Dual-retarding acid liquid system and preparation method thereof

Abstract

The invention discloses a dual-retarding acid liquid system and a preparation method thereof. The system comprises organic phosphonic acid and cyclodextrin, and the molar ratio of the organic phosphonic acid to the cyclodextrin is 1: (0.7-1.3). The preparation method mainly comprises the following steps: S1, mixing organic phosphonic acid and cyclodextrin according to the molar ratio to prepare a mixed solution; and S2, culturing the mixed solution under an oscillation condition to prepare the double-retarding acid solution system. According to the double-retarding acid liquid system, the initial number of ionized H < + > is relatively low, and the final total ionization amount is high. Besides, in the acidification measure process, H < + > can be completely ionized, the acid rock reaction rate can be delayed, the hydrogen ion utilization rate can be improved, and the loss of raw materials and the waste of resources can be reduced.

Description

Technical Field

[0001] The invention relates to a double-retarded acid solution system and a preparation method thereof. Background Art

[0002] Acidizing is one of the important measures to stabilize and increase production of oil and water wells, and stabilize and increase injection of water injection wells. It uses acid to remove pollution near the bottom of production wells and water injection wells, restore the permeability of the formation or dissolve the rock skeleton and cementation of the formation to increase the permeability of the formation, and dredge the fluid seepage channel, thereby restoring and improving the production capacity of the well.

[0003] Due to the fast acid-rock reaction, most of the acid is consumed near the wellbore, resulting in a short penetration distance of the acid, which can only eliminate damage near the wellbore. Therefore, whether it is sandstone or carbonate salt reservoir, reducing the acid-rock reaction rate is the focus of the current research and development of slow-rate acid systems. The slow-rate acid for sandstone relies on the gradual ionization of H + , slowly generates HF acid with fluoride salts, and keeps a low concentration of HF during the acidification process to reduce the reaction rate; the slow acid used for carbonate rocks relies on controlling H + The reaction rate can be reduced by adjusting the ionization rate and mass transfer coefficient.

[0004] In the invention patent "Preparation method of double slow polyhydrogen acid acidification system"

[0005] (ZL200710050148.6) discloses a slow acid solution system. The system is prepared by compounding polyhydrogen acid with cyclodextrin to form an inclusion compound, and then adding ammonium difluoride to the inclusion compound solution. The acidification process includes two slow processes, one is the slow release of polyhydrogen acid by the inclusion compound due to the effect of formation temperature and pressure, and the other is the release of H + It reacts with ammonium bifluoride to generate HF, which can achieve slow acidification and inhibit the adsorption of polyhydrogen acid near the wellbore, reducing the dosage, and can be used in sandstone acidification.

[0006] In the invention patent "A slow-rate acid for high-temperature sandstone reservoirs and its preparation method"

[0007] (ZL201410666732.4) discloses a slow acid solution system. The system is obtained by mixing the inclusion compound formed by cyclodextrin and sulfonic acid with ammonium fluoride in proportion. The inclusion compound slowly decomposes to release sulfonic acid, thereby slowing down the reaction rate of sulfonic acid and increasing the action distance of sulfonic acid; the H released by sulfonic acid + F - Combined with the generated HF, it can be used in sandstone acidizing.

[0008] In the invention patent "Thickened acid and its preparation method" (ZL201910137772.2), a thickened acid liquid system is disclosed. The system mixes a thickener with hydrochloric acid to form an acid liquid system with a certain viscosity, and controls the acid liquid H + The mass transfer coefficient can be reduced to achieve the purpose of reducing the acid-rock reaction rate and can be applied in carbonate rocks.

[0009] However, the existing sandstone slow acid system provides H + are polyhydrogen acids, sulfonic acids, etc., but H + Ionization rate, final ionization H + The total number is still not ideal, and the polyhydrogen acid retarding acid system will waste a lot of effective ingredients while retarding the speed. The carbonate salt retarding acid system has a certain viscosity and is suitable for use in acid fracturing measures, but not for acidizing measures. Summary of the invention

[0010] In order to at least partially solve the above technical problems existing in the prior art, the embodiment of the present invention provides a double-retarded acid solution system and a preparation method thereof, so that the acid solution system of the present invention can reduce the H + The ionization speed is further improved while further increasing the final ionization H + The total number can be further applied to acidizing measures for sandstone, carbonate and other reservoirs.

