Surfactant system for viscosifying water-soluble hydrophobically associating polymers, binary system solutions and use thereof

Abstract

The application discloses a surfactant system for thickening water-soluble hydrophobic associating polymer, a binary system solution and application thereof. The surfactant system for thickening water-soluble hydrophobic associating polymer comprises unsaturated fatty acyl betaine, unsaturated fatty acid polyoxyethylene polyoxypropylene ester and water. The binary system solution comprises water-soluble hydrophobic associating polymer and the surfactant system for thickening water-soluble hydrophobic associating polymer. The surfactant system can double the viscosity of the associating polymer, so that the associating polymer can reach the same viscosity at a lower concentration, and the injection cost of the associating polymer applied in the polymer-surfactant binary system is reduced.

Description

Technical Field

[0001] This invention relates to the field of oilfield chemical technology, specifically to a surfactant system, binary system solution, and its application for thickening water-soluble hydrophobic associating polymers. Background Technology

[0002] Water-soluble associative polymers are a class of macromolecular polymers with an appropriate amount of hydrophobic chains added to a partially hydrophilic long-chain polymeric structure. Associative polymer molecules simultaneously contain a large number of parallel hydrophilic polar groups on the long chains and a small number of non-polar groups with strong hydrophobic interactions. The former contributes to the high viscosity through hydration, while the latter enhances the aggregation between the long polymer chains through the interaction of the non-polar groups in the polar atmosphere of the aqueous solution, further increasing the viscosity of the polymer solution. Compared with traditional polymers, associative polymers possess excellent properties such as temperature resistance, salt resistance, and shear resistance. Polymer solutions with viscosity-enhancing effects can increase the swept volume of the displacing fluid during oil recovery, thereby improving oil recovery.

[0003] Unlike traditional polymers, the high viscosity of associative polymers depends not only on their molecular weight but also on intermolecular interactions. When associative polymers are combined with other components, the intermolecular association of the associative polymer molecules is affected to varying degrees, thus influencing their viscosity. In tertiary oil recovery, polymer-surfactant binary flooding is a common method to enhance oil recovery. Similar to associative polymers, surfactants are molecules that possess both hydrophilic and hydrophobic groups. Their hydrophobic groups, due to structural or polar similarities, readily participate in the intermolecular association of associative polymers, thereby affecting the viscosity-enhancing effect of the associative polymer.

[0004] According to Biggs' three-stage theory, the interaction between most surfactants and associated polymer molecules in solutions above the critical micelle concentration involves three stages: surfactant solubilization in the hydrophobic region of the associated polymer, the formation of a small number of globular micelles, and the formation of a large number of globular micelles. The first two stages are viscosity-increasing stages, with the second stage being slightly stronger than the first. The third stage is a viscosity-reducing stage, with the boundary between the second and third stages determined by whether the number of associated polymer side chains bound in the micelles is less than 2. In practical applications, the surfactant concentration range in the first and second stages is extremely small, failing to meet the concentration requirements for binary surfactant flooding. Once the surfactant concentration increases to the third stage, the viscosity of the binary system solution decreases sharply. This property of surfactants and associated polymers limits the application of associated polymers in binary surfactant flooding. Summary of the Invention

[0005] This invention addresses the aforementioned problems by researching and designing a surfactant system, a binary solution, and its applications for thickening water-soluble hydrophobic associating polymers. The technical means employed in this invention are as follows:

[0006] A surfactant system for thickening water-soluble hydrophobic associative polymers, comprising unsaturated fatty acyl betaine, unsaturated fatty acid polyoxyethylene polyoxypropylene ester, and water;

[0007] The general formula for unsaturated fatty acyl betaine is:

[0008]

[0009] In the formula, R1 is an unsaturated alkyl group, R1 has 9 to 25 carbon atoms, n1 is a natural number between 2 and 4, R2 is one of methyl, ethyl, propyl, hydroxyethyl, and hydroxypropyl, R3 is one of methyl, ethyl, propyl, hydroxyethyl, and hydroxypropyl, R4 is one of ethyl-1,2-idene, propionyl-1,3-idene, 2-hydroxypropyl-1,3-idene, and butionyl-1,4-idene, and A is a phosphate or sulfonate group;

[0010] The general formula for unsaturated fatty acid polyoxyethylene polyoxypropylene ester is:

[0011]

[0012] In the formula, R5 is an unsaturated alkyl group, R5 has 9 to 25 carbon atoms, n2 is a natural number between 3 and 10, and n3 is a natural number between 3 and 20.

