Anode-nonionic imbibition oil displacement surfactant as well as preparation method and application thereof

Abstract

The invention relates to the technical field of oil field chemicals, and discloses a cationic-nonionic imbibition oil displacement surfactant, a preparation method and application. The preparation method of the imbibition oil displacement surfactant comprises the following steps: dissolving a first raw material dodecyl dimethyl tertiary amine and a second raw material epichlorohydrin in a solvent to obtain a first mixed solution; carrying out distillation treatment and drying treatment on the first mixed solution to obtain an intermediate; dissolving the intermediate in a third raw material fatty alcohol-polyoxyethylene ether to obtain a second mixed solution; performing distillation treatment and drying treatment on the second mixed solution to obtain a product. By adopting the synthesis method provided by the invention, the imbibition oil-displacing surfactant with low interfacial tension, good temperature resistance, good adsorption resistance and good wettability can be prepared; the preparation process is simple, low in cost and easy to operate. Meanwhile, the product is low in residual monomer content, less in pollution and easy for large-scale industrial production; therefore, the method is particularly suitable for low-permeability reservoirs so as to improve the recovery efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of oilfield chemicals, and in particular to a cationic-nonionic imbibition oil-flooding surfactant, a preparation method and application thereof. Background Art

[0002] Currently, tight oil reserves have become an important part of my country's oil resource exploitation. However, the structural characteristics of tight oil reservoirs are low permeability and complex pore structure, which are largely different from the development characteristics of high permeability reservoirs. Fracturing and water injection development are the only way to achieve sustainable development of low permeability reservoirs.

[0003] During waterflooding, the high permeability of the fracture system leads to a high water flooding efficiency, while the low permeability of the matrix leads to a starting pressure gradient for fluid flow in the pores, which results in a low water flooding efficiency. Capillary imbibition is an important water flooding mechanism for fractured low permeability reservoirs.

[0004] A large number of indoor studies and development practices have shown that for low permeability (permeability less than 50mD) and fractured reservoirs, crude oil can gradually converge from pores with smaller pores to large pores under the action of capillary force, ultimately achieving oil-water replacement and increasing single well production and recovery. Giving full play to the imbibition effect of capillary force can be an effective way to develop such reservoirs, so the development of efficient imbibition flooding surfactants is of great significance.

[0005] The document with application number "202010672992.8" discloses "compositions containing anionic nonionic and cationic nonionic surfactants, preparation methods and applications thereof". The preparation method is to carry out alkoxylation reaction of alkylphenol with the required amount of propylene oxide and ethylene oxide in the presence of an alkaline catalyst to obtain alkyl polyoxypropylene polyoxyethylene ether; mix the synthesized alkyl polyoxypropylene polyoxyethylene ether with a halogenating agent, carry out halogenation reaction, and obtain the halide of alkyl polyoxypropylene polyoxyethylene ether; carry out quaternization reaction of (R1 R2R3)N tertiary amine compound and the synthesized alkyl polyoxypropylene polyoxyethylene ether halide in a solvent. Because the synthesized cationic nonionic surfactant can reduce the interfacial tension by 10 -4 mN / m, the lower interfacial tension leads to a decrease in capillary force, which cannot push out the residual oil in the tiny pore throats and leads to low imbibition efficiency.

[0006] The document with application number "202210345564.3" discloses "nanoemulsion oil displacement agent, molybdenum-containing gemini surfactant and preparation method thereof". The preparation method is to obtain a tertiary amine by a twinning reaction of tertiary amine and dichloroethyl ether; and to react a mixed twinning tertiary amine, isopropanol and molybdenum dioxide dichloride. For low permeability sandstone, there are problems of low recovery rate, poor temperature resistance and anti-adsorption performance, resulting in a large adsorption loss to the formation. Summary of the invention

[0007] In order to overcome the defects of low imbibition efficiency, low recovery rate, poor temperature resistance and poor adsorption resistance in the prior art, the present invention provides a cationic-nonionic imbibition oil displacement surfactant, a preparation method and an application thereof.