[0011] As one aspect of the present invention, it relates to a dual-retarded acid solution system, which includes organic phosphonic acid and cyclodextrin, and the molar ratio of the organic phosphonic acid to the cyclodextrin is 1: (0.7-1.3).

[0012] In one or some possible embodiments, the organic phosphonic acid is selected from one of ethylenediaminetetramethylenephosphonic acid, 2-hydroxyphosphonoacetic acid or a phosphonocarboxylic acid copolymer.

[0013] In one or some possible embodiments, the cyclodextrin is selected from α-cyclodextrin, β-cyclodextrin or hydroxypropyl-cyclodextrin.

[0014] As another aspect of the present invention, it relates to a method for preparing the above-mentioned dual-retarded acid solution system, the method comprising the following steps:

[0015] S1, mixing the organic phosphonic acid and the cyclodextrin according to the molar ratio to prepare a mixed solution;

[0016] S2. Cultivating the mixed solution under shaking conditions to obtain a dual slow acid solution system.

[0017] In one or some possible embodiments, in S2, the oscillation rate is 60-100 r / min.

[0018] In one or some possible embodiments, in S2, the culture time is 6 to 7 hours, and the culture temperature is 30 to 50°C.

[0019] The beneficial effects of the above technical solution provided by the embodiment of the present application include at least:

[0020] The dual slow acid system of the present invention, ionized H + The initial amount is low and the final ionization amount is high. In addition, the dual slow acid system of the present invention can be used to reduce H + Complete ionization slows down the acid-rock reaction rate, improves hydrogen ion utilization, and can reduce the loss of raw materials and waste of resources.

[0021] The dual slow-rate acid solution system prepared by the present invention has a viscosity similar to that of water and can be applied to acidification measures for both sandstone and carbonate reservoirs.

[0022] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention are realized and obtained by the structures particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0024] Figure 1 H in the double retarded acid system of the present invention + Ionization curve diagram;

[0025] Figure 2 H in the polyhydrogen acid retarded acid system + ionization curve diagram. DETAILED DESCRIPTION

[0026] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0027] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0028] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the art to which the invention belongs. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0029] In the description of the present invention, it should be noted that the terms "include", "including", "have", "contain" and the like are open terms, meaning including but not limited to.

[0030] The present invention is further described below in conjunction with specific examples, and the protection scope of the present invention is not limited by the following examples. The sources of materials mainly involved in the examples are all conventional commercial products.

[0031] Example 1

[0032] The dual-retarded acid solution system of this embodiment is prepared by the following steps:

[0033] 80 g of the phosphonocarboxylic acid copolymer solution was taken, 100 g of β-cyclodextrin was added, and the mixed solution was cultured in a shaker at 35° C. for 7 hours at a rotation speed of 80 r / min to obtain a product.

[0034] The product was subjected to ultraviolet absorption spectrum test with a wavelength range of 200-240 mm, which proved the generation of inclusion complex, that is, the dual slow acid liquid system was prepared.

[0035] The viscosity of the dual-retardation acid solution system of the present invention was measured by a rheometer and found to be 1.27 mPa·s.

[0036] The double slow acid solution system prepared in Example 1 was titrated using an automatic potentiometric titrator. + Titrate to obtain H + Ionization data. Take another 100 g of the polyhydrogen acid slow acid solution (the inclusion complex of hydroxyethylidene diphosphonic acid and β-cyclodextrin, the same below) and perform H + Titrate to obtain H+ The above data results are recorded in the following Table 1.

[0037] Table 1 H + Ionization data

[0038] substance 1 ionization 2nd ionization 3 times ionization Total ionization number Double retarded acid system 4.3mol 4.4mol 8.6mol 17.3mol Polyhydrogen acid slow acid system 7.9mol 4.03mol 0mol 11.93mol

[0039] According to Table 1, H + The ionization data show that the H + The number of H2O2 was 45.6% lower than that of the polyhydrogen acid slow acid system; a total of 17.3 mol of H2O2 was released through three ionizations. + , which is 45% higher than that of the polyhydrogen acid retarded acid system.

[0040] Example 2

[0041] The dual-retarded acid solution system of this embodiment is prepared by the following steps:

[0042] Take 90 g of 2-hydroxyphosphonoacetic acid solution, add 100 g of β-cyclodextrin, and incubate the mixed solution in a shaker at 35° C. for 7 hours at a rotation speed of 80 r / min to obtain a product;

[0043] The product was subjected to ultraviolet absorption spectrum test with a wavelength range of 200-240 mm, which proved the generation of inclusion complex, that is, the dual slow acid liquid system was prepared.

