Carbonate reservoir acidification diverting agent, preparation method of diverting agent and acidification acid liquor

Abstract

The invention relates to the technical field of exploitation auxiliary materials for carbonate reservoir oil and gas wells, and particularly discloses a carbonate reservoir acidification diverting agent, a preparation method of the diverting agent and acidification acid liquor. The acidification diverting agent is obtained by free radical polymerization reaction of a monomer a, a monomer b and a monomer c; wherein the monomer a is acrylamide, the monomer b is 1-vinyl-3-propyl imidazole sulfonate, and the monomer c is octadecyl dimethyl allyl ammonium chloride; the molar ratio of the monomer a to the monomer b to the monomer c is (73-83): (85-91): (2-4). The acid liquor has the beneficial effects that the acid liquor still keeps the structural stability at high temperature, and keeps certain viscosity; secondary damage to the stratum is avoided; the structure can be subjected to gel breaking and viscosity reduction in the stratum, and flowback is facilitated.

Description

Technical Field

[0001] The invention relates to the technical field of oil / gas mining auxiliary materials, in particular to a carbonate reservoir acidification diverter, a preparation method of the diverter, and acidification acid solution. Background Art

[0002] In the process of oil and gas production, for some special reservoirs, it is necessary to use acidification methods to treat underground reservoirs. For example, injecting several acid solutions or acid mixtures into the formation through the wellbore, dissolving the rocks, formation pores and blockages, etc., dissolving the connecting pores or natural fracture wall rocks in the reservoir, which will effectively form channels that facilitate oil and water seepage, restore the permeability of the formation, and improve the conductivity of the formation.

[0003] However, there is heterogeneity in carbonate reservoirs; specifically, after the acid enters the formation, it cannot be simply assumed that it flows evenly in the medium, but will follow the principle of least resistance, bypassing areas with low permeability and entering areas with high permeability, resulting in the acid being unable to enter the low permeability formation and failing to achieve the purpose of acidification treatment.

[0004] The acidification diversion agents commonly used at home and abroad at present include: foam diversion acid technology, viscoelastic surfactant diversion technology, cross-linked polymer diversion acidification technology, etc.

[0005] For the viscoelastic surfactant steering technology, it is composed of acid, viscoelastic surfactant and other acid additives. It uses the change of pH value to control the steering of the acid and has a self-steering function. However, the problem is that a large amount of surfactant needs to be added. Surfactants are low-molecular substances, and there are problems such as excessive addition and unsatisfactory temperature resistance.

[0006] For the foam diversion acid technology, foam and acid are alternately injected into the formation, a surfactant solution is injected into the porous medium, and then gas is injected to generate foam, or the injected gas and surfactant solution are mixed to generate foam. The foam diversion mechanism is more complicated. The foam will not directly change the viscosity of the liquid phase, but the foam will greatly reduce the mobility of the gas phase, thereby indirectly reducing the relative permeability of the liquid phase. It has the advantages of high foam viscosity, strong carrying capacity, no solid matter that damages the permeability of the formation, and good retarding properties. However, this technical process is complex and easily affected by temperature and permeability, but there are problems such as high friction and difficult flowback. In addition, emulsified acid acidization requires a large amount of oil as a dispersed phase, which is costly.

[0007] Cross-linked polymer diversion acid is generally composed of acid-soluble polymer, pH buffer, cross-linking agent and depolymerizing agent. Cross-linked polymer diversion acid mainly utilizes variables in acid-rock reaction, such as pH value, temperature, etc. to activate cross-linking agent, so that cross-linking agent can cross-link polymer molecular chains to form a cross-linked system. The system has high viscosity, which prevents acid from flowing to high permeability areas and transfers acid to low permeability areas. However, its cross-linking time and conditions are difficult to control, and the formed cross-linking system is not easy to break completely and is easy to remain in the formation. Metal cross-linking agents are easy to form sulfide precipitation in sulfur-containing wells, causing secondary damage.