[0013] Furthermore, the mass ratio of the unsaturated fatty acyl betaine to the unsaturated fatty acid polyoxyethylene polyoxypropylene ester is 9:1 to 7:3, and the water content is 50% to 80%.

[0014] A binary system solution comprising a water-soluble hydrophobic associating polymer and a surfactant system for thickening the water-soluble hydrophobic associating polymer as described in this invention.

[0015] Further, the concentration of the water-soluble hydrophobic associating polymer is 0.05% to 0.3%, preferably 0.1% to 0.2%, and the concentration of the surfactant system is 0.03% to 0.06%.

[0016] The application of the surfactant system described in this invention in the thickening of water-soluble hydrophobic associating polymers.

[0017] An application of the surfactant system described in this invention in crude oil recovery.

[0018] An application of the binary system solution described in this invention in crude oil recovery.

[0019] Compared with existing technologies, the surfactant system described in this invention can significantly increase the viscosity of associative polymers, enabling them to achieve the same viscosity at lower concentrations, reducing polymer usage, and lowering the injection cost of associative polymers in polydimer flooding. Attached Figure Description

[0020] Figure 1 This is a graph showing the viscosity increase rate of unsaturated fatty acyl betaine and unsaturated fatty acid polyoxyethylene polyoxypropylene ester at different ratios in Example 1 of the present invention.

[0021] Figure 2 This is a graph showing the thickening performance of different tackifier concentrations at different APP7 concentrations in Embodiment 1 of the present invention.

[0022] Figure 3 This is a trend graph showing the viscosity of APP7 at different concentrations and the viscosity of tackifier at different concentrations when there is no tackifier in the first embodiment of the present invention.

[0023] Figure 4 This is a graph showing the thickening performance of different tackifier concentrations at different APP7 concentrations in Embodiment 2 of the present invention.

[0024] Figure 5 This is a trend graph showing the viscosity of APP7 at different concentrations and the viscosity of tackifier at different concentrations when there is no tackifier in the second embodiment of the present invention.

[0025] Figure 6 This is a graph showing the thickening performance of different tackifier concentrations at different APP7 concentrations in Embodiment 3 of the present invention.

[0026] Figure 7 This is a trend graph showing the viscosity of APP7 at different concentrations and the viscosity of tackifier at different concentrations when there is no tackifier in Embodiment 3 of the present invention.

[0027] Figure 8 This is a graph showing the thickening performance of different tackifier concentrations at different APP7 concentrations in Embodiment 4 of the present invention.

[0028] Figure 9 This is a trend graph showing the viscosity of APP7 at different concentrations and the viscosity of tackifier at different concentrations when there is no tackifier in the fourth embodiment of the present invention. Detailed Implementation

[0029] A surfactant system for thickening water-soluble hydrophobic associative polymers, comprising unsaturated fatty acyl betaine, unsaturated fatty acid polyoxyethylene polyoxypropylene ester, and water;

[0030] The general formula for unsaturated fatty acyl betaine is:

[0031]

[0032] In the formula, R1 is an unsaturated alkyl group, R1 has 9 to 25 carbon atoms, preferably 13 to 21, n1 is a natural number between 2 and 4, preferably 2 or 3, R2 is one of methyl, ethyl, propyl, hydroxyethyl, and hydroxypropyl, R3 is one of methyl, ethyl, propyl, hydroxyethyl, and hydroxypropyl, R4 is one of ethyl-1,2-idene, propionyl-1,3-idene, 2-hydroxypropyl-1,3-idene, and butionyl-1,4-idene, and A is a phosphate or sulfonate group;

[0033] The general formula for unsaturated fatty acid polyoxyethylene polyoxypropylene ester is:

[0034]

[0035] In the formula, R5 is an unsaturated alkyl group, R5 has 9 to 25 carbon atoms, preferably 13 to 21, n2 is a natural number between 3 and 10, preferably 3 to 9, and n3 is a natural number between 3 and 20, preferably 5 to 15.

