Oil-displacing agent as well as preparation method and application thereof

Abstract

The invention relates to the field of oil and gas exploitation, and discloses an oil-displacing agent which comprises a gemini surfactant, a cosurfactant, an oil phase and water, wherein the gemini surfactant contains a compound shown in a formula (I): # imgabs0 #, R and R'are independently selected from substituted or unsubstituted C10-C16 alkyl or alkenyl, and n is selected from 2, 3, 4 or 6. The oil displacement agent prepared by the invention has the characteristics of ultralow interfacial tension and high static dialysis efficiency, and can be applied to the field of oil and gas exploitation.

Description

Technical Field

[0001] The present invention relates to the field of oil and gas exploitation, and in particular to an oil displacement agent and a preparation method and application thereof. Background Art

[0002] Mahu Oilfield is located in the central area of ​​Mahu Sag in Junggar Basin. It is the world's largest conglomerate oilfield with deep burial depth, low permeability, high closure pressure, undeveloped natural fractures, poor flow conditions, etc. Its natural liquid production capacity cannot reach industrial production standards. At present, the "horizontal well + volume fracturing" method is mainly used to transform tight oil reservoirs to enhance the seepage capacity of the reservoir. The initial production increase effect is obvious. Therefore, this method has also become the most effective means of mobilization for tight oil development at home and abroad. However, the elastic production of volume fracturing horizontal wells in ultra-low porosity and ultra-low permeability oil reservoirs is obviously characterized by high initial production capacity, rapid production decline, and insufficient formation energy in the later stage. How to increase production capacity economically and effectively still faces many difficulties.

[0003] Domestic and foreign studies have shown that the huff-and-puff of oil displacement agent solution can effectively supplement the formation energy deficit after volume fracturing and depletion development of low permeability reservoirs. At the same time, the single well production and ultimate reservoir recovery rate can be greatly increased through mechanisms such as greatly reducing the oil-water interface tension and imbibition oil displacement by oil displacement agents. However, the conventional oil displacement agents used for huff-and-puff of Mahu tight oil reservoirs currently have problems such as poor interfacial activity and low imbibition oil displacement efficiency.

[0004] CN113136193A discloses a high-activity nano oil-displacing agent and a preparation method thereof, wherein a nano-nano oil-displacing agent is disclosed, wherein the oil-displacing agent uses toluene as a solvent, and adopts a silane coupling agent to graft-modify nano silicon dioxide to obtain nano silicon dioxide modified by the silane coupling agent; then, using toluene as a solvent, the surface of the nano silicon dioxide modified by the silane coupling agent is modified by polyoxyethylene ether, filtered, and dried to obtain a silicon-based nanofluid; finally, using glycerol as a solvent, the silicon-based nanofluid and alkanolamide or (with) alkyl glycoside are ripened to obtain a high-activity nano oil-displacing agent.

[0005] CN107384356A discloses a method for preparing a nanocomposite material used in a nano oil-displacing agent and a nano oil-displacing agent prepared using the nanocomposite material. A nano oil-displacing agent is disclosed, which comprises 0.1-1 parts of a nanocomposite material and 99-99.9 parts of a NaCl solution by weight. The method for preparing the nanocomposite material is as follows: tetrabutyl titanate is mixed with anhydrous ethanol to obtain a first solution; polyacrylamide is mixed with an HNO3 solution to obtain a second solution; the first solution is mixed with the second solution to obtain a sol; the sol is subjected to a hydrothermal reaction to obtain a nanocomposite material. Alternatively, titanium dioxide is added to deionized water to obtain a suspension; polyacrylamide is mixed with an HNO3 solution to obtain a third solution; the suspension is mixed with the third solution to obtain a nanocomposite material. The method for preparing the nano oil-displacing agent comprises adding the nanocomposite material to a NaCl solution to obtain a nano oil-displacing agent.

