An oilfield profile control water plugging agent, a synthetic method and application thereof

Abstract

The application belongs to the technical field of tertiary oil recovery, and particularly relates to an oilfield profile control water plugging agent and a synthetic method and application thereof. The synthetic method is as follows: a reactor is sequentially added with 1-vinyl-2-pyrrolidone, allyldimethyl(4-methoxyphenyl)silane, 2-acrylamido-2-methylpropanesulfonic acid, allylmalonic acid, bisphenol A glycerol diacrylic acid, TX-10, hydroxypropyl methyl cellulose, sodium dihydrogen phosphate and deionized water, and stirring is performed; an initiator solution is added into the reactor, and the temperature is raised to 45-50 DEG C, and the stirring is continuously performed until the solution becomes viscous, and then the temperature is continuously raised to 75-80 DEG C, and the stirring is continuously performed for 2-3 h, and the pH is adjusted to 7-8 by using a sodium hydroxide solution, and the temperature is reduced to below 40 DEG C, so that a viscous liquid is obtained; the viscous liquid is dried and granulated to obtain a product water plugging agent with a particle size of 1-4 mm. The profile control water plugging agent has the characteristics of high breakthrough pressure gradient and high water plugging rate.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of tertiary oil recovery, and particularly relates to an oilfield profile control water plugging agent and a synthesis method and application thereof. BACKGROUND

[0002] Water injection development technology is an important means to improve recovery efficiency and is widely used in major oilfields around the world. With the deepening of water injection development, the problem of water production in oil wells gradually emerges. Due to the heterogeneity of the formation and the hydrodynamic effect, the injected water often preferentially enters the high-permeability layer, causing these layers to be flooded too early, while the low-permeability layer cannot be effectively utilized, forming a "water flow short circuit" phenomenon, which leads to these layers being flooded too early. The low-permeability layer, however, cannot be effectively utilized, forming a "dead oil zone", which seriously reduces the recovery efficiency of the oilfield and increases the subsequent treatment cost, posing a potential threat to the environment. Therefore, as an effective technical means, the demand for water plugging agents arises at the historic moment, aiming to precisely control the water production of oil wells and ensure the sustainable development of oilfields.

[0003] The water plugging agent can precisely plug the high-permeability layer or water-producing layer, allowing the injected fluid to enter the medium- and low-permeability layers in turn, improving the sweep efficiency and thus improving the recovery efficiency.

[0004] A good water plugging agent has good dispersibility, adsorbs on the surface of the rock after swelling, and plugs the large pores. Generally, there is a retention phenomenon of the water plugging and profile control agent in the pore structure. Due to the retention effect, the permeation resistance of the high-permeability layer is increased, the liquid absorption pressure difference of the medium- and low-permeability layers is improved, the deep liquid flow is forced to divert, enters the low-permeability zone, and starts the reservoir with a higher oil saturation, so that the liquid absorption amount and sweep volume of the medium- and low-permeability layers are increased, deep profile control and flooding are achieved, the swept volume of the injected water is expanded, the water flooding development effect is improved, and the purpose of further improving the recovery efficiency is achieved.

[0005] CN102876305B discloses an oil well water plugging agent and an oil well water plugging method. The oil well water plugging agent comprises anionic surfactant, non-ionic-anionic surfactant, C1-C8 fatty alcohol, thick oil and water, and has the characteristics of strong resistance to high salinity water, strong temperature resistance, strong stability, low cost and no pollution to the formation. However, the water plugging agent for large pores in the oil layer needs to have a certain strength. The molecular weight of the components in this invention is relatively small, and the strength of the product is limited, so the plugging effect will be greatly affected, and therefore the application range is limited. SUMMARY

[0006] The present application provides an oilfield profile control water plugging agent and a synthesis method and application thereof to solve the problems in the prior art. The profile control water plugging agent of the present application has the characteristics of high breakthrough pressure gradient and high water plugging rate.

