High-temperature-resistant cable for geothermal well

Abstract

The invention relates to the technical field of cables, and provides a high-temperature-resistant cable for a geothermal well, which sequentially comprises a wire core, an insulating layer, a shielding layer, a high-temperature-resistant layer, a waterproof layer and a sheath layer from inside to outside, the sheath layer is prepared from the following raw materials in parts by weight: 100 parts of raw ethylene propylene diene monomer rubber, 20-30 parts of ethylene-vinyl acetate copolymer, 15-20 parts of plasticizer, 20-30 parts of filler, 1-2 parts of accelerant, 0.5-1 part of vulcanizing agent, 1-2 parts of antioxidant, 5-8 parts of flame retardant and 2-3 parts of lubricant, and the filler comprises wollastonite fiber and white carbon black powder in a mass ratio of 3: 7-9: 1. According to the technical scheme, the problem of poor high temperature resistance of the cable for the geothermal well in the prior art is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of cables, and in particular to a high temperature resistant cable for geothermal wells. Background Art

[0002] Geothermal energy is an energy resource from the earth's interior, which can be divided into three categories: high temperature, medium temperature and low temperature. Temperatures above 150°C are high temperature geothermal energy; temperatures between 90°C and 150°C are medium temperature geothermal energy; and temperatures between 25°C and 90°C are low temperature geothermal energy. Geothermal energy has a wide range of uses. High temperature geothermal energy is suitable for power generation, medium temperature geothermal energy can be used for house heating, and low temperature geothermal energy can be used for bathing, medical treatment, greenhouse planting, aquaculture, etc.

[0003] A geothermal well is an artificial well for exploiting geothermal energy, usually a device that uses geothermal energy at a depth of about 3,500 meters or hot spring water with a water temperature greater than 30°C to generate electricity. Geothermal well cables are mainly used for power transmission of submersible pumps or other equipment in geothermal wells. They have excellent waterproof, mechanical, and thermal conductivity properties. Due to their special use environment, the high temperature resistance of current geothermal well cables needs to be further improved. Summary of the invention

[0004] The present invention provides a high temperature resistant cable for geothermal wells, which solves the problem of poor high temperature resistance of the cable for geothermal wells in the related art.

[0005] The technical solution of the present invention is as follows: The present invention provides a high-temperature resistant cable for geothermal wells, which comprises, from inside to outside, a wire core, an insulating layer, a shielding layer, a high-temperature resistant layer, a waterproof layer, and a sheath layer. The raw materials of the sheath layer include the following components in parts by weight: 100 parts of EPDM raw rubber, 20-30 parts of ethylene-vinyl acetate copolymer, 15-20 parts of plasticizer, 20-30 parts of filler, 1-2 parts of accelerator, 0.5-1 part of vulcanizer, 1-2 parts of antioxidant, 5-8 parts of flame retardant, and 2-3 parts of lubricant. The filler includes wollastonite fiber and white carbon black powder in a mass ratio of 3:7-9:1.

[0006] As a further technical solution, the mass ratio of the wollastonite fiber to the white carbon black powder is 5:5 to 7:3.

[0007] The present invention further improves the high temperature resistance of the high temperature resistant cable for geothermal wells by limiting the mass ratio of wollastonite fiber to white carbon black powder to 5:5-7:3.

[0008] As a further technical solution, the white carbon black powder is a modifier-modified white carbon black powder, and the modifier of the modifier-modified white carbon black powder is a compound containing hydroxyl and halogen.

[0009] The present invention limits the white carbon black powder to a modifier-modified white carbon black powder, wherein the modifier is a compound containing a hydroxyl group and a halogen, wherein the hydroxyl group at one end of the modifier forms a hydrogen bond with the hydroxyl group on the surface of the white carbon black powder, and the halogen on the surface of the modified white carbon black powder forms a synergistic effect with the wollastonite fiber, thereby further improving the high temperature resistance of the high temperature resistant cable for geothermal wells.

[0010] As a further technical solution, the modifier is diethyl (2,2,2-trifluoro-1-hydroxyethyl)phosphonate.

[0011] As a further technical solution, the raw material of the modifier-modified white carbon black powder includes the modifier and the white carbon black powder in a mass ratio of 1 to 5:30.