[0008] In order to achieve the above object, the first aspect of the present invention provides a cationic-nonionic imbibition flooding surfactant having a structure as shown in formula (1):

[0009]

[0010] Wherein, in formula (1), n ​​is 5, 7, and 9, respectively, and the corresponding raw materials are fatty alcohol polyoxyethylene ether AEO-5, AEO-7, or AEO-9.

[0011] Furthermore, the above-mentioned fatty alcohol polyoxyethylene ether is preferably fatty alcohol polyoxyethylene ether AEO-7.

[0012] The second aspect of the present invention provides a method for preparing a cationic-nonionic imbibition flooding surfactant, comprising the following steps:

[0013] Step 1, dissolving a first raw material and a second raw material in a solvent to obtain a first mixed solution; wherein the first raw material is dodecyl dimethyl tertiary amine, the second raw material is epichlorohydrin, and the solvent is ethanol;

[0014] Step 2: distilling and drying the first mixed solution to obtain an intermediate;

[0015] Step 3, dissolving the intermediate obtained in step 2 in a third raw material to obtain a second mixed solution; the third raw material is fatty alcohol polyoxyethylene ether;

[0016] Step 4: The second mixed solution is distilled and dried to obtain a product.

[0017] Furthermore, in the above step 1, by weight, the content of dodecyldimethyl tertiary amine is 10-40 g, the content of epichlorohydrin is 5-30 g, and the solvent is 100 g; the content of fatty alcohol polyoxypropylene ether in the step 3 is 10-50 g.

[0018] Furthermore, the fatty alcohol polyoxyethylene ether in the above step 3 is 30-50g, and its weight average molecular weight is 400-600.

[0019] Furthermore, the mixing conditions of the above step 1 are: stirring speed of 300-380 rpm, temperature of 30-40° C., and time of 2.5-3.5 h.

[0020] Furthermore, the mixing conditions of the above step three are: stirring speed 250-350 rpm, temperature 80-90° C., and time 6-8 h.

[0021] A third aspect of the present invention provides an application of a cationic-nonionic imbibition flooding surfactant in oil and gas development.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The present invention conducts a two-step reaction (ring-opening reaction and quaternization reaction) of fatty alcohol polyoxyethylene ether, epichlorohydrin, dodecyl dimethyl tertiary amine and solvent to obtain a cationic-nonionic imbibition oil displacement surfactant having a cationic group and a nonionic group. Since the surfactant contains a quaternary ammonium salt structure, it can be adsorbed in the reservoir rock, so that the reservoir changes from oil-wet to water-wet, and the wettability is changed well. In addition, because it has a nonionic group with good affinity and good interfacial tension. The combination of the two can reduce capillary force, improve imbibition efficiency, and increase recovery rate.

[0024] 2. The preparation method provided by the present invention adopts low-temperature compounding reaction, has simple preparation process, low cost and easy operation. At the same time, the product of the present invention has low residual monomer content and less pollution, and is easy for large-scale industrial production.

[0025] 3. Since the product of the present invention has good wettability and good salt resistance, it is particularly suitable for low permeability reservoirs to improve the recovery rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is the infrared spectra of the fatty alcohol polyoxyethylene ether AEO-7, the quaternary ammonium intermediate and the target product of the present invention. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the attached examples. Obviously, the described embodiments are only part of the embodiments of the present invention and are only used to illustrate the present invention, but not to limit the scope of the present invention.

[0028] In the present invention, raw materials not described can be obtained from general commercial sources, and those skilled in the art can purchase them as needed, and they will not be described in detail in the present invention.

[0029] The molecular structures of dodecyl dimethyl tertiary amine and epichlorohydrin are as follows:

[0030]

[0031] Fatty alcohol polyoxyethylene ether: purchased from Jiangsu Hai'an Petrochemical Plant;

[0032] Epichlorohydrin: purchased from Aladdin Company;

[0033] Dodecyl dimethyl tertiary amine: purchased from Aladdin Company.

