Small-molecular-particle-size surfactant for improving recovery efficiency of low-permeability oil and gas field and preparation method of small-molecular-particle-size surfactant

Abstract

The invention relates to the technical field of oil field chemicals, and provides a small-molecular-particle-size surfactant for improving the recovery ratio of a low-permeability oil and gas field and a preparation method of the small-molecular-particle-size surfactant for improving the recovery ratio of the low-permeability oil and gas field. Comprising the following raw materials in parts by weight: 20-40 parts of polyoxyethylene lauryl ether, 5-10 parts of sodium dodecyl benzene sulfonate, 5-10 parts of a solubilizer, 1-3 parts of a pH regulator, 3-5 parts of an anti-calcium agent, 10-15 parts of a fluidity control agent and 60-70 parts of deionized water. The mass ratio of the lauryl alcohol polyoxyethylene ether to the sodium dodecyl benzene sulfonate is (1: 5)-(5: 1). According to the technical scheme, the problem that the recovery efficiency of the low-permeability oil and gas field is low in the prior art is solved.

Description

Technical Field

[0001] The invention relates to the technical field of oilfield chemicals, and in particular to a small-molecular-size surfactant for improving the recovery rate of low-permeability oil and gas fields and a preparation method thereof. Background Art

[0002] At present, major oil fields in my country have entered the middle and late stages of exploitation and are facing many severe challenges. On the one hand, reservoir conditions have become increasingly complex, formation heterogeneity is serious, and the distribution of remaining oil is intricate. On the other hand, although low-permeability reservoirs have abundant oil and gas resources, they have small porosity and low permeability, which makes water flooding and oil washing inefficient, with a small swept volume, high injection pressure, and greatly increased development difficulty. Traditional mining technologies often have limited effects when facing these problems, which seriously hinders the sustained and efficient development of oil fields. Surfactants, as an important chemical agent, have shown great potential in improving oil and gas recovery. Therefore, the development of a small-molecule particle size surfactant for improving the recovery rate of low-permeability oil and gas fields has become the key to solving the recovery rate problem of low-permeability oil and gas fields. Summary of the invention

[0003] The invention provides a small-molecular-size surfactant for improving the recovery rate of low-permeability oil and gas fields and a preparation method thereof, which solves the problem of low recovery rate of low-permeability oil and gas fields in the related art.

[0004] The technical scheme of the present invention is as follows: The present invention proposes a small-molecule particle size surfactant for improving the recovery rate of low-permeability oil and gas fields, comprising the following component raw materials in parts by weight: 20-40 parts of lauryl alcohol polyoxyethylene ether, 5-10 parts of sodium dodecylbenzene sulfonate, 5-10 parts of solubilizer, 1-3 parts of pH regulator, 3-5 parts of anticalcium agent, 10-15 parts of fluidity control agent, and 60-70 parts of deionized water; The mass ratio of the lauryl alcohol polyoxyethylene ether to the sodium dodecylbenzene sulfonate is 1:5 to 5:1.

[0005] As a further technical solution, the mass ratio of the lauryl alcohol polyoxyethylene ether to the sodium dodecylbenzene sulfonate is 3:1-2.

[0006] As a further technical solution, the lauryl alcohol polyoxyethylene ether consists of a first lauryl alcohol polyoxyethylene ether and a second lauryl alcohol polyoxyethylene ether, and the first lauryl alcohol polyoxyethylene ether and the second lauryl alcohol polyoxyethylene ether have different cloud points.

[0007] As a further technical solution, the cloud point of the first lauryl alcohol polyoxyethylene ether is 50-70°C, the cloud point of the second lauryl alcohol polyoxyethylene ether is 70-95°C, and the mass ratio of the first lauryl alcohol polyoxyethylene ether to the second lauryl alcohol polyoxyethylene ether is 1-2:1.

[0008] In the present invention, lauryl alcohol polyoxyethylene ethers with different cloud points are mixed and used, and the mass ratio of the two is adjusted to exert the synergistic effect of the two, optimize the distribution and action mode of the surfactant in the pores of oil reservoir rocks, reduce interfacial surface tension, and improve the recovery rate of low-permeability oil and gas fields.

[0009] As a further technical solution, the solubilizer is an alcohol solubilizer, and the alcohol solubilizer includes one or more of ethanol, isopropanol, and isobutanol.

[0010] As a further technical solution, the solubilizer further comprises an amide phenyl ether compound, and the mass ratio of the amide phenyl ether compound to the alcohol solubilizer is 1-2:4.

[0011] In the present invention, an amide phenyl ether compound is added as a solubilizer, and the solubility and dispersibility of the lauryl alcohol polyoxyethylene ether are improved by enhancing the interaction between the amide phenyl ether compound and the lauryl alcohol polyoxyethylene ether, thereby increasing the recovery rate of low-permeability oil and gas fields.

