A perforating charge liner composite powder with self-cleaning performance and its preparation method

Abstract

The present invention discloses a perforating ammunition liner composite powder with self-cleaning performance and a preparation method thereof, which relates to the technical field of perforating. In the composite powder of the present invention, each component is calculated by mass percentage and respectively includes: 48% - 52% tungsten powder; 21% - 25% electrolytic copper powder; 3% - 5% aluminum powder; 17% - 19% lead powder and 4% - 6% electrolytic nickel powder. On the basis of the original powder formula of inert tungsten powder, lead powder and copper powder, the present invention adds metal aluminum and nickel powders with an energetic effect, and then prepares a composite powder by adding a binder and a lubricant. The self-cleaning perforating charge produced by using this kind of powder has the advantages of cleaning the hole channel and improving the flow efficiency of the hole channel after perforating. The product is applied to the development process of unconventional oil and gas reservoirs such as shale gas, which helps to solve problems such as high formation fracture pressure and has a good application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of perforation, and more particularly to a perforating ammunition liner composite powder with self-cleaning performance and a preparation method thereof. Background Art

[0002] Oil is the material basis of modern industry and modern civilization, and is an important energy source and important industrial raw material that cannot be ignored in the development of the modern economy. All walks of life have a high dependence on oil. At present, large oil fields in China have entered the "three highs" exploitation stage of high water cut, high oil production rate, and high recovery degree in the middle and late stages, posing a severe challenge to the work of increasing production and reducing consumption in oil development. The efficient perforating completion technology is the key technology to improve oil production capacity, including shaped charge perforation technology, combined perforation technology, etc. Oil perforating charges are multipliers for the productivity and efficiency of oil wells, and the liner is the most important component of oil perforating charges. After the explosive detonates, the collapsed liner will quickly converge to form a metal jet. The size of the perforation diameter and perforation depth formed after the metal jet penetrates directly affects the oil production ratio of the oil well. Traditional oil perforating charge liners mostly use copper material. The jet formed by this elemental metal material is prone to chugging during the penetration process, specifically manifested as serious chugging and hole enlargement phenomena, which greatly affect the oil production rate of oil and gas wells.

[0003] In the patent application publication document with the publication number CN111894533A, the publication date of November 6, 2020, and the name of "An Energetic Powder Liner", an energetic powder liner is disclosed, which is applicable to self-cleaning perforating charges in the oil exploitation industry. The energetic powder liner is a conical liner with variable wall thickness, and its top outer wall surface is a plane, and the inner wall surface has an arc transition. The diameter of the energetic powder liner is within the range of Ф32mm to Ф46mm, and the material is a mixture of 50% to 85% copper powder, 10% to 25% zirconium-based amorphous powder, and 5% to 25% tungsten powder, and the total mass fraction of the mixture is 100%. The perforation diameter of the energetic powder liner described in this invention can be increased by 10% to 25%, and the perforation depth remains basically unchanged, and the effects of self-cleaning, no chugging, large aperture, and high penetration depth can be achieved.

[0004] The above-mentioned prior art uses 50% - 85% copper powder, 10% - 25% zirconium-based amorphous powder, and 5% - 25% tungsten powder as the components of the energetic powder liner. Among them, the characteristic of zirconium powder is its low ignition point and fast combustion speed, and it is often used as the primary explosive of detonators. Such detonators can also explode underwater. There are certain potential safety hazards in the safety of the perforating charge liner pressed with this kind of powder, and the price is relatively high. The copper powder used in this prior art is usually atomized copper powder (the microscopic morphology is spherical or near-spherical). After the atomized copper powder is pressed into a green body, a pseudo-alloy is formed on the interfaces such as tungsten powder and copper powder. Due to the limited contact surface between the powder crystals (or amorphous substances), the formed van der Waals force is relatively small, and the strength of the formed green body is relatively low, resulting in problems such as difficult forming and difficult demolding.

