Sodium silicate composite microgel plugging agent and preparation and application methods thereof

Abstract

The invention provides a water glass composite microgel plugging agent and a preparation and application method thereof, and the plugging agent is prepared according to the following steps: adding water into a container, starting a stirring device, adding polyacrylamide, curing for 10-15min, then sequentially adding sodium dodecyl benzene sulfonate, aluminum dihydrogen phosphate, N, N-dimethylformamide and water glass, stirring for 5-10min every time one material is added, and then adding water into the container for stirring for 5-10min. After the water glass is completely added, continuously stirring for 10-15 minutes to obtain water glass inorganic gel; and grinding, and adding a thickening agent and water in the grinding process to obtain the water glass composite microgel plugging agent. Compared with the prior art, the water glass inorganic gel is firstly prepared and then ground for use, a single-phase low-viscosity fluid is formed, the fluidity is better, after the water glass inorganic gel is injected into a stratum and sheared through a pore throat, gel particles can be gathered again to form silicic acid water-absorbing micellar particles, multiple times of plugging are achieved, certain gaps exist between the gel particles, and the water-absorbing performance of the gel particles is improved. And under the action of water, the oil can be re-dispersed without causing blockage of the pore throat of the medium-low permeability oil reservoir.

Description

Technical Field

[0001] The invention relates to the technical field of oil and water well plugging agents, and in particular to a water glass composite microgel plugging agent and a preparation and application method thereof. Background Art

[0002] In the middle and late stages of oilfield development, with continuous strong injection and strong production, the heterogeneity of the reservoir will generally increase, the permeability difference will increase, and the high permeability zone will further develop into a large pore, which will reduce the effect of water injection and polymer injection or cause water flooding or polymer channeling in the oil well. In order to improve the effect of water injection and chemical flooding and increase the utilization of reserves in low permeability areas, water well profile control and oil well water plugging have become very important measures.

[0003] The profile control and water plugging agents currently used in oil fields are mainly organic systems. This type of system is not only costly, but also has poor thermal stability in high-temperature formations, is easy to degrade, and has a short effective period for controlling the seepage profile of the formation. At the same time, since the initial viscosity of this type of system is generally high, when constructing medium and low permeability reservoirs, the injection pressure is too high to meet the construction requirements, or the injection volume is insufficient, so that the seepage profile cannot be effectively controlled. Commonly used easy-to-inject low-viscosity and temperature-resistant gel materials are mainly inorganic salts, such as water glass silicate. The inorganic water glass gel material is not only cheap, but also has a low-viscosity aqueous solution in the initial state, which can enter the small gaps in the formation. Moreover, because its gel structure is an inorganic silicon-oxygen structure, it has more outstanding high-temperature thermal stability than the organic polymer system. However, it has the problem of short gelation time. Generally, it can only treat the formation of 1.5-3.0m around the wellbore. Moreover, the higher the formation temperature, the shorter the gelation time, and it will dehydrate and condense into a dense glass body at high temperature, resulting in the failure of profile control and water plugging measures. Therefore, it has gained a certain application space in oil field development, but is also subject to application limitations.

[0004] Patent CN103627376 discloses a water glass inorganic gel plugging agent and its preparation and use method, which can be used in high temperature, medium and low permeability oil reservoirs, and has the characteristics of low initial viscosity and easy injection. However, in actual application, the water glass inorganic gel plugging agent needs to be prepared with soft water with low mineral content. When it comes into contact with underground minerals after injection, it is easy to gel in advance, and the predetermined plugging effect cannot be achieved. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a water glass composite microgel plugging agent and a preparation and application method thereof. The plugging agent system is a single-phase low-viscosity fluid, and the injection pressure of medium and low permeability oil reservoirs is low; after the system is gelled, it becomes silicate water-absorbing microgel particles, which are dense and hard structures or silicate precipitations formed by unconventional water glass plugging agents. The water glass composite gel has both high strength and construction safety.