[0007] One of the purposes of the present application discloses an oilfield profile control water plugging agent, the molecular structure formula of the oilfield profile control water plugging agent is as follows:

[0008]

[0009] Wherein:

[0010] a=2500-50000;

[0011] b=50000-500000;

[0012] c=25000-500000;

[0013] d=5000-100000;

[0014] e=5000-100000;

[0015] f=2500-50000;

[0016] g=50000-500000;

[0017] h=25000-500000;

[0018] i=5000-100000;

[0019] j=5000-100000.

[0020] Preferably, the viscosity average molecular weight of the profile control water plugging agent is 30000000-40000000.

[0021] Another purpose of the present application discloses a synthesis method of the above-mentioned profile control water plugging agent, the specific steps of the synthesis method are as follows:

[0022] (1) the reactor is sequentially added with 1-vinyl-2-pyrrolidone, allyl dimethyl (4-methoxyphenyl) silane, 2-propenamide-2-methyl propane sulfonic acid, allyl malonic acid, bisphenol A glycerol diacrylic acid, TX-10, hydroxypropyl methyl cellulose, sodium dihydrogen phosphate, deionized water, high-speed stirring at 800-1000 rpm, until all raw materials become a uniform emulsion, and the pH is adjusted to 7-8 with sodium hydroxide solution;

[0023] (2) the reactor is purged with nitrogen for 5-10 min, and nitrogen is slowly introduced in the later process to ensure that oxygen is isolated as much as possible during the synthesis process; the initiator solution is added to the reactor, and the temperature is raised to 45-50 DEG C, and the stirring is continued, until the solution becomes viscous, and the temperature is continuously raised to 75-80 DEG C, and the stirring is continued for 2-3 h, the pH is adjusted to 7-8 with sodium hydroxide solution, and the temperature is lowered to below 40 DEG C, to obtain a viscous liquid;

[0024] (3) The above viscous liquid is dried and granulated to a particle size of 1-4 mm to obtain the product water-blocking agent.

[0025] In this invention, preferably, the molar ratio of allyl dimethyl (4-methoxyphenyl)silane, 2-acrylamido-2-methylpropanesulfonic acid, allyl malonic acid, bisphenol A glycerol diacrylate and 1-vinyl-2-pyrrolidone is 0.5-1:0.1-0.2:0.1-0.2:0.05-0.1:1.

[0026] In this invention, preferably, in step (1), the mass ratio of TX-10, hydroxypropyl methylcellulose, sodium dihydrogen phosphate, deionized water and 1-vinyl-2-pyrrolidone is 0.1-0.2:0.2-0.4:0.05-0.1:10-15:1.

[0027] In this invention, preferably, in step (2), the initiator is a mixed solution of persulfate and sodium bisulfite, wherein the concentration of persulfate is 8-12 wt%, the concentration of sodium bisulfite is 4-6 wt%, and the mass ratio of initiator to 1-vinyl-2-pyrrolidone is 0.2-0.4:1.

[0028] In a preferred embodiment, the persulfate is one of ammonium persulfate, sodium persulfate, or potassium persulfate.

[0029] The synthesis reaction equation for the profile control and water-blocking agent of this invention is as follows:

[0030]

[0031]

[0032] The third objective of this invention is to disclose the application of the above-mentioned water shut-off agent in water shut-off and profile control in oilfields.

[0033] The oilfield profile control and water shut-off agent of this invention is a polymeric water shut-off agent with 1-vinyl-2-pyrrolidone, allyl dimethyl (4-methoxyphenyl)silane, 2-acrylamido-2-methylpropanesulfonic acid, allyl malonic acid, and bisphenol A glycerol diacrylate as polymer units. 1-Vinyl-2-pyrrolidone is a rigid monomer that can significantly increase the strength of the product; allyl dimethyl (4-methoxyphenyl)silane contains a silicone surfactant and is lipophilic, allowing it to seamlessly bond with the rock surface, greatly improving the plugging rate of large pores in the formation and enhancing water shut-off efficiency; 2-Acrylamido-2-methylpropanesulfonic acid and allyl malonic acid contain sulfonic acid and carboxyl anions, which are hydrophilic groups, enabling the product molecules to adsorb onto the surface of large-pore rock formations, thus improving water shut-off efficiency; allyl dimethyl (4-methoxyphenyl)silane molecules contain a silicone surfactant, allowing it to seamlessly bond with the rock surface, greatly improving the plugging rate of large pores in the formation and enhancing water shut-off efficiency; bisphenol A glycerol diacrylate is a crosslinking agent that can significantly increase the molecular weight and viscosity of the product; hydroxypropyl methylcellulose is a dispersant that can prevent the emulsion droplets of the polymerized product from becoming excessively large, enhancing stability and improving the polymerization effect.

