High-strength soluble aluminum alloy material for shale oil and gas exploitation tool and preparation method

Abstract

The invention discloses a high-strength soluble aluminum alloy material for a shale oil and gas exploitation tool and a preparation method of the high-strength soluble aluminum alloy material. The tensile strength of the Al-Zn-Mg-Cu series alloy is 300 to 750 MPa, the yield strength of the Al-Zn-Mg-Cu series alloy is 280 to 720 MPa, and the ductility of the Al-Zn-Mg-Cu series alloy is 0.5 to 9 percent; the corrosion rate of the alloy in a 3% KCl solution at 93 DEG C is 20-185 mg.cm <-2 >. H <-1 >. The prepared soluble Al-Zn-Mg-Cu alloy is short in technological process, has excellent strength-plasticity balance, is high in dissolution rate and can be fully dissolved underground, and secondary drilling is not needed. The Al-Zn-Mg-Cu soluble aluminum alloy disclosed by the invention has a wide application prospect in the field of oil and gas exploitation.

Description

Invention Field

[0001] This invention belongs to the field of functional and structural integrated alloy materials, specifically relating to a high-strength soluble aluminum alloy material for shale oil and gas extraction tools and its preparation method. Background Technology

[0002] Since the end of the last century, unconventional oil and gas resources, represented by shale oil and gas, have been discovered and have gradually become the dominant energy source in today's society. In addition, my country has abundant reserves of unconventional oil and gas resources. Accelerating the exploration and exploitation of unconventional shale oil and gas resources is a major strategic requirement to ensure national energy security.

[0003] The core of shale oil and gas extraction is horizontal well staged fracturing technology, and downhole plugging tools are the core equipment of this technology. Traditional steel and cast iron plugging tools need to be drilled into powder and extracted downhole after the fracturing operation, which makes the operation time-consuming, costly, and complicated, and prone to blockage, preventing oil and gas from being discharged to the surface normally.

[0004] To address these issues, fracturing plugging tools have evolved from drillable to dissolvable types. After the operation is completed, they can dissolve on their own under the action of the flowback fluid, eliminating the need for drilling and avoiding the potential risk of clogging pipelines. This reduces costs and improves oil and gas production efficiency.

[0005] Aluminum alloys have the characteristics of low density, high strength, excellent casting performance, and good electrical and thermal conductivity, making them the preferred material for soluble tools. Especially under extreme service conditions, the increased temperature and pressure in deep wells place higher demands on the performance of soluble tools.

[0006] Patent document 1 (US 10, 352, 125 B2) discloses a downhole tool made of a soluble aluminum / magnesium alloy and a polymeric acid. The downhole tool material is composed of Al and Mg, Si, Cu, Li or Mn, Zn, In metallic elements. It mentions that such elements can improve the strength of the alloy or the downhole dissolution rate, but does not mention the specific composition and proportion of the alloy, nor does it provide the tensile strength, yield strength and elongation of the alloy. Therefore, it is impossible to determine whether it meets the requirements for downhole operations.

[0007] Patent document 2 (CN 104480354 B) discloses a high-strength soluble aluminum alloy material, with Sn, Si, Mn, Mg, Ga, In and Zn as the main added elements. The specific content of each element is also given. However, the solubility of the alloy is mainly considered under the conditions of 40℃ and 50℃, while the extraction temperature of unconventional shale oil and gas is higher. Moreover, the mechanical properties of the alloy material are not given, so it cannot be compared with the requirements of actual working conditions.

[0008] Patent document 3 (US 2007 / 0181224A1) discloses a soluble metal material composition comprising one or more active metals in a major proportion and one or more alloying products in a minor proportion, mainly including functional elements such as Ga, In, Zn, and Bi. This composition is characterized by its controllable activity and degradability under specific conditions; however, the material has low compressive strength, only reaching tens of megapascals, which cannot meet the requirements of practical use.

