Oil displacement composition, oil displacement agent, and method for preparing and using the same

Abstract

This invention relates to the field of oilfield oil recovery technology, providing an oil displacement composition and its application, an oil displacement agent and its preparation method and application. The oil displacement composition comprises an alkyl glycoside hydroxyalkyl sulfonate and a betaine-type surfactant. The oil displacement agent comprises an alkyl glycoside hydroxyalkyl sulfonate, a betaine-type surfactant, and water. The oil displacement agent provided by this invention has advantages such as high interfacial activity, strong emulsifying ability, good emulsification effect, and strong stability. It has a large adsorption capacity at the oil-water interface, effectively reduces interfacial tension, and can reduce injection pressure, exhibiting good enhanced oil recovery performance. When applied to enhanced oil recovery, it can significantly improve crude oil recovery. The preparation method is simple, it is convenient to use in oilfields, and it has biodegradability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil extraction, in particular to a kind of oil displacement composition and application thereof, a kind of oil displacement agent and preparation method and application thereof. BACKGROUND

[0002] As a kind of rare non-renewable resources, oil has very wide effect in social economic development, and is one of important energy sources indispensable for industrial construction. China is poor in oil resources reserves, and with the continuous exploitation of domestic oil fields, most of the conventional oil fields have entered the late high water cut stage, and the production gradually decreases, which cannot meet the current needs. At present, low-permeability and ultra-low-permeability reservoirs account for a high proportion, but they are difficult to inject water and develop, and the water cut rises rapidly, so the primary and secondary oil production is low. Therefore, it has great practical and strategic significance to take appropriate stimulation measures to improve the production of low-permeability reservoirs.

[0003] A large number of indoor researches and field applications prove that surfactant flooding has good oil displacement effect. Surfactant can emulsify the residual oil that does not flow in the formation after water flooding, thereby reducing the residual oil saturation and improving the production of low-permeability reservoirs. However, the conditions of various reservoirs are complex, and the commonly used oil displacement surfactants have poor temperature and salt resistance, which can easily change structure or precipitate in high-temperature and high-salt formations. In addition, surfactants are easily adsorbed by rocks during migration in the formation, resulting in adsorption loss, reduction of effective concentration, reduction of the emulsification ability of surfactants for crude oil, and poor enhanced oil recovery effect. The anionic / zwitterionic surfactant system has the advantages of temperature and salt resistance, strong interfacial activity of zwitterionic surfactants and low cost and small adsorption loss of anionic surfactants, which can solve the problems of poor temperature and salt resistance and large adsorption loss of surfactant flooding. However, the existing anionic / zwitterionic surfactant system still has poor effect when applied to enhanced oil recovery, and has problems such as insufficient interfacial activity and emulsification ability and excessive injection pressure. SUMMARY

[0004] The present application aims to provide an oil displacement composition, an oil displacement agent and a preparation method thereof, to solve the technical problem of poor effect of the existing anionic / zwitterionic surfactant system applied to enhanced oil recovery.

[0005] To achieve the above-mentioned purpose, the technical solution adopted by the present application is as follows:

[0006] In a first aspect, the present application provides an oil displacement composition, comprising alkyl glycoside hydroxyalkyl sulfonate and betaine surfactant.

[0007] According to some embodiments of the present application, the structure of the alkyl glycoside hydroxyalkyl sulfonate is shown in formula (I),

[0008]

[0009] Wherein, n is 1 to 5, preferably 1 to 2; m is 4 to 14, preferably 12 to 14; M is selected from any one of alkali metal ions and alkaline earth metal ions, when M is an alkali metal ion, x is 1, when M is an alkaline earth metal ion, x is 0.5; preferably, M is sodium ion.

[0010] According to some embodiments of the present invention, the betaine-type surfactant includes at least one of dodecyl dimethyl betaine (BS-12), tetradecyl dimethyl betaine (BS-14), hexadecyl dimethyl betaine (BS-16), octadecyl dimethyl betaine (BS-18), and docosyl dimethyl betaine (BS-22).

