A biosurfactant compound foam oil displacement agent and its preparation and application

Abstract

The application discloses a kind of biosurfactant compound foam oil displacement agent and its preparation method and application, belong to the technical field of oil exploitation.The foam oil displacement agent is composed of the following components by mass percentage: rhamnolipid 15~35%, sophorolipid 10~25%, functional additive A 5~15%, functional additive B 3~10%, synergistic agent 2~8%, and the balance is deionized water to 100%;The mass ratio of rhamnolipid and sophorolipid is 1.3~1.5:1.The application also provides the preparation method and application of the oil displacement agent.The foam oil displacement agent of the application has the characteristics of large foaming volume, long foam half-life, excellent temperature resistance and salt resistance, high biodegradation rate, mild and simple preparation process, and is suitable for three times oil recovery in reservoir with temperature ≤120℃, salinity ≤30×10 4 mg / L, which can significantly improve the oil recovery rate and meet the requirements of green oilfield construction.

Description

Technical Field

[0001] This invention belongs to the field of petroleum extraction technology, specifically relating to a bio-foam flooding agent for improving crude oil recovery, particularly to a bio-surfactant compound foam flooding agent and its preparation method, as well as the application of the foam flooding agent in tertiary oil recovery in oil fields. Background Technology

[0002] As oilfield development enters its mid-to-late stages, the recovery rates of primary and secondary oil recovery are nearing their technical limits, with most oilfields achieving only 30% to 40% recovery, leaving a large amount of crude oil trapped in reservoir pores. Among tertiary oil recovery technologies, foam flooding has become a research hotspot in recent years due to its advantages such as reducing mobility ratio, increasing swept volume, and blocking high-permeability channels. The core of foam flooding is the foam flooding agent, whose performance directly determines the oil displacement effect.

[0003] Currently, most foam flooding agents widely used in oilfields are chemical surfactants, which have the following prominent problems: First, they are costly, and large-scale field applications are economically burdensome; second, they have poor biodegradability, and long-term use can easily cause soil and groundwater pollution; third, they have limited temperature and salt resistance, and the foam is prone to breakage in high-temperature and high-salt reservoirs; and fourth, they are highly corrosive to oilfield equipment.

[0004] To address the environmental concerns associated with chemical foam displacement agents, the industry has gradually explored the use of biosurfactants such as rhamnolipids and sophorolipids. However, single biosurfactants have significant performance limitations: rhamnolipids alone exhibit poor foam stability, and sophorolipids alone have insufficient foaming capacity. Existing compounding technologies suffer from issues such as illogical compounding logic, insignificant synergistic effects, complex preparation processes, and poor on-site adaptability. Currently, bio-foam displacement agents possessing high foaming capacity, high stability, excellent temperature and salt resistance, and environmentally friendly biodegradability are still under development. Summary of the Invention

[0005] This invention provides a biosurfactant compound foam flooding agent, its preparation method and application. The flooding agent has high foaming properties, high stability, excellent temperature and salt resistance, and environmentally friendly and biodegradable characteristics, and can be applied to improve the recovery rate in tertiary oil recovery in oil fields.

[0006] A compound foam oil displacement agent composed of biosurfactants comprises the following components by mass percentage: rhamnolipin 15-35%, preferably 20-30%; sophorolipid 10-25%, preferably 15-20%; functional additive A 5-15%, preferably 8-12%; functional additive B 3-10%, preferably 5-8%; synergist 2-8%, preferably 3-5%; and the balance being deionized water, to be made up to 100%.

[0007] In the aforementioned compound foam oil displacement agent based on biosurfactants, the mass ratio of rhamnolipin to sophorolipid is 1.3~1.5:1.

[0008] In the aforementioned biosurfactant compound foam oil displacement agent, the functional additive A is composed of the following components by mass percentage: 40-50% nano-silica modifier, 30-40% cellulose derivative, and 10-20% polyphenolic compound.

[0009] In the aforementioned biosurfactant compound foam oil displacement agent, the functional additive B is composed of the following components by mass percentage: 50-60% betaine amphoteric surfactant, 25-35% polyethylene glycol derivative, and 10-20% organophosphonate.

[0010] In the aforementioned compound foam oil displacement agent based on biosurfactants, the synergistic agent is composed of the following components by mass percentage: 40-50% tea saponin, 30-40% Sapindus mukorossi extract, and 10-20% soybean lecithin.

