CN104818008A - Vesicle oil-displacing agent formed by anionic surfactant compounded system and application thereof - Google Patents

Abstract

The invention relates to a vesicle oil-displacing agent formed by an anionic surfactant compounded system. The vesicle oil-displacing agent is prepared by mixing a surfactant B, a surfactant C and mineralized water and stirring a mixture under the trigger of an auxiliary agent. Mass concentration of the surfactant B and the surfactant C is 0.3-0.8 wt%. The ratio of the addition amount of the auxiliary agent to the total mass of the surfactants B and C is 1:3-5. Total salinity of the mineralized water is 500-5000 ppm. The vesicle oil-displacing agent of the anionic surfactant compounded system has strong oil-water interface adsorption tendency. By in-situ assembling, a predetermined interface layer is formed. Thus, interfacial tension can be rapidly reduced to an ultralow level by oil-water. Without any alkali, 10<-3>mN.m<-1> of ultralow interfacial tension can be formed with crude oil. The effect of reducing the oil-water interfacial tension is prominent, and the action time is short. The interfacial tension can be reduced to 10<-3>mN.m<-1> within 10-15 min. The vesicle oil-displacing agent is suitable for tertiary oil recovery for enhancing crude oil recovery.

Description

A kind of vesicle oil displacement agent formed by anionic surfactant complex system and its application

technical field

The invention relates to a vesicle oil displacement agent formed by an anionic surfactant compound system, which can rapidly reduce the interfacial tension of oil and water to ultra-low (10 ^-3 mN·m ^-1 ), and is applied in tertiary oil recovery to improve crude oil recovery The rate belongs to the technical field of oil field chemistry.

Background technique

Petroleum is a very important non-renewable resource. With the rapid economic growth, the society's demand for oil has risen sharply, and the possibility of rediscovering large reserves of oil reservoirs has decreased, making the improvement of the recovery rate of developed oil fields attract much attention. It is imminent to adopt technical means to improve the recovery factor of developed oilfields.

During oil production, the fluid flow in the reservoir is affected by geological factors such as reservoir sandstone pore structure and system wettability, as well as factors such as crude oil/water interfacial tension. Because the surfactant has interfacial activity, it can significantly reduce the oil/water interfacial tension, increase the capillary number, and promote the desorption and effective dispersion of crude oil from the rock, so as to effectively drive the residual oil and improve the recovery factor. The most commonly used oil repellant. To reduce the oil-water interfacial tension to an ultra-low 10 ^-3 mN·m ^-1 is an important index for screening surfactants as chemical oil displacement agents.

It is well known that under different conditions, surfactants can form various association structures in aqueous solution, such as micelles, microemulsions, liquid crystals, and vesicles. According to existing literature reports, micelles and microemulsions formed by surfactants with specific compositions can reduce the oil-water interfacial tension to an ultra-low 10 ^-3 mN·m ^-1 , which can be used as oil displacement agents to enhance oil recovery There have been a lot of reports on the relevant mechanism research and system exploration, and good results have been achieved in field applications. It is also reported in the literature that the liquid crystal system formed by surfactants can reduce the oil-water interfacial tension to an ultra-low 10 ^-3 mN·m ^-1 , but its application in tertiary oil recovery is limited due to the high concentration of surfactants used in the formation of liquid crystals . At present, there have been reports on the theoretical research of vesicles in the frontier fields of simulating biomembranes, drug carriers, and preparing nanomaterials, but their application potential in industrial applications has not been revealed, and there is no report on the application in tertiary oil recovery.

At present, the development potential of high-salt oil reservoirs is great, but due to the challenge brought by high salinity to the salt resistance of surfactants, most surfactant systems cannot be formed under high-salt conditions, which can reduce the interfacial tension of oil and water. Ultra-low micelles or microemulsions, which can be applied to high-salt reservoirs to enhance oil recovery systems and related technologies are seriously lacking.