[0005] The invention patent application document with the publication number CN111119803A, the publication date of May 8, 2020, and the title of "A liner for large-aperture deep-penetrating perforating charges and its preparation method" discloses a liner for large-aperture deep-penetrating perforating charges and its preparation method. The formula composition of the liner includes electrolytic copper powder, bismuth powder, and tungsten powder. It is characterized in that it further includes bismuth powder, lead powder, aluminum powder, tin powder, iron powder, zinc powder, and lubricating oil; it solves the problem that the existing liner cannot release a large amount of heat energy and can only use the high-speed metal flow to impact the target to complete the formation of the hole channel, resulting in the need for a liner with a complex structure to obtain the desired jet quality and velocity distribution.

[0006] The liner formula in the above-mentioned prior art can only enlarge the casing aperture, but it will reduce the perforating depth. And the flow efficiency of the formed channel has an important relationship with the aperture and depth of the formed hole channel, that is, the hole channel volume. The above-mentioned prior art sacrifices the hole depth to enlarge the aperture, and its improvement of the hole channel volume is not overly excellent. Summary of the Invention

[0007] In order to overcome the defects and deficiencies existing in the above-mentioned prior art, the present invention provides a composite powder for a perforating charge liner with self-cleaning performance and its preparation method. The object of the present invention is to improve the hole channel volume, enhance the strength of the liner, improve the consistency of the overall density of the liner, and facilitate pressing into a green body and demolding on the premise that the total amount of charge in a single perforating charge remains unchanged. The present invention adds energetic metal aluminum and nickel powders to the original powder formula of inert tungsten powder, lead powder, and copper powder, and then prepares a composite powder by adding a binder and a lubricant. The self-cleaning perforating charges produced with this kind of powder have the advantages of cleaning the hole channel and improving the flow efficiency of the hole channel after perforation. The product is applied in the development process of unconventional oil and gas reservoirs such as shale gas, which helps to solve problems such as high formation fracture pressure and has good application prospects.

[0008] To solve the problems existing in the above-mentioned prior art, the present invention is achieved through the following technical solutions.

[0009] In the first aspect of the present invention, there is provided a perforating ammunition liner composite powder with self-cleaning performance. The composite powder includes tungsten powder, electrolytic copper powder, aluminum powder, and lead powder, and also includes electrolytic nickel powder;

[0010] Each component in the composite powder is included by mass percentage as follows:

[0011] 48% - 52% tungsten powder; 21% - 25% electrolytic copper powder; 3% - 5% aluminum powder; 17% - 19% lead powder and 4% - 6% electrolytic nickel powder.

[0012] Furthermore, each component in the composite powder is included by mass percentage as follows: 50% tungsten powder, 23% electrolytic copper powder, 4% aluminum powder, 18% lead powder, and 5% electrolytic nickel powder.

[0013] Further, the purity of the tungsten powder is ≥99.95%; the apparent density is between 5.6 - 8.0 g / cm 3 ; the oxygen content is ≤0.05%; the flow rate is ≤25 s / 50 g; the microscopic morphology is quasi-spherical or spherical.

[0014] Furthermore, the screening index of the tungsten powder is: +100 mesh < 15%, -100 - +200 mesh 15% - 50%; -200 mesh - +325 mesh 25% - 50%; -325 mesh 15% - 65%.

[0015] Further, the purity of the electrolytic copper powder is ≥99.6%; the apparent density is between 1.8 - 2.3 g / cm 3 ; the oxygen content is ≤0.15%; the microscopic morphology is dendritic.

[0016] Furthermore, the screening index of the electrolytic copper powder is -200 mesh ≥ 90%; -325 mesh ≥ 60%.

[0017] Further, the aluminum powder is the aluminum powder produced by the dry ball milling method. Its grade is FLQ355A.

[0018] Further, the purity of the lead powder is ≥99.7%; the apparent density is between 4.5 - 6 g / cm 3 ; the oxygen content is ≤0.15%; the microscopic morphology is near-spherical.

[0019] Furthermore, the screening index of the lead powder is -200 mesh ≥ 80%.

[0020] Further, the electrolytic nickel powder is selected to conform to the standard grade FND - 1 of GB / T5247 - 2012.

[0021] The second aspect of the present invention provides a method for preparing a perforating ammunition liner composite powder with self-cleaning performance, and the preparation method includes the following steps:

[0022] S1. Prepare solvent oil: Dissolve sliced paraffin in D70 solvent oil at a low temperature; the addition amount is 0.4 g of sliced paraffin and 80 ml of D70 solvent oil per 1 kg of composite powder.