[0008] Based on this, our company has developed an acidizing diverter for carbonate reservoirs. Summary of the invention

[0009] The purpose of the present invention is to overcome the shortcomings of the prior art, provide a carbonate reservoir acidification diverter, a preparation method of the diverter, and an acidizing acid solution, and solve the deficiencies of various existing acidification diverters.

[0010] It should be noted that, as described in the background technology, the various existing diverting agents have disadvantages. The present invention provides an acidified self-thickening non-cross-linked polymer, which combines the characteristics of VES viscoelastic surfactant and acidified self-thickening polymer. The polymer acid can thicken as the acid-rock reaction occurs, thereby having the ability to divert the acid subsequently injected into the formation to the low permeability formation. In addition, due to the introduction of imidazole groups, the acid has good shear and temperature resistance, and can reduce viscosity when encountering water in the formation, thereby reducing damage to the formation.

[0011] The purpose of the present invention is achieved through the following technical solutions:

[0012] In a first aspect, the present invention provides a carbonate reservoir acidification diversion agent, which is obtained by free radical polymerization of monomer a, monomer b, and monomer c;

[0013] Wherein, monomer a is acrylamide, monomer b is 1-vinyl-3-propyl imidazole sulfonate, and monomer c is octadecyl dimethyl allyl ammonium chloride; in terms of molar weight, monomer a: monomer b: monomer c is (73-83): (85-91): (2-4);

[0014] Among them, the structural formula of monomer a is The structural formula of monomer b is The structural formula of monomer c is

[0015] After the polymerization reaction, the structural formula of the carbonate reservoir acidification diversion agent obtained is:

[0016]

[0017] Among them, x+y+z=1, and x, y and z are all greater than 0.

[0018] In a second aspect, the present invention also provides a method for preparing a carbonate reservoir acidification diversion agent, which mainly comprises the following steps:

[0019] S1, dissolving a certain amount of N-vinylimidazole in appropriate dichloromethane, dissolving a certain amount of 1,3-propane sultone solution in appropriate dichloromethane, and fully stirring to dissolve; then dropping the 1,3-propane sultone solution into the N-vinylimidazole solution; heating and continuing the reaction, after the reaction is completed, purifying and drying the white precipitate, and finally obtaining 1-vinyl-3-propyl imidazole sulfonate;

[0020] S2, mixing 1-vinyl-3-propyl imidazole sulfonate, acrylamide, octadecyl dimethyl allyl ammonium chloride and water to obtain a mixed solution;

[0021] S3, after adjusting the pH to 6-8, adding the initiator dissolved in water, reacting at a constant temperature for a period of time, and then cooling to room temperature to obtain a gelled product;

[0022] S4. Wash, dry and crush the gelled product to obtain an acidification diverting agent.

[0023] Preferably, the specific operation of the above S4 is: washing the gel product with ethanol for 3 to 5 times, drying it at a temperature range of 50° C. to 60° C. for 20 to 24 hours, and then crushing it to finally obtain the acidification diverting agent.

[0024] Preferably, the initiator used is azobisisobutylamidine hydrochloride, ammonium persulfate / sodium bisulfite, potassium persulfate / sodium bisulfite or more. And the amount of the initiator used is 0.6% to 1.0% of the total reaction amount by weight.

[0025] In a third aspect, the present invention also provides a carbonate reservoir acidizing acid solution, which comprises, by weight: 0.8 to 1.2 parts of an acidizing diverter, 0.2 to 0.4 parts of a surfactant, and hydrochloric acid; wherein the weight of the hydrochloric acid is 1.0 to 1.6% of the total weight of the acidizing diverter and the surfactant;

[0026] Wherein, the mass concentration of the hydrochloric acid is 15-20%; the acidification diverter refers to any of the above-mentioned acidification diverters; and the surfactant is a long-chain surfactant with at least ten groups connected in sequence.

[0027] Preferably, the surfactant is one or more of octadecyl dimethyl ammonium chloride, dodecyl trimethyl ammonium chloride, tetradecyl trimethyl ammonium chloride, and hexadecyl trimethyl ammonium chloride. More preferably, the surfactant is octadecyl dimethyl ammonium chloride.