[0012] As a further technical solution, the mass ratio of the modifier to the white carbon black powder is 3~4:30.

[0013] The invention further improves the high temperature resistance of the high temperature resistant cable for geothermal wells by limiting the mass ratio of the modifier to the white carbon black powder to 3-4:30.

[0014] As a further technical solution, the method for preparing the modifier-modified white carbon black powder comprises the following steps: The modifier is dissolved in dimethyl sulfoxide, white carbon black powder is added, mixed evenly, and dried to obtain the modifier-modified white carbon black powder.

[0015] As a further technical solution, the method for preparing the sheath layer comprises the following steps: After uniformly mixing EPDM raw rubber, ethylene-vinyl acetate copolymer, plasticizer, filler, accelerator, antioxidant, flame retardant and lubricant, adding vulcanizing agent and mixing evenly, the mixture is extruded on the surface of the waterproof layer to obtain a sheath layer.

[0016] As a further technical solution, the plasticizer includes one or more of paraffin, vaseline, and asphalt.

[0017] As a further technical solution, the accelerator includes one or more of accelerator PZ, accelerator DM, and accelerator TMTD.

[0018] As a further technical solution, the vulcanizing agent includes one or two of vulcanizing agent BPO and vulcanizing agent DCBP.

[0019] As a further technical solution, the antioxidant includes one or more of antioxidant 1010, antioxidant 1076, and antioxidant 264.

[0020] As a further technical solution, the flame retardant includes one or both of aluminum hydroxide and magnesium hydroxide.

[0021] As a further technical solution, the lubricant includes one or both of calcium stearate and zinc stearate.

[0022] The invention also proposes the application of a high temperature resistant cable for a geothermal well in the geothermal well.

[0023] The working principle and beneficial effects of the present invention are: In the present invention, wollastonite fiber and white carbon black powder are selected for compound use, which improves the dispersibility and high temperature resistance of the sheath layer filler, and the sheath layer of the geothermal well cable is formed by combining the ethylene propylene rubber raw rubber, ethylene-vinyl acetate copolymer, plasticizer, accelerator, antioxidant, flame retardant, lubricant, vulcanizer and other components. By adjusting and optimizing the content of each component, the high temperature resistance of the sheath layer is improved, thereby improving the high temperature resistance of the geothermal well cable. After the prepared geothermal well high temperature resistant cable is subjected to heat aging treatment at 135°C and 168h, the change rate of tensile strength can be kept below 10.4%. DETAILED DESCRIPTION

[0024] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] A high temperature resistant cable for geothermal wells includes, from inside to outside, a core, an insulating layer, a shielding layer, a high temperature resistant layer, a waterproof layer, and a sheath layer. The preparation method of the sheath layer is as follows: In the following examples and comparative examples, the parameters of each raw material are as follows: The raw EPDM rubber is Sinopec Mitsui EPDM 3092PM; Ethylene-vinyl acetate copolymer is Yanshan Petrochemical EVA14-2; The model of wollastonite fiber is JLH-SW6, purchased from Shenzhen Jinhaohui Industrial Development Co., Ltd.; The particle size of the white carbon black powder is 2000 mesh.

[0026] Example 1 100 parts of EPDM raw rubber, 20 parts of ethylene-vinyl acetate copolymer, 15 parts of paraffin wax, 6 parts of wollastonite fiber, 14 parts of white carbon powder, 1 part of accelerator PZ, 1 part of antioxidant 1010, 5 parts of aluminum hydroxide and 2 parts of calcium stearate were stirred in a mixer at 100 rpm and 60°C for 20 minutes, 0.5 parts of vulcanizing agent BPO were added and stirred at 400 rpm and 120°C for 15 minutes, and the mixture was extruded on the surface of the waterproof layer and vulcanized to obtain a sheath layer.

[0027] Example 2 100 parts of EPDM raw rubber, 30 parts of ethylene-vinyl acetate copolymer, 20 parts of vaseline, 27 parts of wollastonite fiber, 3 parts of white carbon black powder, 2 parts of accelerator DM, 2 parts of antioxidant 1076, 8 parts of magnesium hydroxide and 3 parts of zinc stearate were stirred in a mixer at 100 rpm and 60°C for 20 minutes, and then 1 part of vulcanizing agent DCBP was added and stirred at 400 rpm and 120°C for 15 minutes. The mixture was extruded on the surface of the waterproof layer and vulcanized to obtain a sheath layer.

