A shale inhibitor and its preparation method and application

Abstract

The present invention relates to a shale inhibitor and a preparation method and application thereof, and relates to the field of oilfield chemical technology. The shale inhibitor comprises the following components: polyetheramine and amino acid modified hydrotalcite; the amino acid modified hydrotalcite is obtained by ion exchange reaction between hydrotalcite and amino acid salt; the weight ratio of the polyetheramine to the amino acid modified hydrotalcite is 1:(0.05-0.10). The present invention adopts amino acid modified hydrotalcite as an additive of polyetheramine shale inhibitor for the first time. The combination of the two not only significantly improves the high temperature resistance of the existing polyetheramine shale inhibitor, but also further enhances its inhibitory effect, thereby broadening its application scenarios in oil and gas drilling.

Description

Technical Field

[0001] The present application relates to the technical field of oilfield chemistry, and in particular to a shale inhibitor and a preparation method and application thereof. Background Art

[0002] Shale is one of the most common rocks in oil fields that must be drilled through to reach the oil layer. It is mainly composed of clay and other minerals. It is a fine, impermeable sedimentary rock. When water-based drilling fluid is used in the drilling process of shale formations, shale hydration and expansion will inevitably occur, resulting in borehole shrinkage, drill sticking, unstable wellbore wall, and easy well collapse. Therefore, the problem of wellbore stability has greatly limited the widespread application of water-based drilling fluids.

[0003] Water-based drilling fluids are mainly composed of shale inhibitors, fluid loss reducers and viscosity enhancers. Among them, shale inhibitors are key treatment agents to ensure the stability of the wellbore of shale, and their research is increasingly valued by drilling fluid workers. There are many types of inhibitors used in existing oil fields, and the performance of each type is also different. At present, the most widely used shale inhibitors are amine shale inhibitors such as polyetheramine, which have the characteristics of low toxicity and good compatibility, but they have poor high temperature resistance and the inhibitory effect needs to be further improved. Summary of the invention

[0004] The present application provides a shale inhibitor and a preparation method and application thereof to solve technical problems such as poor high temperature resistance of existing polyetheramine shale inhibitors; at the same time, further improves its inhibitory effect, thereby broadening its application scenarios in oil and gas drilling.

[0005] In a first aspect, the present application provides a shale inhibitor, which comprises the following components: polyetheramine and amino acid-modified hydrotalcite;

[0006] The amino acid-modified hydrotalcite is obtained by ion exchange reaction between hydrotalcite and amino acid salt;

[0007] The weight ratio of the polyetheramine to the amino acid-modified hydrotalcite is 1:(0.05-0.10).

[0008] Furthermore, the weight ratio of the polyetheramine to the amino acid-modified hydrotalcite is 1:0.08.

[0009] Furthermore, the particle size of the amino acid modified hydrotalcite is 400-500 meshes.

[0010] Furthermore, the amino acid salt includes at least one of sodium 6-aminocaproate and disodium glutamate.

[0011] Furthermore, the hydrotalcite includes magnesium-aluminum hydrotalcite.

[0012] Furthermore, the average relative molecular weight of the polyetheramine is less than 1000.

[0013] Furthermore, the product model of the polyetheramine includes at least one of D230, D400 and T403.

[0014] In a second aspect, the present application provides a method for preparing the shale inhibitor according to any one of the first aspects, the preparation method comprising the following steps:

[0015] Obtaining amino acid modified hydrotalcite;

[0016] Adding the polyetheramine into an organic solvent and performing a first stirring to obtain a mixed solution;

[0017] The amino acid-modified hydrotalcite is added to the mixed solution for a second stirring, and then concentrated and dried to obtain the shale inhibitor.

[0018] In a third aspect, the present application provides the use of the shale inhibitor described in any one of the first aspect, and / or the shale inhibitor prepared by the preparation method described in any one of the second aspect in oil and gas drilling.

[0019] In a fourth aspect, the present application provides a water-based drilling fluid, wherein the water-based drilling fluid contains the shale inhibitor described in any one of the first aspects.

[0020] The above technical solution provided by the embodiment of the present application has at least the following advantages compared with the prior art:

[0021] An embodiment of the present application provides a shale inhibitor, which for the first time uses amino acid-modified hydrotalcite as an additive for a polyetheramine shale inhibitor. The combination of the two not only significantly improves the high-temperature resistance of the existing polyetheramine shale inhibitor, but also further enhances its inhibitory effect, thereby broadening its application scenarios in oil and gas drilling. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0023] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0024] Figure 1 A schematic flow chart of a method for preparing a shale inhibitor provided in an embodiment of the present application. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0026] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0027] In a first aspect, the present application provides a shale inhibitor, which comprises the following components: polyetheramine and amino acid-modified hydrotalcite;

[0028] The amino acid-modified hydrotalcite is obtained by ion exchange reaction between hydrotalcite and amino acid salt;

[0029] The weight ratio of the polyetheramine to the amino acid-modified hydrotalcite is 1:(0.05-0.10).

