A profile control water plugging agent, a preparation method and application thereof

Abstract

The present application relates to the technical field of oil exploitation, in particular to a profile control water plugging agent, a preparation method and application thereof. The method comprises the following steps: (1) mixing a cellulose compound, acrylamide and water, then adding a crosslinking agent, and then adding an initiator to perform a polymerization reaction; (2) mixing the material obtained in the step (1) with a metal salt solution, and then performing solid-liquid separation and drying; wherein the cellulose compound is selected from one or more than two of carboxymethyl cellulose, carboxyethyl cellulose and polyanionic cellulose. The profile control water plugging agent is a hydrogel material with a unique double network structure, and has good stability and still maintains good strength under high temperature and high salt conditions.

Description

Technical Field

[0001] This invention relates to the field of oil extraction technology, specifically to a profile control and water shut-off agent, its preparation method, and its application. Background Technology

[0002] As oilfields are exploited, the natural energy within the reservoir is depleted, requiring additional energy to maintain reservoir pressure. Waterflooding is one of the most important secondary oil recovery methods, using water injection to maintain reservoir pressure and displace residual oil. However, long-term waterflooding can lead to the formation of dominant flow channels within the reservoir, resulting in excessively high water production, severe inefficient and ineffective circulation, decreased oil well production, and a rapid increase in water cut. To improve the swept volume of the injected fluid and control inefficient and ineffective circulation, deep profile control measures are necessary.

[0003] Cross-linked polymer gels are solid or semi-solid colloidal systems with a spatial network structure. They can be injected into oil wells to block high-permeability areas and reduce water production. However, reservoir geological conditions vary, and some reservoirs are characterized by high temperatures or high salinity. This leads to a significant decrease in the mechanical strength and toughness of conventional single polymer network hydrogels after injection, failing to achieve the expected profile control and water shut-off effects. Summary of the Invention

[0004] The purpose of this invention is to overcome the problem that existing profile control and water shut-off agents are not effective in high-temperature and high-salinity reservoirs, and to provide a profile control and water shut-off agent, its preparation method and application.

[0005] To achieve the above objectives, the present invention provides a method for preparing a profile control and water shut-off agent, the method comprising the following steps:

[0006] (1) Mix cellulose compounds, acrylamide and water, then add a crosslinking agent, and then add an initiator to carry out a polymerization reaction;

[0007] (2) Soak the material obtained in step (1) in a metal salt solution, and then perform solid-liquid separation and drying;

[0008] Among them, the cellulose compounds are selected from one or more of carboxymethyl cellulose, carboxyethyl cellulose and polyanionic cellulose.

[0009] Preferably, the crosslinking agent is selected from one or more of N,N-methylenebisacrylamide, N,N'-diallyl tartaric acid diamide, and divinylbenzene.

[0010] Preferably, the initiator is selected from one or more of ammonium persulfate, sodium persulfate, potassium persulfate, and azobisisobutyrazoline hydrochloride.

[0011] Preferably, the weight ratio of acrylamide to initiator is 100:0.1-3.

[0012] Preferably, the weight ratio of cellulose compound to acrylamide is 1:2-10.

[0013] Preferably, in step (1), the conditions for the polymerization reaction include: a temperature of 50-80℃ and a time of 3-9h.

[0014] Preferably, in step (2), the metal salt is selected from one or more of aluminum chloride, calcium chloride, sodium chloride and sodium sulfate;

[0015] Preferably, the concentration of the metal salt in the metal salt solution is 0.2-2 mol / L.

[0016] Preferably, in step (2), the soaking conditions include: a temperature of 15-35℃ and a time of 1-4 days.

[0017] A second aspect of the present invention provides a profile control and water-blocking agent prepared by the method described above.

[0018] The third aspect of this invention provides the application of the profile control and water shut-off agent described above in reservoir profile control and water shut-off.