[0023] S2. Weigh each component of metal powder according to the component ratio of the composite powder; add the weighed metal powders of each component to the solvent oil prepared in step S1 and perform mechanical mixing; lay the uniformly mixed mixture flat in a drying oven for drying treatment.

[0024] S3. Sieve the dried mixture through a 60-mesh standard Tyler sieve, pour it into a V-type mixer for mechanical mixing for 2 hours, and the obtained composite powder is obtained after mixing is completed.

[0025] Further, in step S1, the sliced paraffin is dissolved in D70 solvent oil at a temperature of 80 °C.

[0026] Compared with the prior art, the beneficial technical effects brought by the present invention are shown in:

[0027] 1. A perforating ammunition liner composite powder with self-cleaning performance provided by the present invention adds metal aluminum and nickel powders with an energetic effect on the basis of the original powder formula of inert tungsten powder, lead powder, and copper powder, and then prepares a composite powder by adding a binder and a lubricant. The self-cleaning perforating charges produced with this kind of powder have the advantages of cleaning the hole channel and improving the flow efficiency of the hole channel after perforation. When the product is applied to the development process of unconventional oil and gas reservoirs such as shale gas, it helps to solve problems such as high formation fracture pressure and has a good application prospect.

[0028] 2. Compared with conventional perforating charges, the advantages of the present invention are: First, the lead powder vaporizes and flushes the perforation hole channel to form a positive pressure; second, the ball-milled aluminum powder has high activity and generates aluminum oxide through a high-temperature reaction when heated, further enhancing the positive pressure and improving the hole channel; third, due to the coating of paraffin, a productive liner can be obtained under a high tungsten powder content, which can provide the optimal penetration depth and improve the hole channel volume.

[0029] 3. Compared with CN111894533A, CN111894533A uses an energetic powder with a zirconium powder-added powder material. The zirconium powder is characterized by a low ignition point and a fast combustion rate and is often used as the primary explosive of detonators. Such detonators can also explode underwater. The shaped charge liner pressed with this kind of powder has certain potential safety hazards and a high price. In the present invention, the oxidation reaction of aluminum powder to produce aluminum oxide is a typical exothermic reaction, and a large amount of thermal entropy is generated during the process. The enthalpy value of this reaction is higher than that of zirconium oxide (ZrO2). At the same time, the loose bulk density of electrolytic copper powder is usually 1.6 g / cm 3 ~2.5 g / cm 3 , and there is a large density difference from the added tungsten powder (usually greater than 6.5 g / cm 3 ). Due to different particle sizes and compressibilities of the pressed green body, the green body density formed is usually 60% - 70%, and it contains a porosity of 30% - 40%. The nickel powder added in the present invention is a fine particle powder of 5 - 10 μm, which can effectively fill the voids of the pressed green body, thereby enhancing the overall density of the shaped charge liner and the green body density. In addition, during the perforation process of the shaped charge liner, the added lead powder and nickel powder can form a jet similar to a solid solution mixed state, making it not easy for the jet to form spatial fractures during the stretching process.

[0030] 4. Compared with CN111894533A, the copper powder commonly used in CN111894533A is atomized copper powder (microscopic morphology is spherical or near-spherical). After the atomized copper powder is pressed into a green body, a pseudo-alloy is formed at the interfaces of tungsten powder and copper powder. Since the contact surface between the powder crystals (or non-crystals) of this pseudo-alloy is limited, the van der Waals force formed is small, and the strength of the formed green body is lower than that of the electrolytic copper powder (microscopic morphology is dendritic) used in the present invention. Therefore, CN111894533A indeed has problems of difficult forming and difficult demolding without adding lubricating oil. In the present invention, solvent oil that enhances the wettability of powder particles is added, and a layer of paraffin with excellent lubricity is evenly coated on the surface of the composite powder component particles during the preparation process. During the pressing process, it is easier for dislocation, translation, etc. to occur between the component powder particles during the pressing forming process. The contact surface between the powder particles is larger, the density is higher, and the strength of the pressed shaped charge liner is greater.