[0034] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0035] (1) The oilfield profile control and water shut-off agent of the present invention has a high breakthrough pressure gradient, reaching up to 38.9 MPa / m in low-permeability cores and up to 23.6 MPa / m in high-permeability cores;

[0036] (2) The oilfield profile control and water shut-off agent of the present invention has a high water shut-off rate, reaching up to 99.8% for low-permeability cores and up to 99.6% for high-permeability cores;

[0037] (3) The oilfield profile control and water shut-off agent of the present invention has a high water shut-off rate after 100PV water flushing, reaching up to 98.2% for low-permeability cores and up to 96.3% for high-permeability cores. Detailed Implementation

[0038] 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.

[0039] The present invention will be further described below with reference to specific embodiments:

[0040] Example 1

[0041] (1) 0.2 mol 1-vinyl-2-pyrrolidone, 0.1 mol allyl dimethyl (4-methoxyphenyl)silane, 0.04 mol 2-acrylamido-2-methylpropanesulfonic acid, 0.03 mol allyl malonic acid, 0.01 mol bisphenol A glycerol diacrylate, 3.2 g TX-10, 4.44 g hydroxypropyl methylcellulose, 1.11 g sodium dihydrogen phosphate, and 222 g deionized water were added to the reactor in sequence. The mixture was stirred at 800 rpm until all raw materials were completely formed into a homogeneous emulsion. The pH was adjusted to 7-8 with sodium hydroxide solution.

[0042] (2) Purge the reactor with nitrogen for 5 minutes. In the later stages of the process, slowly introduce nitrogen to ensure that oxygen is isolated as much as possible during the synthesis. Add 4.44 g of initiator solution to the reactor. The initiator contains 12 wt% sodium persulfate and 6 wt% sodium bisulfite. Heat to 45 °C and stir continuously until the solution becomes viscous. Continue to heat to 75 °C and stir for 3 hours. Adjust the pH to 7-8 with sodium hydroxide solution and cool to below 40 °C to obtain a viscous liquid.

[0043] (3) The above viscous liquid is dried and granulated to a particle size of 1-4 mm to obtain the product water-blocking agent.

[0044] Example 2

[0045] (1) 0.2 mol 1-vinyl-2-pyrrolidone, 0.12 mol allyl dimethyl (4-methoxyphenyl)silane, 0.036 mol 2-acrylamido-2-methylpropanesulfonic acid, 0.04 mol allyl malonic acid, 0.012 mol bisphenol A glycerol diacrylate, 2.22 g TX-10, 4.86 g hydroxypropyl methylcellulose, 1.38 g sodium dihydrogen phosphate, and 252 g deionized water were added to the reactor in sequence. The mixture was stirred at 800 rpm until all raw materials were completely formed into a homogeneous emulsion. The pH was adjusted to 7-8 with sodium hydroxide solution.

[0046] (2) Purge the reactor with nitrogen for 6 minutes. In the later stages of the process, slowly introduce nitrogen to ensure that oxygen is isolated as much as possible during the synthesis. Add 4.88 g of initiator solution to the reactor. The initiator contains 8 wt% sodium persulfate and 5 wt% sodium bisulfite. Heat to 50 °C and stir continuously until the solution becomes viscous. Continue to heat to 80 °C and stir for 2 hours. Adjust the pH to 7-8 with sodium hydroxide solution and cool to below 40 °C to obtain a viscous liquid.

[0047] (3) The above viscous liquid is dried and granulated to a particle size of 1-4 mm to obtain the product water-blocking agent.