[0012] As a further technical solution, the amide phenyl ether compound includes one or more of 4-acetylaminoanisole, p-acetylacetylaminophenylethyl ether, and N-acetyl o-aminophenylethyl ether.

[0013] As a further technical solution, the pH regulator includes one or more of sodium carbonate and sodium bicarbonate.

[0014] As a further technical solution, at least one of the following technical features is also included: The anticalcic agent includes one or more of sodium citrate, sodium tartrate, and sodium gluconate; The fluidity control agent includes one or more of hydroxymethyl cellulose, xanthan gum, and guar gum.

[0015] The present invention also provides a method for preparing a small-molecule particle size surfactant for improving the recovery rate of low-permeability oil and gas fields, comprising the following steps: weighing the raw materials, mixing and stirring them evenly to obtain the small-molecule particle size surfactant.

[0016] As a further technical solution, the stirring time is 30-60 minutes, and the stirring temperature is 30-50°C.

[0017] The working principle and beneficial effects of the present invention are: In the present invention, lauryl alcohol polyoxyethylene ether and sodium dodecylbenzene sulfonate are added as raw materials, and their mass ratio is adjusted to give full play to their synergistic effect, thereby improving the wettability of the rock surface, reducing the surface tension of the oil-water interface, and improving the recovery rate of low-permeability oil and gas fields. DETAILED DESCRIPTION

[0018] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only 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.

[0019] In the following examples and comparative examples: The first lauryl alcohol polyoxyethylene ether: model AEO-7, cloud point 50~70℃; The second lauryl alcohol polyoxyethylene ether: model is AEO-9, and the cloud point is 70~95℃.

[0020] Example 1 A method for preparing a small-molecule particle size surfactant for improving the recovery rate of low-permeability oil and gas fields comprises the following steps: weighing 20 parts of lauryl alcohol polyoxyethylene ether, 5 parts of sodium dodecylbenzene sulfonate, 5 parts of ethanol, 1 part of sodium carbonate, 3 parts of sodium citrate, 10 parts of hydroxymethyl cellulose and 60 parts of deionized water, mixing and stirring at 30°C for 60 minutes, and obtaining a small-molecule particle size surfactant after uniform mixing, wherein 20 parts of lauryl alcohol polyoxyethylene ether are the first lauryl alcohol polyoxyethylene ether.

[0021] Example 2 A method for preparing a small-molecule particle size surfactant for improving the recovery rate of low-permeability oil and gas fields comprises the following steps: weighing 32 parts of lauryl alcohol polyoxyethylene ether, 8 parts of sodium dodecylbenzene sulfonate, 8 parts of isopropyl alcohol, 2 parts of sodium carbonate, 4 parts of sodium tartrate, 12 parts of xanthan gum and 65 parts of deionized water, mixing and stirring at 40°C for 45 minutes, and obtaining a small-molecule particle size surfactant after uniform mixing, wherein 32 parts of lauryl alcohol polyoxyethylene ether is a first lauryl alcohol polyoxyethylene ether.

[0022] Example 3 A method for preparing a small-molecule particle size surfactant for improving the recovery rate of low-permeability oil and gas fields comprises the following steps: weighing 40 parts of lauryl alcohol polyoxyethylene ether, 10 parts of sodium dodecylbenzene sulfonate, 10 parts of isobutyl alcohol, 3 parts of sodium bicarbonate, 5 parts of sodium gluconate, 15 parts of guar gum and 70 parts of deionized water, mixing and stirring at 50°C for 30 minutes, and obtaining a small-molecule particle size surfactant after uniform mixing, wherein the 40 parts of lauryl alcohol polyoxyethylene ether are the first lauryl alcohol polyoxyethylene ether.

[0023] Example 4 Compared with Example 1, Example 4 is different in that 20 parts of lauryl alcohol polyoxyethylene ether and 5 parts of sodium dodecylbenzene sulfonate are replaced by 18.75 parts of lauryl alcohol polyoxyethylene ether and 6.25 parts of sodium dodecylbenzene sulfonate.

[0024] Example 5 Compared with Example 1, the difference of Example 5 is that 20 parts of lauryl alcohol polyoxyethylene ether and 5 parts of sodium dodecylbenzene sulfonate are replaced by 15 parts of lauryl alcohol polyoxyethylene ether and 10 parts of sodium dodecylbenzene sulfonate.

[0025] Example 6 Compared with Example 1, Example 6 is different in that 20 parts of lauryl alcohol polyoxyethylene ether and 5 parts of sodium dodecylbenzene sulfonate are replaced by 12 parts of lauryl alcohol polyoxyethylene ether and 13 parts of sodium dodecylbenzene sulfonate.

[0026] Example 7 Compared with Example 5, the difference of Example 7 is that 15 parts of lauryl alcohol polyoxyethylene ether are an equal amount of the second lauryl alcohol polyoxyethylene ether.