[0011] According to some embodiments of the present invention, the molar ratio of the alkyl glycoside hydroxyalkyl sulfonate and the betaine-type surfactant is 1:(1 to 4), for example, it can be 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, etc.

[0012] In a second aspect, the present invention provides an oil displacement agent comprising an alkyl glycoside hydroxyalkyl sulfonate, a betaine-type surfactant, and water.

[0013] According to some embodiments of the present invention, the structure of the alkyl glycoside hydroxyalkyl sulfonate is as shown in formula (I).

[0014]

[0015] Wherein, n is 1 to 5, preferably 1 to 2; m is 4 to 14, preferably 12 to 14; M is selected from any one of alkali metal ions and alkaline earth metal ions, when M is an alkali metal ion, x is 1, when M is an alkaline earth metal ion, x is 0.5; preferably, M is sodium ion.

[0016] According to some embodiments of the present invention, the betaine-type surfactant includes at least one of dodecyl dimethyl betaine (BS-12), tetradecyl dimethyl betaine (BS-14), hexadecyl dimethyl betaine (BS-16), octadecyl dimethyl betaine (BS-18), and docosyl dimethyl betaine (BS-22).

[0017] According to some embodiments of the present invention, the molar ratio of the alkyl glycoside hydroxyalkyl sulfonate to the betaine-type surfactant is 1:(1-4), for example, it can be 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, etc.; the sum of the mass of the alkyl glycoside hydroxyalkyl sulfonate and the betaine-type surfactant accounts for 0.1-2.0 wt% of the mass of the oil displacement agent, for example, it can be 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.8 wt%, 0.9 wt%, 1.0 wt%, 1.2 wt%, 1.5 wt%, 1.6 wt%, 1.7 wt%, 1.9 wt%, 2.0 wt%, etc.

[0018] Thirdly, the present invention provides a method for preparing the oil displacement agent described in the second aspect, comprising: adding the alkyl glycoside hydroxyalkyl sulfonate and the betaine-type surfactant to water, mixing and stirring to obtain the oil displacement agent.

[0019] According to some embodiments of the present invention, the mixing temperature is 30–50°C.

[0020] According to some embodiments of the present invention, the mixing and stirring time is 30 to 60 minutes.

[0021] Fourthly, the present invention provides the application of the oil displacement composition described in the first aspect or the oil displacement agent described in the second aspect in reducing the interfacial tension of oil / water.

[0022] Fifthly, the present invention provides the use of the oil displacement composition of the first aspect or the oil displacement agent of the second aspect in emulsified crude oil.

[0023] In a sixth aspect, the present invention provides the application of the oil displacement composition described in the first aspect or the oil displacement agent described in the second aspect in enhanced oil recovery.

[0024] The beneficial effects of this invention are at least as follows:

[0025] (1) The oil displacement agent provided by the present invention has the advantages of high interfacial activity, strong emulsification ability, good emulsification effect and strong stability. It has a large adsorption capacity at the oil-water interface, a good effect of reducing interfacial tension, and can reduce injection pressure, thus having good performance in improving oil recovery. When applied to enhanced oil recovery, it can significantly improve the oil recovery rate.

[0026] (2) The oil displacement agent provided by the present invention is a compound of alkyl glycoside hydroxyalkyl sulfonate and betaine-type surfactant. The two surfactants have a synergistic adsorption effect, and can completely emulsify crude oil under low energy conditions (such as low stirring speed). The raw materials are widely available and low in cost. When the total amount of surfactant is low, it can form a stable emulsion with underground crude oil, which has good prospects for oilfield application.

