Preparation method of a thermoplastic elastomer material for oil well cement

Abstract

The present invention provides a preparation method of a thermoplastic elastomer material for oil well cement, comprising: performing a first mixing of a reactive solvent and an oil-soluble initiator to obtain a mixed solution; dissolving a water-soluble monomer in water and adjusting the pH value to obtain a dissolved solution; performing a second mixing of the dissolved solution, the mixed solution and the thermoplastic elastomer material to obtain a mixture; performing a third mixing of a water-soluble initiator and the mixture and then reacting to obtain a thermoplastic elastomer material for oil well cement. The present invention provides a thermoplastic elastomer material TKA with a core-shell structure for oil well cement. Using a thermoplastic elastomer (TPE) as the core, it is added to a mixed solution of a reactive solvent and a water-soluble monomer to initiate polymerization, and a hydrophilic shell is formed on the surface through chemical bond action, enabling it to retain its own mechanical properties while being hydrophilic and improving the mechanical properties of the cement stone. The present invention does not require special production equipment, the reaction conditions are simple, and it is suitable for large-scale production.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil and gas well cementing, and particularly relates to a preparation method of a thermoplastic elastomer for oil well cement. Background Art

[0002] Cementing engineering is an operation to reinforce the wellbore, ensure continuous drilling, seal oil, gas and water layers, ensure stratified oil testing during exploration and reasonable oil and gas production during the entire exploitation. Therefore, high-quality steel pipes are lowered, and cement is filled in the annulus between the wellbore and the steel pipes. In recent years, with the vigorous development of shale gas wells, the number of shale gas wells and gas storage wells has increased day by day, and higher requirements have been put forward for the elasticity and toughness of the cement slurry system.

[0003] Currently, the commonly used toughening materials for cement slurry mainly include latex, fibers and rubber, all of which have certain defects. For example, the latex system is sensitive to the addition amount and prone to flocculation. Rubber is a hydrophobic material and prone to suspension stability problems. Thermoplastic elastomers are called the third-generation rubber, with excellent high-temperature plasticity and certain thermal expansion properties, and are ideal materials for improving the elasticity and toughness of cement stone. However, due to their hydrophobicity, they cannot be directly used in the cement slurry system.

[0004] Therefore, it is very necessary to develop a toughening material for oil well cement based on thermoplastic elastomers, which does not aggregate and has good suspension stability during the pumping process of cement slurry, is evenly dispersed after the cement stone is cured, and further improves the elasticity and toughness of the cement stone at high temperatures. During the later fracturing of shale gas wells and the repeated high-pressure gas injection process of gas storage wells, the integrity of the cement sheath is ensured to achieve long-term sealing. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a preparation method of a thermoplastic elastomer for oil well cement. The thermoplastic elastomer for oil well cement prepared by the method provided by the present invention has good performance.

[0006] The present invention provides a preparation method of a thermoplastic elastomer for oil well cement, including:

[0007] Performing a first mixing on a reactive solvent and an oil-soluble initiator to obtain a mixed solution;

[0008] Dissolving a water-soluble monomer in water and adjusting the pH value to obtain a dissolved solution;

[0009] Performing a second mixing on the dissolved solution, the mixed solution and the thermoplastic elastomer to obtain a mixture;

[0010] Performing a third mixing on a water-soluble initiator and the mixture and then reacting to obtain a thermoplastic elastomer for oil well cement.

[0011] Preferably, the reactive solvent is selected from one or more of 3-methacryloxypropyltrimethylsilane, vinyltrimethoxysilane, and vinyltriethoxysilane (A-172).

[0012] Preferably, the oil-soluble initiator is selected from one or more of azobisisobutyronitrile and benzoyl peroxide.

[0013] Preferably, the mass ratio of the reactive solvent to the oil-soluble initiator is (100 - 200):(0.5 - 1.5).

