Preparation method of thick polycrystalline diamond compact for oil and gas drilling

Abstract

The present application relates to the preparation method of thick polycrystalline diamond compact for oil and gas drilling, which comprises the following steps: mixing two or more kinds of diamond powder with impurities removed; sand blasting the cemented carbide substrate; sequentially loading the impurity storage layer, the diamond powder mixture layer, the low-melting-point metal sheet, the cobalt sheet and the cemented carbide substrate into a high-temperature-resistant metal cup; placing the high-temperature-resistant metal cup into a synthetic block and then into a six-surface press; performing two-stage high-temperature and high-pressure sintering, wherein the first stage is sintering at a pressure of 5.5-5.8 GPa and a temperature of 800-1300 DEG C for 60-150 seconds, and the second stage is sintering at a pressure of 6-8 GPa and a temperature of 1490-1580 DEG C for 450-700 seconds; and taking out at room temperature and normal pressure. The impurity storage layer, the low-melting-point metal sheet and the cobalt sheet are arranged, and the high-temperature and high-pressure scanning sintering method is adopted, so that the thickness of the diamond layer reaches 3-4 mm after sintering, and the service life is greatly prolonged.

Description

TECHNICAL FIELD

[0001] The application relates to a preparation method of a thick polycrystalline diamond compact for oil and gas drilling, and belongs to the technical field of superhard material manufacturing. BACKGROUND

[0002] The thick polycrystalline diamond compact for oil and gas drilling is composed of a diamond layer and a cemented carbide substrate, and the diamond layer is sintered from a large number of diamond particles under the catalysis of a metal catalyst Co under high temperature and high pressure. The thick polycrystalline diamond compact is used for oil and gas drilling, and the size of the polycrystalline diamond compact used in the industry has been standardized, and the diameter and height mainly have the following specifications (unit: mm): Φ13.44*13.2, Φ15.88*13.2, Φ19.05*13.2, etc. Limited by the sintering technology, the thickness of the diamond layer of the traditional product is about 2.0 mm. The polycrystalline diamond compact has the characteristics of high hardness and super wear resistance of diamond, high impact resistance of cemented carbide, and the cemented carbide can also provide good weldability, so that the polycrystalline diamond compact is firmly welded on the body of the diamond drill bit. With the continuous development of oil and gas drilling to deeper places on the earth, the drilling depth is continuously deepened from the traditional 2000-3000 meters to 4000-5000 meters, and the exploration well depth can reach 7000-8000 meters. The deeper the depth is, the more complex the geological environment is, and the more severe the hardness, abrasiveness and impact resistance of the stratum are, which puts forward higher requirements on the service life of the polycrystalline diamond compact.

[0003] The thickness of the diamond layer determines the content of the diamond, the thicker the diamond layer is, the more the content is, the longer the service life of the compact is, and the higher the drilling efficiency is.

[0004] The difficulty in increasing the thickness of the diamond layer lies in that the polycrystalline diamond compact is sintered from a diamond powder layer and a cemented carbide substrate under high temperature (about 1490 DEG C) and high pressure (about 5.5 GPa), in the sintering process, the cobalt in the cemented carbide substrate or other cobalt sources is melted, there is a cobalt concentration gradient between the cobalt source and the diamond powder layer, under the driving of high pressure, the melted cobalt migrates and sweeps to the diamond powder layer, and the sintering of the polycrystalline diamond is completed, which is called a high-temperature and high-pressure sweeping sintering method, and the method is generally suitable for the preparation of the diamond compact with the diamond layer thickness of 0.5-2 mm. When the thickness of the polycrystalline diamond layer is greater than 2 mm, the cobalt in the cemented carbide substrate or other cobalt sources is difficult to completely sweep through the thick diamond powder layer. Upon closer examination, there are some impurities in the diamond powder layer, such as oxygen, nitrogen, silicon, sodium and the like, and the impurities hinder the sweeping of the cobalt and weaken the catalytic effect of the cobalt.

[0005] Therefore, the preparation method of the polycrystalline diamond compact by the high-temperature and high-pressure sintering method needs to be researched and improved, especially the purification environment of the diamond powder layer under the high-temperature and high-pressure conditions is improved, the smooth migration and long distance sintering of the molten cobalt in the diamond powder layer are created, and the thickness of the sintered diamond layer is ensured to be 3-4 mm, the diamond content of the single polycrystalline diamond compact is 50-100% more than that of the traditional polycrystalline diamond compact, and the requirements of the oil and gas drilling on the polycrystalline diamond compact are met. SUMMARY

[0006] The purpose of the present application is to overcome the shortcomings of the prior art and provide a preparation method of a thick polycrystalline diamond compact for oil and gas drilling.