Contents of the invention

Aiming at the deficiencies of the prior art, the present invention provides a vesicle oil-displacing agent formed from an anionic surfactant compound system. The vesicle oil-displacing agent can reduce the oil-water interfacial tension to an ultra-low level, and is suitable for tertiary oil recovery to improve crude oil recovery factor. The anionic surfactant compound system vesicle oil displacement agent of the present invention has good adaptability to mineralized water, can also form vesicles under high-salt conditions, and can further reduce interfacial tension, and is especially suitable for high-salt applications Oil reservoir enhanced oil recovery.

Technical scheme of the present invention is as follows:

A vesicular oil displacing agent formed by an anionic surfactant compound system, characterized in that, after mixing surfactant B, surfactant C and mineralized water, at a temperature of 20-30° C. Under stirring for 0.2 to 0.5 hours to prepare the vesicle oil displacing agent,

In the prepared vesicle oil displacement agent, the total mass concentration of surfactant B and surfactant C is 0.3%-0.8wt%, and the mass ratio of surfactant B:surfactant C is (1-5):( 5~1), the ratio of the amount of additives added to the total mass of surfactant B and surfactant C is: 1:3~5, the total salinity of mineralized water is 500~5000ppm,

The surfactant B molecule contains at least one negatively charged polar hydrophilic group and a hydrophobic group with a total carbon chain length of C8-C24, and the hydrophobic group contains two branched chains;

The surfactant C molecule contains at least one negatively charged polar hydrophilic group and a hydrophobic group with a carbon chain length of C8-C24, and the hydrophobic group is a single chain;

The auxiliary agent is a carboxylic acid with a carbon chain length of C6-C18 and 1-3 carboxyl groups in the molecule.

Preferably in the present invention, the surfactant B is selected from branched alkyl sulfates, branched alkyl polyoxyethylene ethers, branched alkyl sulfonates or branched alkyl carboxylates.

Further preferably, the surfactant B is branched-chain sodium lauryl sulfate, branched-chain lauryl polyoxyethylene ether, branched-chain sodium dodecylsulfonate or branched-chain sodium dodecyl carboxylate.

Preferably in the present invention, the surfactant C is selected from alkylbenzene sulfonate, alkyl sulfate, α-olefin sulfonate, petroleum sulfonate or fatty acid ethyl ester sulfonate.

Further preferably, the surfactant C is sodium dodecylbenzene sulfonate, sodium dodecyl sulfate, sodium α-olefin sulfonate, sodium petroleum sulfonate or sodium fatty acid ethyl ester sulfonate.

Preferably in the present invention, the auxiliary agent is selected from one or more mixtures of citric acid, higher fatty acid or oxalic acid.

Further preferably, the additives are citric acid and oleic acid, and the mass ratio of citric acid to oleic acid is 1:2.

Preferably in the present invention, surfactant B: the mass ratio of surfactant C is (3～5):(1～3), the addition of auxiliary agent and surfactant B and surfactant C total mass ratio are: 1: 4~5.

Preferably in the present invention, in the prepared vesicle oil displacement agent, the total mass concentration of the surfactant B and the surfactant C is 0.5%-0.6wt%, and the total salinity of the mineralized water is 1000-4000ppm.

The application of the vesicle oil displacement agent formed by the above-mentioned anionic surfactant compound system is applied to low permeability reservoirs, carbonate reservoirs, and conventional sandstone reservoirs in the late stage of high water cut or to enhance oil recovery after polymer injection. The salinity range that the oil displacement agent can tolerate is: the total salinity is 1-30,000ppm, and the total concentration of calcium and magnesium ions is 1-1,000ppm.

The technical characteristics and beneficial effects of the vesicle oil displacement agent formed by the anionic surfactant compound system of the present invention:

Surfactant B and surfactant C of the present invention form vesicles under the induction of calcium and magnesium ions and auxiliary agents. The vesicles have a strong adsorption tendency at the oil-water interface, and the in-situ assembly forms a predetermined interface layer, which reduces the oil-water interfacial tension to an ultra-low, lower than 10 ^-3 mN·m ^-1 . After induction of adsorption on the interface, the newly assembled The resulting interfacial layer is mainly composed of external surfactants and additive molecules, which is less affected by the composition of crude oil and has universal oil phase properties, so it has good reservoir adaptability. Surfactant B and Surfactant C undergo interface self-assembly under the induction of calcium and magnesium ions to spontaneously form vesicles, avoiding the precipitation of surfactant molecules and inorganic cations, and improving the salt resistance of surfactants. Therefore, the vesicles The oil displacement agent has good adaptability to formation mineralized water. In addition, due to the strong adsorption tendency of the selected surfactant interface, the oil/water interfacial tension quickly drops to ultra-low, and the use concentration is low.

