A high temperature resistant temporary plugging agent capable of controlled acidification degradation and its preparation method and application

Abstract

The present invention discloses a high temperature resistant temporary plugging agent with controllable acidification degradation and its preparation method and application. The high temperature resistant temporary plugging agent, by weight, comprises the following components: 60-80 parts of resin matrix; 20-40 parts of alkaline inorganic filling material; 0.1-2 parts of antioxidant; 0.1-2 parts of coupling agent; 0.1-2 parts of lubricant; wherein the resin matrix is ​​a mixture of polyamide and thermoplastic polyimide in a weight ratio of 1-9:1. The high temperature resistant temporary plugging with controllable acidification degradation provided by the present invention has good heat resistance, sealing and pressure resistance, can be used in underground environments at a temperature of 200°C or in energy fracturing mining, and can withstand a pressure of at least 50MPa. In addition, the high temperature resistant temporary plugging agent can use an acidic solution to regulate its degradation rate, thereby realizing controllable unblocking of the temporary plugging agent.

Description

Technical Field

[0001] The present invention relates to the technical field of oilfield chemical industry, and more specifically, to a high temperature resistant temporary plugging agent capable of controlled acidification degradation, and a preparation method and application thereof. Background Art

[0002] Temporary plugging fracturing technology refers to the technology of injecting temporary plugging agents into channels or cracks along with fracturing fluid to form a shield to achieve plugging during oil, gas or geothermal production, thereby forcing the pressure to concentrate at a new location, generating new cracks, and increasing oil well production. In the above process, the temporary plugging agent is required to have a strong pressure-bearing capacity to resist the clamping force of the formation and the fracturing injection pressure. At the same time, as the depth of the formation increases, the formation temperature continues to increase, especially in the geothermal production process. Therefore, HIA requires the temporary plugging agent to have the characteristics of temperature resistance, pressure resistance and hydrolysis resistance. However, when the formation environment remains unchanged, the stronger the rigidity and the more heat-resistant and pressure-resistant the temporary plugging agent is, the slower the hydrolysis rate is. In other words, the temporary plugging performance of heat-resistant and pressure-resistant is contradictory to the rapid hydrolysis to achieve unblocking.

[0003] In the prior art, the commonly used temporary plugging agents are mostly rigid temporary plugging agents (such as ceramsite, etc.). This type of temporary plugging agent is stable in nature and has good plugging ability, but the rigid temporary plugging agent has general processability and is difficult to unblock. Therefore, with the development of technology, polymer resin materials with good pressure bearing capacity and self-hydrolysis are gradually adopted as the matrix material of temporary plugging agents. On the one hand, polymer resins usually have viscoelasticity, and can offset pressure by deformation under the action of pressure, and can adjust the deformation appropriately in the cracks to achieve plugging; on the other hand, especially polyester, polyamide, and polyimide polymers can be hydrolyzed under certain temperature conditions. When hydrolyzed to a certain extent, the molecular chain rupture structure of the resin material is destroyed, and the temperature and pressure resistance of the material is greatly reduced, thereby achieving unblocking. However, in order to achieve higher temperature and pressure resistance, the polymer resin temporary plugging agent in the prior art often sacrifices part of the hydrolysis property. Even so, its heat resistance temperature is difficult to reach 200°C, which still cannot meet the higher requirements of geothermal exploitation. Therefore, it is of great significance to seek a new temporary plugging agent based on polymer resin with high strength, controllable degradation rate and good heat resistance. Summary of the invention

[0004] Based on the above background, the first purpose of the present invention is to provide a high temperature resistant temporary plugging agent with controllable acidification degradation. The temporary plugging agent not only has good heat resistance and pressure resistance, is easy to process, and has stable temporary plugging performance, but also can be induced to degrade by acidic solution, and the degradation speed can be adjusted according to actual needs.

[0005] The second object of the present invention is to provide a method for preparing the above-mentioned high-temperature resistant temporary plugging agent capable of controlled acidification degradation.