[0028] Example 3 The only difference from Example 1 is that 18 parts of wollastonite fiber and 2 parts of white carbon black powder are used.

[0029] Example 4 The only difference from Example 1 is: 10 parts of wollastonite fiber and 10 parts of white carbon black powder.

[0030] Example 5 The only difference from Example 1 is that 14 parts of wollastonite fiber and 6 parts of white carbon black powder are used.

[0031] Example 6 S1. Dissolve 1 part of diethyl (2,2,2-trifluoro-1-hydroxyethyl)phosphonate in 40 parts of dimethyl sulfoxide, add 30 parts of white carbon black powder, mix well, and dry to obtain modifier-modified white carbon black powder; S2. Stir 100 parts of EPDM raw rubber, 20 parts of ethylene-vinyl acetate copolymer, 15 parts of paraffin wax, 10 parts of wollastonite fiber, 10 parts of white carbon black powder, 1 part of accelerator PZ, 1 part of antioxidant 1010, 5 parts of aluminum hydroxide and 2 parts of calcium stearate in a mixer at 100 rpm and 60°C for 20 minutes, add 0.5 parts of vulcanizing agent BPO and stir for 15 minutes at 400 rpm and 120°C, extrude on the surface of the waterproof layer, and vulcanize to obtain a sheath layer.

[0032] Example 7 The only difference from Example 6 is: 5 parts of diethyl (2,2,2-trifluoro-1-hydroxyethyl)phosphonate.

[0033] Example 8 The only difference from Example 6 is: 3 parts of diethyl (2,2,2-trifluoro-1-hydroxyethyl)phosphonate.

[0034] Example 9 The only difference from Example 6 is: 4 parts of diethyl (2,2,2-trifluoro-1-hydroxyethyl)phosphonate.

[0035] Comparative Example 1 100 parts of EPDM raw rubber, 20 parts of ethylene-vinyl acetate copolymer, 15 parts of paraffin, 20 parts of wollastonite fiber, 1 part of accelerator PZ, 1 part of antioxidant 1010, 5 parts of aluminum hydroxide and 2 parts of calcium stearate were stirred in a mixer at 100 rpm and 60°C for 20 minutes, then 0.5 parts of vulcanizing agent BPO were added and stirred at 400 rpm and 120°C for 15 minutes, extruded on the surface of the waterproof layer, and vulcanized to obtain a sheath layer.

[0036] Comparative Example 2 The only difference from Comparative Example 1 is that the wollastonite fiber is replaced by an equal amount of white carbon black powder.

[0037] Test example The sheath layer of the high temperature resistant cable for geothermal wells prepared in Examples 1 to 9 and Comparative Examples 1 to 2 was cut axially according to the method in GB / T2951.11-2008, and a narrow strip was prepared into a dumbbell specimen with a thickness of 3 mm. The specimen was subjected to heat aging treatment (135°C, 168h) according to the standard of GB / T2951.12-2008. After the treated specimen was placed in an environment of 25°C for 16h, a tensile test was performed on the specimens before and after the heat aging treatment according to the standard of GB / T 2951.11-2008, and the change rate of tensile strength was calculated according to the following formula: Tensile strength change rate = (tensile strength before treatment - tensile strength after treatment) ÷ tensile strength before treatment × 100%; The results are shown in Table 1.

[0038] Table 1 Tensile strength test results of Examples 1 to 9 and Comparative Examples 1 to 2

[0039] Compared with Comparative Examples 1~2, the high-temperature resistant cables for geothermal wells prepared in Example 1 and Examples 3~5 are a compound of wollastonite fiber and white carbon black powder. As a result, the tensile strength of Example 1 and Examples 3~5 before treatment is greater than that of Comparative Examples 1~2, and the tensile strength change rate is smaller than that of Comparative Examples 1~2, indicating that the compound use of wollastonite fiber and white carbon black powder can improve the high temperature resistance of the sheath layer of the high-temperature resistant cable for geothermal wells, thereby improving the high temperature resistance of the high-temperature resistant cable for geothermal wells.