[0006] At present, conventional chemical flooding surfactants such as petroleum sulfonates and zwitterionic betaine are difficult to achieve ultra-low interfacial tension, have low dialysis oil recovery efficiency, and have poor adaptability in tight oil / shale oil reservoirs, which easily leads to pore blockage. Therefore, in order to further improve the oil recovery efficiency of oil recovery agents and enhance the throughput effect of oil recovery agents in tight reservoirs, it is necessary to develop a gemini surfactant with good interfacial activity, temperature resistance and salt resistance. Summary of the invention

[0007] The purpose of the present invention is to overcome the problems of low dialysis oil displacement efficiency and poor interfacial activity in the prior art, and to provide an oil displacement agent and a preparation method and application thereof.

[0008] In order to achieve the above-mentioned object, the first aspect of the present invention provides an oil displacing agent, wherein the oil displacing agent comprises a gemini surfactant, a co-surfactant, an oil phase and water;

[0009] Wherein, the gemini surfactant contains a compound represented by formula (I)

[0010] wherein R and R' are selected from substituted or unsubstituted C 10 -C 16 An alkyl or alkenyl group; n is 2, 3, 4 or 6.

[0011] A second aspect of the present invention provides a method for preparing an oil-displacing agent, the method comprising:

[0012] (1) reacting the compound represented by formula (2) and / or the compound represented by formula (3) with a fatty diamine under alkaline conditions, and post-treating to obtain a gemini surfactant;

[0013]

[0014] (2) Mixing the gemini surfactant, the oil phase and the co-surfactant with water to form a clear liquid to obtain the oil displacement agent.

[0015] Wherein, in formula (2) and formula (3), R and R' are selected from substituted or unsubstituted C 10 -C 16 An alkyl or alkenyl group;

[0016] Wherein, the fatty diamine is selected from at least one of ethylenediamine, propylenediamine, butylenediamine and hexamethylenediamine.

[0017] The third aspect of the present invention provides an oil displacing agent prepared by the method described in the second aspect of the present invention.

[0018] The fourth aspect of the present invention provides an application of the oil displacement agent prepared according to the first and third aspects of the present invention in the field of oil and gas production.

[0019] Through the above technical solution, compared with the prior art, the present invention has the following beneficial effects:

[0020] (1) The main agent of the oil displacement agent of the present invention is a gemini surfactant, which has high interfacial activity and can make the crude oil reach ultra-low interfacial tension within a relatively low concentration range;

[0021] (2) The main agent of the oil displacement agent of the present invention has both an amide group and a sulfonic acid group, and has a good chelating function, thus showing good temperature and salt resistance;

[0022] (3) The production and preparation are simple, easy to implement and low in cost. DETAILED DESCRIPTION

[0023] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0024] As mentioned above, the first aspect of the present invention provides an oil displacing agent, wherein the oil displacing agent comprises a gemini surfactant, a co-surfactant, an oil phase and water;

[0025] Wherein, the gemini surfactant contains a compound represented by formula (I):

[0026] wherein R and R' are selected from substituted or unsubstituted C 10 -C 16 An alkyl or alkenyl group; n is 2, 3, 4 or 6.

[0027] Wherein, the co-surfactant is selected from C1-C6 monohydric alcohols, preferably at least one selected from n-butanol, n-pentanol, isopentanol and n-hexanol.

[0028] The oil phase is selected from hydrocarbon oil with a distillation range of 180-340° C., preferably selected from at least one of diesel, biodiesel and kerosene.

[0029] Among them, in the oil-displacing agent, the mass concentration of the gemini surfactant is 10-20%; the mass concentration of the co-surfactant is 3-10%; the mass concentration of the oil phase is 1-10%; and the mass concentration of water is 60-86%.

[0030] A second aspect of the present invention provides a method for preparing an oil-displacing agent, the method comprising:

[0031] (1) reacting the compound represented by formula (2) and / or the compound represented by formula (3) with a fatty diamine under alkaline conditions, and post-treating to obtain a gemini surfactant;

[0032]

[0033] (2) Mixing the gemini surfactant, the oil phase and the co-surfactant with water to form a clear liquid to obtain the oil displacement agent.