[0006] The third object of the present invention is to provide an application of the above-mentioned high temperature resistant temporary plugging agent capable of controlled acidification degradation.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a high temperature resistant temporary plugging agent capable of controlled acidification degradation, comprising the following components by weight:

[0009] Resin matrix 60-80 parts;

[0010] 20-40 parts of alkaline inorganic filler;

[0011] Antioxidant 0.1-2 parts;

[0012] Coupling agent 0.1-2 parts;

[0013] Lubricant 0.1-2 parts;

[0014] The resin matrix is ​​formed by mixing polyamide and thermoplastic polyimide in a weight ratio of 1-9:1.

[0015] Among them, the high temperature resistant temporary plugging agent with controllable acidification degradation of the present invention is based on a resin matrix, and the resin matrix has excellent temperature and pressure resistance (compressive strength ≥ 100MPa, melting point ≥ 290°C). In addition, the amide bond and imide bond in the chemical structure of the resin matrix can undergo a slow hydrolysis reaction in a high-temperature aqueous solution, and the presence of hydrogen ions (acidic solution) will greatly accelerate the hydrolysis of the amide bond and the imide bond, causing the resin matrix to depolymerize, the molecular chain to break, and gradually become oligomers or small molecules to be discharged with the water flow, thereby achieving the unblocking of the temporary plugging agent.

[0016] The alkaline inorganic filler material is evenly distributed in the resin matrix under the action of the screw processing shear force and the coupling agent. On the one hand, a specific proportion of the alkaline inorganic filler material can cooperate with the resin matrix to optimize the mechanical properties of the temporary plugging agent. On the other hand, the alkaline inorganic filler material can be used as an acid sensitizer. When encountering acidic fracturing fluid or aqueous solution, the alkaline inorganic filler material reacts with the acid to cause voids or defects in the temporary plugging agent, thereby coordinating with the matrix resin to regulate the degradation rate of the temporary plugging agent and accelerate the unblocking of the temporary plugging agent.

[0017] Furthermore, the alkaline inorganic filler material is magnesium hydroxide and / or aluminum hydroxide, wherein magnesium hydroxide and / or aluminum hydroxide can better regulate the acidification degradation rate and mechanical properties of the high temperature resistant temporary plugging agent.

[0018] Furthermore, the polyamide is selected from one or more of nylon 9T, nylon 46 and nylon 10T. Among them, the polyamide with a specific structure can better improve the temperature resistance, pressure resistance and hydrolysis resistance of the high temperature resistant temporary plugging agent.

[0019] Furthermore, the particle size of the alkaline inorganic filler material is 0.5 μm-20 μm. The alkaline filler material with this particle size can better improve the processing performance of the high temperature resistant temporary plugging agent.

[0020] Furthermore, the lubricant is TAF.

[0021] Furthermore, the antioxidant is antioxidant 1098.

[0022] Furthermore, the coupling agent is KH560. The coupling agent can improve the compatibility between the resin matrix and the powder, making the temporary plugging agent easy to extrude in batches.

[0023] Furthermore, acid is used to control the acidification degradation of the high temperature resistant temporary plugging agent; the acid is hydrochloric acid, sulfuric acid or formic acid.

[0024] Furthermore, the acid solution is formic acid, and preferably, the pH value of the formic acid is 3-4.5. The formic acid with this pH value is mild in nature and better compatible with fracturing equipment.

[0025] In a second aspect, the present invention provides a method for preparing the above-mentioned high temperature resistant temporary plugging agent capable of controlled acidification degradation, comprising the following steps:

[0026] The components are mixed in proportion, extruded by a twin-screw, and pelletized by water cooling to obtain a temporary plugging agent masterbatch, and the temporary plugging agent masterbatch is cryogenically crushed to obtain a controllably acid-degradable, high-temperature resistant temporary plugging agent of a desired particle size.