[0019] This invention discloses a profile control and water shut-off agent suitable for high-temperature and high-salinity oil reservoirs. The agent is a hydrogel material with a unique dual-network structure, exhibiting good stability and maintaining good strength even under high-temperature and high-salinity conditions. After injection into the formation, the hydrogel can block water in high-permeability areas, improving formation heterogeneity, increasing the water drive sweep area, and thus enhancing oil recovery. Attached Figure Description

[0020] Figure 1 This is a graph showing the yield stress test results from Test Example 2;

[0021] Figure 2 This is a graph showing the viscoelasticity test results from Test Example 3. Detailed Implementation

[0022] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0023] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0024] This invention provides a method for preparing a profile control and water-blocking agent, the method comprising the following steps:

[0025] (1) Mix cellulose compounds, acrylamide and water, then add a crosslinking agent, and then add an initiator to carry out a polymerization reaction;

[0026] (2) The material obtained in step (1) is mixed with a metal salt solution, and then solid-liquid separation and drying are performed;

[0027] Among them, the cellulose compounds are selected from one or more of carboxymethyl cellulose, carboxyethyl cellulose and polyanionic cellulose.

[0028] In this invention, in step (1), the cellulose compound itself has good temperature resistance. When polymerized with acrylamide as a monomer, a hydrogel with two network structures can be obtained: one is a polyelectrolyte network structure with high cross-linking density (rigid and brittle), which disperses external stress; the other is a loosely cross-linked neutral network structure (soft and tough), which fills the rigid network, providing a scaffold for the hydrogel, maintaining its shape, and enabling the whole to better adapt to the high-temperature, high-salinity reservoir environment. Then, the material obtained in step (1) is mixed with a metal salt solution. The metal ions can further react with the network structure formed by the cellulose compound to enhance the stability of the network structure. Based on this, the profile control and water shut-off agent prepared using the method described in this invention can strongly block high-permeability channels and change the pressure balance and aqueous phase flow path. It has high strength and can achieve profile control and shut-off under high-temperature, high-salinity conditions, as well as in alkaline environments, improving the recovery rate of high-temperature, high-salinity reservoirs and meeting the actual needs of reservoir development in the later stages.

[0029] In a preferred embodiment, the crosslinking agent is selected from one or more of N,N-methylenebisacrylamide, N,N'-diallyl tartrate diamide, and divinylbenzene.

[0030] In a preferred embodiment, the initiator is selected from one or more of ammonium persulfate, sodium persulfate, potassium persulfate, and azobisisobutyrazoline hydrochloride.

[0031] In this invention, to further improve the temperature and salt resistance and plugging efficiency of the profile control and water shut-off agent, the dosage of acrylamide and initiator can be reasonably controlled. In a preferred embodiment, the weight ratio of acrylamide to initiator is 100:0.1-3; specifically, it can be 100:0.1, 100:0.2, 100:0.25, 100:0.3, 100:0.35, 100:0.36, 100:0.5, 100:6, 100:0.7, 100:0.72, 100:0.75, 100:0.8, 100:1, 100:1.5, 100:2, 100:2.5 or 100:3.

[0032] In this invention, in order to further improve the temperature and salt resistance and plugging efficiency of the profile control and water plugging agent, the dosage of cellulose compounds and acrylamide can be reasonably controlled; in a preferred embodiment, the weight ratio of cellulose compounds to acrylamide is 1:2-10; specifically, it can be 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9 or 1:10.

[0033] In a preferred embodiment, in step (1), the weight ratio of acrylamide to crosslinking agent is 100:0.1-0.5; specifically, it can be 100:0.1, 100:0.14, 100:0.15, 100:0.2, 100:0.25, 100:0.28, 100:0.3, 100:0.35, 100:0.4 or 100:0.5.

[0034] In a preferred embodiment, in step (1), the polymerization reaction conditions include: a temperature of 50-80°C and a time of 3-9 hours. Specifically, the polymerization reaction temperature can be 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, or 80°C; and the time can be 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, or 9 hours.

[0035] In a preferred embodiment, there are no special requirements for the amount of water used in step (1), as long as the polymerization reaction proceeds smoothly.

[0036] In a preferred embodiment, in step (2), the metal salt is selected from one or more of aluminum chloride, calcium chloride, sodium chloride and sodium sulfate.

[0037] More preferably, the concentration of the metal salt in the metal salt solution is 0.2-2 mol / L; specifically, it can be 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.8 mol / L, 1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.5 mol / L, 1.6 mol / L, 1.8 mol / L, or 2 mol / L.

[0038] In a preferred embodiment, the metal salt solution may be an aqueous solution of a metal salt.

[0039] In a preferred embodiment, in step (2), the mixing conditions include: a temperature of 15-35°C and a time of 1-4 days. Specifically, the temperature is 15°C, 20°C, 25°C, 30°C, or 35°C; and the time is 1 day, 2 days, 3 days, or 4 days.