[0028] For ease of understanding, the principles and core innovations of this solution are explained:

[0029] In the present invention, the acidification diversion agent has a certain proportion of hydrophobic associating monomers and betaine monomers with imidazole groups, and then it is applied to the preparation process of carbonate reservoir acidification acid. When the acid enters the high permeability layer in the initial stage, the pollution degree of these layers is low, and the acid reacts with the rock formation to generate Ca 2+ . This process promotes the formation of association of hydrophobic associative monomers in the system and enhances the stability of the network association structure. Due to the introduction of imidazole groups, the acid can maintain a certain viscosity under high temperature conditions. As the viscosity of the acid increases, the high permeability layer is effectively blocked, forcing the remaining acid to flow to the medium and low permeability layers that have not been acidified and to deeper layers of the formation. This mechanism ensures that the acid can be evenly distributed throughout the entire reformed layer, achieving an automatic steering effect during the acidizing process.

[0030] The present invention has the following advantages:

[0031] Compared with the traditional viscoelastic surfactant acid diverter, the present acid diverter has the following advantages: a. Due to the introduction of imidazole groups, the acid solution can still maintain a certain viscosity and a stable structure under high temperature environment, and in the provided carbonate reservoir acidizing acid solution, due to the addition of positively charged long-chain quaternary ammonium surfactant, it can generate electrostatic bonding with the negatively charged sulfonate ions in the acid diverter, thereby enhancing the network structure of the acid diverter in the acid solution, thereby further increasing the viscosity of the acid solution; b. At the same time, the present acid diverter does not require the addition of a cross-linking agent, thereby avoiding the metal cross-linking agent from easily precipitating in sulfur-containing wells and causing secondary damage to the formation; c. In addition, the structure will be destroyed by the action of water, oil and gas in the formation, so that the degumming and viscosity reduction of the acid solution system can be achieved without the addition of a degumming agent, which is beneficial to flowback. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is the infrared spectrum of the acidification diverter in the present invention. DETAILED DESCRIPTION

[0033] The present invention is further described below in conjunction with the accompanying drawings, but the protection scope of the present invention is not limited to the following description.

[0034] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] In the first aspect, a specific embodiment of the present invention discloses a carbonate reservoir acidification diversion agent, which is obtained by free radical polymerization of acrylamide monomer, 1-vinyl-3-propyl imidazole sulfonate monomer, and octadecyl dimethyl allyl ammonium chloride monomer, and the molar ratio of the three is (73-83): (85-91): (2-4);

[0036] Specifically, the structural formula of acrylamide is, The structural formula of 1-vinyl-3-propyl imidazole sulfonate is The structural formula of octadecyl dimethyl allyl ammonium chloride is After the polymerization reaction, the structural formula of the obtained carbonate reservoir acidification diversion agent is:

[0037]

[0038] Among them, x+y+z=1, and x, y and z are all greater than 0.

[0039] In a second aspect, a specific embodiment of the present invention further discloses a method for preparing the above-mentioned carbonate reservoir acidification diversion agent, comprising the following preparation steps:

[0040] S1. First prepare vinyl-3-propyl imidazole sulfonate betaine monomer (PVIS); specifically, dissolve a certain amount of 1,3-propane sultone in appropriate dichloromethane to form 1,3-propane sultone, and dissolve a certain amount of N-vinylimidazole in appropriate dichloromethane to form N-vinylimidazole solution. Slowly drop the dissolved 1,3-propane sultone solution into the N-vinylimidazole solution under stirring with a constant speed magnetic stirrer, and wait for the water bath to heat to 45°C and continue the reaction for 4h-6h. After the reaction is completed, purify and dry the generated white precipitate to obtain 1-vinyl-3-propyl imidazole sulfonate (PVIS);

[0041] S2, then according to the above molar ratio, acrylamide, octadecyl dimethyl allyl ammonium chloride, and the prepared 1-vinyl-3-propyl imidazole sulfonate (PVIS) are mixed with water, and then the initiator dissolved in water is added, and the reaction is carried out at a constant temperature for 5 hours, and then cooled to room temperature to obtain a gel product;

