A high-temperature retarding type phenolic resin plugging agent, a preparation method and application thereof

Abstract

The application relates to the technical field of oil field chemistry, in particular to a high-temperature slow-setting phenolic resin plugging agent and a preparation method and application thereof. The plugging agent is prepared from the following raw materials in a mass percentage: a main agent 5-30%, a toughening agent 1-6%, a regulator 3-5%, a slow-setting agent 0.5-3%, and the rest is water; the main agent is a product obtained by reacting formaldehyde and phenol under the condition of an alkaline catalyst, and the product comprises a hydroxymethyl active group. The preparation process is simple, the operability is high, the curing time can be controlled to be 3-5 hours at 160 DEG C high temperature, the strength after curing is high, the salt resistance and acid resistance are good, and the plugging agent can be widely applied to plugging operations under various high-temperature working conditions in the field of petroleum engineering.

Description

Technical Field

[0001] This invention relates to the field of oilfield chemical technology, specifically to a high-temperature slow-setting phenolic resin plugging agent, its preparation method, and its application. Background Technology

[0002] In the 21st century, high-temperature and high-pressure oil and gas reservoirs have become a key area for increasing oil and gas reserves and production, occupying a pivotal position in my country's petroleum industry. However, the extreme reservoir conditions in fields such as the Tarim Oilfield, Qinghai Oilfield, and Xinjiang Oilfield significantly increase the difficulty of extraction due to their high temperature and high pressure characteristics, limiting many production-enhancing measures.

[0003] With the continuous advancement of oil and gas exploration and development technologies, the number of high-temperature and ultra-high-temperature wells has increased significantly. Many oilfields in my country, such as Tarim, Daqing, and Shengli, have temperatures exceeding 160℃, even reaching 180-190℃, posing a severe challenge to downhole chemical materials. Currently, commonly used plugging agent systems mainly include polymer-based, inorganic cement-based, and resin-based plugging agent systems. Widely used polymer-based plugging agents have limited temperature resistance. Although the use of nanomaterials or solid particles such as silica and lithium saponite can improve temperature resistance to some extent, it is still difficult to meet the requirements of ultra-high-temperature reservoirs. Inorganic cement-based plugging agents have poor acid resistance, are brittle and easily broken, and cannot avoid shrinkage problems after solidification.

[0004] Resin-based plugging agents have adjustable viscosity, good rheological properties, and strong retention capacity, effectively preventing significant leakage and forming an effective seal in a short time. After curing, they form a stable three-dimensional network structure with high sealing strength and good temperature resistance, acid resistance, and compressive strength, showing great promise for downhole operations such as well completion and workover. However, resin-based plugging agents still suffer from short curing times under high-temperature environments, potentially curing prematurely before reaching the target layer, seriously threatening wellbore safety. Summary of the Invention

[0005] The purpose of this invention is to provide a high-temperature retarding phenolic resin sealing agent, its preparation method, and its application in order to solve at least one of the above-mentioned technical problems, which has the properties of resisting ultra-high temperature while also taking into account the problems of strength and delayed curing.

[0006] The present invention achieves the above objectives through the following technical solutions:

[0007] A high-temperature retarding phenolic resin plugging agent, wherein the plugging agent is prepared from the following raw materials in the indicated mass percentages: 5-30% main agent, 1-6% toughening agent, 3-5% regulator, 0.5-3% retarder, and the remainder being water;

[0008] The main agent is the product obtained by reacting formaldehyde and phenol under alkaline catalytic conditions, and the product includes a hydroxymethyl active group.

[0009] Furthermore, the sealing agent is prepared from the following raw materials in the indicated mass percentages: 15-30% main agent, 1-3% toughening agent, 5% regulator, 1.5-3% retarder, and the remainder is water.

[0010] Furthermore, the toughening agent is one of nano-silica, lithium saponite, and montmorillonite.

[0011] Furthermore, the regulator is an acrylamide monomer.

[0012] Furthermore, the retarder is sodium metasilicate.

[0013] Furthermore, the curing time of the sealing agent can be adjusted by adjusting the mass percentage of the retarder and / or the mass percentage of the main agent.

[0014] A method for preparing a high-temperature retarded phenolic resin plugging agent, used to produce any of the high-temperature retarded phenolic resin plugging agents described above, the method comprising the following steps:

[0015] Step S102: Dissolve the toughening agent in water by stirring to obtain mixture A;

[0016] Step S104: Dissolve the regulator in mixture A by stirring to obtain mixture B;

[0017] Step S106: Add a certain mass of the main agent to a beaker, then add 10% of the main agent mass of retarder, and stir thoroughly with a glass rod to obtain mixture C;

[0018] Step S108: Add mixture C to mixture B and stir evenly to obtain a high-temperature retarded phenolic resin sealant.

