Oil-water selective plugging system and application thereof

Abstract

The invention discloses an oil-water selective plugging system and application thereof, and belongs to the technical field of oilfield chemistry, the plugging system comprises, by mass, 0.5%-5% of modified composite curable swellable particles, 0.5%-1% of a structure enhancer, 0.5%-1% of a curing agent and water.The oil-water selective plugging system has good hot salt stability and oil-water selectivity, and the oil-water selective plugging system can be used for plugging oil-water well. The system composition can be dynamically adjusted according to the physical property of a reservoir, the environmental adaptability is high, after entering a reservoir water channeling channel, particles absorb water, expand, solidify and adhere, a spatial three-dimensional network structure is formed, high-strength plugging of the water channeling channel is achieved, the relative permeability of a water phase is reduced, damage to an oil phase channel is small, and the plugging effect is good. The plugging agent has the characteristic of selectively plugging water channeling channels.

Description

Technical Field

[0001] The invention relates to the technical field of oilfield chemistry, in particular to an oil-water selective plugging system and application thereof. Background Art

[0002] During oil and gas field development, water injection through injection wells is a crucial method for replenishing formation energy. However, reservoirs are commonly characterized by heterogeneity and fractures, which are favorable seepage pathways. This can lead to injected water rapidly flowing through these pathways into production wells, causing water breakthrough. Premature water breakthrough in production wells not only significantly reduces crude oil production but also directly impacts the economic benefits of oilfield development. Therefore, water plugging is necessary.

[0003] Selective water plugging technology offers the advantage of relatively simple processes because it eliminates the need to isolate oil and water layers. However, many oil reservoirs are characterized by deep burial depths, high formation temperatures, and high salinity. High temperatures easily induce dehydration shrinkage in polymers, while high salinity causes the polymer molecular chains to curl, ultimately leading to a decrease in plugging strength and even failure. Consequently, existing selective water plugging agents generally face technical bottlenecks such as insufficient temperature resistance, poor selectivity, and limited plugging strength, which hinder their effectiveness in reducing water flow and increasing oil production. For example, Chinese patent publication number CN 118421046 A discloses a modified resin curable system for selective water plugging. This modified resin curable system can selectively plug water channeling channels in reservoirs under high-temperature, high-salinity conditions. While it exhibits selective plugging characteristics and excellent thermal-salinity stability, the system exhibits low plugging strength against water channeling channels, and the plugging structure is easily damaged, leading to plugging failure. Therefore, there is an urgent need to develop an oil-water selective plugging agent suitable for the complex environments of high-temperature, high-salinity reservoirs, with high plugging strength and excellent selectivity. Summary of the Invention

[0004] In view of this, in order to solve the deficiencies of existing technical conditions, one purpose of the present invention is to propose an oil-water selective plugging system. The oil-water selective plugging system of the present invention is suitable for the complex environment of high-temperature and high-salinity oil reservoirs. At the same time, it has high plugging strength and good selectivity.

[0005] In order to achieve the above object, the technical solution provided by the present invention is as follows: An oil-water selective plugging system, calculated by mass fraction, is composed of the following raw materials: Modified composite curable bulk particles, 0.5% to 5%; Structural enhancer, 0.5% to 1%; Curing agent, 0.5% to 1%; The balance is water; The preparation of the modified composite curable bulk particles comprises the following steps: S1, adding a silane coupling agent to alkaline water for hydrolysis, and then adding a surfactant to obtain a silane coupling agent hydrolyzed solution containing a surfactant, wherein the mass ratio of water, the silane coupling agent and the surfactant is 1:(0.01-0.03):(0.003-0.005); S2. Evenly mixing oil-soluble resin particles, curable resin particles, and a silane coupling agent hydrolyzed solution in a mass ratio of (0.05-0.07):(0.01-0.02):1 to obtain a resin dispersion solution, wherein the oil-soluble resin particles are C5 petroleum resin particles or C9 petroleum resin particles, and the curable resin particles are phenolic resin 7522 particles or terpene phenolic resin DA-21 particles; S3. Mix the acrylamide monomer, crosslinking agent, initiator, oxygen scavenger, sodium montmorillonite, N-vinyl pyrrolidone and resin dispersion solution in a mass ratio of (0.2-0.3):(0.002-0.003):(0.0001-0.0002):(0.0001-0.0002):(0.1-0.15):(0.004-0.006):1 to obtain a base solution; S4. Place the basic solution in a sealed container and heat it to form a gel, then dry and crush it to obtain modified composite curable bulk particles.