[0031] 5. Compared with CN111119803A, CN111119803A can only enlarge the casing hole diameter, but it will reduce the perforation depth. And the flow efficiency of the formed channel has an important relationship with the diameter and depth of the formed hole, that is, the hole volume. This technology enlarges the hole diameter at the expense of the hole depth, and its improvement of the hole volume is not overly excellent. Different from the purpose of having a high tungsten powder content in the present invention and generating a large amount of heat from the oxidation of aluminum powder to produce aluminum trioxide to form a larger hole diameter, the present invention requires an optimized design of the hole diameter and depth to form an optimized hole volume under the condition of constant explosive amount. Therefore, the tungsten powder content, the addition amount of aluminum powder, and the addition of lead powder and nickel powder in the present invention all have their existing meanings. The energy in the jet penetration process comes from the explosion of the explosive. In the ideal state, the charge of the perforating cartridge explodes completely, generating a large amount of highly compressed gas mixtures such as N2, CO2, H2O, etc. in an instant, with the local pressure reaching hundreds of thousands of atmospheres, and a large amount of heat is released at the same time. These energies diffuse outward in the form of shock waves, acting on the metal of the liner, causing it to deform and form a high-temperature and powerful metal jet to penetrate the oil well casing and the rock formation. During the jet penetration process, the liner is strongly impacted by the formation rock and reacts instantaneously. Mainly, the reactive metals Al and Ni undergo shock-induced chemical reactions (SICR) to form intermediate metals that can significantly output energy. This reaction varies depending on the forms, ratios of the metals Al and Ni, and the shock conditions. Figure 4 is the Al / Ni system phase diagram. Based on this phase diagram, the specific reactions that may occur in the jet material are as follows:

[0032] Al + 3Ni = Ni 3 Al △H = —38.3kJ / mol

[0033] Al + Ni = AlNi △H = —59.2kJ / mol

[0034] 3Al + 2Ni = Ni 2 Al 3 △H = —56.5kJ / mol

[0035] 3Al + Ni = NiAl 3 △H = —37.7kJ / mol

[0036] The above reactions are extremely fast, capable of generating a high temperature of 5000K within 100 nanoseconds. The energy density generated instantaneously in the reaction is similar to that of TNT explosion, which can enhance the aftereffect of the jet generated by the perforating cartridge and clean the compacted zone of the hole. Through the above analysis, the combination of aluminum powder and nickel powder will form a certain chemical reaction, thereby generating a large amount of heat entropy.

[0037] 6. In the preparation method of the present invention, a solvent oil for enhancing the wettability of metal powder particles of each component is added. During the preparation process, a layer of paraffin with excellent lubricity is evenly coated on the surface of the composite powder component particles. During the pressing process, it is easier for the dislocation, translation, etc. of the component powder particles to form the pressing process. The contact surface between the powder particles is larger, the density is higher, and the strength of the pressed liner is greater.

[0038] 7. The present invention needs to ensure the optimized penetration performance of the self-cleaning liner on the premise of ensuring good pore characteristics formed by the combustion of aluminum powder. The density of the overall blank must be further improved on the premise of the formula limitation. There is the following theoretical relationship between the density of the liner and its penetration depth:

[0039] Calculate the energy deposition of the penetrating jet according to the hydrodynamic penetration model. When the penetration distance dp is extremely small, the energy deposited by the jet is the energy consumed by the jet penetrating the dp distance (only considering the kinetic energy loss of the jet at this time). When the penetration depth of the jet is dp, the length consumed by the jet is dl. According to the incompressible theory of the jet, it can be obtained that in the formula, dj and dt represent the densities of the jet material and the target plate material. The quasi-steady theory of the above formula shows that the penetration depth of the jet is proportional to the square root of the jet material density. Therefore, increasing the density of the jet material is the most direct and effective method to increase the penetration depth of the jet.

[0040] 8. In the present invention, tungsten powder, as the powder that contributes the most to the penetration performance in the composite powder formula of the liner, the application of spherical or near-spherical powder particles can provide a more excellent penetration type. According to the common formula of kinetic energy , where m is the mass and v is the velocity, the kinetic energy and the energy that an object has due to motion. The greater the velocity of the object and the greater the mass, the more kinetic energy it has. For objects with the same motion velocity, the greater the mass, the greater its kinetic energy. During the explosion process, spherical tungsten powder particles can bring a greater monomer mass.