[0040] The tensile strength of the high-temperature resistant cables for geothermal wells prepared in Examples 4 to 5 before treatment is greater than that in Example 1 and Example 3, and the change rate of tensile strength is smaller than that in Example 1 and Example 3, indicating that the mass ratio of wollastonite fiber and white carbon black powder is 5:5 to 7:3, which further improves the high temperature resistance of the sheath layer of the high-temperature resistant cable for geothermal wells, thereby further improving the high temperature resistance of the high-temperature resistant cable for geothermal wells.

[0041] The tensile strength of the high-temperature resistant cables for geothermal wells prepared in Examples 6 to 9 before treatment is greater than that in Example 4, and the change rate of tensile strength is smaller than that in Example 4, indicating that the white carbon black powder is a modified white carbon black powder containing a compound containing hydroxyl and halogen, which further improves the high temperature resistance of the sheath layer of the high-temperature resistant cable for geothermal wells, thereby further improving the high temperature resistance of the high-temperature resistant cable for geothermal wells.

[0042] The tensile strength of the high-temperature resistant cables for geothermal wells prepared in Examples 8 to 9 before treatment is greater than that in Examples 6 to 7, and the change rate of tensile strength is smaller than that in Examples 6 to 7, indicating that the mass ratio of the modifier to the white carbon black powder is 3 to 4:30, which further improves the high temperature resistance of the sheath layer of the high-temperature resistant cable for geothermal wells, thereby further improving the high temperature resistance of the high-temperature resistant cable for geothermal wells.

[0043] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A high temperature resistant cable for geothermal wells, comprising, from inside to outside, a core, an insulation layer, a shielding layer, a high temperature resistant layer, a waterproof layer, and a sheath layer, characterized in that: The raw materials of the sheath layer include the following components in parts by weight: 100 parts of EPDM raw rubber, 20-30 parts of ethylene-vinyl acetate copolymer, 15-20 parts of plasticizer, 20-30 parts of filler, 1-2 parts of accelerator, 0.5-1 part of vulcanizer, 1-2 parts of antioxidant, 5-8 parts of flame retardant, and 2-3 parts of lubricant. The filler includes wollastonite fiber and white carbon black powder in a mass ratio of 3:7-9:

1.

2. A high temperature resistant cable for geothermal wells according to claim 1, characterized in that: The mass ratio of the wollastonite fiber to the white carbon black powder is 5:5-7:

3.

3. A high temperature resistant cable for geothermal wells according to claim 2, characterized in that: The white carbon black powder is a modifier-modified white carbon black powder, and the modifier of the modifier-modified white carbon black powder is a compound containing a hydroxyl group and a halogen.

4. A high temperature resistant cable for geothermal wells according to claim 3, characterized in that: The modifier is diethyl (2,2,2-trifluoro-1-hydroxyethyl)phosphonate.

5. A high temperature resistant cable for geothermal wells according to claim 3, characterized in that: The raw materials of the modifier-modified white carbon black powder include the modifier and the white carbon black powder in a mass ratio of 1 to 5:

30.

6. A high temperature resistant cable for geothermal wells according to claim 5, characterized in that: The mass ratio of the modifier to the white carbon black powder is 3-4:

30.

7. A high temperature resistant cable for geothermal wells according to claim 3, characterized in that: The method for preparing the modifier-modified white carbon black powder comprises the following steps: The modifier is dissolved in dimethyl sulfoxide, white carbon black powder is added, mixed evenly, and dried to obtain the modifier-modified white carbon black powder.

8. A high temperature resistant cable for geothermal wells according to any one of claims 1 to 7, characterized in that: The method for preparing the sheath layer comprises the following steps: After uniformly mixing EPDM raw rubber, ethylene-vinyl acetate copolymer, plasticizer, filler, accelerator, antioxidant, flame retardant and lubricant, adding vulcanizing agent and mixing evenly, the mixture is extruded on the surface of the waterproof layer to obtain a sheath layer.

9. A high temperature resistant cable for geothermal wells according to claim 1, characterized in that: The plasticizer includes one or more of paraffin, vaseline and asphalt.

10. Use of a high temperature resistant cable for geothermal wells according to any one of claims 1 to 9 in geothermal wells.

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