[0036] As a preferred embodiment, the mass ratio of the unsaturated fatty acyl betaine to the unsaturated fatty acid polyoxyethylene polyoxypropylene ester is 9:1 to 7:3, and the water content is 50% to 80%.

[0037] The method for preparing the surfactant system for thickening water-soluble hydrophobic associating polymers described in this embodiment is as follows: Unsaturated fatty acyl betaine is added to unsaturated fatty acid polyoxyethylene polyoxypropylene ether according to the mass ratio, and stirred until homogeneous. A measured amount of water is slowly added during stirring until the finished product is homogeneous.

[0038] Large micelles are a special type of micelle formed by the aggregation of multiple surfactant molecules. Their configurations can be three-dimensional tubular, multi-capsule, or planar, and their size can reach the micrometer scale. The surfactant system for thickening water-soluble hydrophobic associating polymers described in this embodiment can aggregate to form large micelles. Because they are much larger than spherical micelles, large micelles can potentially absorb the hydrophobic side chains of two or more widely spaced associating polymer molecules, thereby enhancing association. In contrast, spherical micelles can generally only absorb one hydrophobic side chain, thus hindering the association between associating polymer molecules. Therefore, this embodiment can significantly increase the viscosity of the associating polymer, enabling it to achieve the same viscosity at a lower concentration, reducing polymer usage, and lowering the injection cost of associating polymers in polydimer flooding applications.

[0039] The viscosity testing method of this invention is as follows:

[0040] Weigh out wg of polymer (effective content 5g) and evenly sprinkle it into (1000-w)g of target block injected water or simulated mineralized water while stirring. Stir for 4 hours to form a homogeneous solution, which is 0.5% polymer mother liquor.

[0041] Add 40g of polymer mother liquor to a 250mL beaker, add (60-x)g of block injection water or simulated mineralized water, and add xg of the surfactant system (referred to as "tackifier" in this embodiment) of the water-soluble hydrophobic associating polymer described in this example (x = 0 to 1, corresponding to 0% to 1% of the tackifier dosage). Stir for 30 minutes to obtain the test solution.

[0042] The viscosity of each solution was determined using a Brookfield DVⅡ type with an ultra-low viscosity test kit (ULV(0) rotor) at a test temperature of 60°C.

[0043] Calculate the viscosity increase rate after compounding using the formula:

[0044]

[0045] In the formula:

[0046] R—Tackification rate after compounding of various concentrations of tackifiers, %;

[0047] η SP —The viscosity of the solution after compounding different concentrations of thickeners, in millipascals per second (mPa·s).

[0048] η P — Viscosity of the blank solution, in millipascal-seconds (mPa·s);

[0049] Example 1

[0050] The water-soluble hydrophobic associative polymer used in this embodiment is APP7 produced by Sichuan Guangya Polymer Chemical Co., Ltd. The unsaturated fatty acyl betaine and unsaturated fatty acid polyoxyethylene polyoxypropylene ester used in this embodiment are from Shanghai Chuxing Chemical Co., Ltd., specifically linoleamide propyl dimethyl hydroxypropyl phosphate betaine and oleic acid polyoxyethylene (7) polyoxypropylene (5) ester.

[0051] The structural formula of linoleamide-propyl dimethylhydroxypropyl phosphate betaine is as follows:

[0052]

[0053] The structural formula of oleic acid polyoxyethylene (7) polyoxypropylene (5) ester is as follows:

[0054]

[0055] With a fixed water content of 50%, samples with different mass ratios of unsaturated fatty acyl betaine (code T) and unsaturated fatty acid polyoxyethylene polyoxypropylene ether (code F) were prepared. The surfactant composition of each sample is shown in the table below.

[0056]

[0057] The thickening effect of each of the above thickeners was determined according to the aforementioned method when the APP7 concentration was 0.2% and the thickener concentration was 0.03%. From... Figure 1 As can be seen, TF has a significant thickening effect under various mass ratios, with a minimum thickening rate of 40%. The thickening rate is higher in the range of TF mass ratio of 9:1 to 7:3, exceeding 80%. When the TF mass ratio is 8:2, the thickening rate is as high as 110% to 120%.