[0006] As a specific embodiment of the present invention, in step S1, the silane coupling agent is one of KH-540, KH-550, KH-560, and KH-792, and the surfactant is one of APG-0810, APG-1214, DAB-35, and ODAB-35.

[0007] As a specific embodiment of the present invention, in step S3, the initiator is one of ammonium persulfate (APS), potassium persulfate (KPS), lauroyl peroxide (LPO), and azobisisobutylamidine hydrochloride (AIBA); the cross-linking agent is one of N,N-methylenebisacrylamide (MBA) and an organic zirconium cross-linking agent; and the oxygen scavenger is one of thiourea and sodium bisulfite.

[0008] As a specific embodiment of the present invention, the gelling temperature in step S4 is 80° C. and the time is 72 hours.

[0009] As a specific embodiment of the present invention, the structure enhancer is one of paraformaldehyde, hexamethoxymethylmelamine (HMMM), and hexamethylenetetramine (HMTA).

[0010] As a specific embodiment of the present invention, the curing agent is one of NL curing agent and triethylenediamine (TEDA).

[0011] Another object of the present invention is to provide an application method of an oil-water selective plugging system, wherein the above-mentioned oil-water selective plugging system is injected into the oil reservoir in different ways according to different conditions of the oil field: for oil fields with production profile test data, a fixed-point injection method is adopted, and the oil-water selective plugging system solidifies after entering the water-producing channel to achieve water plugging operation; for oil fields without production profile test data, it can be injected directly from the oil pipeline channel, and after the oil-water selective plugging system enters the water-containing channel under high temperature conditions, the modified composite solidifiable body expandable particles absorb water and swell in the water phase, and adhere to each other under the joint action of the structural enhancer and the curing agent to form a high-strength spatial three-dimensional network structure, which effectively blocks the reservoir water channel. At the same time, since the oil-water selective plugging system of the present invention has good solubility in the oil phase, it causes less damage to the oil phase channel, and thus can achieve selective plugging of the water phase channel.

[0012] The technical effects of the present invention are: (1) The oil-water selective plugging system of the present invention combines curable resin, oil-soluble resin and bulk-swelling particles, so that the system has excellent water absorption and expansion properties, curable adhesion properties and oil solubility. The three properties work together to selectively plug high-temperature and high-salt water production channels with good plugging performance, high plugging strength and good selectivity.

[0013] (2) After the oil-water selective plugging system of the present invention is injected into the water channeling channel of the oil reservoir, it absorbs water, expands, solidifies, and adheres under high temperature conditions, forming a high-strength spatial three-dimensional network structure, achieving high-strength plugging of the reservoir water channeling channel. At the same time, the resin particles can enhance the mechanical properties of the system. After the plugging system enters the oil phase channel, the oil-soluble components in the modified composite solidifiable bulk particles can be miscible with the oil phase, and the particles are peeled off from the inner wall of the channel and flow with the crude oil, eliminating the damage.

[0014] (3) The oil-water selective plugging system of the present invention is temperature responsive. Within a certain temperature range, as the temperature rises, the modified composite solidifiable bulk particles have better water absorption and expansion effects, higher curing strength, and the formed three-dimensional network structure has a larger size, which has a better effect on plugging water channel and exhibits a certain high-temperature synergistic effect.

[0015] (4) The oil-water selective plugging system of the present invention has good environmental adaptability and injectivity. The system composition and particle size can be dynamically adjusted according to the physical properties of the reservoir to achieve deep matching with the reservoir environment, thereby effectively plugging the reservoir water channel. DETAILED DESCRIPTION

[0016] The present invention will be further described in detail below with reference to the examples, but the embodiments of the present invention are not limited thereto. The experimental methods used in the following examples are conventional methods unless otherwise specified; the materials, reagents, etc. used therein are all commercially available unless otherwise specified.

[0017] Example 1

[0018] S1. Preparing modified composite curable bulk particles, comprising the following steps: S11. Weigh 1000 mL of deionized water, adjust the pH value of the solution to 10, add 10 g of silane coupling agent KH-540 to prepare a silane coupling agent hydrolysis solution, add 3 g of surfactant APG-0810 at 40° C., and stir evenly for later use.

[0019] S12. Start the constant temperature magnetic stirrer, set the temperature to 55°C and the speed to 1000 r / min, and add 5% of C5 oil-soluble resin particles (from Shandong Qilong Chemical Co., Ltd.) and 1% of phenolic resin 7522 particles (from Shenzhen Jitian Chemical Co., Ltd.) to the hydrolyzed silane coupling agent solution containing a surfactant, based on the mass of the solution. Stir thoroughly for 15 minutes until the particles are evenly dispersed to obtain a resin dispersion solution.