[0034] In formula (2) and formula (3), R and R' are each independently selected from substituted or unsubstituted C 10 -C 16 alkyl or alkenyl.

[0035] The post-treatment process includes performing reduced pressure distillation at 60° C. and a vacuum degree of −0.09 MPa.

[0036] In some preferred embodiments of the present invention, preferably, in formula (2) and formula (3), R and R' are selected from unsubstituted C 10 -C 16 alkyl or alkenyl.

[0037] Wherein, the fatty diamine is selected from at least one of ethylenediamine, propylenediamine, butylenediamine and hexamethylenediamine.

[0038] In some preferred embodiments of the present invention, preferably, the pH value of the alkaline condition is 9-10.

[0039] In some preferred embodiments of the present invention, preferably, the alkaline condition is achieved by adding an alkaline substance to the reaction, and the alkaline substance is selected from at least one of NaOH, KOH, and Ba(OH)2.

[0040] In some preferred embodiments of the present invention, preferably, the oil phase is selected from hydrocarbon oils with a distillation range of 180-340° C., preferably selected from at least one of diesel, biodiesel and kerosene.

[0041] In some preferred embodiments of the present invention, preferably, the monohydric alcohol of C1-C6 of the co-surfactant is preferably selected from at least one of n-butanol, n-pentanol, isopentanol and n-hexanol.

[0042] In some preferred embodiments of the present invention, preferably, in step (1), the mass ratio of the compound represented by formula (2) and / or the compound represented by formula (3) to the fatty diamine is (6-17):1.

[0043] In some preferred embodiments of the present invention, preferably, in step (1), the reaction temperature is 120-150° C.; and the reaction time is 6-12 h.

[0044] In some preferred embodiments of the present invention, preferably, in step (2), in parts by weight, the gemini surfactant is 10-20 parts, the co-surfactant is 3-10 parts, the oil phase is 1-10 parts, and the water is 60-86 parts.

[0045] Wherein, the sum of the weight parts of the gemini surfactant, the co-surfactant, the oil phase and the water is 100 parts.

[0046] The third aspect of the present invention provides an oil displacing agent prepared by the method described in the second aspect of the present invention.

[0047] The fourth aspect of the present invention provides an application of the oil displacement agent prepared according to the first and third aspects of the present invention in the field of oil and gas production.

[0048] Example 1

[0049] A mixture of a compound represented by formula (2) and a compound represented by formula (3) (wherein R and R' are C 10 -C 16 alkyl) and propylenediamine (mass ratio 10.9:1) were added into the reactor, and then an aqueous solution of NaOH (40%) was added to adjust the pH to 10. The system was reacted at 120°C for 6h, and then reduced pressure distillation was carried out at 60°C and a vacuum degree of -0.09MPa to obtain a yellow solid gemini surfactant A.

[0050] Take 10% of nano oil-displacing agent A and dissolve it in water. Add 3% of 0# diesel under stirring, then add 5% of n-butanol dropwise, and stir until it becomes clear and transparent to form oil-displacing agent 1.

[0051] Example 2

[0052] A mixture of a compound represented by formula (2) and a compound represented by formula (3) (R and R' are selected from substituted or unsubstituted C 10 -C 16 alkyl) and ethylenediamine (mass ratio 15:1) were added into the reactor, and then an aqueous solution of KOH (40%) was added to adjust the pH to 9. The system was reacted at 135°C for 9 hours, and then reduced pressure distillation was carried out at 60°C and a vacuum degree of -0.09 MPa to obtain a yellow solid gemini surfactant B.

[0053] Take 15% of nano oil-displacing agent B and dissolve it in water. Add 2% of diesel and 3% of kerosene while stirring. Then add 5% of n-pentanol dropwise and stir until it becomes clear to form oil-displacing agent 2.