[0027] Exemplarily, the particle size of the masterbatch is 2mm-5mm;

[0028] For example, the temporary plugging agent has a particle size of 0.075 mm to 2.0 mm, and an average particle size of 0.35 mm to 0.55 mm. The temporary plugging agent in this particle size range can meet the size requirements of bridge plugging cracks in temporary plugging of fracturing.

[0029] Exemplarily, the cryogenic pulverization is performed at a temperature of ≤-50° C. Wherein, the cryogenic pulverization can be performed in a cryogenic pulverizer, cooled by liquid nitrogen.

[0030] In a third aspect, the present invention provides a high temperature resistant temporary plugging agent capable of controlled acidification degradation for use in oil and gas production or geothermal production.

[0031] It should also be noted that, unless otherwise specified, any range described in the present invention includes the end value and any value between the end values ​​and any sub-range formed by the end value or any value between the end values. The preparation methods in the present invention are conventional methods unless otherwise specified, the raw materials used can be obtained from public commercial channels or prepared according to the prior art unless otherwise specified, the solutions are aqueous solutions unless otherwise specified, and the reagents are analytically pure unless otherwise specified.

[0032] Beneficial Effects of the Invention

[0033] 1) The controllable acidification-degradable high-temperature resistant temporary plugging agent provided by the present invention has excellent heat resistance, pressure resistance and plugging properties, and is used in underground environments with a temperature of 200°C or in energy fracturing and mining, and can withstand a pressure of at least 50 MPa during the temporary plugging period.

[0034] 2) The controllable acidification-degradable high-temperature resistant temporary plugging agent provided by the present invention is a polymer resin temporary plugging agent. The acidic solution can induce the breakage of the resin matrix molecular chain. At the same time, the hydrogen ions in the acidic solution interact with the alkaline inorganic filling material to induce the temporary plugging agent to fail or produce defects, further accelerating the depolymerization reaction of the resin matrix, thereby achieving controllable unblocking of the temporary plugging agent.

[0035] 3) The controllably acidified and degradable high-temperature resistant temporary plugging agent provided by the present invention can be gradually hydrolyzed after use and discharged out of the well with the water flow. The hydrolysis product does not stick to the wall and can be discharged with the flowing water, causing little pollution to the formation.

[0036] 4) The controllably acid-degradable high-temperature resistant temporary plugging agent provided by the present invention has good processing performance, can be directly extruded into particles of different shapes, and can be prepared into particles of different sizes by deep cold crushing, and can be directly used in bridge plugging.

[0037] 5) The raw materials of the controllable acidification-degradable high-temperature resistant temporary plugging agent provided by the present invention are widely available, low-priced and easily available, and the preparation method is simple and feasible, and is suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 The schematic diagram shows the state of the controllably acidified and degradable high-temperature resistant temporary plugging agent prepared in Example 1 after being treated in 200° C. hot water for 120 hours. DETAILED DESCRIPTION

[0039] The present invention is described in detail below by way of examples. It is necessary to point out that the examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Those skilled in the art in this field can make some non-essential improvements and adjustments based on the content of the above invention. In the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

[0040] Unless otherwise specified, the raw materials used in the present invention can be obtained from public commercial channels or prepared according to existing technologies.

[0041] The thermoplastic polyimide in the following examples was purchased from RTP Company, USA, model number 4200.

[0042] Example 1

[0043] A high temperature resistant temporary plugging agent capable of controlled acidification degradation, comprising the following components:

[0044] Thermoplastic polyimide 100g;

[0045] Nylon 9T 500g;

[0046] Mg(OH)2 400g (particle size 1μm-10μm);

[0047] Lubricant TAF 3g;

[0048] Antioxidant (1098) 3g;

[0049] Coupling agent (KH560) 3g.

[0050] The preparation method thereof comprises the following steps:

[0051] The components are mixed evenly in proportion, extruded by a twin-screw, and water-cooled and pelletized to obtain temporary plugging agent masterbatch, the particle size of which is 2mm-5mm.