[0020] S13. Turn on the constant temperature magnetic stirrer, set the temperature to 60°C and the speed to 1000 r / min, and add 20% of acrylamide monomer, 0.2% of cross-linking agent N,N-methylenebisacrylamide, 0.01% of initiator ammonium persulfate and 0.01% of deoxidizer thiourea to the resin dispersion solution in sequence based on the mass of the resin dispersion solution. Continue stirring for 15 minutes, then add 10% of sodium montmorillonite and 0.4% of N-vinyl pyrrolidone, and stir thoroughly for 5 minutes to obtain a basic solution.

[0021] S14. Place the basic solution obtained in step S13 in a sealed container, heat it in an oven at 80°C for 72 hours until it is completely gelled, then take it out and continue heating it in an oven for 72 hours until it is completely dried, then place the dried gel in a grinder and grind it, and use a sieve to sieve out particles of different particle sizes, and after sieving with the sieve, modified composite curable bulk particles of different particle sizes are obtained.

[0022] S2. Turn on the constant temperature magnetic stirrer, take 98.5 mL of deionized water, add 0.5 g of modified composite curable bulk particles (60 mesh) to the water at 55 ° C, stir at 3000 r / min until uniform, then add 0.5 g of structural enhancer urotropine and 0.5 g of curing agent triethylenediamine, maintain the stirring speed for 0.5 h, and obtain an oil-water selective plugging system.

[0023] Example 2

[0024] S1. Preparing modified composite curable bulk particles, comprising the following steps: S11. Weigh 1000 mL of deionized water, adjust the pH value of the solution to 10, add 12 g of silane coupling agent KH-560 to prepare a silane coupling agent hydrolysis solution, add 4 g of surfactant APG-1214 at 40° C., and stir evenly for later use.

[0025] S12. Start the constant temperature magnetic stirrer, set the temperature to 55°C and the speed to 2000 r / min, and add 6% of C9 oil-soluble resin particles (from Shandong Donghao Chemical Co., Ltd.) and 1.5% of terpene phenolic resin DA-21 particles (from Shenzhen Jitian Chemical Co., Ltd.) to the hydrolyzed solution of the silane coupling agent containing a surfactant, based on the mass of the hydrolyzed solution of the silane coupling agent containing a surfactant. Stir thoroughly for 15 minutes until the particles are evenly dispersed to obtain a resin dispersion solution.

[0026] S13. Turn on the constant temperature magnetic stirrer, set the temperature to 60°C and the speed to 1000 r / min, and add 25% of acrylamide monomer, 0.25% of organic zirconium cross-linking agent, 0.015% of initiator azobisisobutyramidine hydrochloride and 0.015% of deoxidizer sodium bisulfite to the resin dispersion solution in sequence based on the mass of the resin dispersion solution. Continue stirring for 15 minutes, then add 12% of sodium montmorillonite and 0.5% of N-vinyl pyrrolidone, and stir thoroughly for 5 minutes to obtain a basic solution.

[0027] S14. Place the basic solution obtained in step S13 in a sealed container, heat it in an oven at 80°C for 72 hours until it is completely gelled, then take it out and continue heating it in an oven for 72 hours until it is completely dried, then place the dried gel in a grinder and grind it, and use a sieve to sieve out particles of different particle sizes, and after sieving with the sieve, modified composite curable bulk particles of different particle sizes are obtained.

[0028] S2. Turn on the constant temperature magnetic stirrer, take 96.6 mL of deionized water, add 2 g of modified composite curable bulk particles (60 mesh) to the water at 55 ° C, stir at 4000 r / min until uniform, then add 0.7 g of structural enhancer hexamethoxymethyl melamine (HMMM) and 0.7 g of NL curing agent, maintain the stirring speed for 0.5 h, and obtain an oil-water selective plugging system.

[0029] Example 3

[0030] The difference between this comparative example and Example 2 is that the water in step S2 has a mineralization degree of 20×10 4 mg / L of simulated formation water.

[0031] Example 4

[0032] The difference between this comparative example and Example 2 is that the 60-mesh modified composite curable bulking particles in step S2 are adjusted to 80-mesh modified composite curable bulking particles.

[0033] Comparative Example 1 The difference between this comparative example and Example 2 is that the water in step S2 has a mineralization degree of 20×10 4 mg / L of simulated formation water without adding curing agent.

[0034] Comparative Example 2 The difference between this comparative example and Example 2 is that in step S12, the terpene phenolic resin DA-21 particles are replaced with C9 oil-soluble resin particles of equal mass, that is, only the oil-soluble resin particles are added without adding curable resin particles.