[0007] The purpose of the present application is achieved by the following technical solutions.

[0008] The preparation method of the thick polycrystalline diamond compact for oil and gas drilling has the following characteristics: two or more kinds of diamond powders with surface impurity treatment are mixed as a diamond powder mixture layer; the hard alloy substrate is subjected to sand blasting treatment; the impurity receiving layer, the diamond powder mixture layer, the low-melting-point metal sheet, the cobalt sheet and the hard alloy substrate are sequentially loaded into a high-temperature-resistant metal cup; the high-temperature-resistant metal cup is placed into a synthetic block and placed into a six-surface pressing machine; two-stage high-temperature and high-pressure sintering is performed, the first stage is sintering at a pressure of 5.5-5.8 GPa and a temperature of 800-1300 DEG C for 60-150 seconds, the second stage is sintering at a pressure of 6-8 GPa and a temperature of 1490-1580 DEG C for 450-700 seconds; the temperature and pressure are reduced to room temperature and normal pressure to obtain a thick polycrystalline diamond compact blank.

[0009] Further, the preparation method of the thick polycrystalline diamond compact for oil and gas drilling, wherein the thick polycrystalline diamond compact blank obtained after high-temperature and high-pressure sintering comprises a diamond working layer and a hard alloy substrate, and has an upper and lower structure, and the thickness of the diamond working layer is 3-4 mm.

[0010] Further, the preparation method of the thick polycrystalline diamond compact for oil and gas drilling, wherein the impurity receiving layer material is a single particle size of high-strength ceramic or superhard material particles.

[0011] Further, the preparation method of the thick polycrystalline diamond compact for oil and gas drilling, wherein the impurity receiving layer is granular alumina, silicon carbide, cubic boron nitride or diamond, and the particle size of the particles is greater than or equal to 1.5 times the particle size of the coarsest particles in the diamond powder mixture layer.

[0012] Further, the preparation method of the thick polycrystalline diamond compact for oil and gas drilling, wherein the low-melting-point metal sheet is made of magnesium, aluminum, silver, copper or manganese.

[0013] Further, the preparation method of the thick polycrystalline diamond compact for oil and gas drilling, wherein the low-melting-point metal sheet is made of magnesium, aluminum, silver, copper or manganese.

[0014] Further, the preparation method of the thick polycrystalline diamond compact for oil and gas drilling, wherein the low-melting-point metal sheet is made of magnesium, aluminum, silver, copper or manganese.

[0015] Further, the preparation method of the thick polycrystalline diamond compact for oil and gas drilling, wherein the low-melting-point metal sheet is made of magnesium, aluminum, silver, copper or manganese.

[0016] Further, the preparation method of the thick polycrystalline diamond compact for oil and gas drilling, wherein the low-melting-point metal sheet is made of magnesium, aluminum, silver, copper or manganese.

[0017] Further, the preparation method of the thick polycrystalline diamond compact for oil and gas drilling, wherein the low-melting-point metal sheet is made of magnesium, aluminum, silver, copper or manganese.

[0018] The present application has the advantages and beneficial effects compared with the prior art, which are embodied in the following aspects:

[0019] ①By setting the impurity storage layer, the low-melting-point metal sheet and the cobalt sheet, and using the two-stage high-temperature and high-pressure scanning sintering method, the diamond powder layer is dynamically purified during high-temperature and high-pressure sintering, and cobalt can smoothly migrate and scan for a long distance in the powder layer, so that the thickness of the sintered diamond layer reaches 3-4mm;

[0020] ②Adding the cobalt sheet as the main source of cobalt ensures that enough cobalt penetrates into the thick diamond layer; adding the metal material with a lower melting point than cobalt and higher chemical activity between the cobalt sheet and the diamond powder layer, which melts and penetrates into the diamond powder layer before cobalt scans and penetrates into the diamond powder layer, and due to the higher chemical activity, it reacts with various impurities in the powder layer and continuously moves upward, carrying away the impurities, and plays a role in dynamically purifying the diamond powder layer;