[0034] Example 1

[0035] This embodiment provides a method for preparing a cationic-nonionic imbibition flooding surfactant, comprising the following steps:

[0036] Step 1: Add 21.3 g of dodecyldimethyl tertiary amine and 9.25 g of epichlorohydrin in an oil bath at 35° C., using 100 g of ethanol as a solvent, and then stir at 350 rpm for 3 h to obtain a first mixed solution.

[0037] Step 2: The first mixed solution is sequentially distilled and dried to obtain a quaternary ammonium intermediate.

[0038] Step 3: At 85°C, the intermediate obtained above was mixed evenly with 49.5 g of fatty alcohol polyoxyethylene ether AEO-7, stirred at 350 rpm for 7 h, and distilled and dried to obtain the imbibition displacement surfactant NS1.

[0039] Example 2

[0040] This embodiment provides a method for preparing an imbibition flooding surfactant, the method comprising:

[0041] Step 1: Add 30 g of dodecyldimethyl tertiary amine and 5.25 g of epichlorohydrin into a 40° C. oil bath, using 100 g of ethanol as a solvent, and then stir at 380 rpm for 2.5 h to obtain a first mixed solution.

[0042] Step 2: The first mixed solution is sequentially distilled and dried to obtain an intermediate.

[0043] Step 3: At 90°C, the intermediate obtained above was mixed evenly with 49.5 g of fatty alcohol polyoxyethylene ether AEO-7, stirred at 250 rpm for 8 h, and distilled and dried to obtain the imbibition flooding surfactant NS2.

[0044] Example 3

[0045] This embodiment provides a method for preparing an imbibition flooding surfactant, the method comprising:

[0046] Step 1: Add 15 g of dodecyldimethyl tertiary amine and 15 g of epichlorohydrin into an oil bath at 40° C., use 100 g of ethanol as solvent, and then stir at 350 rpm for 3.5 h to obtain a first mixed solution.

[0047] Step 2: The first mixed solution is sequentially distilled and dried to obtain an intermediate.

[0048] Step 3: At 90°C, the intermediate obtained above was mixed with 30g of fatty alcohol polyoxyethylene ether, stirred at 350rpm for 6h, and distilled and dried to obtain the imbibition flooding surfactant NS3.

[0049] Example 4

[0050] Step 1: Add 40 g of dodecyldimethyl tertiary amine and 9.25 g of epichlorohydrin in a 40° C. oil bath, using 100 g of ethanol as a solvent, and then stir at 350 rpm for 3 h to obtain a first mixed solution.

[0051] Step 2: The first mixed solution is sequentially distilled and dried to obtain an intermediate.

[0052] Step 3: At 85° C., mix the intermediate obtained above with 24.8 g of fatty alcohol polyoxyethylene ether AEO-7, stir at 250 rpm for 8 hours, and perform distillation and drying to obtain the imbibition flooding surfactant NS4.

[0053] Example 5

[0054] Step 1: Add 10 g of dodecyldimethyl tertiary amine and 9.25 g of epichlorohydrin in a 40° C. oil bath, using 100 g of ethanol as a solvent, and then stir at 350 rpm for 3.5 h to obtain a first mixed solution.

[0055] Step 2: The first mixed solution is sequentially distilled and dried to obtain an intermediate.

[0056] Step 3: At 90° C., mix the intermediate obtained above with 10.3 g of fatty alcohol polyoxyethylene ether AEO-7, stir at 250 rpm for 8 h, and perform distillation and drying to obtain the imbibition flooding surfactant NS5.

[0057] Example 6

[0058] In this comparative example, an imbibition displacement surfactant was prepared in a similar manner to Example 2, except that an equal weight of fatty alcohol polyoxyethylene ether AEO-5 was used to replace fatty alcohol polyoxyethylene ether AEO-7.

[0059] The remaining steps are the same as those in Example 2.