[0009] Patent document 4 (CN 106834767 B) discloses a method for refining the grains of soluble aluminum alloy materials, which uses mechanical vibration, external magnetic field and other methods. The tensile strength involved can generally reach 400~600MPa. Although the mechanical properties are relatively excellent, the corrosion performance of soluble aluminum alloy materials used in oil and gas extraction tools needs to be considered, but this is not mentioned.

[0010] Patent document 5 (CN 106488992 B) discloses a high-strength soluble aluminum alloy containing metal oxides, thus belonging to an aluminum-based composite material. In the given embodiments, the compressive strength of the alloy is less than 400 MPa, indicating low strength. Furthermore, in actual service, the material is used in downhole operations, where tensile strength and yield strength are the primary considerations. Therefore, it is impossible to determine whether the alloy meets the service requirements.

[0011] In summary, considering the composition and processing requirements of high-strength soluble aluminum alloy materials for shale oil and gas extraction tools, the designed high-strength soluble aluminum alloy not only needs to control the corrosion rate to meet the requirements of certain downhole tools, but also must possess considerable mechanical properties. Therefore, this invention has conducted careful research in this regard. Summary of the Invention

[0012] To address the aforementioned problems, the present invention aims to provide a high-strength soluble aluminum alloy material and its preparation method. The soluble aluminum alloy uses Zn, Mg, and Cu as main elements. By controlling the type and content of Al-Zn-Mg-Cu alloying elements, soluble aluminum alloys containing different second phases are formed, causing changes in the potential difference between the matrix and the second phase, thereby accelerating alloy dissolution. Furthermore, the soluble aluminum alloy has advantages such as low cost and excellent comprehensive mechanical and corrosion resistance. It is mainly used in shale oil and gas development using soluble fracturing tools, but is not entirely limited to this field and can also be used in other areas.

[0013] One technical solution of the present invention is as follows:

[0014] A high-strength soluble aluminum alloy material for shale oil and gas extraction tools, characterized in that...

[0015] The aluminum alloy contains Zn, Mg, Cu, and M elements (i.e., the alloy composition is Al-Zn-Mg-Cu-M), and each element is expressed as a mass percentage:

[0016] Zn: 4.0~12.0 wt.%, Mg: 1.0~5.0 wt.%, Cu: 0.5~4.0 wt.%;

[0017] M is at least one of Ga, In, and Sn, wherein Ga: 0.1~4.0 wt.%, In: 0.1~4.0 wt.%, Sn: 0.1~4.0 wt.%;

[0018] The margin is Al.

[0019] The aluminum alloy has a tensile strength of 300-750 MPa, a yield strength of 280-720 MPa, and an elongation of 0.5-9%; the alloy has a corrosion rate of 20-185 mg·cm⁻¹ in a 3% KCl solution at 93°C. -2 ·h -1 .

[0020] Preferably, the alloy has a tensile strength of 400-750 MPa, a yield strength of 300-720 MPa, and an elongation of 1.5-8.5%; the alloy has a corrosion rate of 50-180 mg·cm⁻¹ in a 3% KCl solution at 93°C. -2 ·h -1 .

[0021] Preferably, the high-strength soluble aluminum alloy has an alloy composition of Al-Zn-Mg-Cu-M, and the preferred mass percentages of each element are:

[0022] Zn: 6.0~10.0 wt.%, Mg: 2.0~4.0 wt.%, Cu: 1.0~3.0 wt.%;

[0023] M is at least one of Ga, In, and Sn, with Ga: 0.5~3.0 wt.%, In: 0.5~2.0 wt.%, Sn: 0.5~2.0 wt.%;

[0024] The margin is Al.

[0025] More preferably, Ga: 0.5~2.0 wt.%, In: 0.5~1.5 wt.%, Sn: 0.5~1.5 wt.%;

[0026] The margin is Al.