[0040] In the method described in this invention, there are no special requirements for the solid-liquid separation and drying processes in step (2), and conventional methods in the art can be used. For example, the solid-liquid separation method can be filtration, and the drying method can be vacuum drying.

[0041] A second aspect of the present invention provides a profile control and water-blocking agent prepared by the method described above.

[0042] The third aspect of this invention provides the application of the profile control and water shut-off agent described above in reservoir profile control and water shut-off.

[0043] The present invention will be described in detail below through embodiments, but the scope of protection of the present invention is not limited thereto.

[0044] Unless otherwise specified, all reagents used in the following examples and comparative examples are commercially available products.

[0045] Example 1

[0046] (1) Mix 1g of cellulose compound (carboxymethyl cellulose), 6g of acrylamide and 43g of deoxygenated ultrapure water, then add 0.0085g of crosslinking agent (N,N-methylenebisacrylamide), followed by 0.0215g of initiator (ammonium persulfate) to carry out polymerization reaction. The polymerization reaction temperature is 60℃ and the reaction time is 4h. The weight ratio of acrylamide to initiator is 100:0.36, the weight ratio of acrylamide to crosslinking agent is 100:0.14, and the weight ratio of cellulose compound to acrylamide is 1:6.

[0047] (2) The material obtained in step (1) is mixed with a 2 mol / L aluminum chloride aqueous solution at 30°C for 1 day, and then filtered and dried to obtain profile control and water shut-off agent S1.

[0048] Example 2

[0049] (1) Mix 1g of cellulose compound (carboxyethyl cellulose), 6g of acrylamide and 43g of deoxygenated ultrapure water, then add 0.0085g of crosslinking agent (N,N-methylenebisacrylamide), followed by 0.0215g of initiator (ammonium persulfate) to carry out polymerization reaction. The polymerization reaction temperature is 60℃ and the reaction time is 4h. The weight ratio of acrylamide to initiator is 100:0.36, the weight ratio of acrylamide to crosslinking agent is 100:0.14, and the weight ratio of cellulose compound to acrylamide is 1:6.

[0050] (2) The material obtained in step (1) is mixed with a 2 mol / L aluminum chloride aqueous solution at 30°C for 1 day, and then filtered and dried to obtain profile control and water plugging agent S2.

[0051] Example 3

[0052] (1) Mix 2g of cellulose compound (carboxymethyl cellulose), 6g of acrylamide and 42g of deoxygenated ultrapure water, then add 0.0085g of crosslinking agent (N,N-methylenebisacrylamide), followed by 0.0215g of initiator (ammonium persulfate) to carry out polymerization reaction. The polymerization reaction temperature is 70℃ and the reaction time is 6h. The weight ratio of acrylamide to initiator is 100:0.36, the weight ratio of acrylamide to crosslinking agent is 100:0.14, and the weight ratio of cellulose compound to acrylamide is 1:3.

[0053] (2) The material obtained in step (1) is mixed with 1.5 mol / L aluminum chloride aqueous solution at 30°C for 1 day, and then filtered and dried to obtain profile control and water plugging agent S3.

[0054] Example 4

[0055] (1) Mix 1g of cellulose compound (carboxymethyl cellulose), 6g of acrylamide and 43g of deoxygenated ultrapure water, then add 0.0085g of crosslinking agent (N,N-methylenebisacrylamide), followed by 0.0215g of initiator (ammonium persulfate) to carry out polymerization reaction. The polymerization reaction temperature is 80℃ and the reaction time is 3h. The weight ratio of acrylamide to initiator is 100:0.36, the weight ratio of acrylamide to crosslinking agent is 100:0.14, and the weight ratio of cellulose compound to acrylamide is 1:6.

[0056] (2) The material obtained in step (1) is mixed with a 1 mol / L aluminum chloride aqueous solution at 30°C for 1 day, and then filtered and dried to obtain profile control and water shut-off agent S4.

[0057] Example 5

[0058] (1) Mix 1g of cellulose compound (carboxymethyl cellulose), 6g of acrylamide and 43g of deoxygenated ultrapure water, then add 0.017g of crosslinking agent (N,N-methylenebisacrylamide), followed by 0.043g of initiator (ammonium persulfate) to carry out the polymerization reaction. The polymerization reaction temperature is 60℃ and the reaction time is 4h. The weight ratio of acrylamide to initiator is 100:0.72, the weight ratio of acrylamide to crosslinking agent is 100:0.28, and the weight ratio of cellulose compound to acrylamide is 1:6.