[0060] The imbibition flooding surfactant NSA1 was obtained.

[0061] Example 7

[0062] In this comparative example, an imbibition displacement surfactant was prepared in a similar manner to Example 2, except that an equal amount of fatty alcohol polyoxyethylene ether AEO-9 was used to replace fatty alcohol polyoxyethylene ether AEO-7.

[0063] The remaining steps are the same as those in Example 2.

[0064] The imbibition flooding surfactant NSA2 was obtained.

[0065] Example 8

[0066] In this comparative example, an imbibition displacement surfactant is prepared in a manner similar to that of Example 2, except that the mass of the fatty alcohol polyoxypropylene ether AEO-9 used is 20.1 g.

[0067] The remaining steps are the same as those in Example 2.

[0068] The imbibition flooding surfactant NSA3 was obtained.

[0069] Example 9

[0070] In this comparative example, an imbibition oil displacement surfactant is prepared in a manner similar to that of Example 2, except that the mass of the fatty alcohol polyoxyethylene ether AEO-5 used is 24.42 g.

[0071] The remaining steps are the same as those in Example 2.

[0072] The imbibition flooding surfactant NSA4 was obtained.

[0073] The imbibition flooding surfactants prepared in the above Examples 1-9 were subjected to performance tests, including surface tension, interfacial tension, contact angle and imbibition efficiency. The specific test results are shown in Table 3.

[0074] The surface tension test method is as follows: dilute the imbibition oil displacement surfactant in the embodiment and the comparative example by 200 times with the aforementioned formation simulated water to obtain a sample to be tested, and then test the sample to be tested with a surface tension meter at 25°C, and measure three times continuously to obtain an average value;

[0075] The test method of interfacial tension is as follows: dilute the imbibition oil displacement surfactant in the embodiment and the comparative example by 200 times with the aforementioned formation simulated water to obtain a sample to be tested, and use a TX-500 type rotating drop interfacial tension meter at 60°C, with crude oil in simulated formation water as the oil sample, to measure three times in a row and take the average value;

[0076] The contact angle test method is as follows: dilute the imbibition oil displacement surfactant in the embodiment and the comparative example by 200 times with the aforementioned formation simulation water to obtain the sample to be tested; prepare a low-permeability sandstone core slice with a thickness of about 5 mm, polish the cut surface with sandpaper, wash the sandstone core slice with alcohol and distilled water, place it in an oven at 150°C for 24 hours, and then put the core slice into Changqing crude oil, soak it at 60°C for more than 48 hours for aging, so that it becomes an oil-wet surface; take out the sandstone core slice, wipe the surface oil with paper, and then soak it in the sample to be tested, place it in an oven at 60°C for 24 hours, use the Krues DSA25 contact angle meter to measure the three-phase contact angle of the core slice surface, air, and water, and measure three times in a row to take the average value;

[0077] The test method of the imbibition efficiency is as follows: dilute the imbibition oil displacement surfactant in the embodiment and the comparative example by 200 times with the aforementioned formation simulated water to obtain a sample to be tested;

[0078] (1) Core preparation: The experimental cores were drilled and dried, and the gas permeability and porosity were measured. All experimental cores were evacuated and saturated with simulated formation water, and a constant pressure and constant speed pump was used to displace more than 5 PV to measure the water phase permeability. Then, oil-displacing water was performed to displace the experimental cores to the state of bound water, the volume of water displaced was recorded, and the oil phase permeability under bound water was measured.

[0079] (2) Place the experimental core into a self-imbibition instrument containing the sample to be tested, allow the core to self-imbibe and discharge oil, and record the amount of oil discharged over time; when the volume of discharged oil does not change for 72 consecutive hours, record the total volume of discharged oil and calculate the imbibition efficiency.