[0014] Preferably, the water-soluble monomer is selected from one or more of acrylic acid, itaconic acid, and 2-acrylamido-2-methylpropanesulfonic acid.

[0015] Preferably, the water-soluble initiator is selected from one or more of ammonium persulfate and potassium persulfate.

[0016] Preferably, the dissolution temperature is 50 - 70 °C.

[0017] Preferably, the pH value is adjusted using a pH regulator;

[0018] The pH regulator is selected from one or more of sodium hydroxide and potassium hydroxide.

[0019] Preferably, the mass ratio of the reactive solvent to the water-based initiator is (100 - 200):(0.1 - 1).

[0020] Preferably, the thermoplastic elastomer material is selected from one or more of polyester-based and polyurethane-based thermoplastic elastomer materials.

[0021] The present invention modifies thermoplastic elastomeric materials and introduces them into oil and gas well cementing to reduce the elasticity and toughness of the cement stone, ensure wellbore integrity, and achieve long-term sealing. The present invention provides a thermoplastic elastomeric material TKA with a core-shell structure for oil well cement. Using a thermoplastic elastomeric material (TPE) as the core, it is added to a mixed solution of a reactive solvent and a water-soluble monomer to initiate polymerization, and a hydrophilic shell is formed on the surface through chemical bond action, enabling it to retain its own mechanical properties while being hydrophilic and improving the mechanical properties of the cement stone. Compared with toughening materials for oil well cement such as thermoplastic rubber modified by adsorption, the hydrophilic groups on the surface of the hydrophilic shell of TKA have stronger hydration ability and better dispersibility in the cement slurry, and phenomena such as floating and sedimentation will not occur; at the same time, the hydrophilic groups connected by chemical bonds have stronger thermal stability and can be applied to higher cementing construction temperatures; TKA can be evenly dispersed in the cement slurry and can be used in cementing construction with large temperature differences and long well sections, improving the brittleness of the cement stone, enhancing the elasticity and toughness of the cement stone, meeting the requirements of the mechanical properties of the cement stone for later exploitation and staged fracturing, and ensuring the long-term stable development of oil and gas wells. The present invention does not require special production equipment, the reaction conditions are simple, and it is suitable for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is the dispersion state of the modified TKA prepared in Example 4 of the present invention in the cement stone. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other examples modified or polished by those of ordinary skill in the art belong to the protection scope of the present invention. It should be understood that the embodiments of the present invention are only used to illustrate the technical effects of the present invention, rather than to limit the protection scope of the present invention. In the embodiments, the methods used are all conventional methods unless otherwise specified.

[0024] The present invention provides a preparation method for a thermoplastic elastomeric material for oil well cement, including:

[0025] Performing a first mixing of a reactive solvent and an oil-soluble initiator to obtain a mixed solution;

[0026] Dissolving a water-soluble monomer in water and adjusting the pH value to obtain a dissolved solution;

[0027] Performing a second mixing of the dissolved solution, the mixed solution, and the thermoplastic elastomeric material to obtain a mixture;

[0028] Performing a third mixing of a water-soluble initiator and the mixture and then reacting to obtain a thermoplastic elastomeric material for oil well cement.

[0029] In the present invention, the reactive solvent is preferably selected from one or more of 3-methacryloxypropyltrimethylsilane (KH-570), vinyltrimethoxysilane (A-171), and vinyltriethoxysilane (A-172).

[0030] In the present invention, the oil-soluble initiator is preferably selected from one or more of azobisisobutyronitrile and benzoyl peroxide.

[0031] In the present invention, the mass ratio of the reactive solvent to the oil-soluble initiator is preferably (100-200):(0.5-1.5), more preferably (130-170):(0.8-1.2), and most preferably 150:1.

[0032] In the present invention, the first mixing is preferably carried out in an open container; the first mixing is preferably fully and evenly dispersed.

[0033] In the present invention, the water-soluble monomer is preferably selected from one or more of acrylic acid, itaconic acid, and 2-acrylamido-2-methylpropanesulfonic acid.