[0058] With a fixed TF mass ratio of 8:2 and a tackifier concentration ranging from 0.01% to 1%, the tackifying effect of APP7 at different concentrations was tested. The results are as follows: Figure 2 When the APP7 concentration is 0.05%, the hydrophobic chain density in the solution is low, and the associative thickening effect is more pronounced when the thickener concentration is higher than 0.2%. Furthermore, at a concentration of 0.05%, the self-association of APP7 is not significant, and its viscosity value is below 5 mPa·s, which does not meet the viscosity requirements for practical applications. In APP7 solutions of 0.1%, 0.15%, and 0.2%, thickening rates exceeding 100% are observed when the thickener concentration is higher than 0.03%, with the system viscosity increasing exponentially. The area between the dashed lines represents the region where the thickening effect is more pronounced when the thickener dosage is low, with a thickener concentration range of 0.03% to 0.06%. In this example, the thickening rate exceeds 100% (i.e., viscosity retention rate 200%), and even reaches 200% (i.e., viscosity retention rate 300%) within a relatively large concentration range.

[0059] like Figure 3 As shown, comparing the composition of solutions with the same viscosity reveals that the viscosity of 0.1% APP7 + 0.03% thickener is comparable to that of 0.15% APP7, the viscosity of 0.15% APP7 + 0.03% thickener is comparable to that of 0.21% APP7, and the viscosity of 0.175% APP7 + 0.03% thickener is comparable to that of 0.26% APP7. The thickening effect of the thickener is higher than that of the same mass of polymer, while the cost of the thickener is lower than that of the polymer, thus reducing the cost of using polymer solutions of the same viscosity.

[0060] Example 2:

[0061] The water-soluble hydrophobic associative polymer used in this embodiment is APP7, produced by Sichuan Guangya Polymer Chemical Co., Ltd. The unsaturated fatty acyl betaine and unsaturated fatty acid polyoxyethylene polyoxypropylene ester used in this embodiment are from Shanghai Chuxing Chemical Co., Ltd., specifically octadecyltrienoic acid amide ethyl dihydroxyethyl propyl sulfobetaine and oleic acid polyoxyethylene (9) polyoxypropylene (15) ester.

[0062] The structure of octadecyltrienoic acid amide ethyl dihydroxyethylpropyl sulfonyl betaine is as follows:

[0063]

[0064] The structure of oleic acid polyoxyethylene (9) polyoxypropylene (15) ester is as follows:

[0065]

[0066] Tackifiers with different TF mass ratios were prepared according to the aforementioned method. The tackifying effect was measured when the APP7 concentration was 0.2% and the tackifier concentration was 0.03%. The optimal TF mass ratio was found to be 8:2, with a tackifying rate of 120%.

[0067] With a fixed TF mass ratio of 8:2 and a tackifier concentration ranging from 0.01% to 1%, the tackifying effect of APP7 at different concentrations was tested. The results are as follows: Figure 4 In APP7 solutions of 0.1%, 0.15%, and 0.2%, viscosity increases exceeding 100% were observed at tackifier concentrations above 0.03%, with the system viscosity increasing exponentially. However, when the tackifier concentration increased to 1%, the third stage of viscosity reduction due to surfactant-polymer interaction did not occur. Figure 5 As shown, the tackifier has a good tackifying effect in the range of 0.05% to 0.3% of APP7 concentration.

[0068] Example 3:

[0069] The water-soluble hydrophobic associative polymer used in this embodiment is APP7, produced by Sichuan Guangya Polymer Chemical Co., Ltd. The unsaturated fatty acyl betaine and unsaturated fatty acid polyoxyethylene polyoxypropylene ester used in this embodiment are from Shanghai Chuxing Chemical Co., Ltd., specifically erucamide propyl dimethyl hydroxypropyl sulfobetaine and tetradecenoic acid polyoxyethylene (3) polyoxypropylene (9) ester.

[0070] The structure of erucamide propyl dimethyl hydroxypropyl sulfobetaine is as follows:

[0071]

[0072] The structure of tetradecenoic acid polyoxyethylene (3) polyoxypropylene (9) ester is as follows:

[0073]

[0074] Tackifiers with different TF mass ratios were prepared according to the aforementioned method. The tackifying effect was measured when the APP7 concentration was 0.2% and the tackifier concentration was 0.03%. The optimal TF mass ratio was found to be 9:1, with a tackifying rate of 140%.