[0041] 9. In the present invention, the screening indexes of each metal powder are defined. The overall particle size distribution of the powder components shows a normal distribution. This overall particle size distribution can form a blank with a greater density and a lower porosity during the pressing process of the liner.

[0042] 10. The present invention defines that the aluminum powder is the aluminum powder produced by the dry ball milling method, and the grade is FLQ355A. The characteristic of this aluminum powder is that its specific surface area is further increased and its activity is improved after ball milling, and a large amount of heat enthalpy is released when aluminum oxide is formed during the perforation process.

[0043] 11. In the present invention, the lead powder acts as a medium-density powder in the composite powder. Due to its relatively low density and a melting point of only 327 °C, it can be vaporized after explosion, which plays a certain positive role in flushing the perforation channels. In addition, it can also optimize the normal distribution of the composite powder in terms of particle size, which is beneficial to improving the density of the liner. Moreover, as a face-centered crystal structure material, lead has a certain lubricating effect on the mold, which is conducive to the maintenance and demolding of the mold. The limitation of the particle size of the lead powder in the present invention is beneficial to the normal distribution of the overall particle size of the composite powder.

[0044] 12. The present invention selects electrolytic nickel powder that meets the standards, which is conducive to product quality control. In addition, the particle size of this type of electrolytic nickel powder is relatively small, ranging from 5 μm to 25 μm, which is beneficial to filling the pores of the liner. The combination of aluminum powder and nickel powder can form a certain chemical reaction, which plays a positive role in flushing the channels.

[0045] 13. The tungsten powder and lead powder in the present invention are obtained through repeated experiments based on their characteristics of relatively high powder specific gravity and large proportion. The significance of their existence includes the following two aspects: ⑴ A relatively high proportion of tungsten powder and lead powder can ensure that while forming larger channels and pore volumes during the process of the jet flushing the channels, the jet still has the characteristic of good penetration depth. This formula is the result of adjustment based on the optimal matching of the size of the perforation channels and the penetration depth.

[0046] 14. In the present invention, the addition ratio, addition method, and physical state of the sliced paraffin and D70 solvent oil during addition are crucial. If the addition ratio is too high, the overall density of the powder will be low, and it will be difficult to degrease during the subsequent sintering process. If the addition ratio is too low, cracking of the green body will occur during the process of pressing the green body. The solvent oil in the present invention is beneficial to degreasing during the subsequent sintering process and can effectively solve the problem of cracking of the green body during the process of making the blank. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 It is a sectional view of the target penetration of the self-cleaning perforating charge liner of the present invention;

[0048] Figure 2 It is a sectional view of the target penetration of the liner of a conventional perforating charge;

[0049] Figure 3 Performance comparison diagram between the self-cleaning perforating charge liner of the present invention and the liner of a conventional perforating charge;

[0050] Figure 4 It is a phase diagram of the Al / Ni reaction process simulated by SICR;

[0051] Figure 5 It is a curve diagram of the relationship between the density of the liner and the strength of the tungsten-copper green body;

[0052] Figure 6 Schematic diagram of ground simulation piercing target Specific implementation mode

[0053] The present invention will be described based on the embodiments below. However, it should be noted that the present invention is not limited to these embodiments. In the following detailed description of the present invention, some specific details are described in detail. However, for those parts that are not described in detail, those skilled in the art can also fully understand the present invention.

[0054] In addition, those of ordinary skill in the art should understand that the provided drawings are only for illustrating the purpose, features and advantages of the present invention, and the drawings are not actually drawn to scale.

