Oil displacement modified alkyl benzene sulfonate and its preparation process and application

Abstract

The present application relates to the field of oil field chemistry, and particularly relates to a modified alkyl benzene sulfonate for oil displacement, and a preparation process and application thereof. The present application uses C12-C14 alkyl benzene as raw material, adopts a one-step method to mix C14-C18 olefins with alkyl benzene at a specific ratio (in which the proportion of octadecene is up to 55%), and cooperatively optimizes the sulfonation molar ratio, two-stage aging temperature and time, the head pressure of the sulfonator and the neutralization conditions, successfully prepares the modified alkyl benzene sulfonate with high sulfonic acid equivalent suitable for high temperature and high salt reservoir conditions. The product can reduce the oil-water interfacial tension to below 0.01 mN / m, has a remarkable oil displacement effect, and the sulfate, un-sulfonated substance and color index all meet the standards. The implementation of the present application aims to provide a modified alkyl benzene sulfonate product with stable interfacial activity, excellent salt tolerance, feasible process and controllable cost for high temperature and high salt reservoir conditions.

Description

Technical Field

[0001] This invention relates to the field of oilfield chemistry, and more particularly to an oil displacement modified alkylbenzene sulfonate, its preparation process, and its application. Background Technology

[0002] The strategic development of deep and offshore oil and gas resources has become an important direction for ensuring energy supply. Deep oil and gas reservoirs generally have extreme geological conditions such as high temperature (80~120℃) and high salinity (salinity usually exceeds 20,000 mg / L), and these extreme environments cause traditional enhanced oil recovery technologies to generally fail. For example, in the chemical flooding practice of a certain oilfield in high-temperature and high-salinity reservoirs (85℃, salinity 30,000 mg / L), certain breakthroughs have been achieved through technologies such as polymer flooding, alkali-free binary composite flooding, and heterogeneous composite flooding. However, when reservoir conditions further develop towards high temperature (>100℃) and high salinity (>50,000 mg / L), existing chemical flooding systems still face severe challenges. Surfactant flooding is one of the core means of chemical flooding. It can significantly reduce the oil-water interfacial tension, reduce capillary resistance, and thus initiate and effectively displace residual oil in the pores. With the current expansion of chemical flooding technology from traditional mature blocks to complex reservoir types such as high-temperature and high-salinity reservoirs, higher requirements are placed on the temperature and salt resistance of surfactants used for oil displacement.

[0003] Alkylbenzene sulfonates, as one of the most widely used anionic flooding surfactants, have achieved large-scale application in the ASP (alkali-surfactant-polymer) composite flooding field due to their stable raw material sources, excellent emulsifying properties, and relatively controllable production costs. However, under high temperature and high salinity conditions, especially when facing mineralization >50,000 mg / L and rich in... , In extreme formation water environments, alkylbenzene sulfonates are prone to precipitation or significant attenuation of interfacial activity due to electrostatic shielding effects and the electrophilic attraction of salt ions to their head groups, making it difficult to maintain the oil-water interfacial tension stably at 10. - The concentration of N / m below 2 m severely limits its applicability in high-temperature and high-salinity oil reservoirs.

[0004] To address the aforementioned issues, current research primarily focuses on the compound application of sulfonate products. Systematic studies on the chemical modification of alkylbenzene feedstocks and their synergistic optimization with sulfonation process parameters remain relatively limited. A mature production technology that balances high equivalent yield, salt tolerance, and overall performance indicators has not yet been developed. Therefore, developing a simple process for preparing modified alkylbenzene sulfonates suitable for high-temperature, high-salt reservoirs, with good oil displacement performance and a stable and abundant feedstock source, is of great significance. Summary of the Invention

[0005] To enable modified alkylbenzene sulfonate products to significantly reduce oil-water interfacial tension and improve salt resistance while ensuring key indicators such as sulfate content, free oil content, and color, making them suitable for tertiary oil recovery, this application provides an oil displacement modified alkylbenzene sulfonate, its preparation process, and its application.

[0006] In one aspect, this application provides a process for preparing an oil-displacement modified alkylbenzene sulfonate, wherein alkylbenzene is mixed with a mixed olefin and then subjected to sulfonation, aging, hydrolysis and neutralization to obtain an oil-displacement modified alkylbenzene sulfonate; wherein the mixed olefin is a C14-C18 olefin and the proportion of octadecene in the mixed olefin is 30-55 wt%.