[0059] (2) The material obtained in step (1) is mixed with a 2 mol / L aluminum chloride aqueous solution at 30°C for 1 day, and then filtered and dried to obtain profile control and water plugging agent S5.

[0060] Example 6

[0061] (1) Mix 1g of cellulose compound (carboxymethyl cellulose), 6g of acrylamide and 43g of deoxygenated ultrapure water, then add 0.0085g of crosslinking agent (N,N'-diallyl tartaric acid diamide), followed by 0.0215g of initiator (sodium persulfate) to carry out polymerization reaction. The polymerization reaction temperature is 60℃ and the reaction time is 4h. The weight ratio of acrylamide to initiator is 100:0.36, the weight ratio of acrylamide to crosslinking agent is 100:0.14, and the weight ratio of cellulose compound to acrylamide is 1:6.

[0062] (2) The material obtained in step (1) is mixed with a 2 mol / L aluminum chloride aqueous solution at 30°C for 1 day, and then filtered and dried to obtain profile control and water plugging agent S6.

[0063] Example 7

[0064] The method described in Example 1 was carried out, except that calcium chloride was used as the metal salt, resulting in profile control and water shut-off agent S7.

[0065] Comparative Example 1

[0066] (1) Mix 6g of acrylamide and 44g of deoxygenated ultrapure water, then add 0.0085g of crosslinking agent (N,N-methylenebisacrylamide), followed by 0.0215g of initiator (ammonium persulfate) to carry out the polymerization reaction. The polymerization reaction temperature is 60℃ and the reaction time is 4h. The weight ratio of acrylamide to crosslinking agent is 100:0.14 and the weight ratio of acrylamide to initiator is 100:0.36.

[0067] (2) The material obtained in step (1) is mixed with a 2 mol / L aluminum chloride aqueous solution at 30°C for 1 day, and then filtered and dried to obtain profile control and water shut-off agent D1.

[0068] Comparative Example 2

[0069] (1) Mix 6g of carboxymethyl cellulose and 44g of deoxygenated ultrapure water, then add 0.0085g of crosslinking agent (N,N-methylenebisacrylamide), followed by 0.0215g of initiator (ammonium persulfate) to carry out the reaction. The reaction temperature is 60℃ and the reaction time is 4h.

[0070] (2) The material obtained in step (1) is mixed with 2 mol / L aluminum chloride aqueous solution at room temperature (30℃) for 1 day, and then filtered and dried to obtain profile control and water plugging agent D2.

[0071] Comparative Example 3

[0072] 1g of a cellulose compound (carboxymethyl cellulose), 6g of acrylamide, and 43g of deoxygenated ultrapure water were mixed, and then 0.0085g of crosslinking agent (N,N-methylenebisacrylamide) was added, followed by 0.0215g of initiator (ammonium persulfate) to carry out a polymerization reaction. The polymerization reaction temperature was 60℃, and the reaction time was 4h. After filtration and drying, product D3 was obtained. The weight ratio of acrylamide to initiator was 100:0.36, the weight ratio of acrylamide to crosslinking agent was 100:0.14, and the weight ratio of cellulose compound to acrylamide was 1:6.

[0073] Test Example 1

[0074] The blocking performance of the products prepared in the examples and comparative examples was tested using the following methods:

[0075] Sand-filled pipes with different permeabilities were prepared by filling with quartz sand. After the pressure stabilized by water drive with simulated formation water (mineralization 14w), the original water phase permeability kw was calculated by the permeability formula.

[0076] The formula for calculating penetration rate is:

[0077]

[0078] Where k is the permeability, in μm 2 μ is the fluid viscosity, mPa·s; Q is the fluid flow rate, cm⁻¹ 3 / s; L is the length of the sand-filled pipe, cm; A is the cross-sectional area of ​​the sand-filled pipe, cm² 2 Δp is the pressure difference between the inlet and outlet ends of the sand-filled pipe, in MPa.

[0079] 1 PV of the test sample (i.e. the product prepared in the examples and comparative examples) was injected into the sand-filled tube and aged at 90°C for 24 h; then, water was injected forward at a rate of 1 mL / min until the pressure stabilized, and then the water phase permeability kw' after plugging was calculated using the permeability calculation formula.