[0021] ③ Set single particle size granular impurity receiving layer, the particle size of the particle is not less than 1.5 times of the particle size of the coarsest particle in the diamond layer of the composite sheet; since it is not a coarse and fine mixture layer, the gap between each coarse particle is large, forming an effective receiving space, and the impurities generated during sintering are stored in this space, and the layer will be removed in the processing and shaping process after sintering is completed;

[0022] ④ The first segment high temperature and high pressure sintering ensures that the diamond particles are not carbonized, and the low melting point metal is melted, sweeps to the diamond powder layer, and carries the impurities into the impurity receiving layer; the second segment high temperature and high pressure sintering under the action of higher temperature and higher pressure, the metal cobalt is melted, sweeps to the diamond powder layer and penetrates, and the low melting point metal or its compound formed by the first segment sintering is pushed into the impurity receiving layer; due to the dynamic purification effect of the first segment sintering, the sintering of the second segment polycrystalline diamond proceeds smoothly, and cobalt can sweep a longer path, so that a diamond layer with a thickness of 3-4 mm can be sintered;

[0023] ⑤ The diamond content of the single piece composite sheet is 50-100% more than that of the traditional composite sheet, the wear resistance is greatly improved, so it has better use performance and longer service life, and is more suitable for drilling tasks in deeper and more complex strata, and meets the requirements of oil and gas drilling on polycrystalline diamond composite sheets.

[0024] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent from the description, or can be learned by practice of the present application. The objects and other advantages of the present application can be achieved and obtained by the structure particularly pointed out in the written description and accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0026] Figure 1 : The structure diagram of the thick polycrystalline diamond composite sheet of the present application;

[0027] Figure 2 : The structure diagram of the metal cup before sintering;

[0028] Figure 3 : The structure diagram of the metal cup after the first segment sintering;

[0029] Figure 4 : The structure diagram of the metal cup after the first segment and the second segment sintering. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. The components of the embodiments of the present application described and shown in the accompanying drawings can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the claimed present application, but merely represents selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0031] It should be noted that: similar reference numerals and letters represent similar items in the following drawings, therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. Meanwhile, in the description of the present application, orientation terms and order terms, etc. are only used for distinguishing description, and cannot be understood as indicating or implying relative importance.

[0032] As shown in Figure 2 The present application adopts "high-temperature and high-pressure sweep sintering method" to prepare thick polycrystalline diamond compact for oil and gas drilling, and solves the problem that the thickness of the diamond layer in the prior art is difficult to reach 3-4 mm by dynamically purifying the diamond powder layer in the synthesis cavity. The preparation process is as follows:

[0033] Two or more kinds of diamond powder with surface impurity treatment are mixed as the diamond powder mixture layer 1. The surface impurities meet the requirements shown in Table 1. According to the use requirements of the compact, the mixing formula is formulated, the mixing machine is loaded, and the mixing is carried out for 4-8 hours.

[0034] Table 1: Impurity content specification of diamond particles

[0035] Norm 40 / 60 30 / 40 20 / 28 11 / 22 8 / 16 7 / 9 4 / 6 1 / 3 ppm of impurities allowed 45 45 55 55 55 70 70 70

[0036] High-strength ceramic or superhard material particles of a single particle size are selected as the impurity storage layer. The impurity storage layer is granular alumina, silicon carbide, cubic boron nitride or diamond, and the particle size of the particles is greater than or equal to 1.5 times the particle size of the coarsest particles in the diamond powder mixture layer.

[0037] The hard alloy substrate 2 is subjected to sand blasting treatment.

[0038] The impurity storage layer 5, the diamond micro-powder mixture layer 1, the low-melting metal sheet 3, the cobalt sheet 4 and the hard alloy substrate 2 are sequentially loaded into the high-temperature-resistant metal cup 6, and the cover cup 7 is buckled; wherein the thickness of the low-melting metal sheet 3 is 0.05-2 mm, the low-melting metal sheet 3 is made of magnesium, aluminum, silver, copper or manganese which has a lower melting point than cobalt and high chemical activity; the cobalt content of the cobalt sheet 4 is 99.9%, and the thickness is 0.02-2 mm; the hard alloy substrate 2 is WC-Co alloy, and the Co content is 10-18 wt%; the material of the high-temperature-resistant metal cup 6 is any one of titanium, zirconium, niobium, tantalum and molybdenum;