[0027] A high-strength soluble aluminum alloy used in shale oil and gas development tools may also contain nitrogen (i.e., the alloy composition is Al-Zn-Mg-Cu-MN), with each element expressed as a mass percentage:

[0028] Zn: 4.0~12.0 wt.%, Mg: 1.0~5.0 wt.%, Cu: 0.5~4.0 wt.%;

[0029] M is at least one of Ga, In, and Sn, wherein Ga: 0.1~4.0 wt.%, In: 0.1~4.0 wt.%, Sn: 0.1~4.0 wt.%;

[0030] N is at least one of the elements Sc, Zr, Ti, Er, and Y, wherein Sc: 0.01~0.5 wt.%, Zr: 0.01~0.5 wt.%, Ti: 0.01~0.5 wt.%, Er: 0.01~0.5 wt.%, and Y: 0.01~0.5 wt.%;

[0031] The margin is Al.

[0032] In a preferred embodiment, the high-strength soluble aluminum alloy has an alloy composition of Al-Zn-Mg-Cu-MN, with each element expressed as a mass percentage as follows:

[0033] Zn: 6.0~10.0 wt.%, Mg: 2.0~4.0 wt.%, Cu: 1.0~3.0 wt.%;

[0034] M is at least one of Ga, In, and Sn, with Ga: 0.5~3.0 wt.%, In: 0.5~2.0 wt.%, Sn: 0.5~2.0 wt.%;

[0035] N is at least one of the elements Sc, Zr, Ti, Er, and Y, wherein Sc: 0.1~0.4 wt.%, Zr: 0.1~0.4 wt.%, Ti: 0.1~0.4 wt.%, Er: 0.1~0.4 wt.%, and Y: 0.1~0.4 wt.%;

[0036] The margin is Al.

[0037] In traditional aluminum alloys, Zn, Mg, and Cu elements typically improve the alloy's mechanical properties, with higher contents resulting in more significant performance enhancements. However, in this invention, in addition to the aforementioned mechanical properties, to meet the high strength and high corrosion rate requirements of unconventional oil and gas extraction, Zn, Mg, and Cu are used as the main elements to form an Al-Zn-Mg-Cu alloy. The composition of the T-phase, S-phase, and... (The sentence is incomplete in the original text.) is controlled by adjusting the Zn, Mg, and Cu contents.η′ phase By controlling the content of the second phase, the quantity, morphology, and size of the second phase can be controlled, thereby improving the mechanical properties and controlling the corrosion rate of Al-Zn-Mg-Cu alloys.

[0038] Furthermore, in the actual service of soluble fracturing tools, high mechanical properties and fast corrosion rates are important performance indicators. Alloying is one of the effective methods to improve their performance. Therefore, in the alloy of this invention, by adding Ga, In, and Sn elements to the Al-Zn-Mg-Cu-M system alloy, second phases such as Ga5Mg2, Al3Sn, and Mg3In that promote corrosion can be formed. These phases form electrical couples with the matrix, which can aggravate pitting corrosion and intergranular corrosion. At the same time, due to their low solubility in the Al matrix, the continuous distribution of the second phase at the grain boundaries provides channels for the penetration of corrosive media, thus aggravating the occurrence of corrosion behavior.

[0039] The following is a detailed explanation of adding element M:

[0040] Ga has extremely low solid solubility in Al (<0.1 wt%), preferentially forming Al3Ga or AlGa intermetallic compounds, typically in the micrometer range, mostly distributed at grain boundaries or between dendrites. In this invention, when Ga content is 0.1~4.0 wt.%, Ga can significantly affect the corrosion performance of the alloy. The formed Al3Ga acts as a cathode phase, promoting pitting corrosion. Simultaneously, Ga locally disrupts the continuity of the Al2O3 oxide film, thereby promoting alloy corrosion.

[0041] In and Sn are almost insoluble in Al (<0.01 wt%), and generally accumulate at grain boundaries to form coarse, continuous AlIn or Al3Sn phases (i.e., corrosion-promoting phases), providing pathways for corrosion propagation and exacerbating intergranular corrosion. When In and Sn are 0.1~4.0 wt.%, the large potential difference between the Al3Sn phase and the Al matrix significantly promotes pitting corrosion in the alloy.

