CN115011319A - Three-phase foam system for temperature resistance, salt tolerance and oil displacement and preparation method and application thereof - Google Patents

Abstract

The invention provides a temperature-resistant salt-tolerant flooding three-phase foam system and a preparation method and application thereof. The three-phase foam system for oil displacement of the invention has the foam volume of 350mL generated by 100mL of foaming liquid through a Blender-Waring method under the conditions of 80 ℃, 100000mg/L NaCl and 500mg/L calcium and magnesium ion concentration, the half-life period is 34min, and the three-phase foam system for oil displacement is used in water flooding and CO flooding ₂ After gas flooding, 0.5PV foam was injected and CO was added ₂ The final oil recovery rate of the gas flooding is 70.78%, which is improved by 39.15% compared with the water flooding. In addition, the invention can still keep the foam stability for a long time under the high temperature condition, has good tolerance to calcium and magnesium ions, effectively reduces gas channeling, starts residual oil after water flooding and gas flooding, obviously improves the recovery ratio, and is suitable for secondary development of high-temperature and high-salinity conventional sandstone oil reservoirs.

Description

A kind of three-phase foam system for oil flooding with temperature resistance and salt resistance and its preparation method and application

technical field

The invention relates to the technical field of oilfield exploration, in particular to a three-phase bubble system for oil flooding with temperature resistance and salt resistance, and a preparation method and application thereof.

Background technique

As more and more oilfields in my country enter the middle and late stages of development, the recovery factor of water injection development gradually decreases, and the water content of produced fluid gradually increases. Foam injection is an effective anti-channeling method. Its anti-channeling mechanism is mainly through the selective plugging of the high-permeability zone by the foam to achieve liquid flow diversion. At the same time, the foam has a high apparent viscosity, which can effectively control the gas-oil mobility. ratio, thereby maximizing the swept volume of the gas. But the foam itself faces the problem of poor stability under reservoir conditions, so most of the current research focuses on improving the stability of foam under harsh conditions.

In response to this problem, researchers at home and abroad have carried out a lot of research, and various foam systems such as nanoparticle-stabilized foam, organic amine-stabilized foam, polymer-stabilized foam, and carboxymethyl cellulose-stabilized foam have been proven to be used to improve recovery. rate work. However, due to limitations such as price, high temperature resistance, and salt resistance, it is difficult for the existing system to play a role in the oil field.

In view of this, the present invention provides a three-phase foam system for oil flooding with temperature resistance and salt resistance and a preparation method thereof.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a three-phase bubble system for temperature-resistant and salt-resistant oil flooding and a preparation method and application thereof in view of the above-mentioned deficiencies of the prior art.

For achieving the above object, the present invention adopts the following technical scheme:

The first object of the present invention is to provide a three-phase foam system for temperature-resistant and salt-resistant oil flooding, which is made of anionic surfactant, zwitterionic surfactant, solid phase particles, dispersant, gas and water. The number of parts by mass of the anionic surfactant is 0.3-0.7 parts, zwitterionic surfactant 0.3-0.5 parts, solid phase particles 3-7 parts, dispersant 2-5 parts, water 100 parts, the gas The volume ratio to the three-phase foam system for oil displacement is 1:1-4:1.

Further, the anionic surfactant is one or both of sodium α-olefin sulfonate (AOS) and sodium dodecylbenzene sulfonate (SDBS).

Further, the zwitterionic surfactant is cocamidopropyl hydroxysulfobetaine (CHSB).

Further, the solid phase particles are fly ash.

Further, the dispersant is sodium soil.

Further, the gas is carbon dioxide.

The second object of the present invention is to provide the preparation method of the above-mentioned temperature-resistant and salt-resistant three-phase foam system for oil flooding, comprising the following steps:

Step S1, pour a certain amount of deionized water into a beaker, add inorganic salts to the beaker, and prepare simulated formation water;

Step S2, place the beaker on the magnetic stirrer, set the first preset rotational speed, add a certain amount of anionic surfactant to the beaker in step S1, and stir until completely dissolved;

Step S3, adding a certain amount of zwitterionic surfactant to step S2, stirring until completely dissolved;

Step S4, adding a certain amount of dispersant to step S3, stirring to make it fully suspended;

Step S5, adding a certain amount of solid phase particles to step S4, stirring to make it fully suspended, to obtain a foaming liquid;

Step S6, sealing the stirred foaming liquid with plastic wrap, and placing it in an incubator for aging;

Step S7, transfer the aged foaming liquid to a high-speed mixer, set a second preset rotational speed, feed carbon dioxide into it for 10 min, set the rotational speed to 8000 r/min, and stir for 2 min, to obtain a three-phase oil drive. foam system.