[0011] The preparation method of the aforementioned biosurfactant compound foam oil displacement agent includes the following steps: 1. Pretreatment: Mix rhamnolipin and sophorolipid in proportion, add to a reaction vessel with stirring and temperature control function, add 30% of the total amount of deionized water, control the temperature at 30~40℃, stir at 300~500rpm for 20~30 minutes, and let stand for 2~4 hours to mature. 2. Additive compounding: Add functional additive A and functional additive B to the product obtained in step 1 after premixing. Control the temperature at 40~50℃ and shear and stir at a high speed of 500~800rpm for 15~20 minutes. Add the synergist and continue stirring for 10~15 minutes. 3. Post-treatment: Add deionized water to the total mass of the system to 100%, adjust the pH value to 6.5~7.5, filter with a 200-mesh filter to remove impurities, fill and seal to obtain the finished product.

[0012] Based on the aforementioned application of a biosurfactant-based foam oil displacement agent, it is suitable for temperatures ≤120℃ and mineralization ≤30×10⁻⁶. 4 Tertiary oil recovery is performed on reservoirs with a concentration of mg / L; the injection concentration is 0.3~0.8%, the slug size is 0.2~0.5PV, the injection rate is 40~60m³ / d, and 0.5~0.8PV of deionized water is subsequently injected for water flooding. Beneficial effects

[0013] Compared with the prior art, the present invention has the following significant advantages: 1. This invention compensates for the shortcomings of poor foam stability of rhamnolipin and insufficient foaming ability of sophorolipid by optimizing the mass ratio of rhamnolipin to sophorolipid to 1.3~1.5:1, thereby achieving a synergistic foaming and foam stabilizing effect of the two. 2. The functional additives A and B and the synergistic synergist compound system of the present invention significantly improve the temperature and salt resistance of the oil displacement agent, and can be applied to temperatures ≤120℃ and salinity ≤30×10⁻⁶. 4 High-temperature and high-salinity oil reservoirs with mg / L have solved the problem of limited temperature and salt resistance of traditional chemical flooding agents; 3. This invention uses biosurfactants as the core, and the biodegradability rate of the oil displacement agent is ≥90%, which solves the problems of poor biodegradability and easy environmental pollution caused by traditional chemical oil displacement agents. Moreover, the raw material cost is lower than that of pure chemical surfactants, which reduces the economic burden of large-scale field application. 4. The preparation process of this invention is mild, does not require high temperature and high pressure conditions, the steps are simple and easy to operate, and it is non-corrosive to oilfield equipment, thus solving the problem of strong corrosion of equipment by traditional oil displacement agents; 5. When the oil displacement agent of the present invention is applied in the field, it can increase the crude oil recovery rate by more than 18% compared with water drive, with a high input-output ratio and significant economic benefits. Detailed Implementation

[0014] Example 1 Formula composition (100kg product): rhamnolipin (90% purity) 25kg, sophorolipid (85% purity) 18kg, functional additive A 10kg (nano-silica modified material 4.5kg, cellulose derivative 4kg, polyphenolic compound 1.5kg), functional additive B 6kg (betaine amphoteric surfactant 3.6kg, polyethylene glycol derivative 1.8kg, organophosphonate 0.6kg), synergist 4kg (tea saponin 2kg, soapberry extract 1.2kg, soybean lecithin 0.8kg), deionized water 37kg.

[0015] Preparation process: Pretreatment temperature 35℃, add 30kg deionized water, stir at 400rpm for 25 minutes, let stand and mature for 3 hours; Additive compounding temperature 45℃, high-speed shearing and stirring at 600rpm for 18 minutes, add synergistic agent and stir for 12 minutes; Posttreatment add deionized water to 100kg, adjust pH to 7.0, filter with 200 mesh filter.

[0016] Example 2 Formula composition (100kg product): rhamnolipin 22kg, sophorolipid 16kg, functional additive A 14kg (nano-silica modified material 6.3kg, cellulose derivative 5.6kg, polyphenolic compounds 2.1kg), functional additive B 5kg (betaine amphoteric surfactant 3kg, polyethylene glycol derivative 1.75kg, organophosphonate 0.25kg), synergist 3kg (tea saponin 1.5kg, Sapindus mukorossi extract 0.9kg, soybean lecithin 0.6kg), deionized water 40kg. The preparation process is the same as in Example 1, with a pretreatment temperature of 40℃, an additive compounding temperature of 50℃, and a high-speed shear stirring time of 20 minutes; the remaining steps remain unchanged.

[0017] Example 3 Formula composition (100kg product): rhamnolipid 28kg, sophorolipid 20kg, functional additive A 8kg (nano-silica modified material 3.6kg, cellulose derivative 3.2kg, polyphenolic compound 1.2kg), functional additive B 10kg (betaine amphoteric surfactant 6kg, polyethylene glycol derivative 3.5kg, organophosphonate 0.5kg), synergist 5kg (tea saponin 2.5kg, Sapindus mukorossi extract 2kg, soybean lecithin 0.5kg), deionized water 29kg. The preparation process is the same as in Example 1, except that the high-speed shear stirring speed is 800 rpm and the stirring time is 15 minutes when compounding the additives; the remaining steps remain unchanged.