[0030] Polyetheramine (PEA) is a type of polymer with a polyether structure as the main chain and an amine as the terminal active functional group. Commercial polyetheramines include monofunctional, difunctional, trifunctional, and a series of products with molecular weights ranging from 230 to 5000, such as D230, D400, and T403. Polyetheramine is a shale inhibitor of the oligoamine class. It can effectively inhibit the hydration of clay minerals by using its own chemical structure and is often used as a shale inhibitor in drilling fluids.

[0031] Hydrotalcite is a layered double hydroxide (LDH), including magnesium aluminum carbonate hydrotalcite (Mg6Al2(OH) 16 CO3·4H2O), etc. Due to its special layered structure, hydrotalcite is widely used in flame retardancy, catalysis, adsorption and other fields. With the widespread application of modern analytical techniques and testing methods, people's research on the structure and application of hydrotalcite has been continuously deepened, but there is no report on its application in shale inhibitors.

[0032] An embodiment of the present application provides a shale inhibitor, which for the first time uses amino acid-modified hydrotalcite as an additive for a polyetheramine shale inhibitor. The combination of the two not only significantly improves the high-temperature resistance of the existing polyetheramine shale inhibitor, but also further enhances its inhibitory effect, thereby broadening its application scenarios in oil and gas drilling.

[0033] In the present application, the amino acid modified hydrotalcite is obtained by ion exchange reaction between hydrotalcite and amino acid salt. In some specific embodiments, the preparation of amino acid modified hydrotalcite can be carried out by the following method: adding hydrotalcite to a proper amount of water at 80 to 95 degrees Celsius, heating and stirring for 1 to 3 hours, then adding amino acid salt and continuing stirring, performing ion exchange for 10 to 24 hours, filtering, and finally washing with water and vacuum drying in sequence to obtain a solid (i.e. amino acid modified hydrotalcite).

[0034] The inventors of the present application have found through further research that when the weight ratio of the polyetheramine and the amino acid modified hydrotalcite is controlled to be 1:(0.05-0.10), the synergistic compatibility of the two is better, and the comprehensive performance of the obtained shale inhibitor is better. If the amount of the additive amino acid modified hydrotalcite is too small, the improvement effect on the polyetheramine shale inhibitor is not obvious; if the amount of the additive amino acid modified hydrotalcite is too large, the inhibitory effect of the polyetheramine shale inhibitor is reduced to a certain extent.

[0035] In some specific embodiments, the weight ratio of the polyetheramine to the amino acid modified hydrotalcite may be 1:0.05, 1:0.06, 1:0.07, 1:0.08, 1:0.09, 1:0.10, etc.; preferably, the weight ratio of the polyetheramine to the amino acid modified hydrotalcite is 1:0.08.

[0036] As an implementation of the examples of the present application, the particle size of the amino acid-modified hydrotalcite is 400-500 mesh.

[0037] The inventors of the present application have found through further research that controlling the particle size of the amino acid-modified hydrotalcite to 400-500 meshes is more conducive to improving the temperature resistance of the polyetheramine shale inhibitor.

[0038] In some specific embodiments, the amino acid-modified hydrotalcite obtained by ion exchange reaction between hydrotalcite and amino acid salt can be crushed and then sieved to obtain the amino acid-modified hydrotalcite with corresponding particle size.

[0039] As an implementation of an example of the present application, the amino acid salt includes at least one of sodium 6-aminocaproate and disodium glutamate, and the hydrotalcite includes magnesium aluminum hydrotalcite.

[0040] In some specific embodiments, the amino acid salt described in the present application can be selected from commercially available ones such as sodium 6-aminocaproate and disodium glutamate, and the hydrotalcite can be selected from commercially available ones such as magnesium aluminum hydrotalcite (CAS No. 11097-59-9); preferably, disodium glutamate and magnesium aluminum hydrotalcite are selected for use in combination, and the amino acid-modified hydrotalcite is obtained after ion exchange. Of course, the amino acid salt and the hydrotalcite described in the present application can be prepared according to the method disclosed in the prior art, and the preparation method of the amino acid salt and the hydrotalcite is not described in detail in this application document.

[0041] As an implementation of the examples of the present application, the average relative molecular weight of the polyetheramine is less than 1000.