[0027] (3) The oil displacement agent preparation method provided by the present invention is simple, convenient to use in oil fields, green and environmentally friendly, with little pollution to the reservoir, and has biodegradability, and will not cause permanent damage to the reservoir. Attached Figure Description

[0028] Figure 1 The diagram shows the particle size distribution of the emulsion of the oil displacement agents in each embodiment and comparative example. Detailed Implementation

[0029] To make the technical problem to be solved, the technical solution, and the beneficial effects of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely for illustrating this patent and do not limit the scope of protection of this invention in any way.

[0030] Unless otherwise defined, the technical terms used in the following embodiments have the same meaning as commonly understood by those skilled in the art. Unless otherwise specified, the reagents used in the following embodiments are conventional biochemical reagents; the raw materials, instruments, and equipment used in the following embodiments can all be obtained commercially or by existing methods; unless otherwise specified, the reagent dosages are those used in routine experimental operations; unless otherwise specified, the experimental methods are conventional methods.

[0031] The oil displacement agent was prepared using the following method:

[0032] Sodium alkyl glycoside hydroxypropyl sulfonate (APGSHS) and a betaine-type surfactant were added to water and stirred with a magnetic stirrer at 40°C for 30 minutes to prepare an aqueous solution with a total concentration of 0.3 wt% of the two surfactants, thus obtaining the oil displacement agent.

[0033] Specific types and molar ratios (n) of alkyl glycoside hydroxypropyl sulfonate sodium and betaine-type surfactants 烷基糖苷 :n 甜菜碱型 As shown in Table 1.

[0034] Table 1

[0035]

[0036] (1) Interface performance research

[0037] Interfacial tension was tested on the oil displacement agents of each embodiment and comparative example.

[0038] The test method for the interfacial tension of oil displacement agents is as follows:

[0039] The instrument used was a TX-500C interfacial tensiometer, with the oil-water density difference set to 0.15 g / cm³. 3 The interfacial tension between each oil displacement agent and crude oil was measured at a test temperature of 50℃ and a speed of 6000 rpm.

[0040] The test results are shown in Table 2.

[0041] Table 2

[0042] Group Interfacial tension (mN / m) Example 1 0.65 Example 2 0.15 Example 3 0.0096 Example 4 0.0041 Example 5 0.0032 Example 6 0.0012 Example 7 0.0084 Example 8 0.0081 Example 9 0.015 Comparative Example 1 2.53 Comparative Example 2 0.051 Comparative Example 3 0.062 Comparative Example 4 0.86 Comparative Example 5 0.031

[0043] The test results above show that the oil displacement agent provided by this invention has good interfacial activity. Compared with oil displacement agents prepared using alkyl glycoside hydroxyalkyl sulfonate alone, the addition of betaine-type surfactants to the oil displacement agent in combination with alkyl glycoside hydroxyalkyl sulfonate can further reduce the oil-water interfacial tension. In particular, when the molar ratio of alkyl glycoside hydroxyalkyl sulfonate to betaine-type surfactant is 1:(1-4), the prepared oil displacement agent can achieve ultra-low interfacial tension, which is not only much lower than that of oil displacement agents prepared using alkyl glycoside hydroxyalkyl sulfonate alone, but also significantly lower than that of oil displacement agents prepared using betaine-type surfactants alone, and also lower than that of oil displacement agents prepared by combining alkyl glycoside hydroxyalkyl sulfonate with other amphoteric surfactants (such as dodecyl dihydroxyethylamine oxide). This is because when the molar ratio of alkyl glycoside hydroxyalkyl sulfonate to betaine-type surfactant is 1:(1-4), there is a synergistic effect between alkyl glycoside hydroxyalkyl sulfonate and betaine-type surfactant. The mixed adsorption of the two surfactant molecules at the interface forms a denser adsorption film, which can significantly reduce the oil-water interfacial tension.

[0044] (2) Emulsification ability test

[0045] The emulsifying ability of the oil displacement agents in each embodiment and comparative example was tested.