[0039] The high-temperature-resistant metal cup 6 is placed into a synthetic block and placed into a six-surface top pressing machine; two-stage high-temperature high-pressure sintering is performed, in the first stage, the sintering pressure is 5.5-5.8 GPa, the sintering temperature is 800-1300℃, and the maintenance time is 60-150 seconds; under the premise of ensuring that the diamond particles are not carbonized, the low-melting metal is melted, sweeps over the diamond micro-powder layer, and carries the impurities into the impurity storage layer 5, so that the diamond layer is purified, as shown in Figure 3 ;

[0040] In the second stage, the sintering pressure is 6-8 GPa, the sintering temperature is 1490-1580℃, and the maintenance time is 450-700 seconds; the temperature and pressure are reduced to room temperature and normal pressure, and the thick polycrystalline diamond composite sheet blank is obtained; under the action of higher temperature and higher pressure, the cobalt is melted, sweeps over and penetrates into the diamond micro-powder layer, the diamond layer is sintered, and the low-melting metal or its compound formed in the first stage is pushed into the impurity storage layer 5, as shown in Figure 4 . After sintering, the mass percentage of the diamond layer is: diamond 92-96 wt%, metal Co and other elements 4-8 wt%.

[0041] The dynamic purification effect in the first stage sintering makes the sintering of the polycrystalline diamond in the second stage progress smoothly, and the cobalt can sweep a longer path, so that a diamond layer with a thickness of 3-4 mm can be sintered;

[0042] The blank is processed and shaped by using a processing technology to complete commercial processing; the impurity storage layer 5 is removed in the processing and shaping process after sintering is completed.

[0043] The cobalt sheet is added as the main source of cobalt to ensure that enough cobalt penetrates into the thick diamond layer; a metal material with a lower melting point than cobalt and high chemical activity is added between the cobalt sheet and the diamond micro-powder layer, which is melted and penetrates into the diamond micro-powder layer before the cobalt sweeps and penetrates into the diamond micro-powder layer, and due to the high chemical activity, it reacts with various impurities in the micro-powder layer and continuously moves upward, carrying away the impurities, and plays a role in dynamically purifying the diamond micro-powder layer.

[0044] The single particle size impurity receiving layer has a particle size not less than 1.5 times of the particle size of the thickest particle in the diamond layer of the composite sheet; since it is not a coarse and fine mixture layer, the gap between the coarse particles is large, forming an effective receiving space, and the impurities generated during sintering are stored in the space, and the layer will be removed in the machining and shaping process after sintering is completed.

[0045] As shown in Figure 1 The thick polycrystalline diamond composite sheet blank obtained after high-temperature and high-pressure sintering comprises a diamond working layer and a cemented carbide substrate, and has an upper and lower structure, and the thickness of the diamond working layer is 3-4 mm. The thickness of the diamond layer is increased by 50-100% compared with the existing diamond composite sheet, which significantly improves the wear resistance and prolongs the service life of the diamond drill bit.

[0046] Example 1

[0047] Three kinds of diamond micropowder with different particle sizes and completed surface impurity removal treatment were selected for mixing, the mixing time was 4 hours, and the diamond ratio was 75wt% 52um+20wt% 16um+5wt% 4.5um; the cemented carbide substrate was sandblasted; a metal zirconium cup was taken, and silicon carbide particles with a particle size of 80um, diamond micropowder mixture, metal magnesium sheet 0.05mm, cobalt sheet 0.05mm, and cemented carbide substrate were sequentially placed in the cup, and the cup was closed with a zirconium cover cup. Then the zirconium cup and the contents were placed in a high-temperature and high-pressure synthesis block, and sintered by two-stage high-temperature and high-pressure in a six-surface high-pressure device.

[0048] The first stage sintering was carried out at a pressure of 5.5GPa and a temperature of 800℃ for 150 seconds to complete the melting and sweeping of the metal magnesium; the second stage sintering was carried out at a pressure of 6.0GPa and a temperature of 1500℃ for 450 seconds, and finally the pressure and temperature were reduced to normal pressure and room temperature, and the sintered polycrystalline diamond composite sheet blank was taken out; the impurity receiving layer was removed by using mechanical grinding, laser and other processing technologies, and the commercial processing was completed. The thick polycrystalline diamond composite sheet for oil and gas drilling comprises a polycrystalline diamond working layer and a Co-based cemented carbide substrate, and the thickness of the diamond layer is 4mm.

