High-temperature retarding type phenolic resin blocking agent as well as preparation method and application thereof

Abstract

The invention relates to the technical field of oilfield chemistry, in particular to a high-temperature retarding type phenolic resin plugging agent and a preparation method and application thereof. The plugging agent is prepared from the following raw materials in percentage by mass: 5-30% of a main agent, 1-6% of a flexibilizer, 3-5% of a regulator, 0.5-3% of a retarder and the balance of water, the main agent is a product obtained by reacting formaldehyde and phenol in the presence of a basic catalyst, and the product comprises a hydroxymethyl active group. The preparation process is simple, the operability is high, the curing time at the high temperature of 160 DEG C can be controlled within 3-5 h, the strength after curing is high, the salt resistance and acid resistance are good, and the plugging agent can be widely applied to plugging operation under various high-temperature working conditions in the field of petroleum engineering.

Description

Technical Field

[0001] The invention relates to the technical field of oilfield chemistry, in particular to a high-temperature slow-setting phenolic resin plugging agent and a preparation method and application thereof. Background Art

[0002] In the 21st century, high-temperature and high-pressure oil and gas reservoirs have become the key areas for increasing reserves and production of oil and natural gas resources, and they play a pivotal role in my country's oil industry. Faced with extreme reservoir conditions such as the Tarim Oilfield, Qinghai Oilfield, and Xinjiang Oilfield, their high-temperature and high-pressure characteristics greatly increase the difficulty of mining, and high-temperature and high-pressure conditions limit many production-increasing measures.

[0003] With the continuous advancement of oil and gas exploration and development technology, the number of high-temperature and ultra-high-temperature wells has increased significantly. The temperature of many oil fields in my country, such as Tarim, Daqing, and Shengli, is above 160°C, and even reaches 180-190°C, which poses a severe challenge to downhole chemical materials. At present, the commonly used plugging agent systems mainly include polymer, inorganic cement, and resin plugging agent systems. The widely used polymer plugging agents have limited heat resistance. Although the use of nanomaterials or solid phase particles such as silica and lithium soapstone can improve the temperature resistance to a certain extent, it is difficult to meet the requirements of ultra-high temperature reservoirs. Inorganic cement plugging agents have poor acid resistance, are brittle and fragile, and cannot avoid shrinkage problems after curing.

[0004] Resin plugging agents have adjustable viscosity, good rheology, and strong retention capacity, which can effectively avoid large-scale leakage of plugging agents and form effective plugging in a short time. After solidification, they form a stable three-dimensional network structure with high plugging strength, good heat resistance, acid resistance and compressive strength, and have good application prospects in downhole operations such as well completion and well repair. However, in high-temperature environments, resin plugging agents still have the problem of short curing time, and may solidify prematurely before reaching the target layer, seriously threatening the safety of the wellbore. Summary of the invention

[0005] The purpose of the present invention is to provide a high-temperature slow-setting phenolic resin plugging agent and its preparation method and application in order to solve at least one of the above technical problems, which has ultra-high temperature resistance while taking into account strength, delayed curing and other issues.

[0006] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0007] A high-temperature slow-setting phenolic resin plugging agent, the plugging agent is prepared by comprising the following raw materials in percentage by mass: 5-30% of a main agent, 1-6% of a toughening agent, 3-5% of a regulator, 0.5-3% of a retarder, and the remainder is water;

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

[0009] Furthermore, the plugging agent is prepared by the following raw materials in percentage by mass: 15-30% of main agent, 1-3% of toughening agent, 5% of regulating agent, 1.5-3% of retarder, and the rest is water.

[0010] Furthermore, the toughening agent is one of nano-silicon dioxide, hectorite and montmorillonite.

[0011] Furthermore, the regulator is acrylamide monomer.

[0012] Furthermore, the retarder is sodium metasilicate.