[0006] To achieve this technical purpose, the present invention adopts the following scheme: In a first aspect, the present invention provides a method for preparing a water glass composite microgel plugging agent, which is carried out according to the following steps: S1. Add water to the container, turn on the stirring device, add polyacrylamide, and ripen for 10 to 15 minutes, then add sodium dodecylbenzene sulfonate, aluminum dihydrogen phosphate, N,N-dimethylformamide and water glass in sequence, stir for 5 to 10 minutes each time adding one material, and continue stirring for 10 to 15 minutes after all are added to obtain the water glass inorganic gel; S2. Grinding the obtained water glass inorganic gel, adding a thickener and water during the grinding process, to obtain a water glass composite microgel plugging agent.

[0007] Furthermore, in step S1, the mass percentages of the components for preparing the water glass inorganic gel are as follows: 10-40% water glass, 0.1-0.3% polyacrylamide, 0.1-0.2% sodium dodecylbenzene sulfonate, 0.1-0.3% aluminum dihydrogen phosphate, 1-6% N,N-dimethylformamide, and the rest is water.

[0008] Furthermore, in step S2, the thickener is one or more of carboxymethyl cellulose, carboxyethyl cellulose, polyanionic cellulose, polyacrylamide, sulfonated phenolic resin, xanthan gum, guar gum, sodium alginate, gum arabic, bentonite, white carbon black, clay or starch.

[0009] Furthermore, in step S2, the mass of the added thickener is 1-10% of the water glass inorganic gel, and the mass of the added water is 50-250% of the water glass inorganic gel.

[0010] Furthermore, in step S2, the grinding speed is 100-350 rpm, and the grinding time is 20-80 min.

[0011] Furthermore, the water glass composite microgel plugging agent has a microgel effective content of 40-50%, an initial particle size of 1.7-6.5 μm, and a swelling multiple of <1.5.

[0012] In a second aspect, the present invention provides a water glass composite microgel plugging agent obtained according to the aforementioned preparation method.

[0013] In a third aspect, the present invention provides an application method of a water glass composite microgel plugging agent, wherein the water glass composite microgel plugging agent is used at an ambient temperature of 85 to 120° C., with a gel time of 4 to 72 hours, and a plugging rate of medium and low permeability cores of >85%.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The present invention first prepares water glass inorganic gel, and then grinds it before use to form a single-phase low-viscosity fluid with better fluidity. After being injected into the formation, after the pore throat is sheared, the gel particles will re-aggregate to form silicate water-absorbing micro-gel particles, and multiple plugging is achieved. In addition, there are certain gaps between the gel particles, which will be redispersed under the action of water, and will not cause the pore throats of medium and low permeability oil reservoirs to be blocked. On the other hand, the inorganic gel is prepared on the ground and then ground into micro-particles. It will not be affected by water quality when used, and will not gel in advance when injected, thereby ensuring the use effect. The gel system of the present invention is injected by a single liquid method when used, which is convenient for construction and has a high utilization rate in the oil reservoir. DETAILED DESCRIPTION

[0015] In order to fully understand the purpose, features and effects of the present invention, the present invention is described in detail through the following specific implementation methods, but the present invention is not limited thereto.

[0016] The raw materials used in the embodiments of the present invention are as follows: Water glass: commonly known as water glass, is a sodium silicate aqueous solution with a solid content of 40% and a modulus of 3.3. Raw material provider: Tangshan Jiyou Ruifeng Chemical Co., Ltd.

[0017] Polyacrylamide: white powdery solid, hydrolysis degree 10%, molecular weight 5 million, quickly soluble in water, can cross-link with high-valent metal ions to form an insoluble gel. Raw material provider: Aisen (China) Flocculant Co., Ltd.

[0018] Sodium dodecylbenzene sulfonate: also called sodium tetrapropylene benzene sulfonate, white or light yellow powder or flake solid. Dissolves in water to form a translucent solution. Mainly used as anionic surfactant. Raw material provider: Tangshan Jiyou Ruifeng Chemical Co., Ltd.

[0019] Aluminum dihydrogen phosphate: colorless, odorless, extremely viscous liquid, aqueous solution with 40% solid content. Raw material provider: Tangshan Jiyou Ruifeng Chemical Co., Ltd.