[0007] This invention uses C12-C14 alkylbenzene as raw material and employs an "integrated method" to mix a specific ratio of C14-C18 olefins with alkylbenzene (with octadecene accounting for up to 55%). By synergistically optimizing the sulfonation molar ratio, two-stage aging temperature and time, sulfonator head pressure, and neutralization conditions, a modified alkylbenzene sulfonate with high sulfonic acid equivalent, suitable for high-temperature and high-salinity oil reservoirs, has been successfully prepared. This product can reduce the oil-water interfacial tension to below 0.01 mN / m, exhibiting significant oil displacement effects, and its sulfate, unsulfonated, and color indicators all meet standards. The implementation of this invention aims to provide an oil-dispatch alkylbenzene sulfonate product with stable interfacial activity, excellent salt resistance, feasible process, and controllable cost for high-temperature and high-salinity oil reservoirs. Compared to traditionally synthesized mixed alkylbenzene sulfonates with complex components that are unsuitable for large-scale production, this patent offers stable raw material sources, a mild process, and ease of large-scale production, making it suitable for tertiary oil recovery. It has significant theoretical and practical value for expanding the application range of alkylbenzene sulfonates in complex oil reservoir environments and improving the economics of tertiary oil recovery technology.

[0008] Furthermore, the alkylbenzene is a C12-C14 straight-chain alkylbenzene.

[0009] Furthermore, the mass ratio of alkylbenzene to mixed olefins is 75-95:5-25.

[0010] Furthermore, the mixed olefins are a composition of C14-C18 olefins, and the addition amount is 8%-12%.

[0011] Furthermore, the preparation process of the oil-displacement modified alkylbenzene sulfonate includes the following preparation steps:

[0012] S1 mixes alkylbenzene with mixed olefins to obtain a mixed organic material, which is then mixed with diluted... The gas undergoes a sulfonation reaction. The molar ratio of the organic material to the mixed organic material is 1:1-1.5;

[0013] After the S2 sulfonation reaction is completed, an aging treatment is performed.

[0014] The material aged by S3 is subjected to hydrolysis, and the hydrolyzed sulfonic acid is neutralized to obtain modified alkylbenzene sulfonate.

[0015] Preferably, in step S1, the dry air is heated by a Roots blower and then enters the evaporator. Liquid SO3 is pressurized from the receiving tank to 0.2-0.3 MPa by a shielded pump, and after the flow rate is metered and controlled, it enters the evaporator. It is heated and vaporized by heat transfer oil and mixed with the dry air to form a SO3 mixed gas. It is then cooled to the sulfonation temperature and demisted to obtain a pure SO3 mixed gas. The molar ratio of SO3 to olefin is 1:1.05.

[0016] Preferably, the mixed olefins comprise a composition of tetradecene, hexadecene, and octadecene in a mass ratio of 15-25:25-35:45-55.

[0017] Preferably, the sulfonation reaction is carried out in a membrane sulfonator with a head pressure of 16-20 kPa.

[0018] Preferably, the specific steps for obtaining the alkylbenzene sulfonate product after the sulfonation reaction in step two are as follows: the ester material output after the sulfonation reaction enters the aging system for aging, hydrolysis, and neutralization. The aging temperature is 50-60℃, and the material passes through aging chamber 1 and aging chamber 2 in sequence. The average residence time in the aging chamber is 15-20 minutes. The aged sulfonic acid enters a static mixer and is fully mixed with process water from the process water pump for hydrolysis. The hydrolyzed sulfonic acid is then neutralized by liquid alkali and converted into alkylbenzene sulfonate to obtain a qualified product.

[0019] Preferably, the flow rate of the organic material is 2750 kg / h and the flow rate of the process water is 45 kg / h.

[0020] Preferably, the neutralization pressure is controlled at 0.2-0.4 MPa, the neutralization temperature at 45±5℃, and the neutralization alkalinity at 1.5-2.5%.

[0021] Furthermore, in step S2, the aging temperature is 50-60℃ and the aging time is 35-40 minutes.

[0022] Secondly, this application provides an oil-displacement modified alkylbenzene sulfonate, wherein the oil-displacement modified alkylbenzene sulfonate obtained by the preparation process described in this application has an average equivalent of 380-460.

[0023] Furthermore, the oil-displacement modified alkylbenzene sulfonate, under conditions of 45°C, [degrades] Na... + / Ca 2+ Salt tolerance: 150,000-200,000 mg / L.

[0024] Furthermore, the oil-displacement modified alkylbenzene sulfonate, under simulated formation water testing at 85°C with a salinity of 150,000 mg / L, exhibited an oil-water interfacial tension consistently below 0.01 mN / m.