[0034] In the present invention, the mass ratio of the water-soluble monomer to water is preferably (10-50):(20-100), more preferably (20-40):(30-80), still more preferably (25-35):(40-60), and most preferably 30:50.

[0035] In the present invention, the dissolution is preferably complete dissolution to obtain a homogeneous aqueous solution; the temperature of the dissolution is preferably 50-70 °C, more preferably 55-65 °C, and most preferably 60 °C.

[0036] In the present invention, the pH value is preferably adjusted using a pH regulator.

[0037] In the present invention, the pH regulator is preferably selected from one or more of sodium hydroxide and potassium hydroxide.

[0038] In the present invention, the mass ratio of the water-soluble monomer to the pH regulator is preferably (10-50):(10-44), more preferably (20-40):(15-40), still more preferably (25-35):(20-35), and most preferably 30:(25-30).

[0039] In the present invention, the thermoplastic elastomer material is preferably selected from one or more of polyester-based (TPEE) and polyurethane-based (TPU) thermoplastic elastomer materials.

[0040] In the present invention, the mass ratio of the reactive solvent to the thermoplastic elastomer is preferably (100 - 200):100, more preferably (130 - 170):100, and most preferably 150:100.

[0041] In the present invention, the second mixing preferably includes:

[0042] Adding the dissolution liquid into the mixed liquid, mixing evenly, and then adding the thermoplastic elastomer and stirring evenly.

[0043] In the present invention, the water-soluble initiator is preferably one or more selected from ammonium persulfate and potassium persulfate.

[0044] In the present invention, the mass ratio of the reactive solvent to the water-based initiator is preferably (100 - 200):(0.1 - 1), more preferably (130 - 170):(0.2 - 0.8), still more preferably (140 - 160):(0.3 - 0.6), and most preferably 150:(0.4 - 0.5).

[0045] In the present invention, after the third mixing, it preferably further includes:

[0046] Letting the obtained mixture stand and then carrying out the reaction.

[0047] In the present invention, the standing time is preferably 10 - 15 min, more preferably 11 - 14 min, and most preferably 12 - 13 min.

[0048] In the present invention, the reaction temperature is preferably 15 - 90 °C, more preferably 20 - 80 °C, still more preferably 30 - 70 °C, and most preferably 40 - 60 °C; the reaction time is preferably 10 - 15 min, more preferably 11 - 14 min, and most preferably 12 - 13 min.

[0049] In the present invention, after the third reaction is completed, it preferably further includes:

[0050] Crushing and granulating the obtained reaction product to obtain the thermoplastic elastomer for oil well cement.

[0051] In the present invention, the particle size of the thermoplastic elastomer for oil well cement is preferably 74 - 125 microns, more preferably 80 - 120 microns, still more preferably 90 - 110 microns, and most preferably 100 microns.

[0052] In the present invention, the addition amount of the thermoplastic elastomer for oil well cement in the cement is preferably 5 - 15%, more preferably 8 - 12%, and most preferably 10%.

[0053] The preparation process of the thermoplastic elastomer for oil well cement provided by the present invention is simple, without the need for special reaction equipment, and no waste is generated, meeting the environmental protection requirements and suitable for large-scale production. The reactive solvent is grafted onto the surface of the TPE through chemical bonds, and polymerization is initiated by water-soluble monomers and the reactive solvent, so that the surface of the TPE has hydrophilic groups connected by chemical bonds. Compared with toughening materials for oil well cement such as thermoplastic rubber modified by adsorption, the hydrophilic groups connected by chemical bonds have higher thermal stability and are applicable to higher construction temperatures. By grafting, the surface of the TPE is modified to have good hydrophilic properties without changing the main structure of the TPE, enabling it to better exert its own mechanical properties, reducing the elastic modulus of the cement stone and increasing the deformation ability of the cement stone.