[0054] Example 3

[0055] A mixture of a compound represented by formula (2) and a compound represented by formula (3) (R and R' are selected from substituted or unsubstituted C 10 -C 16 alkyl), ethylenediamine and hexamethylenediamine (mass ratio 32:1:2) were added into the reaction kettle, and then an aqueous solution of Ba(OH)2 (40%) was added to adjust the pH to 10. The system was reacted at 150°C for 12h, and then reduced pressure distillation was carried out at 60°C and a vacuum degree of -0.09MPa to obtain a yellow solid gemini surfactant C.

[0056] Take 20% of nano oil-displacing agent C and dissolve it in water. Add 5% of biodiesel under stirring, then add 5% of isoamyl alcohol dropwise, and stir until it becomes clear and transparent to form oil-displacing agent 3.

[0057] Example 4

[0058] In a reaction kettle, a mixture of a compound represented by formula (2) and a compound represented by formula (3) (R and R' are selected from substituted or unsubstituted C 10 -C 16 alkyl) and dibutyleneamine (mass ratio 9:1) are added thereto, and then an aqueous solution of Ba(OH)2 (40%) is added to adjust the pH to 10. The mixture is sealed tightly and placed in a roller furnace. The system temperature is maintained at about 150°C. The reaction is carried out for 12 hours, and then reduced pressure distillation is carried out at 60°C and a vacuum degree of -0.09 MPa to obtain a yellow solid gemini surfactant D.

[0059] Take 18% of nano oil-displacing agent D and dissolve it in water. Add 8% of kerosene while stirring. Then add 8% of n-hexanol dropwise and stir until the solution becomes clear and transparent to form oil-displacing agent 4.

[0060] Example 5

[0061] A mixture of a compound represented by formula (2) and a compound represented by formula (3) (R and R' are selected from substituted or unsubstituted C 10 -C 16 alkyl) and hexamethylenediamine (mass ratio 7.7:1) were added into the reaction kettle, and then an aqueous solution of KOH (40%) was added to adjust the pH to 10. The system was reacted at 120°C for 12h, and then reduced pressure distillation was carried out at 60°C and a vacuum degree of -0.09MPa to obtain a yellow solid gemini surfactant E.

[0062] Take 20% of nano oil-displacing agent E and dissolve it in water. Add 8% of kerosene while stirring. Then add 8% of n-pentanol dropwise and stir until the solution becomes clear and transparent to form oil-displacing agent 5.

[0063] Example 6

[0064] A mixture of a compound represented by formula (2) and a compound represented by formula (3) (R and R' are selected from substituted or unsubstituted C 10 -C 16 alkyl), ethylenediamine and butanediamine (mass ratio 32:1:1.5) were added into the reaction kettle, and then an aqueous solution of NaOH (40%) was added to adjust the pH to 10. The system was reacted at 135°C for 9 hours, and then reduced pressure distillation was carried out at 60°C and a vacuum degree of -0.09 MPa to obtain a yellow solid gemini surfactant F.

[0065] Take 20% of nano oil-displacing agent F and dissolve it in water. Add 10% of 0# diesel under stirring, then add 8% of n-pentanol dropwise, and stir until it becomes clear and transparent to form oil-displacing agent 6.

[0066] Comparative Example 1

[0067] Dissolve 20% sodium dodecyl sulfate in water, add 5% 0# diesel under stirring, then add 8% isoamyl alcohol dropwise, and stir until it becomes clear to form oil displacement agent a.

[0068] The oil-water interfacial tension and static imbibition oil displacement performance of the oil-displacing agents 1-6 in the above examples and the oil-displacing agent a in comparative example 1 were tested respectively. A 0.2 wt% oil-displacing agent solution was prepared using crude oil from the Baikouquan Formation of Mahu Oilfield, simulated formation water (mineralization 11067.1 mg / L), and a simulated core of saturated formation crude oil. The interfacial tension between the oil-displacing agent and crude oil and the static imbibition oil displacement efficiency were tested at 90°C. The results are shown in Table 1 below.