[0025] Furthermore, the modified alkylbenzene sulfonate is characterized by increasing oil recovery by more than 20% compared to waterflooding in core displacement experiments.

[0026] Thirdly, this application provides an application of an oil-displacement modified alkylbenzene sulfonate obtained by the preparation process described in this application, or an oil-displacement modified alkylbenzene sulfonate as described in this application, in oil and gas resource exploitation.

[0027] Beneficial effects: 1. This invention uses an integrated method to mix a specific proportion of long-chain olefins (C14-18 olefins, with C18 olefins having the highest proportion) with straight-chain alkylbenzenes, thereby increasing the average molecular weight of sulfonates and obtaining surfactant products with high sulfonic acid equivalents. The oil-water interfacial tension can be reduced to below 0.01 mN / m. Particularly noteworthy is that this ultra-low interfacial level can be maintained even under extremely high salinity conditions with a total mineralization as high as 150,000 mg / L, and the salt tolerance can reach 200,000 mg / L, far exceeding existing similar products.

[0028] 2. This invention optimizes the sulfonation process parameters, including organic materials and The molar ratio, aging time, and sulfonator head pressure, while reducing the oil-water interfacial tension, ensure that key indicators such as sulfate (≤2.0%), free oil (≤2.0%), and color (≤50 Hazen) of the product meet quality requirements.

[0029] 3. The preparation process of the present invention can be achieved by simple modification of existing sulfonation equipment, the raw material source is stable and sufficient (olefins are industrial grade products), the process conditions are mild, and it is suitable for large-scale production. Attached Figure Description

[0030] Figure 1 This is a process flow diagram of Embodiment 1 of the present invention. Detailed Implementation

[0031] To make the technical solution of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] The main detection methods involved are as follows:

[0033] Oil-water interfacial tension determination: The oil / water interfacial tension was determined using the rotating droplet method with a Texas 500 rotating droplet tensiometer. A series of samples were prepared using simulated formation water for testing. The temperature was set at 85℃, and the motor speed at 3000 r / min (i.e., 20 m / s / r). A quartz tube was filled with the sample solution to be tested, and a drop of appropriately sized oil was added. The quartz tube was sealed and placed in the tensiometer for testing. The change in the oil droplet diameter d over time was observed and recorded.

[0034] Salt tolerance test: Prepare a 0.3wt% surfactant solution, add NaCl and CaCl2 solutions of different concentrations respectively, place the sample solution at 45.0±0.5℃ for equilibration for 24 hours, and observe the transparency of the solution.

[0035] The determination of sulfate content was carried out in accordance with the national standard GB / T6366-2012 "Determination of Inorganic Sulfate Content of Surfactants by Titration Method"; the determination of unsulfonated content was carried out in accordance with GB / T 11989-2008 "Determination of Petroleum Ether Soluble Content of Anionic Surfactants"; and the color was determined in accordance with GB / T 3143-1982 "Determination of Color of Liquid Chemical Products (Hazen Units-Platinum-Cobalt Color Number)".

[0036] Example 1: A preparation process for an oil-displacement modified alkylbenzene sulfonate, such as... Figure 1 As shown, the preparation steps include the following:

[0037] Alkylbenzene (n-tetradecylbenzene) is mixed with a mixture of olefins at a mass ratio of 90:10. The olefins, by mass percentage, are: 20% tetradecylene, 30% hexadecylene, and 50% octadecylene, yielding a mixed organic material. Liquid SO3 is pumped from a shielded pump at a flow rate of 925±25 kg / h and enters an evaporator where it is heated and vaporized by heat transfer oil at a certain temperature. It then comes into full contact with dry air from the main blower outlet to form a SO3 mixture of a certain concentration. After cooling, it enters a nicotine demister to remove acid mist from the mixture, yielding the pure SO3 mixture required for the sulfonation reaction. The mixed organic material and SO3 then enter a membrane sulfonator, with the feed rate of the mixed organic material controlled at 2750±50 kg / h. The molar ratio was controlled at 1:1.05, and the pressure at the sulfonator head was 18 kPa. The mixed organic material flowed along the inner wall of the membrane sulfonator tube, and... Under highly turbulent conditions, the gas undergoes an exothermic reaction to form an acid ester.

[0038] After the sulfonation reaction is completed, the ester material enters the aging system, the aging temperature is 50±5℃, and the average aging residence time is 18±2 min.