[0054] Prepare the cement slurry according to GB / T 19139-2003 "Test Methods for Oil Well Cement" according to the formula;

[0055] Pour the cement slurry into a mold smeared with butter to obtain a specimen;

[0056] Put the specimen into a high-temperature curing kettle and cure the specimen at 150°C and 21 MPa;

[0057] Grind the end face of the cured specimen flat and install the specimen on a press for testing:

[0058] During continuous loading, plot the stress-strain curve of the stress and strain in a rectangular coordinate system; obtain the elastic modulus and Poisson's ratio of the rock sample using this curve:

[0059]

[0060] E - Elastic modulus; Δσ - Change in axial stress; Δε a — Change in axial strain of the rock sample;

[0061]

[0062] Δε r — Change in radial strain of the rock sample; Δε a — Change in axial strain of the rock sample.

[0063] The compressive strength test method is carried out according to the regulations in GB / T 10238-2015.

[0064] In the following examples of the present invention, the TPEE used is the thermoplastic polyester elastomer provided by Weida High Polymer Materials Co., Ltd., and the TUP is the thermoplastic polyurethane elastomer provided by Weida High Polymer Materials Co., Ltd.

[0065] Example 1

[0066] In parts by weight, 150 parts of A171 are weighed and placed in an open container, 0.5 parts of benzoyl peroxide are added and fully dispersed; 10 parts of 2-acrylamido-2-methylpropanesulfonic acid and 20 parts of water are weighed and fully dissolved to form a uniform aqueous solution, and 10 parts of potassium hydroxide are used to adjust the pH and the temperature is 50°C; the aqueous phase solution is directly added to the reactive solution, mixed, and 100 parts of TPEE are added and stirred evenly; 0.1 parts of potassium persulfate are added to the above-mentioned mixed solution, mixed, and allowed to stand for 15 minutes to start the reaction, and the reaction is continued for about 15 minutes to obtain a block product, which is crushed and granulated to form a final product with a particle size of 74 to 125 μm.

[0067] Example 2

[0068] In parts by weight, 150 parts of A172 are weighed and placed in an open container, and 0.5 parts of azobisisobutyronitrile are added and fully dispersed; 10 parts of itaconic acid and 40 parts of water are weighed and fully dissolved to form a uniform aqueous solution, and the pH is adjusted with 20 parts of sodium hydroxide, and the temperature is 50°C; the aqueous phase solution is directly added to the reactive solution, mixed, and 100 parts of TPEE are added and stirred evenly; 0.2 parts of ammonium persulfate are added to the above-mentioned mixed solution, mixed, and allowed to stand for 15 minutes to start the reaction, and the reaction is continued for about 15 minutes to obtain a block product, which is crushed and granulated to form a final product with a particle size of 74 to 125 μm.

[0069] Example 3

[0070] In parts by weight, 200 parts of A172 are weighed and placed in an open container, 1.5 parts of benzoyl peroxide are added and fully dispersed; 50 parts of acrylic acid and 100 parts of water are weighed, fully dissolved to form a uniform aqueous solution, 44 parts of potassium hydroxide are used to adjust the pH, and the temperature is about 70°C; the aqueous phase solution is directly added to the reactive solution, mixed, and 100 parts of TPU are added and stirred evenly; 1.0 part of potassium persulfate is added to the above-mentioned mixed solution, mixed, and allowed to stand for 10 minutes to start the reaction. The reaction is continued for about 10 minutes to obtain a block product, which is crushed and granulated to form a final product with a particle size of 74 to 125 μm.