(1) The vesicle oil displacement agent formed by the anionic surfactant compound system of the present invention has a strong oil-water interface adsorption tendency, and is assembled in situ to form a predetermined interface layer, so that the oil-water can quickly reduce the interfacial tension to ultra-low, It can form an ultra-low interfacial tension of 10 ^-3 mN·m ^-1 with crude oil without any alkali, and has an outstanding effect in reducing the interfacial tension of oil/water. The action time is short, and the interfacial tension can be reduced to 10 within 10-15 minutes ^-3 mN·m ^-1 .

(2) The use concentration is low, and it has strong adaptability to oil phases with different compositions, which is conducive to ensuring the effect of improving the recovery rate of the third recovery.

(3) The vesicle oil displacement agent of the anionic surfactant compound system of the present invention can still reduce the interfacial tension preferably at a higher salinity, has good salt resistance, and has good thermal stability, and is effective in improving high-salt oil It has a great application prospect in the aspect of reservoir recovery.

(4) The anionic surfactant complex system of the present invention can also form a binary composite oil displacement system with a polymer, which not only reduces the oil-water interfacial tension, but also increases the viscosity of the oil displacement agent, thereby greatly increasing the recovery factor.

(5) The process of the present invention is simple, the reaction is easy to control, and the application range is wide.

Description of drawings

Fig. 1 is the transmission electron micrograph of the vesicle oil displacement agent that embodiment 1 makes;

Fig. 2 is the transmission electron micrograph of the vesicle oil displacement agent that embodiment 2 makes;

detailed description

The present invention will be further described below in conjunction with the embodiments and accompanying drawings, but not limited thereto.

Example 1:

A vesicular oil displacing agent formed by an anionic surfactant compound system, after mixing surfactant B, surfactant C and mineralized water with a total salinity of 500ppm, at a temperature of 25°C, in the presence of additives The vesicle oil displacement agent was prepared by stirring for 0.3 h under triggering, and the mineralized water ions were composed of calcium ions and magnesium ions.

In the obtained vesicle oil displacement agent, the total mass concentration of surfactant B and surfactant C is 0.5wt%, the mass ratio of surfactant B:surfactant C is 1:3, and the addition amount of auxiliary agent is the same as The total mass ratio of surfactant B and surfactant C is: 1:3,

Described surfactant B is branched chain sodium lauryl sulfate,

Described surfactant C is sodium dodecylbenzenesulfonate,

The auxiliary agents are citric acid and oleic acid, and the mass ratio of citric acid to oleic acid is 1:2. The scanning electron microscope image of the prepared anionic surfactant complex system vesicle oil displacement agent is shown in Fig. 1 .

The product is tested for interfacial tension:

1. Test instrument: TEXAS-500 spinning drop interfacial tensiometer

2. Temperature: 50°C,

3. Crude oil: experimental standard crude oil (provided by Shengli Oilfield)

4. Water: distilled water

5. Vesicle oil displacing agent: Example 1, main component (w%)

Put the sample tube filled with the above-mentioned solution into it, and after stabilizing for half an hour, add about 1 microliter of Shengtuotuokou crude oil from Shengli Oilfield with a micro-syringe, and read the interfacial tension at regular intervals according to the national standard SY/T5370-1999 method. The interfacial tension reached 0.00458mN/m within 10 minutes.