[0049] Example 2

[0050] Three kinds of diamond micropowder with different particle sizes and completed surface impurity removal treatment were selected for mixing, the mixing time was 5 hours, and the diamond ratio was 70wt% 34um+20wt% 11um+10wt% 4.5um; the cemented carbide substrate was sandblasted; a metal molybdenum cup was taken, and cubic boron nitride particles with a particle size of 55um, diamond micropowder mixture, metal silver sheet 0.05mm, cobalt sheet 0.05mm, and cemented carbide substrate were sequentially placed in the cup, and the cup was closed with a molybdenum cover cup; then the molybdenum cup and the contents were placed in a high-temperature and high-pressure synthesis block, and sintered by two-stage high-temperature and high-pressure in a six-surface high-pressure device.

[0051] The first sintering is performed at a pressure of 5.5 GPa and a temperature of 1100°C for 150 seconds to complete the melting and sweeping of the metallic silver; the second sintering is performed at a pressure of 6.5 GPa and a temperature of 1520°C for 500 seconds; finally, the pressure and temperature are reduced to normal pressure and room temperature, and the sintered polycrystalline diamond compact blank is taken out; the impurity collection layer is removed by using mechanical grinding, laser, and other processing technologies to complete commercial processing. The thick polycrystalline diamond compact for oil and gas drilling includes a polycrystalline diamond working layer and a Co-based hard alloy substrate, and the thickness of the diamond layer is 4 mm.

[0052] Example 3

[0053] The diamond micropowder of four particle sizes and with completed surface impurity removal treatment is selected for mixing, the mixing time is 6 hours, and the diamond ratio is 65wt% 11um+25wt% 8um+7wt% 4um+3wt% 2um; the hard alloy substrate is subjected to sand blasting treatment; a metallic tantalum cup is taken, and the diamond particles with a particle size of 40um, the diamond micropowder mixture, the metallic copper sheet 0.05mm, the cobalt sheet 0.05mm, and the hard alloy substrate are sequentially placed in the tantalum cup, and the tantalum cover cup is buckled; the tantalum cup and the contents are placed in a high-temperature and high-pressure synthesis block, and two-stage high-temperature and high-pressure sintering is performed in a six-surface high-pressure device.

[0054] The first sintering is performed at a pressure of 5.8 GPa and a temperature of 1200°C for 150 seconds to complete the melting and sweeping of the metallic copper; the second sintering is performed at a pressure of 7.2 GPa and a temperature of 1540°C for 580 seconds; finally, the pressure and temperature are reduced to normal pressure and room temperature, and the sintered polycrystalline diamond compact blank is taken out; the impurity collection layer is removed by using mechanical grinding, laser, and other processing technologies to complete commercial processing. The thick polycrystalline diamond compact for oil and gas drilling includes a polycrystalline diamond working layer and a Co-based hard alloy substrate, and the thickness of the diamond layer is 3.5 mm.

[0055] Example 4

[0056] The diamond micropowder of two particle sizes and with completed surface impurity removal treatment is selected for mixing, the mixing time is 7 hours, and the diamond ratio is 88wt% 8um+12wt% 2um; the hard alloy substrate is subjected to sand blasting treatment; a metallic niobium cup is taken, and the cubic boron nitride particles with a particle size of 30um, the diamond micropowder mixture, the metallic manganese sheet 0.05mm, the cobalt sheet 0.05mm, and the hard alloy substrate are sequentially placed in the niobium cup, and the niobium cover cup is buckled; the niobium cup and the contents are placed in a high-temperature and high-pressure synthesis block, and two-stage high-temperature and high-pressure sintering is performed in a six-surface high-pressure device.

[0057] The first sintering is carried out at a pressure of 5.8 GPa and a temperature of 1300 DEG C for 150 seconds to complete the melting and sweeping of the metallic manganese; the second sintering is carried out at a pressure of 7.5 GPa and a temperature of 1560 DEG C for 640 seconds; finally, the pressure and temperature are reduced to normal pressure and room temperature to obtain the sintered polycrystalline diamond compact blank; the impurity storage layer is removed by using mechanical grinding, laser and other processing technologies to complete the commercial processing.