[0071] Example 4

[0072] In parts by weight, 100 parts of KH570 are weighed and placed in an open container, and 1.0 part of azobisisobutyronitrile is added and fully dispersed; 30 parts of acrylic acid and 60 parts of water are weighed, fully dissolved to form a uniform aqueous solution, and 30 parts of sodium hydroxide are used to adjust the pH, and the temperature is about 60°C; the aqueous phase solution is directly added to the reactive solution, mixed, and 100 parts of TPU are added and stirred evenly; 0.5 parts of ammonium persulfate are added to the above-mentioned mixed solution, mixed, and allowed to stand for 10 minutes to start the reaction, and the reaction is continued for about 10 minutes to obtain a block product, which is crushed and granulated to form a final product with a particle size of 74 to 125 μm.

[0073] Example 5

[0074] In parts by weight, 100 parts of KH570 are weighed and placed in an open container, and 1 part of azobisisobutyronitrile is added and fully dispersed; 30 parts of 2-acrylamido-2-methylpropanesulfonic acid and 60 parts of water are weighed and fully dissolved to form a uniform aqueous solution, and 30 parts of sodium hydroxide are used to adjust the pH, and the temperature is about 60°C; the aqueous phase solution is directly added to the reactive solution, mixed, and 100 parts of TPEE are added and stirred evenly; 0.75 parts of ammonium persulfate are added to the above-mentioned mixed solution, mixed, and allowed to stand for 10 minutes to start the reaction, and the reaction is continued for about 15 minutes to obtain a block product, which is crushed and granulated to form a final product with a particle size of 74 to 125 μm.

[0075] Example 6

[0076] In parts by weight, 95 parts of cement (Jiahua G grade), 5 parts of the product prepared in Example 1 (thermoplastic elastic material), and 44 parts of water were used to prepare cement slurry with a density of 1.9 g / cm 3 , cured at 150℃, 21MPa for 48h.

[0077] According to the method of the above technical solution, the elastic modulus of the product prepared in Example 6 was measured to be 5.9 GPa, Poisson's ratio was 0.22, and compressive strength was 34.6 MPa.

[0078] Example 7

[0079] In parts by weight, cement (Jiahua G grade) 95 parts, the product prepared in Example 2 (thermoplastic elastic material) 8 parts, and water 44 parts were used to prepare cement slurry with a density of 1.9 g / cm 3 , cured at 150℃, 21MPa for 48h.

[0080] According to the method of the above technical solution, the elastic modulus of the product prepared in Example 7 was measured to be 5.4 GPa, Poisson's ratio was 0.24, and compressive strength was 29.8 MPa.

[0081] Example 8

[0082] In parts by weight, cement (Jiahua G grade) 95 parts, the product prepared in Example 3 (thermoplastic elastic material) 5 parts, and water 44 parts were used to prepare cement slurry with a density of 1.9 g / cm 3 , cured at 150℃, 21MPa for 48h.

[0083] According to the method of the above technical solution, the elastic modulus of the product prepared in Example 8 was measured to be 6.8 GPa, Poisson's ratio was 0.23, and compressive strength was 35.4 MPa.

[0084] Example 9

[0085] 85 parts of cement (Jiahua G grade), 15 parts of the product prepared in Example 4 (thermoplastic elastomer), and 40 parts of water were used to prepare a cement slurry with a density of 1.9 g / cm 3 , and cured at 150 °C and 21 MPa for 48 h.

[0086] According to the method described in the above technical solution, the elastic modulus of the product prepared in Example 9 was measured to be 2.6 GPa, the Poisson's ratio was 0.25, and the compressive strength was 19.2 MPa.

[0087] The dispersion state of the modified TKA prepared in Example 4 in the cement stone is as Figure 1 shown.

[0088] Example 10

[0089] 90 parts of cement (Jiahua G grade), 10 parts of the product prepared in Example 5 (thermoplastic elastomer), and 42 parts of water were used to prepare a cement slurry with a density of 1.9 g / cm 3 , and cured at 150 °C and 21 MPa for 48 h.

[0090] According to the method described in the above technical solution, the elastic modulus of the product prepared in Example 10 was measured to be 4.4 GPa, the Poisson's ratio was 0.27, and the compressive strength was 26.2 MPa.