[0027] Example 8 Compared with Example 5, the difference of Example 8 is that 15 parts of lauryl alcohol polyoxyethylene ether are the first lauryl alcohol polyoxyethylene ether and the second lauryl alcohol polyoxyethylene ether in a mass ratio of 1:2.

[0028] Example 9 Compared with Example 5, the difference of Example 9 is that the 15 parts of lauryl alcohol polyoxyethylene ether are the first lauryl alcohol polyoxyethylene ether and the second lauryl alcohol polyoxyethylene ether in a mass ratio of 1:1.

[0029] Example 10 Compared with Example 5, the difference of Example 10 is that the 15 parts of lauryl alcohol polyoxyethylene ether are the first lauryl alcohol polyoxyethylene ether and the second lauryl alcohol polyoxyethylene ether in a mass ratio of 2:1.

[0030] Embodiment 11 Compared with Example 5, the difference of Example 11 is that the 15 parts of lauryl alcohol polyoxyethylene ether are the first lauryl alcohol polyoxyethylene ether and the second lauryl alcohol polyoxyethylene ether in a mass ratio of 3:1.

[0031] Example 12 Compared with Example 10, Example 12 is different in that ethanol is replaced by an equal amount of 4-acetamidoanisole.

[0032] Embodiment 13 Compared with Example 10, the difference of Example 13 is that 5 parts of ethanol are replaced by 4-acetamidoanisole and ethanol in a mass ratio of 1:4.

[0033] Embodiment 14 Compared with Example 10, the difference of Example 14 is that 5 parts of ethanol are replaced by 4-acetamidoanisole and ethanol in a mass ratio of 2:4.

[0034] Embodiment 15 Compared with Example 14, Example 15 is different in that 4-acetamidoanisole is replaced with an equal amount of p-acetylacetamidophenyl ether.

[0035] Comparative Example 1 Compared with Example 1, the difference of Comparative Example 1 is that lauryl alcohol polyoxyethylene ether is replaced by an equal amount of sodium dodecylbenzene sulfonate.

[0036] Comparative Example 2 Compared with Example 1, the difference in Comparative Example 2 is that sodium dodecylbenzene sulfonate is replaced by an equal amount of lauryl alcohol polyoxyethylene ether.

[0037] The small molecule particle size surfactants prepared in Examples 1 to 15 and Comparative Examples 1 to 2 were tested according to the following method: 1. Surface tension: According to the plate method specified in GB / T 22237-2008 "Determination of surface tension of surfactants", the prepared small molecular particle size surfactant was added to crude oil to prepare a test sample solution with a concentration of 0.3wt%, and the surface tension of the sample solution was tested.

[0038] 2. Improved oil recovery: First, dry the artificial core to constant weight, measure the core size and gas permeability, saturate the core with water, determine its pore volume, saturate the core with crude oil, and record the saturated crude oil volume; then, at 90°C, inject water to drive oil until the water content of the produced fluid is >99%, that is, the heavy oil retained in the pores cannot be driven out, inject the prepared small molecule particle size surfactant, and inject water to drive oil again until the water content of the produced fluid is >99%, and calculate the percentage of improved oil recovery based on water drive, improved oil recovery = (recovery after adding surfactant - basic recovery) / basic recovery × 100%.

[0039] The test results are shown in the following table: Table 1 Performance test results of small molecule particle size surfactants prepared in Examples 1 to 15 and Comparative Examples 1 to 2

[0040] Compared with Example 1, Comparative Example 1 does not add lauryl alcohol polyoxyethylene ether, and Comparative Example 2 does not add sodium dodecylbenzene sulfonate. As a result, the surface tension of Example 1 is less than that of Comparative Examples 1 and 2, and the recovery rate is improved by more than that of Comparative Examples 1 and 2, indicating that lauryl alcohol polyoxyethylene ether and sodium dodecylbenzene sulfonate play a synergistic role, can reduce the surface tension of the interface, and improve the recovery rate of low permeability oil and gas fields. In Examples 1 and 4 to 6, lauryl alcohol polyoxyethylene ether and sodium dodecylbenzene sulfonate in different mass ratios are added. As a result, the surface tension of Examples 4 and 5 is less than that of Examples 1 and 6, and the recovery rate is improved by more than that of Examples 1 and 6, indicating that when the mass ratio of lauryl alcohol polyoxyethylene ether and sodium dodecylbenzene sulfonate is 3:1 to 2, the small molecule particle size surfactant obtained has better ability to reduce the surface tension of the interface and improve the recovery rate of low permeability oil and gas fields.