[0055] At the same time, unless the context clearly requires, the words such as "including", "comprising" and the like in the whole specification and claims should be interpreted as the meaning of inclusion rather than exclusive or exhaustive meaning; that is, the meaning of "including but not limited to". Embodiment

[0056] As a preferred embodiment of the present invention, this embodiment discloses a perforating ammunition liner composite powder with self-cleaning performance, and the formula of the powder is shown in the following table:

[0057]

[0058] The purity of the tungsten powder is ≥99.95%; the bulk density is between 5.6 and 8.0 g / cm 3 ; the oxygen content is ≤0.05%; the flow rate is ≤25 s / 50 g; the micro-morphology is quasi-spherical or spherical. The screening indexes of the tungsten powder are: +100 mesh < 15%, -100~+200 mesh 15%~50%; -200 mesh~+325 mesh 25%~50%; -325 mesh 15%~65%. The purity of the electrolytic copper powder is ≥99.6%; the bulk density is between 1.8 and 2.3 g / cm 3 ; the oxygen content is ≤0.15%; the micro-morphology is dendritic. The screening index of the electrolytic copper powder is -200 mesh ≥ 90%; -325 mesh ≥ 60%. The aluminum powder is the aluminum powder produced by the dry ball milling method. Its grade is FLQ355A. The purity of the lead powder is ≥99.7%; the bulk density is between 4.5 and 6 g / cm 3 ; the oxygen content is ≤0.15%; the micro-morphology is near-spherical. The screening index of the lead powder is -200 mesh ≥ 80%. The electrolytic nickel powder is selected to meet the standard grade FND-1 of GB / T5247-2012.

[0059] Prepare solvent oil: dissolve sliced paraffin in D70 solvent oil at low temperature; the addition amount is 0.4 g of sliced paraffin and 80 ml of D70 solvent oil per 1 kg of composite powder;

[0060] Weigh each component metal powder according to the component ratio of the composite powder; add the weighed component metal powders to the solvent oil prepared in step S1 and conduct mechanical mixing; lay the evenly mixed mixture flat in a drying oven for drying treatment;

[0061] Pass the dried mixture through a 60-mesh standard Tyler sieve, pour the sieved mixture into a V-type mixer for mechanical mixing for 2 hours, and the composite powder is obtained after the mixing is completed.

[0062] The conventional 89-type perforating charge liner and the 89-type self-cleaning perforating charge liner are sent to the Quality Supervision and Inspection Center for Oil and Gas Field Perforating Equipment in the petroleum industry for product flow efficiency detection. The relevant detection and calculation results are shown in the following table:

[0063]

[0064] The test results of Example 2 are as Figure 1 and the test results of the conventional perforating charge liner are as Figure 2 shown. Through Figure 1 and Figure 2 comparison, it can be clearly found that the hole channels of the test target using the self-cleaning perforating charge are relatively regular, and the diameter of the hole channels is larger than that of the conventional perforating charge. Obvious burning phenomena can be seen at the end of the hole channels.

[0065] It can be seen from the detection results in the above table that the inlet aperture of the self-cleaning perforating charge of the present invention is basically equivalent to that of the conventional perforating charge. In terms of penetration depth, the conventional perforating charge is slightly deeper. In terms of hole channel volume, the self-cleaning perforating charge of the present invention is significantly higher than that of the conventional perforating charge. In terms of average flow rate and flow efficiency, the self-cleaning type perforating charge of the present invention is superior to the conventional perforating charge, as Figure 3 shown.

[0066] Through calculation, it can be obtained that the flow efficiency of the 89-type self-cleaning perforating charge is increased by 15.2% compared with that of the 89-type conventional perforating charge, and the average flow rate is increased by 17.9%.

[0067] Use the formula 1 electrolytic copper powder (-200~+500 mesh) 41.5% in CN11119803A; lead powder (-200~+450 mesh) 17.5%; bismuth powder (-200~+400 mesh) 12%; tungsten powder (-100~+325 mesh) 22.5%; aluminum powder (-100~+325 mesh) 2.3%; tin powder (-100~+325 mesh) 1.2%; iron powder (200~+325 mesh) 1.2%; zinc powder (-300~+500 mesh) 1.8%; lubricating oil 0.05-0.1%; and the powder mixing steps disclosed in this patent document to prepare the liner mixed powder and press it into a liner;

[0068] The composite powder prepared by using the formula and preparation method in the above Embodiment 2 of the present invention is pressed into a liner; a ground simulation target-piercing device as shown in Figure 6 is used; the medium is clear water, and a comparative experiment is carried out, and the final experimental results are shown in the following table:

[0069]

[0070] From the results of the above two comparative experiments, although the aperture of the self-cleaning perforating charge liner of the present invention is lower than that of CN111119803A, its penetration performance is better than that of CN111119803A, and the comprehensive performance shown in the pore volume is the best.