The effects of different concentrations of vesicle oil displacement agents on interfacial tension are shown in Table 1:

Table 1

Vesicle displacement agent concentration (w%) Interfacial tension (mN·m ^-1 ) 0.3 0.156 0.4 0.115 0.5 0.00458 0.55 0.0045 0.6 0.00442 0.65 0.00418 0.7 0.00397

Example 2:

A vesicular oil displacing agent formed by an anionic surfactant compound system, after mixing surfactant B, surfactant C and mineralized water with a total salinity of 1000ppm, at a temperature of 30°C, in the presence of additives The vesicle oil displacement agent was prepared by stirring for 0.5 h under triggering, and the mineralized water ions were composed of calcium ions and magnesium ions.

In the prepared vesicle oil displacement agent, the total mass concentration of surfactant B and surfactant C is 0.6wt%, the mass ratio of surfactant B:surfactant C is 4:1, and the addition amount of auxiliary agent is the same as The total mass ratio of surfactant B and surfactant C is: 1:5,

Described surfactant B is branched chain lauryl polyoxyethylene ether,

Described surfactant C is sodium lauryl sulfate,

The auxiliary agents are citric acid and oleic acid, and the mass ratio of citric acid to oleic acid is 1:2. The scanning electron microscope image of the prepared anionic surfactant complex system vesicle oil displacement agent is shown in Fig. 2 .

The product is carried out interfacial tension test, and the test instrument, crude oil, water, temperature used are the same as embodiment 1;

Vesicle oil displacing agent: embodiment 2, main component (w%)

Put the sample tube filled with the above-mentioned solution into it, and after stabilizing for half an hour, add about 1 microliter of Shengtuotuokou crude oil from Shengli Oilfield with a micro-syringe, and read the interfacial tension at regular intervals according to the national standard SY/T5370-1999 method. The interfacial tension reached 0.00843mN/m within 15 minutes.

The results of the effects of different concentrations of vesicle oil displacement agents on interfacial tension are shown in Table 2:

Table 2

Vesicle displacement agent concentration (w%) Interfacial tension (mN·m ^-1 ) 0.4 0.135 0.5 0.103 0.6 0.00843 0.65 0.00816 0.7 0.0080 0.75 0.00795 0.8 0.00784

Example 3:

A vesicular oil displacing agent formed by an anionic surfactant compound system, after mixing surfactant B, surfactant C and mineralized water with a total salinity of 2500ppm, at a temperature of 30°C, in the presence of additives The vesicle oil displacement agent was prepared by stirring for 0.4 h under triggering, and the mineralized water ions were composed of calcium ions and magnesium ions.

In the obtained vesicle oil displacement agent, the total mass concentration of surfactant B and surfactant C is 0.4wt%, the mass ratio of surfactant B:surfactant C is 1:1, and the addition amount of auxiliary agent is the same as The total mass ratio of surfactant B and surfactant C is: 1:4,

Described surfactant B is branched chain sodium lauryl carboxylate,

Described surfactant C is sodium α-olefin sulfonate,

The auxiliary agents are citric acid and oleic acid, and the mass ratio of citric acid to oleic acid is 1:2.

The product is carried out interfacial tension test, and the test instrument, crude oil, water, temperature used are the same as embodiment 1;

Vesicle oil displacing agent: embodiment 3, main component (w%)

The effects of different concentrations of vesicle oil displacement agents on interfacial tension are shown in Table 3:

table 3

Vesicle displacement agent concentration (w%) Interfacial tension (mN·m ^-1 ) 0.15 0.0187 0.2 0.0168 0.3 0.0102 0.4 0.00624 0.45 0.00603 0.5 0.00588 0.6 0.00574

Comparative Example 1: Commercially available branched chain sodium lauryl sulfate

Comparative example 2: commercially available sodium dodecylbenzenesulfonate

Salt resistance test:

The surface tension of the vesicle displacement agent of Examples 1-3 and Comparative Examples 1 and 2 was measured with simulated formation water under the same conditions, and the test results are shown in Table 5:

Table 4 Composition of simulated formation water

Table 5 The interfacial tension of the vesicle displacement agents of Examples 1-3 and Comparative Examples 1 and 2 to simulated formation water

product Interfacial tension (mN·m ^-1 ) Example 1 0.00458 Example 2 0.00843 Example 3 0.00624 Comparative example 1 0.0125 Comparative example 2 0.0157

Result: As can be seen from Table 5, under the condition that the salinity is greater than 30000 mg/L, the vesicle oil displacement agents of Examples 1-3 of the present invention have ultra-low surface tension, while Comparative Examples 1 and 2 are under high-salt conditions , does not have surface activity, the invention has better salt resistance, and can meet the use requirements of high-salt oil reservoirs.