[0042] S3, after adjusting the pH value of the mixed solution to 6-8, add the initiator dissolved in a portion of pure water in advance, react at a constant temperature for 5 hours, and then cool to room temperature to obtain a gel product;

[0043] It should be noted that the initiator here is preferably one or more of diisobutylamidine hydrochloride (V50), ammonium persulfate / sodium bisulfite, potassium persulfate / sodium bisulfite, and, by weight, the amount of the initiator is 0.6% to 1.0% of the total reaction amount;

[0044] S4. The obtained gel product is washed with ethanol for 3-5 times, dried at 50-60°C for 20-24 hours, and crushed to obtain an acidification diverting agent.

[0045] In a third aspect, a specific embodiment of the present invention further discloses a carbonate reservoir acidizing acid solution prepared based on the above carbonate reservoir acidizing diverter: calculated by weight, comprising 0.8 to 1.2 parts of acidizing diverter, 0.2 to 0.4 parts of surfactant, and hydrochloric acid; wherein the weight of the hydrochloric acid is 1.0 to 1.6% of the total weight of the acidizing diverter and the surfactant;

[0046] The mass concentration of hydrochloric acid is 15-20%; the acidification diverter refers to any of the above acidification diverters; and the surfactant is a long-chain surfactant with at least ten groups connected in sequence.

[0047] It should be noted that the surfactant is preferably one or more of octadecyl dimethyl ammonium chloride, dodecyl trimethyl ammonium chloride, tetradecyl trimethyl ammonium chloride, and hexadecyl trimethyl ammonium chloride. The best choice is octadecyl dimethyl ammonium chloride.

[0048] The idea of ​​the present invention is exemplified below.

[0049] (Example 1)

[0050] A carbonate reservoir acidification diverter and a preparation method thereof.

[0051] The polymer monomer acrylamide, the polymer monomer 1-vinyl-3-propyl imidazole sulfonate (PVIS), and the polymer monomer octadecyl dimethyl allyl ammonium chloride were dissolved in deionized water in molar amounts of 78.2 mol, 88.4 mol, and 2.72 mol, respectively, to obtain a mixed solution with a mass concentration of 25%;

[0052] The pH value of the mixed solution was adjusted to 7.0 using sodium hydroxide as an alkaline regulator, and azobisisobutylamidine hydrochloride was added as an initiator to initiate the polymerization reaction in an amount of 0.60% of the total mass of the polymer. The polymerization reaction was carried out at 50° C. for 5 hours to obtain a gel product;

[0053] The obtained gel product was washed with ethanol three times, dried at 50°C for 24 hours, and crushed to obtain the synthesized acidification diverting agent;

[0054] 1.2 parts of the synthetic acid diverter agent and 0.4 parts of octadecyltrimethylammonium chloride are used with 20% mass concentration of hydrochloric acid to prepare an acid solution system for carbonate reservoir acidification with a total mass concentration of 1.6%, which is recorded as diverter acid one.

[0055] (Example 2)

[0056] The difference from Example 1 lies in the difference in mole percentages of the polymerized monomers.

[0057] The polymer monomer acrylamide, the polymer monomer 1-vinyl-3-propyl imidazole sulfonate (PVIS), and the polymer monomer octadecyl dimethyl allyl ammonium chloride were dissolved in deionized water in molar amounts of 73.1 mol, 85 mol, and 2.04 mol, respectively, to obtain a mixed solution with a mass concentration of 25%;

[0058] The pH value of the mixed solution was adjusted to 7.0 using sodium hydroxide as an alkaline regulator, and azobisisobutylamidine hydrochloride was added as an initiator to initiate the polymerization reaction in an amount of 0.60% of the total mass of the polymer. The polymerization reaction was carried out at 50° C. for 5 hours to obtain a gel product;

[0059] The obtained gel product was washed with ethanol three times, dried at 50°C for 24 hours, and crushed to obtain a synthesized acidification diverting agent;

[0060] 1.2 parts of the synthesized acid diverter and 0.4 parts of octadecyltrimethylammonium chloride were taken and used with 20% mass concentration of hydrochloric acid to prepare an acid solution system for carbonate reservoir acidification with a total mass concentration of 1.6%, which was recorded as diverter acid II.