[0042] Preferably, the average relative molecular weight of the polyetheramine described in the present application is less than 1000, and specifically commercially available products such as product models D230, D400 and T403 can be selected; preferably T403.

[0043] It should be noted that the component raw materials involved in the shale inhibitor provided in the embodiments of the present application, such as polyetheramine, hydrotalcite, etc., can be directly used as commercial products unless otherwise specified or specified.

[0044] In a second aspect, based on a general inventive concept, the present application provides a method for preparing a shale inhibitor as described in any one of the first aspects, such as Figure 1 As shown, the preparation method comprises the following steps:

[0045] Obtaining amino acid modified hydrotalcite;

[0046] Adding the polyetheramine into an organic solvent and performing a first stirring to obtain a mixed solution;

[0047] The amino acid-modified hydrotalcite is added to the mixed solution for a second stirring, and then concentrated and dried to obtain the shale inhibitor.

[0048] The preparation method of the shale inhibitor provided in the present application is simple to operate, does not require additional specific equipment, and is suitable for industrial production. At the same time, the preparation method of the shale inhibitor is based on the shale inhibitor described in any one of the first aspects above, so it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be repeated here one by one.

[0049] In some specific embodiments, the organic solvent is preferably a neutral organic solvent such as dichloromethane, carbon tetrachloride, 1,2-dichloroethane, etc.; preferably 1,2-dichloroethane; the amount of the organic solvent used can ensure that the polyetheramine and the amino acid-modified hydrotalcite form a mixed solution, for example, it can be 3 to 100 times the total weight of the polyetheramine and the amino acid-modified hydrotalcite.

[0050] In some specific embodiments, the first stirring and the second stirring may be carried out by conventional mechanical stirring so that the polyetheramine and the amino acid-modified hydrotalcite can be fully mixed.

[0051] It should be noted that the operation steps involved in the preparation method provided in the present application can be carried out in a conventional manner in the art unless otherwise specified or limited, such as the first stirring, the second stirring, concentration and drying, etc. can all be carried out in a conventional manner in the art.

[0052] In a third aspect, the present application provides the use of the shale inhibitor described in any one of the first aspect, and / or the shale inhibitor prepared by the preparation method described in any one of the second aspect in oil and gas drilling.

[0053] The shale inhibitor provided in the present application has excellent temperature resistance and inhibitory effect, which not only effectively solves the problem of wellbore stability, but also further broadens its application scenarios in oil and gas drilling, and meets the more stringent usage requirements in the actual drilling process.

[0054] In a fourth aspect, the present application provides a water-based drilling fluid, wherein the water-based drilling fluid contains the shale inhibitor described in any one of the first aspects.

[0055] The water-based drilling fluid provided in the present application is realized based on the shale inhibitor described in any one of the first aspects above, and therefore has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be described one by one here.

[0056] In some specific embodiments, the water-based drilling fluid may also be adaptively added with other components such as fluid loss reducers and viscosity enhancers according to the prior art, which will not be described in detail in this application document.

[0057] In some specific embodiments, the content of shale inhibitor in the water-based drilling fluid may be 0.1-3.0 wt %, preferably 1 wt %, in terms of weight percentage.

[0058] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are intended only to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for which specific conditions are not specified in the following examples are usually measured according to national standards. If there is no corresponding national standard, then the conditions recommended by the manufacturer are followed.

[0059] Example 1

[0060] This example provides a shale inhibitor, which includes a polyetheramine and an amino acid-modified hydrotalcite in a weight ratio of 1:0.05, and a preparation method thereof includes the following steps:

[0061] 1.31 g of 6-aminocaproic acid and 10 mL of 1.0 mol / L sodium hydroxide were mixed evenly to prepare a 6-aminocaproate sodium solution, and then 0.8 L of distilled water and 97 g of magnesium aluminum hydrotalcite were added to a 1 L stainless steel reactor, heated to 80 ° C and stirred vigorously for 2 hours, and the above 6-aminocaproate sodium solution was added, and stirred at 90 ° C for 12 hours. The filtered product was washed with distilled water for several times, and the obtained solid was vacuum dried to constant weight, and then crushed and ground, and passed through a 400-500 mesh sieve to obtain amino acid modified hydrotalcite;

[0062] 10 g of polyetheramine D230 was added into 50 ml of 1,2-dichloroethane for first stirring for 10 minutes to obtain a mixed solution;

[0063] 0.5 g of the amino acid-modified hydrotalcite prepared above was added to the mixed solution for a second stirring for 1 hour, and then the mixture was concentrated under reduced pressure to remove 1,2-dichloroethane. Finally, the obtained solid was vacuum dried to obtain the shale inhibitor.