[0013] Furthermore, the curing time of the plugging agent is 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 slow-setting phenolic resin plugging agent, used for preparing any of the high-temperature slow-setting phenolic resin plugging agents described above, the method comprising the following steps:

[0015] Step S102: stirring and dissolving the toughening agent in water to obtain a mixed solution A;

[0016] Step S104: stirring and dissolving the regulator in the mixed solution A to obtain a mixed solution B;

[0017] Step S106: adding a certain mass of the main agent into a beaker, and then adding a retarder of 10% of the mass of the main agent, and stirring well with a glass rod to obtain a mixed solution C;

[0018] Step S108: Add the mixed solution C into the mixed solution B, stir evenly, and obtain a high-temperature slow-setting phenolic resin plugging agent.

[0019] Further, 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 sum of the mass of the main agent and water is 100 g;

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

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

[0024] An application of a high temperature slow-setting phenolic resin plugging agent, using any of the high temperature slow-setting phenolic resin plugging agents described above, characterized in that the plugging agent is used for plugging cracks in high temperature and high pressure oil and gas wells.

[0025] The beneficial effects of the present invention are:

[0026] The high-temperature slow-setting phenolic resin plugging agent of the present invention has a simple preparation process and strong operability. Hydroxylmethyl active groups can be generated during the synthesis of the main agent, and the agent can be spontaneously cured under high temperature conditions to form a three-dimensional network structure. The agent has good heat and pressure resistance, and the curing time can be controlled within 3-5 hours at a high temperature of 160° C. The agent has high strength after curing, good salt and acid resistance, and can be widely used in various plugging operations under high temperature conditions in the field of petroleum engineering, thereby making up for the defects of most plugging agents having poor stability and fast curing at high temperatures. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0028] Figure 2 This is a bar graph of stress values ​​corresponding to the resin plugging agent to which different concentrations of hectorite are added at 160° C. when the strain is 12% according to Example 2 of the present invention. DETAILED DESCRIPTION

[0029] The content of the present invention will now be discussed with reference to exemplary embodiments. It should be understood that the embodiments discussed are only to enable those skilled in the art to better understand and thus implement the content of the present invention, rather than implying any limitation on the scope of the present invention.

[0030] As used herein, the term “including” and variations thereof are to be interpreted as open-ended terms meaning “including, but not limited to.” The term “based on” is to be interpreted as “based, at least in part, on.” The terms “one embodiment” and “an embodiment” are to be interpreted as “at least one embodiment.”

[0031] A high-temperature slow-setting phenolic resin plugging agent is mainly made of the following components in percentage by mass: 5-30% of a main agent, 1-6% of a toughening agent, 3-5% of a regulator, 0.5-3% of a retarder, and the remainder being water.

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

[0033] The main agent is a product obtained by the reaction of formaldehyde and phenol under alkaline catalyst conditions; the toughening agent is lithium laponite; the regulating agent is acrylamide monomer; and the retarder is sodium metasilicate.

[0034] Preparation Example

[0035] A method for preparing a high-temperature slow-setting phenolic resin plugging agent comprises the following steps:

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

[0037] Step S104: After the mixture is fully stirred in step S102, a certain mass percentage of a regulator is added and stirred for 30 minutes;

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

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

[0040] Example 1

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

[0042] Example 2

[0043] This embodiment provides a high temperature slow setting phenolic resin plugging agent A2, which is prepared according to the method of the preparation example, specifically by mass percentage: 30% main agent (the product obtained by the reaction of formaldehyde and phenol under alkaline catalyst conditions) + 1-6% toughening agent (hectorite). It is worth noting that the toughening agent is fully dissolved first, and then the main agent (the mass of the main agent and water is 100g) is added, and 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 slow setting phenolic resin plugging agent A3, which is prepared according to the method of the preparation example, specifically by mass percentage: 30% main agent (the product obtained by the reaction of formaldehyde and phenol under alkaline catalyst conditions) + 3% toughening agent (hectorite) + 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 is added (the 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 slow setting phenolic resin plugging agent A4, which is prepared according to the method of the preparation example, specifically by mass percentage: 30% main agent (the product obtained by the reaction of formaldehyde and phenol under alkaline catalyst conditions) + 3% toughening agent (hectorite) + 5% regulator (acrylamide) + 3% retarder (sodium metasilicate). It is worth noting that the toughening agent is fully dissolved first, and then the regulator is added, and the retarder is added to the main agent (the mass of the main agent and water is 100g) and fully stirred and added to the mother liquor. The total volume of the system is 100ml.