[0035] Comparative Example 3 The difference between this comparative example and Example 2 is that in step S12, the C9 oil-soluble resin particles are replaced with terpene phenolic resin DA-21 particles of equal mass, that is, only curable resin particles are added without adding oil-soluble resin particles.

[0036] To further illustrate the product effect, the performance of the product of the present invention will be evaluated in conjunction with the examples below.

[0037] Test Example 1 (System Water Absorption and Swelling Performance Test) The oil-water selective plugging systems of each of the above examples and comparative examples were placed in a temperature-resistant and pressure-resistant container. The container was placed in a 120°C oven and continuously heated. After 5 days, the container was taken out and the volume of the three-dimensional network structure formed by the particles absorbing water, expanding, solidifying and adhering was measured. The measurement results are shown in Table 1: Table 1 Evaluation results of water absorption and expansion performance of each plugging system

[0038] As shown in Table 1, all oil-water selective plugging systems have water absorption and expansion capabilities; the water absorption and expansion multiple of Example 3 is slightly lower than that of Example 2, indicating that the water absorption and expansion performance of the system will decrease under high salinity conditions; the water absorption and expansion multiple of Example 4 is increased compared with Example 2, which shows that changing the particle size has an effect on its water absorption and expansion multiple; the water absorption and expansion multiple of Comparative Example 1 is lower than that of Example 3, which is because the addition of a curing agent will promote the system to absorb water and expand and adhere and solidify, and the block structure formed by the system will be larger in volume, which is conducive to improving water absorption and expansion. The water absorption expansion ratio of comparative example 2 is significantly lower than that of embodiment 2, which shows that without adding curable resin particles, the spatial three-dimensional network structure formed by the water absorption and expansion of the system is smaller. It can be seen that the system can have curable properties only after adding curable resin, and the particles in the system can adhere to each other and solidify to form a larger spatial structure, thereby promoting the blocking of the aqueous phase channel; the water absorption expansion ratio of comparative example 3 is slightly lower than that of embodiment 2, which shows that the oil-soluble resin particles have little effect on the water absorption and expansion properties of the system.

[0039] Test Example 2 (Plugging Performance Evaluation) A physical model of a sand-filled tube with a permeability of 100 mD was prepared and heated in an oven. Water flooding and oil displacement experiments were carried out at 100°C and 120°C respectively to evaluate the oil-water selective plugging performance of the system under high temperature conditions.

[0040] Water flooding experiment: The model was flooded with water. After the pressure stabilized, the initial water phase permeability (permeability before injection of the system) was calculated. Then, 0.5 PV of the oil-water selective plugging system was injected into the model. The valve was closed and heated for 5 days before continuing the water flooding. After the pressure stabilized, the subsequent water phase permeability of the core (permeability after injection of the system) was calculated. Oil displacement experiment: Crude oil was injected into the model. After the pressure stabilized, the initial oil phase permeability (permeability before injection) was calculated. Then, 0.5 PV of the oil-water selective plugging system was injected into the model. The valve was closed and heated for 5 days before continuing to inject crude oil. After the pressure stabilized, the subsequent oil phase permeability (permeability after injection) was calculated. The selective plugging performance of the oil-water selective plugging system for the water and oil phases was examined (the water-to-oil plugging ratio is the ratio of the water-phase plugging rate to the oil-phase plugging rate). The test results are shown in Tables 2 to 4. Table 2 Flow test results of various plugging systems at 100°C

[0041] Table 3 Flow test results of various plugging systems at 120°C

[0042] Table 4 Selective plugging performance of each plugging system at different temperatures

[0043] The above results show that, for the sand-filled pipe model with a permeability of 100 mD, the oil-water selective plugging system of each embodiment can achieve a plugging rate of more than 70% for the water phase channel, and a plugging rate for the oil phase channel is less than 15%, with good water phase plugging performance, oil-water selectivity and hot salt stability. At the same time, the plugging rate of the water phase increases with increasing temperature, showing a high-temperature synergistic effect; the plugging rates and oil-water selectivity of the oil-water selective plugging systems of each comparative example are quite different. Among them, Comparative Example 3 has a high water phase plugging rate of more than 85%, but its plugging rate for the oil phase is also very high, more than 35%, which results in its poor oil-water selectivity. Comparative Examples 1 and 2 have good oil-water selectivity, but poor plugging ability for the water phase, both below 50%. In summary, the oil-water selective plugging systems of each embodiment have a high plugging rate for the water phase channel and good oil-water selectivity, which are significantly better than the oil-water selective plugging systems of each comparative example.