[0061] (Implementation 3)

[0062] The difference between the embodiment 1 and the embodiment 1 lies in the difference in the mole percentages of the polymerized monomers.

[0063] The polymer monomer acrylamide, the polymer monomer 1-vinyl-3-propyl imidazole sulfonate (PVIS), and the polymer monomer octadecyl dimethyl allyl ammonium chloride were dissolved in deionized water in molar amounts of 83.3 mol, 91.8 mol, and 3.4 mol, respectively, to obtain a mixed solution with a mass concentration of 25%;

[0064] The pH value of the mixed solution was adjusted to 7.0 using sodium hydroxide as an alkaline regulator, and azobisisobutylamidine hydrochloride was added as an initiator to initiate the polymerization reaction in an amount of 0.60% of the total mass of the polymer. The polymerization reaction was carried out at 50° C. for 5 hours to obtain a gel product;

[0065] The obtained gel product was washed with ethanol three times, dried at 50°C for 24 hours, and crushed to obtain a synthesized acidification diverting agent;

[0066] 1.2 parts of the synthesized acid diverter and 0.4 parts of octadecyltrimethylammonium chloride were taken and used with 20% mass concentration of hydrochloric acid to prepare an acid solution system for carbonate reservoir acidification with a total mass concentration of 1.6%, which was recorded as diverter acid three.

[0067] (Example 4)

[0068] The difference from Example 1 is that the temperature of the polymerization reaction is different.

[0069] The polymer monomer acrylamide, the polymer monomer 1-vinyl-3-propyl imidazole sulfonate (PVIS), and the polymer monomer octadecyl dimethyl allyl ammonium chloride were dissolved in deionized water in molar amounts of 83.3 mol, 91.8 mol, and 3.4 mol, respectively, to obtain a mixed solution with a mass concentration of 25%;

[0070] The pH value of the mixed solution was adjusted to 7.0 using sodium hydroxide as an alkaline regulator, and azobisisobutylamidine hydrochloride was added as an initiator to initiate the polymerization reaction in an amount of 0.60% of the total mass of the polymer. The polymerization reaction was carried out at 45° C. for 5 hours to obtain a gel product;

[0071] The obtained gel product was washed with ethanol three times, dried at 50°C for 24 hours, and crushed to obtain a synthesized acidification diverting agent;

[0072] 1.2 parts of the synthesized acid diverter and 0.4 parts of octadecyltrimethylammonium chloride were taken, and 20% mass concentration of hydrochloric acid was used to prepare an acid solution system for carbonate reservoir acidification with a total mass concentration of 1.6%, which was recorded as diverter acid four.

[0073] (Example 5)

[0074] The difference from Example 1 is the polymerization reaction temperature.

[0075] The polymer monomer acrylamide, the polymer monomer 1-vinyl-3-propyl imidazole sulfonate (PVIS), and the polymer monomer octadecyl dimethyl allyl ammonium chloride were dissolved in deionized water in molar amounts of 83.3 mol, 91.8 mol, and 3.4 mol, respectively, to obtain a mixed solution with a mass concentration of 25%;

[0076] The pH value of the mixed solution was adjusted to 7.0 using sodium hydroxide as an alkaline regulator, and azobisisobutylamidine hydrochloride was added as an initiator to initiate the polymerization reaction in an amount of 0.60% of the total mass of the polymer. The polymerization reaction was carried out at 55° C. for 5 hours to obtain a gel product;

[0077] The obtained gel product was washed with ethanol three times, dried at 50°C for 24 hours, and crushed to obtain a synthesized acidification diverting agent;

[0078] 1.2 parts of the synthesized acid diverter and 0.4 parts of octadecyltrimethylammonium chloride were taken and used with 20% mass concentration of hydrochloric acid to prepare an acid solution system for carbonate reservoir acidification with a total mass concentration of 1.6%, which was recorded as diverter acid five.