[0020] N,N-Dimethylformamide: colorless liquid with a faint special odor. Raw material provider: Tangshan Jiyou Ruifeng Chemical Co., Ltd. Example 1

[0021] In 50g of 0.2% polyacrylamide aqueous solution, add 0.1g of sodium dodecylbenzene sulfonate, 0.1g of aluminum dihydrogen phosphate, and 1g of N,N-dimethylformamide in sequence while stirring, stirring for 5 to 10 minutes each time each material is added, and finally add 10g of water glass solution and 38.8g of water, stirring for 10 minutes to form a water glass inorganic gel; The obtained water glass inorganic gel was put into a grinding tool for grinding. After grinding for 10 minutes, 2 g of carboxyethyl cellulose and 100 g of water were added, and grinding was continued for 60 minutes to obtain a water glass composite microgel plugging agent.

[0022] The water glass composite microgel plugging agent is a transparent low-viscosity aqueous solution with a viscosity of 48mPa·s, a gel effective content of 42%, an initial particle size of 1.7~6.5μm, and a swelling multiple of <1.5. The gel time of the system is 70h at an ambient temperature of 85℃, 32h at an ambient temperature of 100℃, and 10h at an ambient temperature of 120℃. After gelation, it is a milky white gel. Example 2

[0023] In 50g of 0.4% polyacrylamide aqueous solution, add 0.15g of sodium dodecylbenzene sulfonate, 0.2g of aluminum dihydrogen phosphate, and 3g of N,N-dimethylformamide in sequence while stirring, stirring for 5 to 10 minutes each time each material is added, and finally add 20g of water glass solution and 26.65g of water, stirring for 10 minutes to form a water glass inorganic gel; The obtained water glass inorganic gel was put into a grinding tool for grinding. After grinding for 10 minutes, 5 g of polyacrylamide and 200 g of water were added, and grinding was continued for 60 minutes to obtain a water glass composite microgel plugging agent.

[0024] The water glass composite microgel plugging agent is a transparent low-viscosity aqueous solution with a viscosity of 47mPa·s, a gel effective content of 45%, an initial particle size of 1.7~6.5μm, and a swelling multiple of <1.5. The gel time of the system is 62h at an ambient temperature of 85℃, 27h at an ambient temperature of 100℃, and 9h at an ambient temperature of 120℃. After gelation, it is a milky white gel. Example 3

[0025] In 50g of 0.6% polyacrylamide aqueous solution, add 0.2g of sodium dodecylbenzene sulfonate, 0.3g of aluminum dihydrogen phosphate, and 6g of N,N-dimethylformamide in sequence while stirring, stirring for 5 to 10 minutes each time each material is added, and finally, add 40g of water glass solution and 3.5g of water, stirring for 10 minutes to form a water glass inorganic gel; The obtained water glass inorganic gel was put into a grinding tool for grinding. After grinding for 10 minutes, 8 g of gum arabic and 250 g of water were added, and grinding was continued for 60 minutes to obtain a water glass composite microgel plugging agent.

[0026] The water glass composite microgel plugging agent is a transparent low-viscosity aqueous solution with a viscosity of 45mPa·s, a gel effective content of 47%, an initial particle size of 1.7~6.5μm, and a swelling multiple of <1.5. The gel time of the system is 50h at an ambient temperature of 85℃, 20h at an ambient temperature of 100℃, and 8h at an ambient temperature of 120℃. After gelation, it is a milky white gel. Comparative Example 1

[0027] In 50g of 0.6% polyacrylamide aqueous solution, add 0.2g of sodium dodecylbenzene sulfonate, 0.3g of aluminum dihydrogen phosphate, and 6g of N,N-dimethylformamide in sequence while stirring. Stir for 5 to 10 minutes after adding each material. Finally, add 40g of water glass solution and 3.5g of water. Stir for 10 minutes to form a water glass inorganic gel plugging agent.