[0075] With a fixed TF mass ratio of 9:1 and a tackifier concentration ranging from 0.01% to 1%, the tackifying effect of APP7 at different concentrations was tested. The results are as follows: Figure 6 In APP7 solutions of 0.1%, 0.15%, and 0.2%, viscosity increases exceeding 100% were observed at tackifier concentrations above 0.03%, with the system viscosity increasing exponentially. However, when the tackifier concentration increased to 1%, the third stage of viscosity reduction due to surfactant-polymer interaction did not occur. Figure 7 As shown, the tackifier has a good tackifying effect in the range of 0.05% to 0.3% of APP7 concentration.

[0076] Example 4:

[0077] The water-soluble hydrophobic associative polymer used in this embodiment is APP7, produced by Sichuan Guangya Polymer Chemical Co., Ltd. The unsaturated fatty acyl betaine and unsaturated fatty acid polyoxyethylene polyoxypropylene ester used in this embodiment are from Shanghai Chuxing Chemical Co., Ltd., specifically tetradecenoic acid amide propyl diethyl hydroxypropyl phosphate betaine and erucic acid polyoxyethylene (9) polyoxypropylene (12) ester.

[0078] The structure of tetradecenoic acid amamidopropyl diethylhydroxypropyl phosphate betaine is as follows:

[0079]

[0080] The structure of erucic acid polyoxyethylene (9) polyoxypropylene (12) ester is as follows:

[0081]

[0082] Tackifiers with different TF mass ratios were prepared according to the aforementioned method. The tackifying effect was measured when the APP7 concentration was 0.2% and the tackifier concentration was 0.03%. The optimal TF mass ratio was found to be 7:3, with a tackifying rate of 90%.

[0083] With a fixed TF mass ratio of 7:3 and a tackifier concentration ranging from 0.01% to 1%, the tackifying effect of APP7 at different concentrations was tested. The results are as follows: Figure 8 In APP7 solutions of 0.1%, 0.15%, and 0.2%, thickening rates exceeding 60% were observed at thickening agent concentrations above 0.03%. Even when the thickening agent concentration increased to 1%, the third stage of viscosity reduction due to surfactant-polymer interaction did not occur. Figure 9 As shown, the tackifier has a good tackifying effect in the range of 0.05% to 0.3% of APP7 concentration.

[0084] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A surfactant system for thickening water-soluble hydrophobic associating polymers, characterized in that, Including unsaturated fatty acyl betaine, unsaturated fatty acid polyoxyethylene polyoxypropylene ester, and water; The general formula for unsaturated fatty acyl betaine is: In the formula, R1 is an unsaturated alkyl group with 9 to 25 carbon atoms, n1 is a natural number between 2 and 4, R2 is one of methyl, ethyl, propyl, hydroxyethyl, and hydroxypropyl, R3 is one of methyl, ethyl, propyl, hydroxyethyl, and hydroxypropyl, R4 is one of ethyl-1,2-idene, propionyl-1,3-idene, 2-hydroxypropyl-1,3-idene, and butionyl-1,4-idene, and A is a phosphate or sulfonate group; The general formula for unsaturated fatty acid polyoxyethylene polyoxypropylene ester is: In the formula, R5 is an unsaturated alkyl group, R5 has 9 to 25 carbon atoms, n2 is a natural number between 3 and 10, and n3 is a natural number between 3 and 20; The mass ratio of the unsaturated fatty acyl betaine to the unsaturated fatty acid polyoxyethylene polyoxypropylene ester is 9:1 to 7:3, and the water content is 50% to 80%.

2. A binary system solution, characterized in that, The system comprises a water-soluble hydrophobic associating polymer and the surfactant system for thickening the water-soluble hydrophobic associating polymer as described in claim 1; The concentration of the water-soluble hydrophobic associative polymer is 0.05% to 0.3%, and the concentration of the surfactant system is 0.03% to 0.06%.

3. The application of the surfactant system according to claim 1 in thickening of water-soluble hydrophobic associating polymers.

4. The application of the surfactant system according to claim 1 in crude oil recovery.

5. The application of the binary system solution according to claim 2 in crude oil recovery.

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