Further, the first preset rotation speed is 350r/min˜400r/min, and the second preset rotation speed is 6000r/min˜8000r/min.

Further, the aging time in step S6 is 48h-60h.

The third object of the present invention is to provide the above-mentioned three-phase foam system solution for oil flooding for the preparation of oil field foam adjusting and flooding agent.

Compared with the prior art, the beneficial effects brought by the technical scheme provided by the present invention are:

(1) The three-phase foam system for oil flooding of the present invention is at 80° C., 100,000 mg/L NaCl, and 500 mg/L of calcium and magnesium ion concentration. In 34min, after water flooding and CO ₂ gas flooding, 0.5PV foam was injected and then CO ₂ gas flooding was carried out. The final crude oil recovery was 70.78% higher than that of water flooding by 39.15%. In addition, the present invention can still maintain foam stability for a long time under high temperature conditions, and has good tolerance to calcium and magnesium ions, effectively reduces gas channeling, and the residual oil after water flooding and gas flooding is activated, and the sodium ion concentration is lower than 150000mg/ When the concentration of L, calcium and magnesium ions is lower than 5000mg/L, and the temperature is lower than 120℃, the foam can be kept stable, and the recovery factor can be significantly improved. It is suitable for the secondary development of high-temperature and high-salt conventional sandstone reservoirs.

(2) The three-phase foam system for oil displacement provided by the present invention forms a gas-liquid-solid three-phase foam system by introducing solid-phase particles of fly ash, which can block high water content and high permeability areas, and make the displacement fluid It is transferred to the low-permeability and high-oil-bearing areas that have not been swept before, and can be used for the secondary development of conventional sandstone reservoirs after water flooding and gas flooding. Anionic surfactants and positively charged fly ash particles in the three-phase foam system for oil flooding can have a synergistic effect. Some anionic surfactants are adsorbed on the surface of fly ash particles, so that the hydrophobicity of fly ash particles is enhanced, and they are arranged on the gas-liquid interface instead of entering the liquid phase to enhance the stability of the foam. The suspension of fly ash is poor, and it is easy to settle after being dispersed in the solution, so it is necessary to add sodium soil as a dispersant to the system. The sodium soil is negatively charged, and the fly ash is positively charged, and the two are prone to attract. Phase foam properties.

(3) The technical conditions of the preparation method provided by the present invention are mild, simple and easy to implement, and have environmental friendliness and broad market development potential.

Description of drawings

Figure 1 is a schematic diagram of the principle of fly ash improving foam stability;

Figure 2 shows the effect of sodium soil on the suspension of fly ash; obviously, the sedimentation time of the fly ash suspension after adding sodium soil is delayed by 3 hours, the particle size of fly ash is micron, and the suspension is poor. , attached to the fly ash particles, which can effectively delay the sedimentation time of the suspension.

Figure 3 shows the experimental data of core flooding; in the foam flooding stage, the water content decreased, the injection pressure increased, and the recovery rate increased, indicating that the invention can adjust the injection profile, increase the injection pressure, and improve the recovery rate; at 80 Under the conditions of ℃, NaCl concentration of 100,000 mg/L, and calcium and magnesium ion concentration of 500 mg/L, the oil recovery rate is 39.15% higher than that of water flooding;

Fig. 4 is the foam performance comparison chart of the three-phase foam system for oil flooding prepared in Examples 1-4; obviously in different embodiments, the temperature, salinity and formula content are different, and the obtained foam performance is different, and the corresponding volume of 50mL of elution volume is different. The time is the liquid half-life, and the corresponding foam half-life of embodiment 1-4 is 34min, 31min, 25min, 19min respectively;

Figure 5 is a schematic diagram of the core flooding experimental device.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the specific embodiments of the present invention will be described in further detail below with reference to specific embodiments and accompanying drawings.

Example 1-4 Complete the determination of crude oil recovery by core flooding experiment

The schematic diagram of the core flooding experimental device is shown in Figure 5, and the specific test steps are as follows:

(1) Evacuate the core used (permeability 200mD/1600mD heterogeneous core), and then saturate the formation water.

(2) The incubator is heated to the experimental temperature, and the back pressure of the end is set to atmospheric pressure, and the ring pressure is set to 5MPa.

(3) Saturate the core with oil and age it in an incubator for 12 hours.

(4) Water flooding 1PV, _CO2 flooding 0.5PV, foam flooding 0.5PV, and subsequent _CO2 flooding 0.5PV.