[0080] The blocking effect is calculated according to the blocking rate calculation formula;

[0081] The formula for calculating the blocking rate is:

[0082]

[0083] Where Ew is the plugging rate; kw is the permeability before plugging, in μm 2 ; kw' represents the permeability after plugging, in μm 2 .

[0084] The results are shown in Table 1.

[0085] Table 1

[0086] serial number Blocking rate / % serial number Blocking rate / % Example 1 94.2 Example 6 84.6 Example 2 92.1 Example 7 83.9 Example 3 91.6 Comparative Example 1 70.2 Example 4 89.5 Comparative Example 2 71.5 Example 5 90.9 Comparative Example 3 73.1

[0087] As shown in Table 1, the profile control and water shut-off agent prepared by the method described in this invention has excellent plugging performance in high-temperature and high-salinity oil reservoirs.

[0088] Test Example 2

[0089] Yield stress represents the strength of a material. The higher the yield stress value, the greater the material strength. The products prepared in Example 1 and Comparative Example 1 were placed in simulated formation water (14w salinity) and aged at 90°C for 24 hours. After aging, they were removed and the yield stress was measured using an MCR50 rheometer (Antonpah, Austria). The test conditions included a control time of 180 s and a stress range of 0-500 Pa. The test results are as follows: Figure 1 As shown.

[0090] Depend on Figure 1 It can be seen that the yield stress of the product prepared in Comparative Example 1 is 9.0 Pa, and the yield stress of the product prepared in Example 1 is 31.0 Pa, which is 3.4 times that of Comparative Example 1.

[0091] Test Example 3

[0092] Storage modulus and loss modulus are two important parameters characterizing materials. Storage modulus, also known as elastic modulus (G'), represents the energy stored by the elastic deformation of particles under vibration testing mode; it represents the elasticity of the water material. Loss modulus, also known as viscous modulus (G''), represents the energy lost by the hydrogel due to viscous deformation under vibration testing mode; it reflects the viscosity of the material. The products prepared in Example 1 and Comparative Example 1 were placed in simulated formation water (14w salinity) and aged at 90°C for 24 hours. After aging, they were removed and their viscoelastic moduli were measured using an MCR50 rheometer (Antonpah, Austria). The test conditions included a control time of 600 s and a vibration frequency of 0.1-10 Hz. The test results are as follows: Figure 2 As shown.

[0093] As shown in the figure, the G′ and G″ of the product prepared in Example 1 are much larger than those in Comparative Example 1. Example 1 has better viscoelasticity and good elastic deformation ability.

[0094] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing a profile control water plugging agent, characterized in that, The method comprises the following steps: (1) mixing cellulose compound, acrylamide and water, then adding crosslinking agent, and then adding initiator to carry out polymerization reaction; (2) mixing the material obtained in step (1) with metal salt solution, then carrying out solid-liquid separation and drying; The cellulose compound is selected from one or more than two of carboxymethyl cellulose, carboxyethyl cellulose and polyanionic cellulose; the crosslinking agent is selected from one or more than two of N, N-methylene bisacrylamide, N, N'-diallyl tartaric acid diamide and divinyl benzene; The weight ratio of the amount of cellulose compound to the amount of acrylamide is 1:2-10; The weight ratio of the amount of acrylamide to the amount of crosslinking agent is 100:0.1-0.5; The concentration of metal salt in the metal salt solution is 0.2-2 mol / L; In step (2), the mixing conditions include: temperature is 15-35℃, and time is 1-4 days.

2. The method of claim 1, wherein, The initiator is selected from one or more than two of ammonium persulfate, sodium persulfate, potassium persulfate and azobis isobutylimidazoline hydrochloride.

3. The method according to claim 1 or 2, characterized in that, The weight ratio of the amount of acrylamide to the amount of initiator is 100:0.1-3.

4. The method according to claim 1 or 2, characterized in that, In step (1), the polymerization reaction conditions include: temperature is 50-80℃, and time is 3-9h.

5. The method of claim 1, wherein, In step (2), the metal salt is selected from one or more than two of aluminum chloride, calcium chloride, sodium chloride and sodium sulfate.

6. The profile control water plugging agent prepared by the method in any one of claims 1-5.

7. The use of the profile control water plugging agent in claim 6 in oil reservoir profile control and water plugging.

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