[0028] The water glass inorganic gel plugging agent is a transparent low-viscosity aqueous solution with a viscosity of 108 mPa·s and a gel effective content of 75%. The gel time of the system is 80 hours at an ambient temperature of 85°C, 42 hours at an ambient temperature of 100°C, and 8 hours at an ambient temperature of 120°C. Example 4

[0029] The water glass composite microgel plugging agent formula in Example 3 was used to conduct a physical simulation experiment. The initial water permeability was 0.542 μm 2 , 2.015μm 2 and 3.249 μm 2 0.3PV water glass composite microgel plugging agent was injected into the cores, and the injection resistance coefficient was 2-3. The three cores were cured at 120℃ for 10h to ensure that the water glass composite microgel plugging agent was gelled. The water permeability was 5.69×10 -3 μm 2 、0.094μm 2 and 0.080μm 2 , the corresponding plugging rates are 98.95%, 95.34% and 97.55%. After the subsequent water flooding of 15PV, the plugging rate decreased by less than 1%. This shows that the water glass composite microgel plugging agent has excellent injectability, good plugging ability and water scouring resistance after gelation, and is suitable for the system for profile control and water plugging work, especially for profile control and water plugging work in medium and low permeability reservoirs. After continuing to water flood for 300PV, the plugging rate dropped to below 50%, indicating that the water glass composite gel plugging is reversible and more friendly to the geological environment.

[0030] Finally, it should be noted that the above are only preferred embodiments of the present invention. Of course, those skilled in the art can make changes and modifications to the present invention. If these modifications and variations fall within the scope of the claims of the present invention and their equivalent technologies, they should be considered to be within the scope of protection of the present invention.

Claims

1. A method for preparing a water glass composite microgel plugging agent, characterized in that: Follow these steps: S1. Add water to the container, turn on the stirring device, add polyacrylamide, and ripen for 10 to 15 minutes, then add sodium dodecylbenzene sulfonate, aluminum dihydrogen phosphate, N,N-dimethylformamide and water glass in sequence, stir for 5 to 10 minutes each time adding one material, and continue stirring for 10 to 15 minutes after all are added to obtain the water glass inorganic gel; S2. Grinding the obtained water glass inorganic gel, adding a thickener and water during the grinding process, to obtain a water glass composite microgel plugging agent.

2. The method for preparing the water glass composite microgel plugging agent according to claim 1, characterized in that: In step S1, the mass percentages of the components for preparing the water glass inorganic gel are as follows: 10-40% water glass, 0.1-0.3% polyacrylamide, 0.1-0.2% sodium dodecylbenzene sulfonate, 0.1-0.3% aluminum dihydrogen phosphate, 1-6% N,N-dimethylformamide, and the rest is water.

3. The method for preparing the water glass composite microgel plugging agent according to claim 1, characterized in that: In step S2, the thickener is one or more of carboxymethyl cellulose, carboxyethyl cellulose, polyanionic cellulose, polyacrylamide, sulfonated phenolic resin, xanthan gum, guar gum, sodium alginate, gum arabic, bentonite, white carbon black, clay or starch.

4. The method for preparing the water glass composite microgel plugging agent according to claim 1, characterized in that: In step S2, the mass of the added thickener is 1-10% of the water glass inorganic gel, and the mass of the added water is 50-250% of the water glass inorganic gel.

5. The method for preparing the water glass composite microgel plugging agent according to claim 1, characterized in that: In step S2, the grinding speed is 100-350 rpm, and the grinding time is 20-80 min.

6. The method for preparing the water glass composite microgel plugging agent according to claim 1, characterized in that: The water glass composite microgel plugging agent has a microgel effective content of 40-50%, an initial particle size of 1.7-6.5 μm, and a swelling multiple of <1.

5.

7. A water glass composite microgel plugging agent obtained by the preparation method of the water glass composite microgel plugging agent according to any one of claims 1 to 6.

8. An application method of the water glass composite microgel plugging agent according to claim 7, characterized in that: The water glass composite microgel plugging agent is used at an ambient temperature of 85-120°C, with a gel time of 4-72 hours, and the plugging rate of medium and low permeability cores is >85%.