[0041] Compared with Examples 5 and 7, Examples 8 to 11 simultaneously add the first lauryl alcohol polyoxyethylene ether and the second lauryl alcohol polyoxyethylene ether, and the surface tension of Examples 8 to 11 is less than that of Examples 5 and 7, and the recovery rate is improved more than that of Examples 5 and 7, indicating that the first lauryl alcohol polyoxyethylene ether and the second lauryl alcohol polyoxyethylene ether play a synergistic role, can reduce the surface tension of the interface, and improve the recovery rate of low permeability oil and gas fields. In Examples 8 to 11, the first lauryl alcohol polyoxyethylene ether and the second lauryl alcohol polyoxyethylene ether in different mass ratios are added, and the surface tension of Examples 9 and 10 is less than that of Examples 8 and 11, and the recovery rate is improved more than that of Examples 8 and 11, indicating that when the mass ratio of the first lauryl alcohol polyoxyethylene ether and the second lauryl alcohol polyoxyethylene ether is 1 to 2: 1, the small molecule particle size surfactant obtained has better ability to reduce the surface tension of the interface and improve the recovery rate of low permeability oil and gas fields.

[0042] Compared with Example 10, Examples 13 to 15 simultaneously added an alcohol solubilizer and an amide phenyl ether compound. As a result, the surface tension of Examples 13 to 15 was less than that of Example 10, and the increased recovery factor was greater than that of Example 10, indicating that the alcohol solubilizer and the amide phenyl ether compound exerted a synergistic effect, which could reduce the surface tension of the interface and improve the recovery factor of low-permeability oil and gas fields.

[0043] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A small molecular particle size surfactant for improving the recovery rate of low permeability oil and gas fields, characterized in that: The invention comprises the following raw materials in parts by weight: 20-40 parts of lauryl alcohol polyoxyethylene ether, 5-10 parts of sodium dodecylbenzene sulfonate, 5-10 parts of solubilizer, 1-3 parts of pH regulator, 3-5 parts of anticalcium agent, 10-15 parts of fluidity control agent and 60-70 parts of deionized water; the mass ratio of the lauryl alcohol polyoxyethylene ether to the sodium dodecylbenzene sulfonate is 1:5-5:

1.

2. A small-molecule particle size surfactant for improving the recovery rate of low-permeability oil and gas fields according to claim 1, characterized in that: The mass ratio of the lauryl alcohol polyoxyethylene ether to the sodium dodecylbenzene sulfonate is 3:1-2.

3. The small-molecule particle size surfactant for improving the recovery rate of low-permeability oil and gas fields according to claim 1, characterized in that: The lauryl alcohol polyoxyethylene ether consists of a first lauryl alcohol polyoxyethylene ether and a second lauryl alcohol polyoxyethylene ether, and the first lauryl alcohol polyoxyethylene ether and the second lauryl alcohol polyoxyethylene ether have different cloud points.

4. A small-molecule particle size surfactant for improving the recovery rate of low-permeability oil and gas fields according to claim 3, characterized in that: The cloud point of the first lauryl alcohol polyoxyethylene ether is 50-70° C., the cloud point of the second lauryl alcohol polyoxyethylene ether is 70-95° C., and the mass ratio of the first lauryl alcohol polyoxyethylene ether to the second lauryl alcohol polyoxyethylene ether is 1-2:

1.

5. The small-molecule particle size surfactant for improving the recovery rate of low-permeability oil and gas fields according to claim 1, characterized in that: The solubilizer is an alcohol solubilizer, and the alcohol solubilizer includes one or more of ethanol, isopropanol, and isobutanol.

6. A small-molecule particle size surfactant for improving the recovery rate of low-permeability oil and gas fields according to claim 5, characterized in that: The solubilizing agent further comprises an amide phenyl ether compound, and the mass ratio of the amide phenyl ether compound to the alcohol solubilizing agent is 1-2:

4.

7. A small molecular particle size surfactant for improving the recovery rate of low permeability oil and gas fields according to claim 6, characterized in that: The amide phenyl ether compound includes one or more of 4-acetylaminoanisole, p-acetylacetylaminophenylethyl ether, and N-acetyl o-aminophenylethyl ether.

8. The small-molecule particle size surfactant for improving the recovery rate of low-permeability oil and gas fields according to claim 1, characterized in that: The pH adjuster includes one or both of sodium carbonate and sodium bicarbonate.

9. The small-molecule particle size surfactant for improving the recovery rate of low-permeability oil and gas fields according to claim 1, characterized in that: It also includes at least one of the following technical features: The anticalcic agent includes one or more of sodium citrate, sodium tartrate, and sodium gluconate; The fluidity control agent includes one or more of hydroxymethyl cellulose, xanthan gum, and guar gum.

10. The method for preparing a small-molecule particle size surfactant for improving the recovery rate of low-permeability oil and gas fields according to any one of claims 1 to 9, characterized in that: The method comprises the following steps: weighing the raw materials, mixing and stirring them uniformly to obtain a surfactant with a small molecular particle size.

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