[0039] The aged material enters a hydrolysis and neutralization system. The neutralization pressure is 0.2-0.3 MPa, the neutralization temperature is 45±5℃, and the neutralization alkalinity is 2±0.5%. After neutralization and cooling, a modified alkylbenzene sulfonate product suitable for high-temperature and high-salinity oil reservoir conditions is obtained. The feeding and process parameters are shown in Table 1-1, and the main index parameters of the product in this example are shown in Table 1-2.

[0040] Table 1-1. Raw Materials and Process Parameters

[0041]

[0042] Table 1-2. Product Indicators

[0043]

[0044] Example 2, a preparation process for an oil-displacement modified alkylbenzene sulfonate, comprising the following preparation steps:

[0045] Similar to Example 1, SO3 diluted with dry air flows into the sulfonation system at a rate of 900 kg / h. The mixed raw materials are evenly distributed in each tube of the sulfonator at a flow rate of 2700-2800 kg / h, and sulfonate with the SO3 mixture entering the sulfonator. The sulfonated ester enters the aging system for aging, and then undergoes hydrolysis, neutralization, and cooling to obtain the product alkylbenzene sulfonate. The difference between this example and Example 1 is that the mixed olefin ratio is 30% tetradecanene, 30% hexadecene, and 40% octadecene (the olefins are a mixture of INEOS olefins and SABIC olefins, which is a mixed olefin). The remaining process parameters are the same as in Example 1. The main performance parameters of the product in this example are shown in Table 2-1.

[0046] Table 2-1. Product Specifications

[0047]

[0048] Example 3, a preparation process for an oil-displacement modified alkylbenzene sulfonate, comprising the following preparation steps:

[0049] Similar to Example 1, SO3 diluted with dry air flows into the sulfonation system at a rate of 900 kg / h. The mixed raw materials are evenly distributed in each tube of the sulfonator at a flow rate of 2700-2800 kg / h, and sulfonate with the SO3 mixture entering the sulfonator. The sulfonated ester enters the aging system for aging, and then undergoes hydrolysis, neutralization, and cooling to obtain the product alkylbenzene sulfonate. The difference between this example and Example 1 is that the mixed olefin ratio is 15% tetradecanene, 25% hexadecene, and 55% octadecene; the remaining process parameters are the same as in Example 1. The process and feed parameters are basically the same as in Example 1. The main indicator parameters of the product in this example are shown in Table 3-1.

[0050] Table 3-1. Product Specifications

[0051]

[0052] Note: When the proportion of octadecene reaches a maximum of 55%, the oil-water interfacial tension can be as low as 0.007 mN / m.

[0053] Example 4: A preparation process for an oil-displacement modified alkylbenzene sulfonate, comprising the following preparation steps:

[0054] Similar to Example 1, SO3 diluted with dry air flows into the sulfonation system at a rate of 900 kg / h. The mixed raw materials are evenly distributed in each tube of the sulfonator at a flow rate of 2700-2800 kg / h, and sulfonate with the SO3 mixture entering the sulfonator. The sulfonated ester enters the aging system for aging, and then undergoes hydrolysis, neutralization, and cooling to obtain the product alkylbenzene sulfonate. The difference between this example and Example 1 is that the amount of mixed olefins added is 8% (i.e., the mass ratio of alkylbenzene to mixed olefins is 92:8). The process and feeding parameters are basically the same as in Example 1. The main indicator parameters of the product in this example are shown in Table 4-1.

[0055] Table 4-1. Product Specifications

[0056]

[0057] Note: When the amount of mixed olefins added is reduced, the salt tolerance decreases to 150,000 mg / L, but it is still better than conventional products.

[0058] The oil-displacement modified alkylbenzene sulfonates obtained in the embodiments of this application have an average equivalent range of 380-460.

[0059] Comparative Example 1: A preparation process for an oil-displacement modified alkylbenzene sulfonate includes the following preparation steps:

[0060] For ease of comparison, this comparative example provides a conventional synthesis process for alkylbenzene sulfonates. The feed and process parameters are basically the same as in Example 1, except that no olefin is added; that is, the organic material is pure C12-C14 alkylbenzene. The main performance parameters of the product in this comparative example are shown in Table 5-1.