[0044] 30 g of the dual retarded acid solution system prepared in this example was taken, 10 g of calcium carbonate particles (analytical grade) were added, and the dissolution rate test was performed at room temperature and 90° C.; 30 g of the polyhydrogen acid retarded acid solution system solution was taken, 10 g of calcium carbonate particles (analytical grade) were added, and the dissolution rate test was performed at 90° C. The test results are recorded in Table 2 below.

[0045] Table 2 Dissolution rate test results

[0046]

[0047]

[0048] The dissolution rate test results in Table 2 show that at 90° C., the reaction rate of the double-retarded acid solution system prepared in the present invention for dissolving calcium carbonate particles is extended by 1.3 times compared with that of the polyhydrogen acid-retarded acid solution system, further improving the effect of retarded acidification.

[0049] Example 3

[0050] The dual-retarded acid solution system of this embodiment is prepared by the following steps:

[0051] Take 90 g of ethylenediaminetetramethylenephosphonic acid solution, add 100 g of β-cyclodextrin, and incubate the mixed solution in a shaker at 35° C. for 7 hours at a rotation speed of 80 r / min to obtain a product;

[0052] The product was subjected to ultraviolet absorption spectrum test with a wavelength range of 200-240 mm, which proved the generation of inclusion complex, that is, the dual slow acid liquid system was prepared.

[0053] The double slow acid solution system prepared in Example 3 was titrated using an automatic potentiometric titrator. + Titrate to obtain H + Take another 100g of polyhydrogen acid slow acid solution and titrate H + Titrate to obtain H + The above data results are recorded in Table 3 below, and the ionization curves of the two systems are provided.

[0054] Table 3H + Ionization potential

[0055]

[0056] In the ionization curve, when pH=7, U=0mv; when U>0, pH<7; when U<0, pH>7. Figure 1 , 2 Combined with the data in Table 3, it can be seen that the double slow acid solution system prepared by the present invention can ionize multiple H contained in itself through three ionizations under the condition of pH <7, that is, during the acidification process. + All ionization; while in the polyhydrogen acid slow acid system, some H + It needs to be ionized under the condition of pH>7, and the acidification process is acidic, so this part of H + is invalid.

[0057] In summary, the double slow acid system prepared by the present invention can ionize H + The initial amount is low and the final ionization amount is high. In addition, the dual slow acid system of the present invention can be used to reduce H + Complete ionization slows down the acid-rock reaction rate, improves hydrogen ion utilization, and can reduce the loss of raw materials and waste of resources.

[0058] Although the description of the present invention has been quite detailed and has been described in particular with respect to several described embodiments, it is not intended to be limited to any of these details or embodiments or any particular embodiment, so as to effectively cover the intended scope of the present invention. In addition, the present invention is described above with the embodiments foreseeable by the inventors, and its purpose is to provide a useful description, and those non-substantial changes to the present invention that are not currently foreseen may still represent equivalent changes of the present invention.

[0059] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0060] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A dual slow acid solution system, characterized in that: The system comprises organic phosphonic acid and cyclodextrin, and the molar ratio of the organic phosphonic acid to the cyclodextrin is 1:(0.7-1.3).

2. The dual-retarded acid solution system according to claim 1, characterized in that: The organic phosphonic acid is selected from one of ethylenediaminetetramethylenephosphonic acid, 2-hydroxyphosphonoacetic acid or phosphonocarboxylic acid copolymer.

3. The dual slow acid solution system according to claim 1, characterized in that: The cyclodextrin is selected from one of α-cyclodextrin, β-cyclodextrin or hydroxypropyl-cyclodextrin.

4. A method for preparing the dual-retarded acid solution system according to any one of claims 1 to 3, characterized in that: The method comprises the following steps: S1, mixing the organic phosphonic acid and the cyclodextrin according to the molar ratio to prepare a mixed solution; S2. Cultivating the mixed solution under shaking conditions to obtain a dual slow acid solution system.

5. The method for preparing the dual-retarded acid solution system according to claim 4, characterized in that: In S2, the oscillation rate is 60-100 r / min.

6. The method for preparing the dual-retarded acid solution system according to claim 4, characterized in that: In S2, the culture time is 6 to 7 hours, and the culture temperature is 30 to 50°C.

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