[0052] The masterbatch is dried and added into a cryogenic pulverizer, cooled by liquid nitrogen, and ground and pulverized at -50°C to obtain a high temperature resistant temporary plugging agent with a particle size of 0.075 mm to 2.0 mm and an average particle size of 0.4 mm.

[0053] Temperature and pressure resistance test:

[0054] The high temperature resistant temporary plugging agent was treated in pure water, formic acid solution (pH 3.5), and formic acid solution (pH 4.5) at 200°C for 120 hours, respectively, with the pressure being the saturated vapor pressure at the temperature, and then taken out for drying to test the mass loss rate and compressive strength. The results are shown in Table 1.

[0055] Depend on Figure 1 It can be seen that the high temperature resistant temporary plugging agent of this example is gradually hydrolyzed into tiny particles after being treated in 200°C pure water for 120 hours, and the hydrolysis product does not stick to the wall.

[0056] Example 2

[0057] A high temperature resistant temporary plugging agent capable of controlled acidification degradation, comprising the following components:

[0058] Thermoplastic polyimide 400g;

[0059] Nylon 9T 400g;

[0060] Al(OH)3 200g (particle size 5μm-15μm);

[0061] Lubricant TAF 2g;

[0062] Antioxidant (1098) 2g;

[0063] Coupling agent (KH560) 2g.

[0064] The preparation method thereof comprises the following steps:

[0065] The components are mixed evenly in proportion, extruded by a twin-screw, and water-cooled and pelletized to obtain temporary plugging agent masterbatch, the particle size of which is 2mm-5mm.

[0066] The masterbatch is dried and added into a cryogenic pulverizer, cooled by liquid nitrogen, and ground and pulverized at -50°C to obtain a high-temperature resistant temporary plugging agent with a particle size of 0.075 mm to 2.0 mm and an average particle size of 0.5 mm.

[0067] Temperature and pressure resistance test:

[0068] The high temperature resistant temporary plugging agent was treated in pure water and formic acid solution (pH 3.5) at 200°C for 120 hours, respectively, with the pressure being the saturated vapor pressure at the temperature, and then taken out for drying to test the mass loss rate and compressive strength. The results are shown in Table 1.

[0069] Example 3

[0070] A high temperature resistant temporary plugging agent capable of controlled acidification degradation, comprising the following components:

[0071] Thermoplastic polyimide 200g;

[0072] Nylon 46 500g;

[0073] Mg(OH)2 300g (particle size 3μm-15μm);

[0074] Lubricant TAF 5g;

[0075] Coupling agent (KH560) 2g;

[0076] Antioxidant (1098) 5g.

[0077] The preparation method thereof comprises the following steps:

[0078] The components are mixed evenly in proportion, extruded by a twin-screw, and water-cooled and pelletized to obtain temporary plugging agent masterbatch, the particle size of which is 2mm-5mm.

[0079] The masterbatch is dried and added into a cryogenic pulverizer, cooled by liquid nitrogen, and ground and pulverized at -50°C to obtain a high-temperature resistant temporary plugging agent with a particle size of 0.075 mm to 2.0 mm and an average particle size of 0.55 mm.

[0080] Temperature and pressure resistance test:

[0081] The high temperature resistant temporary plugging agent was treated in pure water and formic acid solution (pH 3.5) at 200°C for 120 hours, respectively, with the pressure being the saturated vapor pressure at the temperature, and then taken out for drying to test the mass loss rate and compressive strength. The results are shown in Table 1.

[0082] Example 4

[0083] A high temperature resistant temporary plugging agent capable of controlled acidification degradation, the formula and preparation method of which are the same as those of Example 1, except that the polyamide in the component is PA10T.

[0084] Temperature and pressure resistance test:

[0085] The high temperature resistant temporary plugging agent was treated in pure water and formic acid solution (pH 3.5) at 200°C for 120 hours, respectively, with the pressure being the saturated vapor pressure at the temperature, and then taken out for drying to test the mass loss rate and compressive strength. The results are shown in Table 1.