[0048] Experimental Example 1

[0049] This experimental example is used to test the stress-strain curve of the phenolic resin plugging agent (after aging for 24 hours) prepared by adding different toughening agents (nano-silicon dioxide, hectorite, montmorillonite) in Example 1. The results are shown in Figure 1 .

[0050] Test method: The compression sample used in this experiment is a phenolic resin plugging agent that is fully cured at 160°C, cylindrical, with a diameter of about 45mm and a height of about 50mm. An electronic universal testing machine is used to test the stress-strain relationship of the plugging agent sample, and the compression rate is set to 10mm / min.

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

[0052] Experimental Example 2

[0053] This experimental example is used to test the stress value bar graph corresponding to the phenolic resin plugging agent (after aging for 24 hours) prepared by adding different concentrations of toughening agent (hectorite) in Example 2 when the strain = 12%. The results are shown in Figure 2 .

[0054] Test method: The compression sample used in this experiment is a phenolic resin plugging agent that is fully cured at 160°C, cylindrical, with a diameter of about 45mm and a height of about 50mm. An electronic universal testing machine is used to test the stress-strain relationship of the plugging agent sample, and the compression rate is set to 10mm / min.

[0055] Figure 2 This is a bar graph of the stress values ​​corresponding to the resin plugging agent with different concentrations of hectorite added at 160°C when the strain is 12% according to Example 2 of the present invention. Figure 2 It can be seen that in Example 2, different concentrations (0%, 1%, 2%, 3%, 4%, 5%, 6%) of toughening agent (lithium laponite) were added at 160°C to prepare the plugging agent samples. When the strain = 12%, the corresponding stress values ​​were 254, 320, 336, 383, 352, 293, and 281 kPa. It can be seen that 3% lithium laponite has the best strengthening and toughening effect on the plugging agent.

[0056] Experimental Example 3

[0057] This experimental example is used to test the curing time of the phenolic resin plugging agent in Example 3 at high temperature (160° C.), see Table 1.

[0058] Time / min 60 90 120 140 160 180 190 200 Curing conditions Uncured Uncured Curing Curing Curing Curing Curing Curing

[0059] Table 1

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

[0061] Experimental Example 4

[0062] This experimental example is used to test the curing time of the phenolic resin plugging agent in Example 4 at high temperature (160° C.), see Table 2.

[0063] Time / min 60 90 120 140 160 180 190 200 Curing conditions Uncured Uncured Uncured Uncured Uncured Curing Curing Curing

[0064] Table 2

[0065] As can be seen from Table 2, after adding the retarder, the curing time of the plugging agent at high temperature (160°C) is about 180 minutes, which has been greatly extended, improving the safety of wellbore pumping. It is worth mentioning that when dealing with downhole operations with low plugging strength requirements, the main agent concentration can be reduced or the retarder concentration can be increased to control the high-temperature curing time of the plugging agent to 3-5 hours.

[0066] The results obtained in Examples 1-4 and Experimental Examples 1-4 show that the present invention provides a plugging agent for delayed curing of high-temperature reservoirs. The main agent can spontaneously cure under high temperature conditions to form a three-dimensional network structure, and has good heat and pressure resistance. The toughening agent can reinforce the three-dimensional network structure formed by the main agent and enhance the impact resistance of the plugging agent. The regulator can make up for the inherent curing shrinkage problem of the plugging agent and improve the plugging ability. The retarder makes up for the defect of fast curing of the plugging agent at high temperature, and has the application potential of high-ultra-high temperature reservoirs.