[0080] Among them, the imbibition efficiency = (self-imbibition oil volume / oil-water displacement water volume) × 100%

[0081] Table 1

[0082] Interfacial tension / mN / m Contact angle / ° Imbibition efficiency / % Example 1 0.013 36 40.56 Example 2 0.021 39 39.16 Example 3 0.015 42 40.25 Example 4 0.017 38 38.22 Example 5 0.019 44 38.92 Example 6 0.371 56 29.63 Example 7 0.276 48 22.21 Example 8 0.290 59 21.85 Example 9 0.348 63 28.69

[0083] It can be seen from the results in Table 1 that the composition provided by the present invention can be used to prepare an imbibition flooding surfactant with low interfacial tension, good anti-adsorption performance, and outstanding wettability change ability, and the imbibition flooding surfactant is used in low permeability sandstone to effectively improve the recovery rate.

[0084] Among them: Embodiments 1-3 are preferred embodiments, and embodiment 1 is the best embodiment.

[0085] The infrared spectra of the raw material fatty alcohol polyoxyethylene ether AEO-7, the quaternary ammonium intermediate and the target product are as follows Figure 1 As shown, the intermediate product is at 2952 cm -1 、2868cm -1The absorption peaks near are the stretching vibration peaks of -CH3 and -CH2; 1467cm -1 The absorption peak near is the deformation vibration absorption peak of -CH3 connected to N; 960cm -1 Nearby is the bending vibration absorption peak of epoxy group; 1249cm -1 The target product is at 1098cm -1 The absorption peak near 3383cm is the stretching vibration of COC; -1 The absorption peak near the -OH stretching vibration absorption peak indicates that the epoxy group is ring-opened to produce hydroxyl groups. In summary, the infrared absorption peaks of the target products can correspond to the designed structures.

[0086] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A cationic-nonionic imbibition flooding surfactant, characterized in that: The imbibition flooding surfactant is a compound having a structure as shown in formula (1): In formula (1), n ​​is 5, 7, and 9, respectively, and the corresponding raw materials are fatty alcohol polyoxyethylene ether AEO-5, AEO-7, or AEO-9.

2. A cationic-nonionic imbibition flooding surfactant according to claim 1, characterized in that: The fatty alcohol polyoxyethylene ether is preferably fatty alcohol polyoxyethylene ether AEO-7.

3. The method for preparing a cationic-nonionic imbibition flooding surfactant according to claim 1, characterized in that: The following steps are involved: Step 1, dissolving a first raw material and a second raw material in a solvent to obtain a first mixed solution; wherein the first raw material is dodecyl dimethyl tertiary amine, the second raw material is epichlorohydrin, and the solvent is ethanol; Step 2: distilling and drying the first mixed solution to obtain an intermediate; Step 3, dissolving the intermediate obtained in step 2 in a third raw material to obtain a second mixed solution; the third raw material is fatty alcohol polyoxyethylene ether; Step 4: The second mixed solution is distilled and dried to obtain a product.

4. The method for preparing a cationic-nonionic imbibition flooding surfactant according to claim 3, wherein: In the step 1, by weight, the content of dodecyldimethyl tertiary amine is 10-40 g, the content of epichlorohydrin is 5-30 g, and the solvent is 100 g; the content of fatty alcohol polyoxypropylene ether in the step 3 is 10-50 g.

5. The method for preparing a cationic-nonionic imbibition flooding surfactant according to claim 4, characterized in that: The fatty alcohol polyoxyethylene ether in step 3 is 30-50 g, and its weight average molecular weight is 400-600.

6. A method for preparing a cationic-nonionic imbibition flooding surfactant according to any of claims 3 to 5, characterized in that: The mixing conditions of step 1 are: stirring speed of 300-380 rpm, temperature of 30-40° C., and time of 2.5-3.5 h.

7. The method for preparing a cationic-nonionic imbibition flooding surfactant according to claim 6, wherein: The mixing conditions of step three are: stirring speed 250-350 rpm, temperature 80-90° C., and time 6-8 h.

8. Use of the imbibition oil recovery surfactant of claim 1 in oil and gas development.

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