(5) Foam flooding is foamed by a foam generator, and injected into the core after the foam is generated.

(6) Water flooding, CO ₂ flooding, foam flooding, and subsequent CO ₂ flooding in sequence. Record the pressure, oil production, and water production at each moment until the end of the test.

Example 1

Step S1, pour a certain amount of deionized water into a beaker, add inorganic salts to the beaker, and prepare an inorganic salt solution with a concentration of 100,000 mg/L NaCl and 500 mg/L of calcium and magnesium ions;

Step S2, place the beaker on a magnetic stirrer, set the rotating speed to 350r/min, add 0.5 mass parts of anionic surfactant AOS to the beaker, and stir for 30min to dissolve completely;

Step S3, adding 0.3 parts by mass of the zwitterionic surfactant CHSB to the beaker, and stirring for 30 min to dissolve completely;

Step S4, adding 2.5 parts by mass of dispersant sodium soil to the beaker, stirring for 30min to make it fully suspended;

Step S5, adding 5 mass parts of solid-phase particle fly ash to the beaker, stirring for 30min to make it fully suspended;

Step S6, seal the stirred foaming liquid with plastic wrap, place it in a constant temperature box, and age it at 80°C for 48 hours;

In step S7, the aged foaming liquid is transferred to a high-speed stirrer, and CO ₂ gas is introduced into it for 10 min, the rotation speed is set to 8000 r/min, and the stirring time is 2 min.

The foam volume of 100ml foaming liquid produced by the Blender-Waring method is 350mL, and the half-life is 34min. After water flooding and _CO2 gas flooding, 0.5PV foam is injected and then _CO2 gas flooding is carried out. The final crude oil recovery rate is 70.78%, which is relatively high. Water flooding increased by 39.15%.

Example 2

Step S1, pour a certain amount of deionized water into the beaker, add inorganic salt to the beaker according to actual requirements, and prepare an inorganic salt solution of 150,000 mg/L NaCl;

Step S2, place the beaker on a magnetic stirrer, set the rotating speed to 350r/min, add 0.5 mass part of anionic surfactant SDBS to the beaker, and stir for 30min to dissolve completely;

Step S3, adding 0.3 parts by mass of the zwitterionic surfactant CHSB to the beaker, and stirring for 30 min to dissolve completely;

Step S4, adding 2.5 parts by mass of dispersant sodium soil to the beaker, stirring for 30min to make it fully suspended;

Step S5, adding 5 mass parts of solid-phase particle fly ash to the beaker, stirring for 30min to make it fully suspended;

Step S6, seal the stirred foaming liquid with plastic wrap, place it in a constant temperature box, and age it at 80°C for 48 hours;

In step S7, the aged foaming liquid is transferred to a high-speed stirrer, and CO ₂ gas is introduced into it for 10 min, the rotation speed is set to 8000 r/min, and the stirring time is 2 min.

The foam volume of 100ml foaming liquid produced by the Blender-Waring method is 330mL, and the half-life is 31min. After water flooding and _CO2 gas flooding, 0.5PV of foam is injected and then _CO2 gas flooding. The final crude oil recovery rate is 36.67%, which is relatively high. Water flooding increased by 36.67%.

Example 3

Step S1, pour a certain amount of deionized water into the beaker, add inorganic salts to the beaker according to actual requirements, and prepare a solution with a calcium and magnesium ion concentration of 5000 mg/L;

Step S2, place the beaker on a magnetic stirrer, set the rotating speed to 350r/min, add 0.5 mass parts of anionic surfactant AOS to the beaker, and stir for 30min to dissolve completely;

Step S3, adding 0.3 parts by mass of the zwitterionic surfactant CHSB to the beaker, and stirring for 30 min to dissolve completely;

Step S4, adding 2.5 parts by mass of dispersant sodium soil to the beaker, stirring for 30min to make it fully suspended;

Step S5, adding 5 mass parts of solid-phase particle fly ash to the beaker, stirring for 30min to make it fully suspended;

Step S6, seal the stirred foaming liquid with plastic wrap, and place it in an incubator for aging at 80°C for 48h;

In step S7, the aged foaming liquid is transferred to a high-speed stirrer, and CO ₂ gas is introduced into it for 10 min, the rotation speed is set to 8000 r/min, and the stirring time is 2 min.

The foam volume of 100ml foaming liquid produced by the Blender-Waring method is 310mL, and the half-life is 25min. After water flooding and _CO2 gas flooding, 0.5PV of foam is injected and then _CO2 gas flooding. The final crude oil recovery rate is 63.66%, which is relatively high. Water flooding increased by 32.52%.