[0067] The invention provides a phenolic resin plugging agent for delayed curing of high-temperature oil reservoirs. The preparation process is simple and the operability is strong. The curing time can be controlled within 3-5 hours at a high temperature of 160°C. The strength after curing is high and the salt and acid resistance is good. The agent can be widely used in the plugging operations of various high-temperature oil reservoirs.

[0068] The present invention also provides a method for preparing a high-temperature oil reservoir delayed solidification plugging agent, which basically adopts a "one-pot method", is simple and easy to operate, and is suitable for on-site application.

[0069] The high-temperature slow-setting phenolic resin plugging agent of the present invention can generate hydroxymethyl active groups during the synthesis process of the main agent, can spontaneously solidify under high temperature conditions to form a three-dimensional network structure, has good heat and pressure resistance, introduces a toughening agent to reinforce the three-dimensional network structure formed by the main agent, and enhances the impact resistance of the plugging agent, introduces a regulator to compensate for the inherent curing shrinkage problem of the resin and improves the plugging ability, and simultaneously introduces a retarder to control the curing time of the system, thereby compensating for the defects of most plugging agents, namely, poor stability and fast curing at high temperatures, and has the potential for application in high- and ultra-high-temperature reservoirs.

[0070] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features are replaced with (but not limited to) technical features with similar functions disclosed in the present application.

[0071] It should be understood that the size of the serial numbers of each step in the content of the invention and the embodiments of the present invention does not absolutely mean 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 high temperature slow-setting phenolic resin plugging agent, characterized in that: The plugging agent is prepared by the following raw materials in percentage by weight: 5-30% of main agent, 1-6% of toughening agent, 3-5% of regulating agent, 0.5-3% of retarder, and the rest is water; The main agent is a product obtained by reacting formaldehyde and phenol under alkaline catalyst conditions, and the product includes hydroxymethyl active groups.

2. The high temperature slow-setting phenolic resin plugging agent according to claim 1, characterized in that: The plugging agent is prepared by including the following raw materials in percentage by mass: 15-30% of a main agent, 1-3% of a toughening agent, 5% of a regulator, 1.5-3% of a retarder, and the remainder is water.

3. The high temperature slow-setting phenolic resin plugging agent according to claim 1 or 2, characterized in that: The toughening agent is one of nano silicon dioxide, hectorite and montmorillonite.

4. The high temperature slow-setting phenolic resin plugging agent according to claim 1 or 2, characterized in that: The regulator is acrylamide monomer.

5. The high temperature slow-setting phenolic resin plugging agent according to claim 1 or 2, characterized in that: The retarder is sodium metasilicate.

6. The high temperature slow-setting phenolic resin plugging agent according to claim 5, characterized in that: The curing time of the plugging agent is adjusted by adjusting the mass percentage of the retarder and / or the mass percentage of the main agent.

7. A method for preparing a high temperature slow-setting phenolic resin plugging agent, used for preparing the high temperature slow-setting phenolic resin plugging agent as claimed in any one of claims 1 to 6, characterized in that: The method comprises the following steps: Step S102: stirring and dissolving the toughening agent in water to obtain a mixed solution A; Step S104: stirring and dissolving the regulator in the mixed solution A to obtain a mixed solution B; Step S106: adding a certain mass of the main agent into a beaker, and then adding a retarder of 10% of the mass of the main agent, and stirring well with a glass rod to obtain a mixed solution C; Step S108: Add the mixed solution C into the mixed solution B, stir evenly, and obtain a high-temperature slow-setting phenolic resin plugging agent.

8. The method for preparing the high temperature slow-setting phenolic resin plugging agent according to claim 7, 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 sum of the mass of the main agent and water is 100 g; In step S108, the stirring time is 30 minutes.

9. The method for preparing the high temperature slow-setting phenolic resin plugging agent according to claim 7, characterized in that: The preparation method adopts a "one-pot method".

10. An application of a high temperature slow-setting phenolic resin plugging agent, using the high temperature slow-setting phenolic resin plugging agent as claimed in any one of claims 1 to 6, characterized in that: The plugging agent is applied to plugging cracks in high-temperature and high-pressure oil and gas wells.

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