example 1, except that DTAB was replaced by SB3-14. The concentration of SB3-14 in the fluid was adjusted to 200 ppm.

[0081] Embodiment 11

[0082] An antiscalant fluid was prepared according to Example 1, except that DTAB was replaced by SB3-14. The concentration of SB3-14 in the fluid was adjusted to 400 ppm.

[0083] Example 12

[0084] The antiscalant fluid was prepared according to Example 6, except that DTAB was further added to the fluid. The concentrations of CTAB and DTAB in the fluid were adjusted to 40 ppm and 10 ppm, respectively.

[0085] Comparative Example 1

[0086] Comparative Examples were prepared according to the method provided in Example 1 except that no DTAB was added.

[0087] Evaluation-scale inhibition rate %

[0088] The scale inhibition rates and scale inhibition increase rates (%) of Examples 1-12 and Comparative Example 1 were determined as described in the previous section using Comparative Example 1 as the reference fluid.

[0089] The scale inhibition rates of Examples 1-12 and Comparative Example 1 are shown in Table 1. Table 1 shows that the fluid of Comparative Example 1 (which contains 40 ppm of ATMP and does not contain a cationic surfactant) results in a scale inhibition rate of 67.4%. Scaling was also observed in the fluid of Comparative Example 1. Table 1 further illustrates that by combining the same amount of ATMP as in Comparative Example 1 with various cationic surfactants, the scale inhibition rate % and the scale inhibition increase rate % can be greatly improved. The antiscalant fluids of Examples 1-12 do not show visible scaling, indicating that the combination of phosphonate compounds and cationic surfactants in the exemplary antiscalant fluids provides effective scale inhibition performance.

[0090] Examples 1-5 (which include 40 ppm of ATMP in combination with DTAB at a concentration of 20 ppm to 400 ppm) provide greatly improved scale inhibition %, demonstrating the effective range of concentration of the single positively charged cation-containing surfactant in the antiscalant fluid. Examples 8-11 (which include 40 ppm of ATMP in combination with SB3-14 at a concentration of 40 ppm to 400 ppm) show a scale inhibition rate of 100% over the entire range, demonstrating the effectiveness of zwitterionic cation-containing surfactants in the antiscalant fluid within the above range. In addition, the scale inhibition % of Examples 6 and 12 show that the combination of a single positively charged cation-containing surfactant and a double positively charged cation-containing surfactant can provide enhanced scale inhibition performance.

[0091] Table 1

[0092]

[0093] Although only a few exemplary embodiments have been described in detail above, those skilled in the art will readily appreciate that many modifications may be made in the exemplary embodiments without materially departing from the present invention. Therefore, all such modifications are intended to be included within the scope of the present disclosure as defined by the following claims. Applicants expressly disclaim any limitation to any claim herein that would be by reference to means-plus-function unless the words "means for..." and the associated functions are expressly used in a claim.

Claims

1. An antiscalant fluid comprising: 0.001 ppm to 100 ppm of phosphonate compounds; 20ppm to 400ppm of cationic surfactant; and Aqueous fluids, The cationic surfactant comprises at least one of a single positively charged cationic surfactant, a double positively charged cationic surfactant and a zwitterionic cationic surfactant.

2. The antiscalant fluid according to claim 1, wherein the phosphonate compound is a nitrogen-containing phosphonate compound.

3. The antiscalant fluid according to claim 2, wherein the nitrogen-containing phosphonate compound comprises at least one of aminotrimethylenephosphonic acid (ATMP), diethylenetriaminepenta(methylenephosphonic acid) (DETPMP), bis(hexamethylene)triaminepenta(methylenephosphonic acid) (BHMT) and hydroxyethylamino-bis(methylenephosphonic acid) (MEA).

4. The antiscalant fluid according to any one of the preceding claims, wherein the phosphonate compound comprises at least one of a C-PO(OH)2 group and a C-PO(OR)2 group, wherein R is an alkyl group or an aryl group.

5. The antiscalant fluid according to any one of the preceding claims, wherein at a temperature of 105°C, the antiscalant fluid has an antiscalant % increase of at least 5%.

6. The antiscalant fluid according to any one of the preceding claims, wherein the cation-containing surfactant is the dual positively charged cation-containing surfactant.

7. The antiscalant fluid of claim 6, wherein at a temperature of 105°C, the antiscalant fluid has an antiscalant % increase of at least 24%.

8. The antiscalant fluid according to any one of claims 1 to 5, wherein the cation-containing surfactant is the zwitterionic cation-containing surfactant, and The concentration of the cationic surfactant in the antiscalant fluid is in the range of 40 ppm to 400 ppm.

9. The antiscalant fluid of claim 8, wherein at a temperature of 105°C, the antiscalant fluid has an antiscalant % increase of at least 30%.

10. A method for inhibiting scaling in a wellbore, the method comprising: introducing a phosphonate compound, a cationic surfactant, and an aqueous fluid into the wellbore to produce an antiscalant fluid; in: The concentration of the phosphonate compound in the antiscalant fluid is in the range of 0.001 ppm to 100 ppm, The concentration of the cationic surfactant in the antiscalant fluid ranges from 20 ppm to 400 ppm, and The cation-containing surfactant includes at least one of a single positively charged cation-containing surfactant, a double positively charged cation-containing surfactant and a zwitterionic cation-containing surfactant.

11. The method of claim 10, wherein the phosphonate compound comprises a nitrogen-containing phosphonate compound.

12. The method of claim 11, wherein the nitrogen-containing phosphonate compound comprises at least one of aminotrimethylenephosphonic acid (ATMP), diethylenetriaminepenta(methylenephosphonic acid) (DETPMP), bis(hexamethylene)triaminepenta(methylenephosphonic acid) (BHMT), and hydroxyethylamino-bis(methylenephosphonic acid) (MEA).

13. The method according to any one of claims 10 to 12, wherein the phosphonate compound comprises at least one of a C-PO(OH)2 group and a C-PO(OR)2 group, wherein R is an alkyl group or an aryl group.

14. A method according to any one of claims 10 to 13, wherein the antiscalant fluid has an antiscalant % increase of at least 5% at a temperature of 105°C.

15. The method according to any one of claims 10 to 14, wherein the cation-containing surfactant is the dipositively charged cation-containing surfactant.

16. The method of claim 15, wherein the antiscalant fluid has an antiscalant % increase of at least 24% at a temperature of 105°C.

17. The method according to any one of claims 10 to 14, wherein the cation-containing surfactant is the zwitterionic cation-containing surfactant, and The concentration of the cationic surfactant in the antiscalant fluid is in the range of 40 ppm to 400 ppm.

18. The method of claim 17, wherein the antiscalant fluid has an antiscalant % increase of at least 30% at a temperature of 105°C.

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