[0018] Table 1 Summary of performance test results for Examples 1-3 Test Project Example 1 Example 2 Example 3 Foaming volume (mL) 580 550 520 Foam half-life (minutes) 52 45 40 Surface tension (mN / m) 28.5 29.2 28.8 Temperature resistance (°C) 110 120 105 <![CDATA[Salt tolerance (×10 4 mg / L)]]> 28 25 35 Biodegradation rate (%) 92 91 90 Note: Foam volume and foam half-life were tested according to GB / T 7462-1994 Determination of foaming power of surfactants - Modified Ross-Miles method; surface tension was tested according to GB / T 22237-2008 Determination of surface tension of surfactants; temperature resistance and salt resistance were determined according to the methods in SY / T 7494-2020 Test evaluation method for foaming agents used in oil and gas fields; biodegradability was tested according to the OECD 301B carbon dioxide generation method standard.

[0019] Example 4: Field Application Test Case Test location: A block in Shengli Oilfield.

[0020] Reservoir conditions: reservoir temperature 85℃, salinity 18×10⁻⁶ 4 mg / L, crude oil viscosity 450 mPa·s, permeability 500 mD, number of test wells: 3 production wells and 1 injection well.

[0021] Injection scheme: The formulation of Example 1 was used, diluted to an injection concentration of 0.5%, with a slug size of 0.3 PV and an injection rate of 50 m³ / d. Subsequent water flooding with 0.7 PV of deionized water was used to maintain reservoir pressure. The test period was 220 days.

[0022] Test results: The crude oil recovery rate increased by 18.5% compared with water drive (water drive recovery rate 32%, total recovery rate after the test 50.5%), the cumulative oil production increased by 2,124 tons (average increase of 708 tons per well), the water cut of the oil well decreased from 93% to 75%, the oil displacement effective period was 200 days, and the input-output ratio was 1:18.2.

[0023] Experimental conclusion: The bio-foam oil displacement agent of the present invention has significant field application effects, can effectively improve crude oil recovery rate, reduce oil well water cut, and has a long effective period and outstanding economic benefits, fully meeting the needs of field industrial application.

Claims

1. A biosurfactant compound foam oil displacement agent, characterized in that, It is composed of the following components by mass percentage: rhamnolipin 15-35%, sophorolipid 10-25%, functional additive A 5-15%, functional additive B 3-10%, synergist 2-8%, and deionized water to make up to 100%; the mass ratio of rhamnolipin to sophorolipid is 1.3-1.5:

1.

2. The biosurfactant compound foam oil displacement agent according to claim 1, characterized in that, The functional additive A is composed of the following components by mass percentage: 40-50% nano-silica modifier, 30-40% cellulose derivative, and 10-20% polyphenolic compound.

3. The biosurfactant compound foam oil displacement agent according to claim 1, characterized in that, The functional additive B is composed of the following components by mass percentage: 50-60% betaine-based amphoteric surfactant, 25-35% polyethylene glycol derivative, and 10-20% organophosphonate.

4. The biosurfactant compound foam oil displacement agent according to claim 1, characterized in that, The synergistic agent is composed of the following components by weight percentage: 40-50% tea saponin, 30-40% soapberry extract, and 10-20% soybean lecithin.

5. The biosurfactant compound foam oil displacement agent according to claim 1, characterized in that, The purity of the rhamnolipin is ≥90%, and the purity of the sophorolipin is ≥85%.

6. A method for preparing a biosurfactant compound foam oil displacement agent according to any one of claims 1 to 5, characterized in that, Includes the following steps: (1) Pretreatment: Mix rhamnolipin and sophorolipid in proportion, add to a reaction vessel with stirring and temperature control function, add 30% of the total amount of deionized water, control the temperature at 30~40℃, stir at 300~500rpm for 20~30 minutes, and let stand for 2~4 hours to mature. (2) Additive compounding: add functional additive A and functional additive B to the product obtained in step (1) after premixing. Control the temperature at 40~50℃ and shear and stir at a speed of 500~800rpm for 15~20 minutes. After adding the synergist, continue stirring for 10~15 minutes. (3) Post-treatment: Add deionized water to the total mass of the system to 100%, adjust the pH value to 6.5~7.5, filter impurities using a 200-mesh filter, fill and seal to obtain the finished product.

7. The application of a biosurfactant compound foam displacement agent according to any one of claims 1 to 5, characterized in that, The foam displacement agent is used in environments with temperatures ≤120℃ and salinity ≤30×10⁻⁶. 4 Tertiary oil recovery is performed on reservoirs with a concentration of mg / L; the injection concentration of the foam flooding agent is 0.3~0.8%, the slug size is 0.2~0.5PV, and the injection velocity is 40~60m. 3 / d, followed by injection of 0.5~0.8PV deionized water for water drive.