[0069] Table 1 Interfacial tension of crude oil and static imbibition recovery efficiency

[0070] sample Interfacial tension (mN / m) Static imbibition oil displacement efficiency (%) Oil displacing agent 1 0.0046 13.71 Oil displacing agent 2 0.0023 15.23 Oil displacing agent 3 0.0058 13.69 Oil displacing agent 4 0.0067 13.34 Oil displacing agent 5 0.0056 12.21 Oil displacing agent 6 0.0061 13.09 Oil displacing agent 0.5775 9.54

[0071] The oil-displacing agents 1-6 all have good interfacial activity, and can achieve ultra-low interfacial tension when added at 0.2 wt %, and the static imbibition efficiency reaches 12.21%-15.23%.

[0072] It can be seen from the results in Table 1 that the oil displacement agent prepared by the embodiment of the method of the present invention has ultra-low interfacial tension and high static dialysis efficiency, and has achieved significantly better results than the comparative example.

[0073] 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. An oil displacing agent, wherein: The oil displacing agent comprises a gemini surfactant, a co-surfactant, an oil phase and water; Wherein, the gemini surfactant contains a compound represented by formula (I): wherein R and R' are each independently selected from substituted or unsubstituted C 10 -C 16 An alkyl or alkenyl group; n is 2, 3, 4 or 6.

2. The oil-displacing agent according to claim 1, wherein The co-surfactant is selected from C1-C6 monohydric alcohols, preferably at least one selected from n-butanol, n-pentanol, isopentanol and n-hexanol.

3. The oil-displacing agent according to claim 1 or 2, wherein The oil phase is selected from hydrocarbon oils with a distillation range of 180-340° C., preferably selected from at least one of diesel, biodiesel and kerosene.

4. The oil-displacing agent according to any one of claims 1 to 3, wherein Based on the total amount of the oil displacing agent, in the oil displacing agent, the mass concentration of the gemini surfactant is 10-20%, the mass concentration of the co-surfactant is 3-10%, the mass concentration of the oil phase is 1-10%, and the mass concentration of water is 60-86%.

5. A method for preparing an oil-displacing agent, the method comprising: (1) reacting the compound represented by formula (2) and / or the compound represented by formula (3) with a fatty diamine under alkaline conditions, and post-treating to obtain a gemini surfactant; (2) mixing the gemini surfactant, the oil phase, the co-surfactant and water to form a clear liquid to obtain the oil displacement agent; Wherein, in formula (2) and formula (3), R and R' are selected from substituted or unsubstituted C 10 -C 16 An alkyl or alkenyl group; Wherein, the fatty diamine is selected from at least one of ethylenediamine, propylenediamine, butylenediamine and hexamethylenediamine.

6. The method according to claim 5, wherein: The pH value of the alkaline condition is 9-10.

7. The method according to claim 5 or 6, wherein: The alkaline condition is achieved by adding an alkaline substance to the reaction, wherein the alkaline substance is selected from at least one of NaOH, KOH, and Ba(OH)2.

8. The method according to any one of claims 5 to 7, wherein: The oil phase is selected from hydrocarbon oil with a distillation range of 180-340° C., preferably selected from at least one of diesel, biodiesel and kerosene.

9. The method according to any one of claims 5 to 8, wherein: The monohydric alcohol C1-C6 of the co-surfactant is preferably selected from at least one of n-butanol, n-pentanol, isopentanol and n-hexanol.

10. The method according to any one of claims 5 to 9, wherein: In step (1), the mass ratio of the compound represented by formula (2) and / or the compound represented by formula (3) to the fatty diamine is (6-17):

1.

11. The method according to any one of claims 5 to 10, wherein: In step (1), the reaction temperature is 120-150° C. and the reaction time is 6-12 h.

12. The method according to any one of claims 5 to 11, wherein: In step (2), in parts by weight, the gemini surfactant is 10-20 parts, the co-surfactant is 3-10 parts, the oil phase is 1-10 parts, and the water is 60-86 parts.

13. An oil-displacing agent obtained by the method according to any one of claims 5 to 12.

14. Use of the oil displacement agent according to any one of claims 1 to 4 and 13 in the field of oil and gas production.

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