[0046] The emulsifying ability of the oil displacement agent was tested using the minimum emulsification speed method, as follows:

[0047] The aqueous phase (oil displacement agent) and the oil phase (crude oil produced from an oil field) were mixed at a volume ratio of 7:3. A top-mounted agitator was used to start stirring at a speed of 50 rpm, and the speed was gradually increased every 2 minutes until the minimum speed that could completely disperse the crude oil in the water was reached.

[0048] At lower rotation speeds, larger oil droplets can be clearly observed; after stirring stops, these droplets rapidly coalesce and separate into layers. However, as the rotation speed increases to a certain value, the crude oil becomes completely dispersed in the solution, and the separation rate is very slow, indicating that the crude oil is completely emulsified. A lower minimum rotation speed indicates better emulsification ability of the oil displacement agent.

[0049] The minimum emulsification speeds for each oil displacement agent are shown in Table 3:

[0050] Table 3

[0051] Group Minimum emulsification speed (r / min) Example 1 500 Example 2 400 Example 3 200 Example 4 50 Example 5 100 Example 6 50 Example 7 200 Example 8 50 Example 9 100 Comparative Example 1 600 Comparative Example 2 200 Comparative Example 3 800 Comparative Example 4 1000 Comparative Example 5 500

[0052] The test results above show that when the molar ratio of alkyl glycoside hydroxyalkyl sulfonate to betaine surfactant is 1:(1-4), the minimum emulsification speed is relatively small, indicating excellent emulsification ability and the ability to form a uniform emulsion under low energy conditions.

[0053] (3) Emulsion particle size test

[0054] Emulsions were prepared using the oil displacement agents from each embodiment and comparative example, and the particle size of the emulsions was tested.

[0055] The preparation method for emulsions is as follows:

[0056] The aqueous phase (oil displacement agent) and the oil phase (crude oil produced from an oil field) were mixed at a volume ratio of 7:3 and emulsified at 3000 rpm for 5 minutes using a homogenizing emulsifier to obtain an emulsion formed by the aqueous and oil phases.

[0057] The particle size of the emulsion was measured using a Malvern laser particle size analyzer, as follows:

[0058] The emulsion was placed in a particle size analyzer, the temperature was set to 30℃, and the particle size distribution curve of the emulsified oil droplets in the emulsion was measured.

[0059] The test results for the particle size distribution of the emulsion are shown in Table 4 and... Figure 1 As shown.

[0060] Table 4

[0061]

[0062] From Table 4 and Figure 1 It can be seen that when the molar ratio of alkyl glycoside hydroxyalkyl sulfonate to octadecyl dimethyl betaine is 1:(1-4), the emulsion has a smaller particle size and a narrower droplet size distribution range, indicating that the emulsion formed by the oil displacement agent and crude oil has strong stability and a long oil droplet aggregation time.

[0063] (4) Oil displacement efficiency test

[0064] The oil displacement efficiency of the oil displacement agents in each embodiment and comparative example was tested.

[0065] The oil displacement efficiency of the oil displacement agent was tested using a low-permeability core displacement experiment, as follows:

[0066] Test procedure: Gas core permeability test → Vacuum the core and saturate it with formation water → Saturate it with crude oil → Water flooding until the water cut reaches 98% → 0.5PV chemical slug flooding → Subsequent water flooding until the water cut reaches 98%.

[0067] The experiment was conducted at a temperature of 50℃, using formation water with a salinity of 5000 mg / L, and the injection pressure, oil production, and water production were recorded.

[0068] The test results of the oil displacement efficiency are shown in Table 5.