[0019] Furthermore, in step S102, the rotation speed is set to 400-500 r / min, and the stirring time is 10 minutes;

[0020] In step S104, the stirring time is 30 minutes;

[0021] In step S106, the total mass of the main agent and water is 100g;

[0022] In step S108, the stirring time is 30 minutes.

[0023] Furthermore, the preparation method employs a "one-pot method".

[0024] An application of a high-temperature retarded phenolic resin plugging agent, using any of the high-temperature retarded phenolic resin plugging agents described above, characterized in that: the plugging agent is applied to the crack plugging of high-temperature and high-pressure oil and gas wells.

[0025] The beneficial effects of this invention are as follows:

[0026] The high-temperature retarded phenolic resin plugging agent of this invention has a simple formulation process and is highly operable. During the synthesis of the main agent, hydroxymethyl active groups can be generated, which can spontaneously cure under high temperature conditions to form a three-dimensional network structure. It has good temperature and pressure resistance. The curing time at 160℃ can be controlled within 3-5 hours. After curing, it has high strength and good salt and acid resistance. It can be widely used in plugging operations under various high-temperature conditions in the petroleum engineering field, making up for the defects of most plugging agents, such as poor stability and fast curing at high temperatures. Attached Figure Description

[0027] Figure 1 The stress-strain curves of resin sealants with different types of toughening agents added at 160°C are shown in Example 1 of the present invention.

[0028] Figure 2 This is a bar chart showing the stress values ​​of resin sealing agents with different concentrations of lithium saponite added at 160°C in Example 2 of the present invention at a strain of 12%. Detailed Implementation

[0029] The invention will now be discussed with reference to exemplary embodiments. It should be understood that the described embodiments are merely intended to enable those skilled in the art to better understand and thus implement the invention, and are not intended to imply any limitation on the scope of the invention.

[0030] As used herein, the term "comprising" and its variations are to be interpreted as open-ended terms meaning "including but not limited to". The term "based on" is to be interpreted as "at least partially based on". The terms "one embodiment" and "an embodiment" are to be interpreted as "at least one embodiment".

[0031] A high-temperature retarding phenolic resin sealing agent is mainly composed of the following components by mass percentage: 5-30% main agent, 1-6% toughening agent, 3-5% regulator, 0.5-3% retarder, and the remainder is water.

[0032] Preferably, a high-temperature retarding phenolic resin sealant is mainly composed of the following components by mass percentage: 15-30% main agent, 1-3% toughening agent, 5% regulator, 1.5-3% retarder, and the remainder is water.

[0033] The main agent is the product obtained by reacting formaldehyde and phenol under alkaline catalytic conditions; the toughening agent is lithium saponite; the regulator is acrylamide monomer; and the retarder is sodium metasilicate.

[0034] Preparation Example

[0035] A method for preparing a high-temperature retarded phenolic resin plugging agent includes the following steps:

[0036] Step S102: Add a certain percentage of toughening agent to a certain mass of water, set the rotation speed to 400-500 r / min, and stir for 10 minutes;

[0037] Step S104: After step S102 has been thoroughly mixed, add a certain percentage of the regulator by mass and stir for 30 minutes.

[0038] Step S106: Take a certain mass of the main agent (the mass of the main agent and water is 100g) and add it to a beaker, then add 10% of the mass of the main agent as a retarder, and stir thoroughly with a glass rod.

[0039] Step S108: Add the solution from step S106 to the solution from step S104, and continue stirring for 30 minutes to obtain the sample mother liquor.

[0040] Example 1

[0041] This embodiment provides a high-temperature retarded phenolic resin plugging agent A1, prepared according to the method described in the preparation example. Specifically, by mass percentage: 30% main agent (the product obtained by reacting formaldehyde and phenol under alkaline catalytic conditions) + 3% toughening agent (nano-silica, lithium saponite, montmorillonite). It is worth noting that the toughening agent is fully dissolved first, and then the main agent (the total mass of the main agent and water is 100g) is added. The 30% main agent plugging agent serves as a comparative example. The total volume of the system is 100ml.