[0086] Example 5

[0087] A high temperature resistant temporary plugging agent with controllable acidification degradation, the formula and preparation method of which are the same as those of Example 1, except that the polyamide in the component is a mixture of nylon 9T 400 g and PA10T 100 g. Temperature and pressure resistance test:

[0088] The high temperature resistant temporary plugging agent was treated in pure water and formic acid solution (pH 3.5) at 200°C for 120 hours, respectively, with the pressure being the saturated vapor pressure at the temperature, and then taken out for drying to test the mass loss rate and compressive strength. The results are shown in Table 1.

[0089] Comparative Example 1

[0090] A high temperature resistant temporary plugging agent capable of controlled acidification degradation, comprising the following components:

[0091] Nylon 9T 800g;

[0092] Mg(OH)2 200g (particle size 0.5μm-10μm);

[0093] Lubricant TAF 5g;

[0094] Antioxidant (1098) 5g;

[0095] Coupling agent (KH560) 5g.

[0096] The preparation method thereof comprises the following steps:

[0097] The components are mixed evenly in proportion, extruded by a twin-screw, and water-cooled and pelletized to obtain temporary plugging agent masterbatch, the particle size of which is 2mm-5mm.

[0098] The masterbatch is dried and added into a cryogenic pulverizer, cooled by liquid nitrogen, and ground and pulverized at -50°C to obtain a high-temperature resistant temporary plugging agent with a particle size of 0.075 mm to 2.0 mm and an average particle size of 0.35 mm.

[0099] Temperature and pressure resistance test:

[0100] The temporary plugging agent was treated in pure water and formic acid solution (pH 4.5) at 200° C. for 120 hours, respectively, with the pressure being the saturated vapor pressure at the temperature, and then taken out for drying and testing the mass loss rate and compressive strength. The results are shown in Table 1.

[0101] Comparative Example 2

[0102] A controllable acidification-degradable high-temperature resistant temporary plugging agent, the components and preparation are the same as those in Example 1, except that the mass of the thermoplastic polyimide is 700g, the mass of PA9T is 100g, and the mass of Mg(OH)2 is 200g (particle size 5μm-10μm).

[0103] Temperature and pressure resistance test:

[0104] The high temperature resistant temporary plugging agent was treated in pure water and formic acid solution (pH 3.5) at 200°C for 120 hours respectively, with the pressure being the saturated vapor pressure at the temperature, and then taken out for drying to test the mass loss rate and compressive strength. The results are shown in Table 1.

[0105] Comparative Example 3

[0106] A high temperature resistant temporary plugging agent capable of controlled acidification degradation, the components and preparation of which are the same as those in Example 1, except that the particle size of Mg(OH)2 is 20 μm-50 μm.

[0107] Results: In this case, Mg(OH)2 is relatively large in size and unevenly dispersed in the polymer matrix, resulting in an unsmooth extrusion granulation process when mixed with polyamide and polyimide, broken strips when drawing, and an uneven and rough surface. Therefore, the effect is poor, and no further pressure resistance and hydrolysis tests were performed.

[0108] Comparative Example 4

[0109] A high temperature resistant temporary plugging agent with controllable acidification degradation, the components and preparation are the same as those in Example 1, the only difference is that the addition amount of Mg(OH)2 is 500g.

[0110] Results: The extrusion granulation process was not smooth during the mixing granulation, the strips were broken during the drawing process, and the surface was uneven and rough, so the effect was poor, and no further pressure resistance and hydrolysis tests were performed.

[0111] Comparative Example 5

[0112] A high temperature resistant temporary plugging agent capable of controlled acidification degradation, the components and preparation of which are the same as those of Example 1, except that the alkaline inorganic filling material is NaOH.

[0113] Results: During the high-temperature screw extrusion process, due to the strong activity and alkalinity of NaOH, a uniform blend could not be obtained, and bubbles would appear at the outlet of the screw head, indicating that the components were decomposed during the extrusion process. Therefore, it was impossible to draw the mixture into strips to obtain a temporary plugging agent with stable properties, and no subsequent pressure resistance and hydrolysis tests were performed.