[0048] Example 3

[0049] (1) 0.2 mol 1-vinyl-2-pyrrolidone, 0.14 mol allyl dimethyl (4-methoxyphenyl)silane, 0.033 mol 2-acrylamido-2-methylpropanesulfonic acid, 0.027 mol allyl malonic acid, 0.013 mol bisphenol A glycerol diacrylate, 2.56 g TX-10, 5.77 g hydroxypropyl methylcellulose, 1.56 g sodium dihydrogen phosphate, and 242 g deionized water were added to the reactor in sequence. The mixture was stirred at 900 rpm until all raw materials were completely formed into a homogeneous emulsion. The pH was adjusted to 7-8 with sodium hydroxide solution.

[0050] (2) Purge the reactor with nitrogen for 8 minutes. In the later stages of the process, slowly introduce nitrogen to ensure that oxygen is isolated as much as possible during the synthesis. Add 5.4 g of initiator solution to the reactor. The initiator contains 10 wt% sodium persulfate and 5 wt% sodium bisulfite. Heat to 45 °C and stir continuously until the solution becomes viscous. Continue to heat to 78 °C and stir for 2.5 h. Adjust the pH to 7-8 with sodium hydroxide solution and cool to below 40 °C to obtain a viscous liquid.

[0051] (3) The above viscous liquid is dried and granulated to a particle size of 1-4 mm to obtain the product water-blocking agent.

[0052] Example 4

[0053] (1) 0.2 mol 1-vinyl-2-pyrrolidone, 0.15 mol allyl dimethyl (4-methoxyphenyl)silane, 0.03 mol 2-acrylamido-2-methylpropanesulfonic acid, 0.025 mol allyl malonic acid, 0.015 mol bisphenol A glycerol diacrylate, 3.1 g TX-10, 6.14 g hydroxypropyl methylcellulose, 1.88 g sodium dihydrogen phosphate, and 268 g deionized water were added to the reactor in sequence. The mixture was stirred at 900 rpm until all raw materials were completely formed into a homogeneous emulsion. The pH was adjusted to 7-8 with sodium hydroxide solution.

[0054] (2) Purge the reactor with nitrogen for 10 min. In the later stages of the process, slowly introduce nitrogen to ensure that oxygen is isolated as much as possible during the synthesis. Add 6.4 g of initiator solution to the reactor. The initiator contains 11 wt% ammonium persulfate and 5 wt% sodium bisulfite. Heat to 48 °C and stir continuously until the solution becomes viscous. Continue to heat to 77 °C and stir for 2.5 h. Adjust the pH to 7-8 with sodium hydroxide solution and cool to below 40 °C to obtain a viscous liquid.

[0055] (3) The above viscous liquid is dried and granulated to a particle size of 1-4 mm to obtain the product water-blocking agent.

[0056] Example 5

[0057] (1) 0.2 mol 1-vinyl-2-pyrrolidone, 0.16 mol allyl dimethyl (4-methoxyphenyl)silane, 0.028 mol 2-acrylamido-2-methylpropanesulfonic acid, 0.028 mol allyl malonic acid, 0.017 mol bisphenol A glycerol diacrylate, 3.4 g TX-10, 6.88 g hydroxypropyl methylcellulose, 2.01 g sodium dihydrogen phosphate, and 298 g deionized water were added to the reactor in sequence. The mixture was stirred at 1000 rpm until all raw materials were completely formed into a homogeneous emulsion. The pH was adjusted to 7-8 with sodium hydroxide solution.

[0058] (2) Purge the reactor with nitrogen for 8 minutes. In the later stages of the process, slowly introduce nitrogen to ensure that oxygen is isolated as much as possible during the synthesis. Add 7.44 g of initiator solution to the reactor. The initiator contains 11 wt% ammonium persulfate and 4 wt% sodium bisulfite. Heat to 50 °C and keep stirring until the solution becomes viscous. Continue to heat to 80 °C and continue stirring for 2 hours. Adjust the pH to 7-8 with sodium hydroxide solution and cool to below 40 °C to obtain a viscous liquid.

[0059] (3) The above viscous liquid is dried and granulated to a particle size of 1-4 mm to obtain the product water-blocking agent.