[0061] Table 5-1. Product Specifications

[0062]

[0063] Table 6. Performance Indicators of Examples and Comparative Examples

[0064]

[0065] Oil displacement effect under high temperature and high salinity reservoir conditions:

[0066] To further verify the actual oil displacement effect of the product of this invention under simulated high-temperature and high-salinity reservoir conditions, core displacement experiments were conducted using the modified alkylbenzene sulfonate product prepared in the above examples. Saturated oil, water flooding, chemical flooding (0.3 PV injection), and subsequent water flooding were performed according to petroleum industry standards. Specific experimental conditions were as follows: simulated homogeneous artificial core, gas permeability 500 × 10⁻⁶. -3 μm², pore volume (PV) approximately 60 cm³. Experimental temperature set at 85℃ (simulating a high-temperature oil reservoir), simulated formation water (total salinity 50,000 mg / L). , The concentration was 2000 mg / L, and the simulated oil viscosity was 10 mPa·s (at 85°C). The chemical flooding system used was 0.3 wt% of the modified alkylbenzene sulfonate of this invention, with the addition of 0.6~0.8 wt% of a weak base system.

[0067] Table 7. Oil displacement effect of the examples and comparative examples

[0068]

[0069] Results Analysis: Under simulated high-temperature (85℃) and high-salinity (50,000 mg / L) reservoir conditions, the modified alkylbenzene sulfonate flooding system prepared in this invention can increase crude oil recovery by more than 20% compared to water flooding in core samples, with a final recovery rate of at least 62%. These experimental results strongly demonstrate that the product of this invention not only achieves ultra-low interfacial tension but also effectively activates residual oil under these extreme reservoir conditions, achieving a highly efficient oil displacement effect.

[0070] The above experiments demonstrate that this invention, by incorporating olefins into alkylbenzene feedstock and optimizing sulfonation process parameters, can prepare a modified alkylbenzene sulfonate suitable for high-temperature, high-salinity oil reservoir conditions, particularly effective against Na+. + Ca 2+ It has a salt tolerance of up to 200,000 mg / L, and at the same time, it can stably reduce the oil-water interfacial tension to below 0.01 mN / m, achieving a high oil displacement effect, and all indicators meet the quality requirements.

[0071] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A preparation process for an oil-displacement modified alkylbenzene sulfonate, characterized in that, Alkylbenzene is mixed with a mixed olefin and then subjected to sulfonation, aging, hydrolysis and neutralization to prepare oil-displacement modified alkylbenzene sulfonic acid; wherein the mixed olefin is a C14-C18 olefin, and the proportion of octadecene in the mixed olefin is 30-55 wt%.

2. The preparation process of an oil-displacement modified alkylbenzene sulfonate according to claim 1, characterized in that, Alkylbenzenes are C12-C14 straight-chain alkylbenzenes.

3. The preparation process of an oil-displacement modified alkylbenzene sulfonate according to claim 1, characterized in that, The amount of C14-C18 mixed olefins added is 8%-12%.

4. The preparation process of an oil-displacement modified alkylbenzene sulfonate according to claim 1, characterized in that, The preparation process includes the following: S1 mixes alkylbenzene with mixed olefins to obtain a mixed organic material, which is then mixed with diluted... The gas undergoes a sulfonation reaction. The molar ratio of the organic material to the mixed organic material is 1:1-1.5; After the S2 sulfonation reaction is completed, an aging treatment is performed. The material aged by S3 is subjected to hydrolysis, and the hydrolyzed sulfonic acid is neutralized to obtain modified alkylbenzene sulfonate.

5. The preparation process of an oil-displacement modified alkylbenzene sulfonate according to claim 1, characterized in that, In step S2, the aging temperature is 50-60℃ and the aging time is 35-40 minutes.

6. An oil-displacement modified alkylbenzene sulfonate obtained by the preparation process according to any one of claims 1-5, characterized in that, Its average equivalent is 380-460.

7. The oil-displacing modified alkylbenzene sulfonate according to claim 6, characterized in that, At 45℃, for Na + / Ca 2+ Salt tolerance: 150,000-200,000 mg / L.

8. The oil-displacement modified alkylbenzene sulfonate according to claim 7 or 6, characterized in that, At 85℃, the simulated formation water with a salinity of 150,000 mg / L showed a stable oil-water interfacial tension of less than 0.01 mN / m.

9. The modified alkylbenzene sulfonate according to claim 8, characterized in that, In core displacement experiments, it can increase oil recovery by more than 20% compared to waterflooding.

10. The application of an oil-displacement modified alkylbenzene sulfonate obtained by the preparation process according to any one of claims 1-5 or the oil-displacement modified alkylbenzene sulfonate according to any one of claims 6-9 in oil and gas resource exploitation.

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