[0042] Example 2

[0043] This embodiment provides a high-temperature retarded phenolic resin plugging agent A2, prepared according to the method described in the preparation example. Specifically, by mass percentage: 30% main agent (the product obtained by reacting formaldehyde and phenol under alkaline catalytic conditions) + 1-6% toughening agent (lithium saponite). It is worth noting that the toughening agent is fully dissolved first, and then the main agent (the total mass of the main agent and water is 100g) is added. A 0% toughening agent plugging agent is used as a comparative example. The total volume of the system is 100ml.

[0044] Example 3

[0045] This embodiment provides a high-temperature retarded phenolic resin sealing agent A3, prepared according to the method described in the preparation example. Specifically, by mass percentage: 30% main agent (the product obtained by reacting formaldehyde and phenol under alkaline catalytic conditions) + 3% toughening agent (lithium saponite) + 5% regulator (acrylamide). It is worth noting that the toughening agent is fully dissolved first, then the regulator is added, and finally the main agent (the total mass of the main agent and water is 100g). The total volume of the system is 100ml.

[0046] Example 4

[0047] This embodiment provides a high-temperature retarded phenolic resin sealing agent A4, prepared according to the method described in the preparation example. Specifically, by mass percentage: 30% main agent (the product obtained by reacting formaldehyde and phenol under alkaline catalytic conditions) + 3% toughening agent (lithium saponite) + 5% regulator (acrylamide) + 3% retarder (sodium metasilicate). It is worth noting that the toughening agent is fully dissolved first, then the regulator is added, and the retarder is added to the main agent (the total mass of the main agent and water is 100g), stirred thoroughly, and then added to the mother liquor. The total volume of the system is 100ml.

[0048] Experimental Example 1

[0049] This experimental example was used to test the stress-strain curves of the phenolic resin sealing agents (after 24 hours of aging) prepared in Example 1 with different toughening agents (nano-silica, lithium saponite, montmorillonite). The results are shown in [Figure 1]. Figure 1 .

[0050] Test Method: The compression sample used in this experiment was a phenolic resin sealant that had been fully cured at 160℃. It was cylindrical, approximately 45 mm in diameter and 50 mm in height. An electronic universal testing machine was used to test the stress-strain relationship of the sealant sample, with a compression rate set at 10 mm / min.

[0051] Figure 1 The stress-strain curves of resin sealants with different types of toughening agents added at 160°C are shown in Example 1 of the present invention. Figure 1 It can be seen that the plugging agent samples prepared by adding different types of toughening agents at 160℃ in Example 1, the 30% main agent and the samples with added nano-silica and montmorillonite respectively, all failed at around strain = 12% and stress = 250kPa, indicating that the strengthening and toughening effects were not obvious. The sample with added lithium saponite had a stress value of 384.21kPa at strain = 18%, indicating that lithium saponite significantly enhanced the strength and toughness of the plugging agent.

[0052] Experiment Example 2

[0053] This experimental example is used to test the stress values ​​of phenolic resin sealing agents (after 24 hours of aging) prepared by adding different concentrations of toughening agent (lithium saponite) in Example 2 at strain = 12% (see bar chart). The results are shown in the figure. Figure 2 .

[0054] Test Method: The compression sample used in this experiment was a phenolic resin sealant that had been fully cured at 160℃. It was cylindrical, approximately 45 mm in diameter and 50 mm in height. An electronic universal testing machine was used to test the stress-strain relationship of the sealant sample, with a compression rate set at 10 mm / min.

[0055] Figure 2 This is a bar chart showing the stress values ​​of resin sealing agents with different concentrations of lithium saponite added at 160°C in Example 2 of the present invention at a strain of 12%. Figure 2 It can be seen that the sealing agent samples prepared by adding different concentrations (0%, 1%, 2%, 3%, 4%, 5%, 6%) of toughening agent (lithium saponite) at 160℃ have stress values ​​of 254, 320, 336, 383, 352, 293, and 281 kPa when the strain = 12%. It can be seen that 3% lithium saponite has the best reinforcing and toughening effect on the sealing agent.

[0056] Experimental Example 3

[0057] This experimental example was used to test the curing time of the phenolic resin sealant in Example 3 at high temperature (160°C), as shown in Table 1.

[0058] Time / min 60 90 120 140 160 180 190 200 Curing situation Not cured Not cured Cured Cured Cured Cured Cured Cured

[0059] Table 1

[0060] As can be seen from Table 1, the curing time of the plugging agent without the addition of a retarder at high temperature (160℃) is about 120 minutes. The curing is relatively fast and may pose a safety threat to downhole operations.

[0061] Experiment Example 4

[0062] This experimental example was used to test the curing time of the phenolic resin sealant in Example 4 at high temperature (160°C), as shown in Table 2.