[0064] Example 2

[0065] This example provides a shale inhibitor, which is different from Example 1 only in that the weight ratio of the polyetheramine to the amino acid-modified hydrotalcite is 1:0.10, and the polyetheramine is D400; specifically, in the process of preparing the shale inhibitor, the amount of the amino acid-modified hydrotalcite is adjusted to 1.0 g, and the polyetheramine D230 is adjusted to D400; the remaining steps and parameters are the same.

[0066] Example 3

[0067] This example provides a shale inhibitor, which is different from Example 1 only in that the weight ratio of the polyetheramine to the amino acid-modified hydrotalcite is 1:0.08; specifically, in the process of preparing the shale inhibitor, the amount of the amino acid-modified hydrotalcite is adjusted to 0.8 g; the remaining steps and parameters are the same.

[0068] Example 4

[0069] This example provides a shale inhibitor, which is different from Example 3 only in that the polyetheramine is T403; specifically, in the process of preparing the shale inhibitor, the polyetheramine D230 is adjusted to T403; the remaining steps and parameters are the same.

[0070] Example 5

[0071] This example provides a shale inhibitor, which is different from Example 4 only in that the amino acid-modified hydrotalcite is obtained by ion exchange between disodium glutamate and magnesium aluminum hydrotalcite; the remaining steps and parameters are the same.

[0072] Example 6

[0073] This example provides a shale inhibitor, which is different from Example 4 only in that the particle size of the amino acid-modified hydrotalcite is 100-200 mesh, and the polyetheramine is D2000; the remaining steps and parameters are the same.

[0074] Comparative Example 1

[0075] This example provides a shale inhibitor, which is different from Example 1 only in that the amino acid-modified hydrotalcite is adjusted to unmodified magnesium-aluminum hydrotalcite; the remaining steps and parameters are the same.

[0076] Comparative Example 2

[0077] This example provides a shale inhibitor, which is different from Example 1 only in that the amino acid-modified hydrotalcite is adjusted to 6-aminocaproic acid sodium solid; the remaining steps and parameters are the same.

[0078] Comparative Example 3

[0079] This example provides a shale inhibitor, which is polyetheramine D230 (ie, no amino acid-modified hydrotalcite is added).

[0080] Comparative Example 4

[0081] This example provides a shale inhibitor, which is different from Example 1 only in that the weight ratio of the polyetheramine to the amino acid-modified hydrotalcite is 1:0.15; specifically, in the process of preparing the shale inhibitor, the amount of the amino acid-modified hydrotalcite is adjusted to 1.5 g; the remaining steps and parameters are the same.

[0082] Test Case

[0083] The shale inhibitors provided by Examples 1 to 6 and Comparative Examples 1 to 4 were subjected to performance tests.

[0084] 1) High temperature resistance test: The shale inhibitors provided in Examples 1 to 6 and Comparative Examples 1 to 4 were prepared into an aqueous solution with a weight fraction of 1 wt% using distilled water as a sample, and an appropriate amount of anhydrous sodium carbonate was added using distilled water as a reference. 10 wt% of bentonite was added at a stirring rate of 100 r / min and stirred for 20 minutes. The mixture was aged at 200° C. for 16 h, and then the rheological parameters of the sample were tested and recorded after the sample was cooled to room temperature.

[0085] Calculation of relative inhibition rate: relative inhibition rate (%) = (X0-X) / X0×100%; wherein X0 is the reading of the base slurry at 100 r / min, and X is the reading of the sample at 100 r / min.

[0086] The test results are shown in Table 1.

[0087] Table 1 Performance of various shale inhibitors after aging at 200 °C for 16 h

[0088] serial number Relative inhibition rate (%) Example 1 89.1 Example 2 88.4 Example 3 92.6 Example 4 96.8 Example 5 97.5 Example 6 88.7 Comparative Example 1 81.4 Comparative Example 2 82.0 Comparative Example 3 80.9 Comparative Example 4 75.3

[0089] As shown in Table 1, after aging at a high temperature of 200°C for 16 hours, the relative inhibition rate of the shale inhibitor provided in the embodiment of the present invention is 88.4% to 97.5%, which is significantly better than that of Comparative Examples 1 to 4. Compared with the polyetheramine shale inhibitor without the addition of amino acid-modified hydrotalcite (Comparative Example 3), the relative inhibition rate of the shale inhibitor provided in the embodiment of the present invention is increased by 9.3% to 20.5%, which significantly improves the high temperature resistance of the existing polyetheramine shale inhibitor.