[0079] (Example 6)

[0080] The difference from Example 1 is the polymerization reaction time.

[0081] The polymer monomer acrylamide, the polymer monomer 1-vinyl-3-propyl imidazole sulfonate (PVIS), and the polymer monomer octadecyl dimethyl allyl ammonium chloride were dissolved in deionized water in molar amounts of 83.3 mol, 91.8 mol, and 3.4 mol, respectively, to obtain a mixed solution with a mass concentration of 25%;

[0082] The pH value of the mixed solution was adjusted to 7.0 using sodium hydroxide as an alkaline regulator, and azobisisobutylamidine hydrochloride was added as an initiator to initiate the polymerization reaction in an amount of 0.60% of the total mass of the polymer. The polymerization reaction was carried out at 55° C. for 4 hours to obtain a gel product;

[0083] The obtained gel product was washed with ethanol three times, dried at 50°C for 24 hours, and crushed to obtain a synthesized acidification diverting agent;

[0084] 1.2 parts of the synthesized acid diverter and 0.4 parts of octadecyltrimethylammonium chloride were taken and used with 20% mass concentration of hydrochloric acid to prepare an acid solution system for carbonate reservoir acidification with a total mass concentration of 1.6%, which was recorded as diverter acid VI.

[0085] (Example 7)

[0086] The difference from Example 1 is the polymerization reaction time.

[0087] The polymer monomer acrylamide, the polymer monomer 1-vinyl-3-propyl imidazole sulfonate (PVIS), and the polymer monomer octadecyl dimethyl allyl ammonium chloride were dissolved in deionized water in molar amounts of 83.3 mol, 91.8 mol, and 3.4 mol, respectively, to obtain a mixed solution with a mass concentration of 25%;

[0088] The pH value of the mixed solution was adjusted to 7.0 using sodium hydroxide as an alkaline regulator, and azobisisobutylamidine hydrochloride was added as an initiator to initiate the polymerization reaction in an amount of 0.60% of the total mass of the polymer. The polymerization reaction was carried out at 55° C. for 6 hours to obtain a gel product;

[0089] The obtained gel product was washed with ethanol three times, dried at 50°C for 24 hours, and crushed to obtain a synthesized acidification diverting agent;

[0090] 1.2 parts of the synthesized acid diverter and 0.4 parts of octadecyltrimethylammonium chloride were taken, and 20% mass concentration of hydrochloric acid was used to prepare an acid solution system for carbonate reservoir acidification with a total mass concentration of 1.6%, which was recorded as diverter acid seven.

[0091] The following tests are performed on the acidification diversion agent and the acid solution system prepared in the above examples to illustrate the structural composition of the acidification diversion agent and the performance of the acid solution system.

[0092] (Test Example 1) The structural composition of the acidification diverting agent prepared in Example 1 was determined by infrared spectrometry.

[0093] The acidification diverting agent obtained by the preparation method of Example 1 is characterized by its infrared spectrum as follows: Figure 1 As shown, the adsorption band at 3437cm-1 represents the stretching vibration of the -OH molecule, and the optical signals shown at 1195cm-1 and 1037cm-1 reflect the presence of the S=O structural unit in PVIS. 1685cm-1 is the stretching vibration absorption peak of the C=O bond, and 1546cm-1 is the in-plane bending vibration absorption peak of the NH bond. 1455cm-1 is the in-plane bending vibration absorption peak of the CN bond, and 747cm-1 is the stretching vibration absorption peak of 5 or more (CH2). It can be obtained from the infrared spectrum analysis that the product structure is consistent with the molecular design structure. According to the above analysis, it can be seen that the acidification diverter prepared in Example 1 contains the initially designed group, indicating that the diverter structure is consistent with the target product.

[0094] (Test Example 2) Evaluate the thickening performance of the acid liquid system during the acid-rock reaction process.

[0095] First, the apparent viscosity of the acid solution system prepared in each embodiment was measured using a ZNN-D6B six-speed rotary viscometer. Then, according to the stoichiometric relationship of the reaction between CaCO3 and HCl, 0 g, 14 g, 28 g, 42 g, and 56 g of CaCO3 powder were added in sequence. After a certain amount of calcium carbonate powder was added each time and the acid solution reacted completely, the apparent viscosity was measured. The measurement conditions were: 90°C, 170 s -1 The results are shown in Table 1 below.