[0060] Example 6

[0061] (1) 0.2 mol 1-vinyl-2-pyrrolidone, 0.18 mol allyl dimethyl (4-methoxyphenyl)silane, 0.025 mol 2-acrylamido-2-methylpropanesulfonic acid, 0.033 mol allyl malonic acid, 0.018 mol bisphenol A glycerol diacrylate, 4.44 g TX-10, 7.29 g hydroxypropyl methylcellulose, 2.22 g sodium dihydrogen phosphate, and 312 g deionized water were added to the reactor in sequence. The mixture was stirred at 850 rpm until all raw materials were completely formed into a homogeneous emulsion. The pH was adjusted to 7-8 with sodium hydroxide solution.

[0062] (2) Purge the reactor with nitrogen for 5 minutes. In the later stages of the process, slowly introduce nitrogen to ensure that oxygen is isolated as much as possible during the synthesis. Add 7.98 g of initiator solution to the reactor. The initiator contains 8 wt% potassium persulfate and 4 wt% sodium bisulfite. Heat to 45 °C and stir continuously until the solution becomes viscous. Continue to heat to 75 °C and stir for 3 hours. Adjust the pH to 7-8 with sodium hydroxide solution and cool to below 40 °C to obtain a viscous liquid.

[0063] (3) The above viscous liquid is dried and granulated to a particle size of 1-4 mm to obtain the product water-blocking agent.

[0064] Example 7

[0065] (1) 0.2 mol 1-vinyl-2-pyrrolidone, 0.2 mol allyl dimethyl (4-methoxyphenyl)silane, 0.02 mol 2-acrylamido-2-methylpropanesulfonic acid, 0.038 mol allyl malonic acid, 0.02 mol bisphenol A glycerol diacrylate, 4.2 g TX-10, 8.88 g hydroxypropyl methylcellulose, 1.96 g sodium dihydrogen phosphate, and 333 g deionized water were added to the reactor in sequence. The mixture was stirred at 950 rpm until all raw materials were completely formed into a homogeneous emulsion. The pH was adjusted to 7-8 with sodium hydroxide solution.

[0066] (2) Purge the reactor with nitrogen for 5 minutes. In the later stages of the process, slowly introduce nitrogen to ensure that oxygen is isolated as much as possible during the synthesis. Add 8.88 g of initiator solution to the reactor. The initiator contains 8 wt% potassium persulfate and 6 wt% sodium bisulfite. Heat to 48 °C and stir continuously until the solution becomes viscous. Continue to heat to 78 °C and stir for 2.6 h. Adjust the pH to 7-8 with sodium hydroxide solution and cool to below 40 °C to obtain a viscous liquid.

[0067] (3) The above viscous liquid is dried and granulated to a particle size of 1-4 mm to obtain the product water-blocking agent.

[0068] Example 8 Performance Test

[0069] The water-blocking agent of the present invention (Examples 1-7) was prepared into a product with a concentration of 5000 mg / L. At 80°C, the breakthrough pressure gradient, water-blocking rate, and water-blocking rate after 100 PV water flushing were tested according to the method in Q / SH1020 1493—2019 "Performance Indicators and Test Methods of Gel-type Water-blocking and Profile Control Agents".

[0070] The core sample used in the test was 0.24 μm. 2 Low-permeability core and 1.16μm 2 The high-permeability core samples were all 4.6 cm in length. The test results are shown in Table 1.

[0071] A comparative experiment was conducted using the water shut-off and profile control agent from Shengli Chemical Co., Ltd. of Shengli Oilfield.

[0072] Table 1. Test results of water blocking rate after overcoming pressure gradient, water blocking rate, and water blocking rate after flushing with 100PV water.

[0073]

[0074] As can be seen from Table 1:

[0075] (1) The oilfield profile control and water shut-off agent of the present invention (Examples 1-7) has a high breakthrough pressure gradient. The breakthrough pressure gradient of low-permeability cores is above 37 MPa / m, with the highest reaching 38.9 MPa / m (Example 5). The breakthrough pressure gradient of high-permeability cores is above 20 MPa / m, with the highest reaching 23.6 MPa / m (Example 1). In contrast, the breakthrough pressure gradients of the low-permeability cores and high-permeability cores in the comparative examples are 10.6 MPa / m and 6.3 MPa / m, respectively, which are significantly lower than those of the present invention.