[0090] 2) Shale expansion rate test: The shale inhibitors provided in Examples 1 to 6 and Comparative Example 3 (i.e., polyetheramine D230 shale inhibitor) were prepared into a 1wt% aqueous solution as a shale inhibitor test solution with distilled water, and 20mL of the shale inhibitor test solution was measured and placed in a beaker for later use; 5g of bentonite for drilling fluid dried at 105°C was weighed and loaded into a test tube, and the plug rod was inserted into the test tube, and kept at 1MPa for five minutes to obtain an experimental core and measure the initial height H1 of the rock sample. The test tube with the core was installed on the shale expansion instrument, and the test fluid was injected into the test tube. After soaking for 24 hours, the core expansion H2 was recorded.

[0091] Calculation of shale expansion rate: shale expansion rate (%) = (H2-H1) / H1×100%.

[0092] The test results are shown in Table 2.

[0093] Table 2

[0094] serial number Shale expansion rate (%) Example 1 26.3 Example 2 27.2 Example 3 23.7 Example 4 18.5 Example 5 17.9 Example 6 27.6 Comparative Example 3 34.2

[0095] As can be seen from Table 2, compared with the polyetheramine shale inhibitor without amino acid modified hydrotalcite (Comparative Example 3), the shale inhibitor provided by the embodiment of the present invention has a better inhibitory effect. At the same time, this example further investigates the effect of the concentration of the shale inhibitor provided by the present invention on the inhibitory performance. The results show that when the shale inhibitor provided by Example 4 is prepared into an aqueous solution with a weight fraction of 0.6wt% for shale expansion rate testing, its shale expansion rate decreases by 8.6% (compared with a 1.0wt% aqueous solution); when the shale inhibitor provided by Example 4 is prepared into a 1.5wt% aqueous solution, its shale expansion rate remains basically unchanged.

[0096] In summary, the embodiments of the present application provide a shale inhibitor, which for the first time uses amino acid-modified hydrotalcite as an additive for a polyetheramine shale inhibitor. The combination of the two not only significantly improves the high temperature resistance of the existing polyetheramine shale inhibitor, but also further enhances its inhibitory effect, thereby broadening its application scenarios in oil and gas drilling.

[0097] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0098] In the description of the specification of the present application, the terms "include", "comprise", etc. mean "including but not limited to". In this article, relational terms such as "first" and "second", etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this article, "and / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. Wherein A and B can be singular or plural. In this article, "at least one" means one or more, and "plurality" means two or more. "At least one", "at least one of the following" or similar expressions refer to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b, or c", or "at least one of a, b and c", can both mean: a, b, c, ab (i.e. a and b), ac, bc or abc, where a, b, c can be single or plural, respectively.

[0099] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A shale inhibitor, characterized in that: The shale inhibitor comprises the following components: polyetheramine and amino acid modified hydrotalcite; The amino acid-modified hydrotalcite is obtained by ion exchange reaction between hydrotalcite and amino acid salt; The weight ratio of the polyetheramine to the amino acid-modified hydrotalcite is 1:(0.05-0.10), and the amino acid salt is sodium 6-aminocaproate or disodium glutamate.

2. The shale inhibitor according to claim 1, characterized in that The weight ratio of the polyetheramine to the amino acid-modified hydrotalcite is 1:0.

08.

3. The shale inhibitor according to claim 1, characterized in that: The particle size of the amino acid modified hydrotalcite is 400-500 meshes.

4. The shale inhibitor according to claim 1, characterized in that: The hydrotalcite includes magnesium aluminum hydrotalcite.

5. The shale inhibitor according to claim 1, characterized in that: The average relative molecular weight of the polyetheramine is less than 1000.

6. The shale inhibitor according to claim 5, characterized in that: The product model of the polyetheramine includes at least one of D230, D400 and T403.

7. A method for preparing a shale inhibitor according to any one of claims 1 to 6, characterized in that: The preparation method comprises the following steps: Obtaining amino acid modified hydrotalcite; Adding the polyetheramine into an organic solvent and performing a first stirring to obtain a mixed solution; The amino acid-modified hydrotalcite is added to the mixed solution for a second stirring, and then concentrated and dried to obtain the shale inhibitor.

8. Use of the shale inhibitor according to any one of claims 1 to 6 or the shale inhibitor prepared by the preparation method of the shale inhibitor according to claim 7 in oil and gas drilling.

9. A water-based drilling fluid, characterized in that: The water-based drilling fluid contains the shale inhibitor according to any one of claims 1 to 6 or a shale inhibitor prepared by the preparation method of the shale inhibitor according to claim 7.

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