[0063] Time / min 60 90 120 140 160 180 190 200 Curing situation Not cured Not cured Not cured Not cured Not cured Cured Cured Cured

[0064] Table 2

[0065] As shown in Table 2, the curing time of the plugging agent at high temperature (160℃) is significantly extended to approximately 180 minutes after the addition of the retarder, thus improving the safety of wellbore pumping. It is worth noting that for downhole operations with lower plugging strength requirements, the concentration of the main agent can be reduced or the concentration of the retarder increased to control the high-temperature curing time of the plugging agent to 3-5 hours.

[0066] The results obtained from Examples 1-4 and Experiments 1-4 show that the present invention provides a delayed-curing plugging agent for high-temperature reservoirs. The main component can spontaneously cure under high-temperature conditions to form a three-dimensional network structure with good temperature and pressure resistance. The toughening agent can strengthen the three-dimensional network structure formed by the main component and enhance the impact resistance of the plugging agent. The regulator can compensate for the inherent curing shrinkage problem of the plugging agent and improve the plugging ability. The retarder compensates for the defect of rapid curing of the plugging agent at high temperatures. It has the potential for application in high- to ultra-high-temperature reservoirs.

[0067] This invention provides a phenolic resin plugging agent for delayed curing in high-temperature oil reservoirs. The preparation process is simple and highly operable. The curing time at 160℃ can be controlled within 3-5 hours. After curing, it has high strength, good salt and acid resistance, and can be widely used in plugging operations of various high-temperature oil reservoirs.

[0068] The present invention also provides a method for preparing a delayed-curing sealing agent for high-temperature oil reservoirs, which basically adopts a "one-pot method", which is simple and easy to operate and suitable for field application.

[0069] The high-temperature retarded phenolic resin plugging agent of this invention can generate hydroxymethyl active groups during the synthesis process. Under high temperature conditions, it can spontaneously cure to form a three-dimensional network structure, exhibiting good temperature and pressure resistance. The toughening agent is introduced to reinforce the three-dimensional network structure formed by the main agent, enhancing the impact resistance of the plugging agent. The regulator is introduced to compensate for the inherent curing shrinkage problem of the resin, improving the plugging ability. At the same time, the retarder is introduced, making the curing time of the system controllable. This overcomes the defects of most plugging agents, such as poor stability and rapid curing at high temperatures, and has the potential for application in high- to ultra-high temperature reservoirs.

[0070] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

[0071] It should be understood that the sequence number of each step in the invention and embodiments of the present invention does not absolutely imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

Claims

1. A retarded phenolic resin sealing agent, characterized in that, The plugging agent is prepared from the following raw materials in the indicated mass percentages: 15-30% main agent, 1-3% lithium saponite, 3-5% acrylamide monomer, 1.5-3% sodium metasilicate, and the remainder being water; wherein the mass of sodium metasilicate is 10% of the mass of the main agent. The main agent is the product obtained by reacting formaldehyde and phenol under alkaline catalytic conditions, and the product includes a hydroxymethyl active group.

2. The retarded phenolic resin plugging agent according to claim 1, characterized in that: The curing time of the sealing agent is adjusted by adjusting the mass percentage of the sodium metasilicate and / or the mass percentage of the main agent.

3. A method for preparing a retarded phenolic resin plugging agent, used to produce the retarded phenolic resin plugging agent as described in any one of claims 1-2, characterized in that, The method includes the following steps: Step S102: Dissolve lithium soapstone in water by stirring to obtain mixture A; Step S104: Dissolve the acrylamide monomer in mixture A by stirring to obtain mixture B; Step S106: Add a certain mass of the main agent to a beaker, then add sodium metasilicate at 10% of the mass of the main agent, and stir thoroughly with a glass rod to obtain a mixture C; Step S108: Add mixture C to mixture B and stir evenly to obtain a retarded phenolic resin sealant.

4. The preparation method of the retarded phenolic resin plugging agent according to claim 3, characterized in that: In step S102, the rotation speed is set to 400-500 r / min and the stirring time is 10 minutes; In step S104, the stirring time is 30 minutes; In step S106, the total mass of the main agent and water is 100g; In step S108, the stirring time is 30 minutes.

5. The preparation method of the retarded phenolic resin plugging agent according to claim 4, characterized in that: The preparation method adopts the "one-pot method".

6. An application of a retarded phenolic resin plugging agent, using the retarded phenolic resin plugging agent as described in any one of claims 1-2, characterized in that: The sealing agent is applied to seal fractures in high-temperature and high-pressure oil and gas wells.

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