[0114] Table 1:

[0115]

[0116]

[0117] As can be seen from Table 1, after the high temperature resistant temporary plugging agent of Examples 1-5 was treated in pure water at 200°C for 120 hours, the mass loss rate was in the range of 6%-16.4%, and the compressive strength was 62MPa-124MPa, indicating that the above-mentioned high temperature resistant temporary plugging agent can be used in a 200°C environment, has a high compressive strength, and can achieve hydrolysis unblocking; after being treated in formic acid at 200°C for 120 hours, the mass loss rate was in the range of 23%-40%, and the compressive strength was 7MPa-24MPa, indicating that the high temperature resistant temporary plugging agent of Examples 1-5 can be accelerated by acid solution. The high temperature resistant temporary plugging agent of Comparative Example 1 cannot be used in a 200°C environment because no thermoplastic polyimide is added. The high temperature resistant temporary plugging agent of Comparative Example 2 has too much thermoplastic polyimide added, and cannot be accelerated by acid solution.

[0118] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not limitations on the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made on the basis of the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the protection scope of the present invention.

Claims

1. A high temperature resistant temporary plugging agent capable of controlled acidification and degradation, characterized in that: By weight, it includes the following components: Resin matrix 60-80 parts; 20-40 parts of alkaline inorganic filler; Antioxidant 0.1-2 parts; Coupling agent 0.1-2 parts; Lubricant 0.1-2 parts; The resin matrix is ​​formed by mixing polyamide and thermoplastic polyimide in a weight ratio of 1-9:

1.

2. The high temperature resistant temporary plugging agent capable of controlled acidification and degradation according to claim 1, characterized in that: The alkaline inorganic filling material is magnesium hydroxide and / or aluminum hydroxide.

3. The high temperature resistant temporary plugging agent capable of controlled acidification and degradation according to claim 1, characterized in that: The polyamide is selected from one or more of nylon 9T, nylon 46 and nylon 10T.

4. The high temperature resistant temporary plugging agent capable of controlled acidification and degradation according to claim 1, characterized in that: The particle size of the alkaline inorganic filling material is 0.5 μm-20 μm.

5. The high temperature resistant temporary plugging agent capable of controlled acidification and degradation according to claim 1, characterized in that: The lubricant is TAF.

6. The high temperature resistant temporary plugging agent capable of controlled acidification and degradation according to claim 1, characterized in that: The antioxidant is antioxidant 1098.

7. The high temperature resistant temporary plugging agent capable of controlled acidification and degradation according to claim 1, characterized in that: The coupling agent is KH560.

8. The high temperature resistant temporary plugging agent capable of controlled acidification and degradation according to any one of claims 1 to 7, characterized in that: Acidic liquid is used to control the acidification degradation of the high temperature resistant temporary plugging agent; the acidic liquid is hydrochloric acid, sulfuric acid or formic acid.

9. The high temperature resistant temporary plugging agent capable of controlled acidification and degradation according to claim 8, characterized in that: The acid solution is formic acid.

10. The high temperature resistant temporary plugging agent capable of controlled acidification and degradation according to claim 9, characterized in that: The pH value of the formic acid is 3-4.

5.

11. A method for preparing a high temperature resistant temporary plugging agent capable of controlled acidification degradation according to any one of claims 1 to 10, characterized in that: The following steps are involved: The components are mixed in proportion, extruded by a twin-screw, and pelletized by water cooling to obtain a temporary plugging agent masterbatch, and the temporary plugging agent masterbatch is cryogenically crushed to obtain a controllably acid-degradable, high-temperature resistant temporary plugging agent of a desired particle size.

12. The preparation method according to claim 11, characterized in that: The deep cold crushing is carried out at a temperature of ≤-50°C.

13. Use of the high temperature resistant temporary plugging agent capable of controlled acidification degradation according to any one of claims 1 to 10 in oil and gas exploitation or geothermal exploitation.

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