[0096] Table 1 Relationship between apparent viscosity of acid solution and amount of calcium carbonate added

[0097]

[0098]

[0099] It can be seen from Table 1 that the apparent viscosity of the acid system in 20% hydrochloric acid is very low (not exceeding 6 mPa·s), which is conducive to the injection of the acid into the formation. As the acid-rock reaction proceeds, the apparent viscosity of the acid gradually increases, and the highest peak viscosity of the acid is 288 mPa·s. It can be seen that the acid system provided by the present invention has excellent diversion ability at high temperature.

[0100] The above embodiments only express preferred implementation modes, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present invention. It should be pointed out that, for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention.

Claims

1. A carbonate reservoir acidification diversion agent, characterized by: It is obtained by free radical polymerization of monomer a, monomer b and monomer c; Wherein, monomer a is acrylamide, monomer b is 1-vinyl-3-propyl imidazole sulfonate, and monomer c is octadecyl dimethyl allyl ammonium chloride; in terms of molar weight, monomer a: monomer b: monomer c is (73-83): (85-91): (2-4); Among them, the structural formula of monomer a is The structural formula of monomer b is The structural formula of monomer c is After the polymerization reaction, the structural formula of the carbonate reservoir acidification diversion agent obtained is: Among them, x+y+z=1, and x, y and z are all greater than 0.

2. The method for preparing the carbonate reservoir acidification diversion agent according to claim 1, characterized in that: The main steps include: S1. Dissolve a certain amount of N-vinylimidazole in appropriate dichloromethane, dissolve a certain amount of 1,3-propane sultone solution in appropriate dichloromethane, and stir thoroughly to dissolve; then drop the 1,3-propane sultone solution into the N-vinylimidazole solution; The temperature is raised and the reaction is continued. After the reaction is completed, the white precipitate is purified and dried to finally obtain 1-vinyl-3-propyl imidazole sulfonate; S2, mixing 1-vinyl-3-propyl imidazole sulfonate, acrylamide, octadecyl dimethyl allyl ammonium chloride and water to obtain a mixed solution; S3, after adjusting the pH to 6-8, adding the initiator dissolved in water, reacting at a constant temperature for a period of time, and then cooling to room temperature to obtain a gelled product; S4. Wash, dry and crush the gelled product to obtain an acidification diverting agent.

3. The method for preparing a carbonate reservoir acidification diversion agent according to claim 2, characterized in that: The S4 specifically refers to: washing the gel product with ethanol for 3 to 5 times, drying it at a temperature range of 50° C. to 60° C. for 20 to 24 hours, and then crushing it to finally obtain an acidification diverting agent.

4. The method for preparing a carbonate reservoir acidification diversion agent according to claim 2, characterized in that: The initiator is one or more of azobisisobutylamidine hydrochloride, ammonium persulfate / sodium bisulfite, potassium persulfate / sodium bisulfite; the amount of the initiator is 0.6% to 1.0% of the total reaction amount by weight.

5. Carbonate reservoir acidizing acid solution, characterized by: The invention comprises, by weight, 0.8 to 1.2 parts of an acidification conversion agent, 0.2 to 0.4 parts of a surfactant, and hydrochloric acid; wherein the weight of the hydrochloric acid is 1.0 to 1.6% of the total weight of the acidification conversion agent and the surfactant; The mass concentration of the hydrochloric acid is 15-20%; The acidification diverter refers to the acidification diverter according to any one of claims 1 to 4; The surfactant is a long-chain surfactant with at least 12 to 18 carbon atoms connected in sequence.

6. The carbonate reservoir acidizing acid according to claim 5, characterized in that: The surfactant is one or more of octadecyldimethylammonium chloride, dodecyltrimethylammonium chloride, tetradecyltrimethylammonium chloride and hexadecyltrimethylammonium chloride.

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