Example 4:

Step S1, pour a certain amount of deionized water into the beaker, add inorganic salt to the beaker according to actual requirements, and prepare an inorganic salt solution with a concentration of 100,000 mg/L NaCl and 500 mg/L of calcium and magnesium ions;

Step S2, place the beaker on a magnetic stirrer, set the rotating speed to 350r/min, add 0.5 mass parts of anionic surfactant AOS to the beaker, and stir for 30min to dissolve completely;

Step S3, adding 0.3 parts by mass of the zwitterionic surfactant CHSB to the beaker, and stirring for 30 min to dissolve completely;

Step S4, adding 2.5 parts by mass of dispersant sodium soil to the beaker, stirring for 30min to make it fully suspended;

Step S5, adding 5 mass parts of solid-phase particle fly ash to the beaker, stirring for 30min to make it fully suspended;

Step S6, sealing the stirred foaming liquid with plastic wrap, placing it in a constant temperature box, and aging at 120° C. for 48 hours;

In step S7, the aged foaming liquid is transferred to a high-speed stirrer, and CO ₂ gas is introduced into it for 10 min, the rotation speed is set to 8000 r/min, and the stirring time is 2 min.

The foam volume of 100ml foaming liquid produced by the Blender-Waring method is 320mL, and the half-life is 19min. After water flooding and _CO2 gas flooding, 0.5PV of foam is injected and then _CO2 gas flooding. The final crude oil recovery rate is 60.82%, which is relatively Water flooding increased by 28.37%.

The above-described embodiments and features of the embodiments herein may be combined with each other without conflict.

The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection of the present invention. within the range.

Claims (10)

1. a three-phase foam system for temperature-resistant and salt-resistant oil flooding, characterized in that, made of anionic surfactant, zwitterionic surfactant, solid-phase particle, dispersant, gas and water, in parts by weight The mass parts of the anionic surfactant are 0.3-0.7 parts, the zwitterionic surfactant 0.3-0.5 parts, the solid phase particles 3-7 parts, the dispersant 2-5 parts, the water 100 parts, the gas and the The volume ratio of the three-phase foam system for oil displacement is 1:1-4:1. 2. a kind of temperature-resistant and salt-resistant oil flooding three-phase foam system as claimed in claim 1, is characterized in that, described anionic surfactant is sodium alpha-olefin sulfonate and sodium dodecylbenzenesulfonate one or both of them. 3. a kind of temperature-resistant and salt-resistant oil flooding three-phase foam system as claimed in claim 1, is characterized in that, described zwitterionic surfactant is cocamidopropyl hydroxysulfobetaine. 4 . The three-phase foam system for temperature-resistant and salt-resistant oil flooding according to claim 1 , wherein the solid phase particles are fly ash. 5 . 5. a kind of temperature-resistant and salt-resistant oil flooding three-phase foam system as claimed in claim 1, is characterized in that, described dispersant is sodium soil. 6 . The three-phase foam system for temperature-resistant and salt-tolerant oil flooding according to claim 1 , wherein the gas is carbon dioxide. 7 . 7. a preparation method of the three-phase foam system for temperature-resistant and salt-resistant oil flooding as described in any one of claims 1-6, is characterized in that, comprises the following steps: S1. Pour a certain amount of deionized water into the container, add inorganic salts to the container, and prepare simulated formation water; S2, place the container on the magnetic stirrer, set the first preset rotational speed, add a certain amount of anionic surfactant to the container, and stir until completely dissolved; S3, add a certain amount of zwitterionic surfactant to the container, and stir until completely dissolved; S4, add a certain amount of dispersant to the container, stir to make it fully suspended; S5, add a certain amount of solid phase particles into the container, stir to make it fully suspended, and obtain a foaming liquid; S6. Seal the stirred foaming liquid with plastic wrap, and place it in a constant temperature box for aging; S7. Transfer the aged foaming liquid to a high-speed agitator, set a second preset rotational speed, feed carbon dioxide into it for 10 min, set the rotational speed to 8000 r/min, and stir for 2 min. 8 . The preparation method according to claim 7 , wherein the first preset rotational speed is 350 r/min˜400 r/min, and the second preset rotational speed is 6000 r/min˜8000 r/min. 9 . 9 . The preparation method according to claim 7 , wherein the aging time in step S6 is 48h～60h. 10 . 10. The application of the three-phase foam system for oil flooding according to any one of claims 1 to 6, wherein the three-phase foam system solution for oil flooding is used to prepare an oil field foam adjusting and flooding agent.

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