[0058] In summary, the present application sets the impurity storage layer, the low melting point metal sheet and the cobalt sheet, and adopts the two-stage high-temperature and high-pressure sweeping sintering method to dynamically purify the diamond powder layer during the high-temperature and high-pressure sintering, so that the cobalt can smoothly migrate and sweep for a long distance in the powder layer, the thickness of the sintered diamond layer reaches 3-4 mm, the diamond content of the single composite sheet is 50-100% more than that of the traditional composite sheet, the wear resistance is greatly improved, thus the present application has better use performance and longer service life, and is more suitable for the drilling tasks of deeper and more complex strata, and meets the requirements of the polycrystalline diamond composite sheet for oil and gas drilling.

[0059] The above merely describes the preferred embodiments of the present application, and is not intended to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

[0060] The above merely describes the preferred embodiments of the present application, and is not intended to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

[0061] It is to be noted that, as used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a component" can include a combination of two or more components. Additionally, the terms "comprise," "comprises," and "comprising," or any variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to those elements, but can include other elements not expressly listed or inherent to such process, method, article, or apparatus. Furthermore, unless otherwise indicated herein, the terms "first," "second," "third," etc., are used herein merely as labels, and are not intended to impose ordinal import.

Claims

1. A method for preparing a thick polycrystalline diamond compact for oil and gas drilling, characterized by: The diamond micropowder of two or more particle sizes and after surface impurity removal treatment is mixed to form a diamond micropowder mixture layer; the cemented carbide substrate is sandblasted; the impurity storage layer, the diamond micropowder mixture layer, the low-melting-point metal sheet, the cobalt sheet and the cemented carbide substrate are sequentially loaded into a high-temperature-resistant metal cup, the impurity storage layer is a single-particle-size superhard material particle; the high-temperature-resistant metal cup is placed into a synthesis block and then into a six-sides press; two-stage high-temperature high-pressure sintering is performed, the first stage is sintering at a pressure of 5.5-5.8 GPa and a temperature of 800-1300 ℃ for 60-150 seconds, the second stage is sintering at a pressure of 6-8 GPa and a temperature of 1490-1580 ℃ for 450-700 seconds; the temperature and pressure are decreased to room temperature and normal pressure to take out the thick polycrystalline diamond composite sheet blank.

2. The method of claim 1, wherein the thick polycrystalline diamond compact for oil and gas drilling is prepared by the steps of: The thick polycrystalline diamond composite sheet blank obtained after high-temperature high-pressure sintering comprises a diamond working layer and a cemented carbide substrate, and has an up-down structure, the thickness of the diamond working layer is 3-4 mm. ​ 3. The method of claim 1, wherein the thick polycrystalline diamond compact for oil and gas drilling is prepared by the steps of: The impurity storage layer is granular alumina, silicon carbide, cubic boron nitride or diamond, the particle size of the particle is greater than or equal to 1.5 times the size of the coarsest particle in the diamond micropowder mixture layer. ​ 4. The method of claim 1, wherein the thick polycrystalline diamond compact for oil and gas drilling is prepared by the steps of: The low-melting-point metal sheet is made of magnesium, aluminum, silver, copper or manganese. ​ 5. The method of producing a thick polycrystalline diamond compact for oil and gas drilling according to claim 1 or 4, characterized in that: The thickness of the low-melting-point metal sheet is 0.05-2 mm.

6. The method of producing a thick polycrystalline diamond compact for oil and gas drilling according to claim 1, characterized in that: The cobalt sheet contains 99.9% of cobalt and has a thickness of 0.02-2 mm.

7. The method of claim 1, wherein the thick polycrystalline diamond compact for oil and gas drilling is prepared by the steps of: a) providing a substrate; b) forming a diamond layer on the substrate; c) forming a transition layer on the diamond layer; d) forming a binder layer on the transition layer; and e) forming a super hard layer on the binder layer. The cemented carbide substrate is WC-Co alloy, and the content of Co is 10-18 wt%.

8. The method of claim 1, wherein the thick polycrystalline diamond compact for oil and gas drilling is prepared by the steps of: providing a substrate; forming a diamond layer on the substrate; and forming a protective layer on the diamond layer. The high-temperature-resistant metal cup is made of any one of titanium, zirconium, niobium, tantalum and molybdenum.

9. The method of claim 1, wherein the thick polycrystalline diamond compact for oil and gas drilling is prepared by the steps of: providing a substrate; forming a diamond layer on the substrate; and forming a protective layer on the diamond layer. After sintering, the diamond working layer contains 92-96 wt% of diamond and 4-8 wt% of metal Co and other elements.

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