Claims (10)

1. an anion surfactant compound system vesica oil-displacing agent, is characterized in that, after being mixed with mineralized water by surfactant B, tensio-active agent C, in temperature 20-30 DEG C, stir 0.2 ~ 0.5h under initiation at auxiliary agent and obtain vesica oil-displacing agent,

In obtained vesica oil-displacing agent, the total mass concentration of surfactant B and tensio-active agent C is 0.3% ~ 0.8wt%, surfactant B: the mass ratio of tensio-active agent C is (1 ~ 5): (5 ~ 1), the add-on of auxiliary agent and surfactant B and tensio-active agent C total mass ratio are: 1:3 ~ 5, the total mineralization of mineralized water is 500 ~ 5000ppm

Be the hydrophobic grouping of C8-C24 containing at least one electronegative polar hydrophilic group and a total carbon chain lengths in described surfactant B molecule, described hydrophobic grouping contains two side chains;

Be the hydrophobic grouping of C8-C24 containing at least one electronegative polar hydrophilic group and a carbon chain lengths in described tensio-active agent C molecule, described hydrophobic grouping is strand;

Described auxiliary agent is the carboxylic acid containing 1-3 carboxyl in carbon chain lengths C6-C18, molecule.

2. anion surfactant compound system vesica oil-displacing agent according to claim 1, it is characterized in that, surfactant B is selected from collateralization alkyl-sulphate, collateralization alkyl polyoxyethylene ether, collateralization alkylsulfonate or collateralization alkyl carboxylate.

3. anion surfactant compound system vesica oil-displacing agent according to claim 2, it is characterized in that, surfactant B is branched dodecyl sodium sulfate, branched dodecyl Soxylat A 25-7, branched dodecyl sodium sulfonate or branched dodecyl carboxylic acid sodium.

4. anion surfactant compound system vesica oil-displacing agent according to claim 1, it is characterized in that, tensio-active agent C is selected from alkylbenzene sulfonate, alkyl-sulphate, sulfonated α-olefin, sulfonated petro-leum or fatty-acid ethyl ester sulfonate.

5. anion surfactant compound system vesica oil-displacing agent according to claim 4, is characterized in that, tensio-active agent C is Sodium dodecylbenzene sulfonate, sodium lauryl sulphate, alpha-olefin sodium sulfonate, petroleum sodium sulfonate or fatty-acid ethyl ester sodium sulfonate.

6. anion surfactant compound system vesica oil-displacing agent according to claim 1, it is characterized in that, auxiliary agent is selected from one or more the mixture in citric acid, higher fatty acid or oxalic acid.

7. anion surfactant compound system vesica oil-displacing agent according to claim 6, it is characterized in that, auxiliary agent is citric acid and oleic acid, and the mass ratio of citric acid and oleic acid is: 1:2.

8. anion surfactant compound system vesica oil-displacing agent according to claim 1, it is characterized in that, surfactant B: the mass ratio of tensio-active agent C is (3 ~ 5): (1 ~ 3), the add-on of auxiliary agent and surfactant B and tensio-active agent C total mass ratio are: 1:4 ~ 5.

9. anion surfactant compound system vesica oil-displacing agent according to claim 1, it is characterized in that, in obtained vesica oil-displacing agent, the total mass concentration of surfactant B and tensio-active agent C is 0.5% ~ 0.6wt%, and the total mineralization of mineralized water is 1000 ~ 4000ppm.

10. the application of the compound system vesica oil-displacing agent of anion surfactant according to claim 1, recovery ratio is improved after being applied to low-permeability oil deposit, carbonate oil reservoir, conventional sandstone oil reservoir late high water content period or polymer injection, the salinity range of vesica oil-displacing agent tolerance is: total mineralization 1-30,000ppm, calcium ions and magnesium ions total concn 1-1,000ppm.