[0076] (2) The oilfield profile control and water shut-off agent of the present invention (Examples 1-7) has a high water shut-off rate. The water shut-off rate of low-permeability cores is 99.2% or higher, with the highest reaching 99.8% (Example 7). The water shut-off rate of high-permeability cores is 98% or higher, with the highest reaching 99.6% (Example 7). In contrast, the water shut-off rates of the comparative low-permeability cores and high-permeability cores are 95.9% and 94.2% respectively, which are significantly lower than those of the present invention.

[0077] (3) The oilfield profile control and water shut-off agent of the present invention (Examples 1-7) has a high water shut-off rate after flushing with 100PV water. The water shut-off rate of low-permeability cores after flushing with 100PV water is greater than 97%, and the highest reaches 98.2% (Example 7). The water shut-off rate of high-permeability cores after flushing with 100PV water is greater than 95%, and the highest reaches 96.3% (Example 7). In contrast, the water shut-off rates of the comparative low-permeability cores and high-permeability cores after flushing with 100PV water are 90.3% and 88.8%, respectively, which are significantly lower than those of the present invention.

[0078] 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 synthesizing an oilfield profile control and water shut-off agent, characterized in that, The specific steps of the synthesis method are as follows: (1) 1-Vinyl-2-pyrrolidone, allyl dimethyl (4-methoxyphenyl)silane, 2-acrylamido-2-methylpropanesulfonic acid, allyl malonic acid, bisphenol A glycerol diacrylate, TX-10, hydroxypropyl methylcellulose, sodium dihydrogen phosphate, and deionized water were added to the reactor in sequence. The mixture was stirred at high speed of 800-1000 rpm until all raw materials were completely formed into a homogeneous emulsion. The pH was adjusted to 7-8 with sodium hydroxide solution. (2) Purge the reactor with nitrogen for 5-10 minutes. In the later stages of the process, slowly introduce nitrogen to ensure that oxygen is isolated as much as possible during the synthesis process. Add the initiator solution to the reactor, heat to 45-50℃, and continue to stir until the solution becomes viscous. Continue to heat to 75-80℃ and continue to stir for 2-3 hours. Adjust the pH to 7-8 with sodium hydroxide solution and cool to below 40℃ to obtain a viscous liquid. (3) The above viscous liquid is dried and granulated to a particle size of 1-4 mm to obtain the product water-blocking agent; The molar ratio of allyl dimethyl (4-methoxyphenyl)silane, 2-acrylamido-2-methylpropanesulfonic acid, allyl malonic acid, bisphenol A glycerol diacrylate and 1-vinyl-2-pyrrolidone is 0.5-1:0.1-0.2:0.1-0.2:0.05-0.1:

1.

2. The method for synthesizing an oilfield profile control and water shut-off agent according to claim 1, characterized in that, In step (1), the mass ratio of TX-10, hydroxypropyl methylcellulose, sodium dihydrogen phosphate, deionized water and 1-vinyl-2-pyrrolidone is 0.1-0.2:0.2-0.4:0.05-0.1:10-15:

1.

3. The method for synthesizing an oilfield profile control and water shut-off agent according to claim 1, characterized in that, In step (2), the initiator is a mixed solution of persulfate and sodium bisulfite.

4. The method for synthesizing an oilfield profile control and water shut-off agent according to claim 3, characterized in that, The concentration of persulfate is 8-12 wt%, and the concentration of sodium bisulfite is 4-6 wt%.

5. The method for synthesizing an oilfield profile control and water shut-off agent according to claim 1 or 3, characterized in that, The mass ratio of the initiator to 1-vinyl-2-pyrrolidone is 0.2-0.4:

1.

6. The method for synthesizing an oilfield profile control and water shut-off agent according to claim 3, characterized in that, The persulfate mentioned is one of ammonium persulfate, sodium persulfate, and potassium persulfate.

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