[0091] Comparative Example 1

[0092] 100 parts of cement (Jiahua G grade) and 44 parts of water were used to prepare a conventional cement slurry with a density of 1.9 g / cm 3 , and cured at 150 °C and 21 MPa for 48 h.

[0093] According to the method described in the above technical solution, the elastic modulus of the product prepared in Comparative Example 1 was measured to be 10 GPa, the Poisson's ratio was 0.19, and the compressive strength was 43.2 MPa.

[0094] It can be seen from Examples 6 to 10 that, compared with Comparative Example 1, the cement stone with the TKA prepared in the example added has a significantly lower elastic modulus, a larger Poisson's ratio, and a higher compressive strength, and the deformation ability of the cement stone is enhanced.

[0095] As can be seen from the above embodiments, the present invention modifies the thermoplastic elastomer material and introduces it into the oil and gas well cementing to reduce the elasticity and toughness of the cement stone, ensure the wellbore integrity, and achieve long-term sealing. The present invention provides a thermoplastic elastomer material TKA with a core-shell structure for oil well cement. Using the thermoplastic elastomer material (TPE) as the core, it is added to a mixed solution of a reactive solvent and a water-soluble monomer to initiate polymerization, and a hydrophilic shell is formed on the surface through chemical bond action, so that while being hydrophilic, it retains its own mechanical properties and improves the mechanical properties of the cement stone. Compared with toughening materials for oil well cement such as thermoplastic rubber modified by adsorption method, the hydrophilic groups on the surface of the hydrophilic shell of TKA have stronger hydration ability and better dispersibility in the cement slurry, and there will be no phenomena such as floating and sedimentation; at the same time, the hydrophilic groups connected by chemical bonds have stronger thermal stability and can be applied to higher cementing construction temperatures; TKA can be evenly dispersed in the cement slurry and can be used in cementing construction with large temperature differences and long well sections, improving the brittleness of the cement stone, enhancing the elasticity and toughness of the cement stone, meeting the requirements of the mechanical properties of the cement stone for later exploitation and staged fracturing, and ensuring the long-term stable development of oil and gas wells. The present invention does not require special production equipment, the reaction conditions are simple, and it is suitable for large-scale production.

[0096] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A preparation method of a thermoplastic elastomer material for oil well cement, comprising: Perform a first mixing of a reactive solvent and an oil-soluble initiator to obtain a mixed solution; Dissolve a water-soluble monomer in water and adjust the pH value to obtain a dissolved solution; Perform a second mixing of the dissolved solution, the mixed solution, and a thermoplastic elastomer material to obtain a mixture; Perform a third mixing of a water-soluble initiator and the mixture and then react to obtain a thermoplastic elastomeric material for oil well cement; The reactive solvent is selected from one or more of 3-methacryloxypropyltrimethylsilane, vinyltrimethoxysilane, and vinyltriethoxysilane; The water-soluble monomer is selected from one or more of acrylic acid, itaconic acid, and 2-acrylamido-2-methylpropanesulfonic acid; The thermoplastic elastomer material is selected from one or more of polyester-based and polyurethane-based thermoplastic elastomer materials; The oil-soluble initiator is selected from one or more of azobisisobutyronitrile and benzoyl peroxide; The water-soluble initiator is selected from one or more of ammonium persulfate and potassium persulfate.

2. The method according to claim 1, characterized in that, The mass ratio of the reactive solvent to the oil-soluble initiator is (100~200):(0.5~1.5).

3. The method according to claim 1, characterized in that, The temperature of the dissolution is 50~70°C.

4. The method according to claim 1, characterized in that, The pH value is adjusted using a pH regulator; The pH regulator is selected from one or more of sodium hydroxide and potassium hydroxide.

5. The method according to claim 1, characterized in that, The mass ratio of the reactive solvent to the water-soluble initiator is (100~200):(0.1~1).

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