[0069] Table 5

[0070]

[0071] The experimental results above show that waterflooding followed by chemical flooding with a single alkyl glycoside hydroxyalkyl sulfonate (Comparative Example 1) can further increase the oil recovery rate by 17.00%, chemical flooding with a single octadecyl dimethyl betaine (Comparative Example 2) can further increase the oil recovery rate by 16.16%, and chemical flooding with a combination of alkyl glycoside hydroxyalkyl sulfonate and dodecyl dihydroxyethylamine oxide (Comparative Example 3) can further increase the oil recovery rate by 18.11%. Furthermore, using the oil displacement agents of Examples 3-5 can further increase the oil recovery rate by 22.34%, 25.45%, and 22.1%, respectively, demonstrating significantly better oil recovery effects. Moreover, compared with the oil displacement agents of Comparative Examples 1-2 and 5, the oil displacement agents of Examples 3-5 can significantly reduce the injection pressure, indicating that the oil displacement efficiency of the oil displacement agents provided by this invention is higher. Therefore, using the oil displacement agents provided by this invention for enhanced oil recovery is more advantageous.

[0072] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. An oil displacement composition, characterized by comprising: The oil displacement composition comprises alkyl polyglycoside hydroxyalkyl sulfonate and betaine surfactant; The structure of the alkyl polyglycoside hydroxyalkyl sulfonate is shown in formula (I), （I） wherein n is 1-5; m is 4-14; M is selected from any one of alkali metal ion and alkaline earth metal ion, when M is alkali metal ion, x is 1, when M is alkaline earth metal ion, x is 0.5; The betaine surfactant comprises at least one of dodecyl dimethyl betaine, tetradecyl dimethyl betaine, hexadecyl dimethyl betaine, octadecyl dimethyl betaine and docosyl dimethyl betaine.

2. The oil displacement composition according to claim 1, characterized by, In formula (I), n is 1-2; and / or m is 12-14; and / or M is sodium ion.

3. The oil displacement composition according to claim 1 or 2, characterized in that, The molar ratio of the alkyl polyglycoside hydroxyalkyl sulfonate to the betaine surfactant is 1: (1-4).

4. An oil displacement agent, characterized by, The oil displacement agent comprises alkyl polyglycoside hydroxyalkyl sulfonate, betaine surfactant and water; The structure of the alkyl polyglycoside hydroxyalkyl sulfonate is shown in formula (I), （I） wherein n is 1-5; m is 4-14; M is selected from any one of alkali metal ion and alkaline earth metal ion, when M is alkali metal ion, x is 1, when M is alkaline earth metal ion, x is 0.5; The betaine surfactant comprises at least one of dodecyl dimethyl betaine, tetradecyl dimethyl betaine, hexadecyl dimethyl betaine, octadecyl dimethyl betaine and docosyl dimethyl betaine.

5. The oil displacement agent according to claim 4, characterized in that, In formula (I), n is 1-2; and / or m is 12-14; and / or M is sodium ion.

6. The oil displacement agent according to claim 4 or 5, characterized in that, The molar ratio of the alkyl polyglycoside hydroxyalkyl sulfonate to the betaine surfactant is 1: (1-4); the sum of the mass of the alkyl polyglycoside hydroxyalkyl sulfonate and the betaine surfactant accounts for 0.1-2.0 wt% of the mass of the oil displacement agent.

7. A process for the preparation of an oil displacement agent as claimed in any one of claims 4 to 6, characterised in that, Comprising: The alkyl polyglycoside hydroxyalkyl sulfonate and the betaine surfactant are added into water, mixed and stirred to obtain the oil displacement agent.

8. The preparation method according to claim 7, characterized in that, The temperature of the mixing and stirring is 30-50℃; And / or, the time of the mixing and stirring is 30-60 min.

9. Use of the oil displacement composition according to any one of claims 1-3 or the oil displacement agent according to any one of claims 4-6 in reducing oil / water interfacial tension.

10. Use of the oil displacement composition according to any one of claims 1-3 or the oil displacement agent according to any one of claims 4-6 in emulsifying crude oil.

11. Use of the oil displacement composition according to any one of claims 1-3 or the oil displacement agent according to any one of claims 4-6 in enhanced oil recovery.

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