[0044] Test Example 3 (Plugging Strength Evaluation) A physical model of a sand-filled pipe with a permeability of 100 m was prepared and placed in an oven for heating at 120°C to carry out experiments to evaluate the injection performance and plugging strength of the system.

[0045] During the experiment, deionized water was injected into the model at a flow rate of 2 mL / min. The initial permeability of the model was measured. Subsequently, 0.5 PV of the oil-water selective plugging system was injected into the model. The valve was closed and heated for 5 days before continuing the water flooding. The water flooding breakthrough pressure during the flooding process was measured. The experimental results are shown in Table 5: Table 5 Breakthrough pressure of each plugging system

[0046] As shown in Table 5, the oil-water selective plugging system of each embodiment has a high water flooding breakthrough pressure, that is, a strong pressure-bearing capacity. The breakthrough pressure of Comparative Example 1 is significantly lower than that of Example 2. This is because the system cannot fully cure and adhere due to the lack of a curing agent, and the mechanical strength of the spatial three-dimensional network structure is greatly reduced. The breakthrough pressure of Comparative Example 2 is significantly lower than that of Example 2. This is because the system does not contain curable resin particles, and the particles in the system cannot cure and adhere to form a spatial three-dimensional network structure. The breakthrough pressure of Comparative Example 3 is significantly better than that of Example 2, which shows that increasing the curable resin content can increase the breakthrough pressure. However, as shown in Tables 2-4, this also leads to a significant decrease in its oil-water selectivity.

[0047] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the embodiments of the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. An oil-water selective plugging system, characterized in that: The raw material composition is as follows in terms of mass fraction: Modified composite curable bulk particles, 0.5% to 5%; Structural enhancer, 0.5% to 1%; Curing agent, 0.5% to 1%; The balance is water; The modified composite curable bulk particles are prepared by a method comprising the following steps: S1, adding a silane coupling agent to alkaline water for hydrolysis, and then adding a surfactant to obtain a silane coupling agent hydrolyzed solution containing a surfactant, wherein the mass ratio of water, the silane coupling agent and the surfactant is 1:(0.01-0.03):(0.003-0.005); S2. Evenly mixing oil-soluble resin particles, curable resin particles, and the silane coupling agent hydrolyzed solution in a mass ratio of (0.05-0.07):(0.01-0.02):1 to obtain a resin dispersion solution, wherein the oil-soluble resin particles are C5 petroleum resin particles or C9 petroleum resin particles, and the curable resin particles are phenolic resin 7522 particles or terpene phenolic resin DA-21 particles; S3. Evenly mix the acrylamide monomer, the cross-linking agent, the initiator, the oxygen scavenger, the sodium montmorillonite, the N-vinyl pyrrolidone and the resin dispersion solution in a mass ratio of (0.2-0.3):(0.002-0.003):(0.0001-0.0002):(0.0001-0.0002):(0.1-0.15):(0.004-0.006):1 to obtain a base solution; S4. The basic solution is placed in a sealed container and heated to form a gel, and then dried and crushed to obtain modified composite curable bulk particles.

2. The oil-water selective plugging system according to claim 1, characterized in that: In step S1, the silane coupling agent is one of KH-540, KH-550, KH-560, and KH-792, and the surfactant is one of APG-0810, APG-1214, DAB-35, and ODAB-35.

3. The oil-water selective plugging system according to claim 1, characterized in that: In step S3, the initiator is one of ammonium persulfate, potassium persulfate, lauroyl peroxide, and azobisisobutylamidine hydrochloride; the cross-linking agent is one of N,N-methylenebisacrylamide and an organic zirconium cross-linking agent; and the oxygen scavenger is one of thiourea and sodium bisulfite.

4. The oil-water selective plugging system according to claim 1, characterized in that: The structure enhancer is one of paraformaldehyde, hexamethoxymethyl melamine and hexamethylenetetramine.

5. The oil-water selective plugging system according to claim 1, characterized in that: The gelling temperature in step S4 is 80° C. and the gelling time is 72 hours.

6. The oil-water selective plugging system according to claim 1, characterized in that: The curing agent is one of NL curing agent and triethylenediamine.

7. An application method of an oil-water selective plugging system, characterized in that: The oil-water selective plugging system described in any one of claims 1 to 6 is used for water plugging operations. For oil fields with production profile test data, water plugging is performed by fixed-point injection into the water production channel. For oil fields without production profile test data, water plugging is performed by direct injection from the oil pipe.

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