[0071] Different from CN111119803A, after the perforating operation service, a channel connecting the oil and gas layer and the casing layer is formed between the casing and the formation in the oil and gas well. The flow efficiency of this channel has an important relationship with the aperture and depth of the formed pore. Briefly described as a quantifiable parameter obtained by multiplying the aperture by the depth, that is, the pore volume (pore capacity). The above invention only unilaterally emphasizes the large aperture. Different from the purpose of the present invention with a high tungsten powder content and the formation of a large aperture due to the release of a large amount of heat during the oxidation of aluminum powder to produce aluminum oxide, the present invention requires an optimal design of the aperture and depth to form an optimal pore volume under the condition of constant explosive charge. Therefore, the tungsten powder content, the addition amount of aluminum powder, and the addition of lead powder and nickel powder in the present invention all have their existing meanings.

[0072] Many models have been established abroad to describe the reaction process of energetic materials under shock. Among them, the shock-induced chemical reaction model is a numerical simulation method of a phenomenological kinetic model of the metal chemical reaction process. As shown in Figure 4 , it is the microscopic mechanical research result of Al / Ni.

[0073] The energy in the jet penetration process comes from the explosion of the explosive. In an ideal state, the complete explosion of the perforating charge generates a large amount of highly compressed gas mixtures such as N 2 , CO 2 , H 2 O in an instant, and the local pressure reaches more than a hundred thousand atmospheres. At the same time, a large amount of heat is released. These energies diffuse outward in the form of shock waves, acting on the liner metal, causing it to deform, forming a high-temperature and powerful metal jet to penetrate the oil well casing and the rock formation.

[0074] During the jet penetration process, the liner is strongly impacted by the formation rock and reacts instantaneously. mainly, the reactive metals Al and Ni undergo shock-induced chemical reactions (SICR) to form intermediate metals that can significantly output energy. This reaction varies depending on the morphology, ratio, and shock conditions of the metals Al and Ni. Figure 4It is the Al / Ni system phase diagram. Based on this phase diagram, the specific reactions that may occur in the jet material are as follows:

[0075] Al + 3Ni = Ni 3 Al △H = —38.3 kJ / mol

[0076] Al + Ni = AlNi △H = —59.2 kJ / mol

[0077] 3Al + 2Ni = Ni 2 Al 3 △H = —56.5 kJ / mol

[0078] 3Al + Ni = NiAl 3 △H = —37.7 kJ / mol

[0079] The above reactions are extremely fast and can generate a high temperature of 5000 K within 100 nanoseconds. The energy density generated instantaneously during the reaction is similar to that of TNT explosion, which can enhance the aftereffect of the jet generated by the perforating charge, clean the pore compaction zone. Through the above analysis, the combination of aluminum powder and nickel powder will form a certain chemical reaction, thereby generating a large amount of thermal entropy.

[0080] In the present invention, on the premise of ensuring that the self-cleaning liner has good pore characteristics due to the combustion of aluminum powder, its optimized penetration performance must be ensured. The density of the overall blank must be further improved under the premise of the formula limitation. There is the following theoretical relationship between the density of the liner and its penetration:

[0081] According to the hydrodynamic penetration model, calculate the energy deposition of the penetrating jet. When the penetration distance dp is extremely small, the energy deposited by the jet is the energy consumed by the jet to penetrate the dp distance (only considering the kinetic energy loss of the jet at this time). When the penetration depth of the jet is dp, the length consumed by the jet is dl. According to the incompressible theory of the jet, we can get. Where dj and dt represent the densities of the jet material and the target plate material. The quasi-steady theory of the above formula shows that the penetration depth of the jet is proportional to the square root of the jet material density, as Figure 5 shown. Therefore, increasing the density of the jet material is the most direct and effective method to increase the penetration depth of the jet.

[0082] The reason for applying the various characteristic parameters of the powders in the present invention is that through the following experimental method, a large amount of data is compared. After comparison, it is found that applying the various powder characteristics described in the present invention can significantly improve the overall density and density of the liner under the condition that the liner formula remains unchanged. The experimental method is as follows:

[0083] Use an electronic analytical balance and the drainage method to measure the volume of the liner, and then calculate the actual density of the liner .

[0084] ; ; After the tungsten copper powder is mixed, its sintered true density (g / cm3) can be calculated according to the following formula:

[0085] ;

[0086] ;

[0087] In the formula, r -----Actual relative density (%); --Actual measured density (g / cm3); ---Theoretical density of W (g / cm3); --Theoretical density of Cu (g / cm3); c 1 ----Mass percentage of W (%); c 2 ---Mass percentage of Cu (%).

Claims

1. A perforating ammunition liner composite powder with self-cleaning performance, the composite powder comprising tungsten powder, electrolytic copper powder, aluminum powder and lead powder, Characterized in that: It further comprises electrolytic nickel powder; In the composite powder, each component is calculated by mass percentage and respectively includes: 48% - 52% tungsten powder; 21% - 25% electrolytic copper powder; 3% - 5% aluminum powder; 17% - 19% lead powder and 4% - 6% electrolytic nickel powder.

2. A perforating ammunition liner composite powder with self-cleaning performance according to claim 1, Characterized in that: In the composite powder, each component is calculated by mass percentage and respectively includes: 50% tungsten powder, 23% electrolytic copper powder, 4% aluminum powder, 18% lead powder and 5% electrolytic nickel powder.

3. A perforating ammunition liner composite powder with self-cleaning performance according to claim 1 or 2, Characterized in that: The purity of the tungsten powder is ≥99.95%; the apparent density is between 5.6 and 8.0 g / cm 3 ; the oxygen content is ≤0.05%; the flow rate is ≤25 s / 50 g; the microscopic morphology is quasi-spherical or spherical.

4. A perforating ammunition liner composite powder with self-cleaning performance according to claim 3, Characterized in that: The screening index of the tungsten powder is: +100 mesh < 15%, -100 to +200 mesh 15% - 50%; -200 mesh to +325 mesh 25% - 50%; -325 mesh 15% - 65%.

5. A perforating ammunition liner composite powder with self-cleaning performance according to claim 1 or 2, Characterized in that: The purity of the electrolytic copper powder is ≥99.6%; the apparent density is between 1.8 and 2.3 g / cm 3 ; the oxygen content is ≤0.15%; and the microscopic morphology is dendritic.

6. A perforating ammunition liner composite powder with self-cleaning performance according to claim 5, Characterized in that: The screening index of the electrolytic copper powder is -200 mesh ≥ 90%; -325 mesh ≥ 60%.

7. A perforating ammunition liner composite powder with self-cleaning performance according to claim 1 or 2, Characterized in that: The aluminum powder is the aluminum powder produced by the dry ball milling method.

8. A perforating ammunition liner composite powder with self-cleaning performance according to claim 1 or 2, Characterized in that: The purity of the lead powder is ≥99.7%; the apparent density is between 4.5 and 6 g / cm 3 ; the oxygen content is ≤0.15%; and the microscopic morphology is nearly spherical.

9. A perforating ammunition liner composite powder with self-cleaning performance according to claim 8, Characterized in that: The screening index of the lead powder is -200 mesh ≥ 80%.

10. A perforating ammunition liner composite powder with self-cleaning performance according to claim 1 or 2, Characterized in that: The electrolytic nickel powder is selected to conform to the standard grade FND-1 of GB / T5247-2012.

11. A preparation method of a perforating ammunition liner composite powder with self-cleaning performance according to claim 1 or 2, Characterized in that, This preparation method includes the following steps: S1. Prepare solvent oil: Melt sliced paraffin in D70 solvent oil at a temperature of 80°C; its addition amount is 0.4 g of sliced paraffin and 80 ml of D70 solvent oil added per 1 kg of composite powder; S2. Weigh each component metal powder according to the component ratio of the composite powder; add the weighed component metal powders to the solvent oil prepared in step S1, and perform mechanical mixing; lay the uniformly mixed mixture flat in a drying oven for drying treatment; S3. Pass the dried mixture through a 60-mesh standard Tyler sieve, pour the sieved mixture into a V-type mixer for mechanical mixing for 2 hours, and the composite powder is obtained after mixing is completed.

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