[0042] Furthermore, based on the Al-Zn-Mg-Cu-M alloy system, other different elements of N can be added, such as at least one of Sc, Zr, Ti, Er, Y, etc., to form an Al-Zn-Mg-Cu-MN six-element alloy system. In addition to the T phase and S phase, the alloy also forms... η′ phase In addition, second phases such as Al3Sc, Al3Zr, Al3Ti, Al3Er, and Al3Y can be formed to improve strength. These phases can effectively hinder dislocation movement, refine grains, and improve the mechanical properties of the alloy, resulting in high-strength soluble aluminum alloys with excellent comprehensive properties. Furthermore, some of the second phases also act as cathode phases, which can also accelerate the corrosion rate of the alloy.

[0043] The following explains the addition of element N:

[0044] Sc forms the Al3Sc phase in aluminum alloys, exhibiting a significant grain-refining effect and contributing to both grain refinement and precipitation strengthening of the alloy's strength. Furthermore, when Sc is in the range of 0.1–0.4 wt.%, during the homogenization process, a large amount of fine, uniform, and dispersed bean-shaped secondary Al3Sc phase precipitates coherently with the matrix. These particles strongly pin dislocations and grain boundaries, hindering recrystallization and maintaining the deformed substructure after solution treatment and aging. This impedes dislocation movement and thus provides substructure strengthening. Simultaneously, the Al3Sc phase, as a cathodic phase, facilitates pitting corrosion, increasing the alloy's corrosion rate.

[0045] Zr reacts with Al to form the Al3Zr phase, which is smaller and more dispersed than the Al3Sc phase. This phase effectively pins grain boundaries and significantly inhibits grain growth during heat exposure or hot working, thus providing a more significant improvement in the high-temperature mechanical properties of the alloy. Furthermore, the Al3Zr phase, as a cathode phase, can also accelerate the corrosion rate of the alloy.

[0046] Ti forms the Al3Ti phase in aluminum alloys. This phase is relatively large and mainly distributed at grain boundaries. During casting, this phase promotes heterogeneous nucleation, reduces dendrite spacing, and primarily enhances the alloy's strength through grain refinement. Furthermore, the coarse Al3Ti phase acts as a cathodic phase, significantly promoting pitting and intergranular corrosion. Simultaneously, Ti enrichment at grain boundaries exacerbates the potential difference between the grain boundaries and the matrix, increasing the corrosion rate.

[0047] Adding rare earth elements Er and Y to Al-Zn-Mg-Cu alloys can generate Al3Er and Al3Y, which can play a role in heterogeneous nucleation and grain refinement, while inhibiting dynamic recrystallization and improving the mechanical properties of the alloy.

[0048] Another technical solution of the present invention is as follows:

[0049] A method for preparing a high-strength soluble aluminum alloy as described above, characterized by the following steps:

[0050] All raw materials for the aluminum alloy as designed above are placed in a container and melted in a pit-type resistance furnace at 700~750℃. After all raw materials have melted, the mixture is allowed to stand for 15~20 minutes for slag removal and stirring, followed by refining. Then, the melt is subjected to electromagnetic treatment at 680~720℃: current 10~100A, frequency 5~50Hz, time 1~30min. After the electromagnetic treatment, the melt is immediately gravity-cast into a mold to obtain the corresponding ingot. The obtained ingot is subjected to solution treatment at 350~470℃ for 0.5~6h, and immediately cooled in tap water after solution treatment. The water-cooled ingot is then subjected to aging treatment at 90~180℃ for 6~48h to obtain the high-strength soluble aluminum alloy of this invention.

[0051] Furthermore, in the above steps, after obtaining the ingot, the ingot can be subjected to homogenization air cooling in sequence: the homogenization temperature is 330~450℃, and the time is 6~24h; then the air-cooled ingot is subjected to hot extrusion, wherein the preheating temperature of the obtained ingot, extrusion die, and extrusion cylinder is the same as the extrusion temperature, the sample preheating time is 1.5~2.0h, the extrusion die and extrusion cylinder preheating time is 4~6h, the extrusion temperature is 350~440℃, the extrusion ratio is 4:1~9:1, and the bar obtained after extrusion is immediately placed in tap water for cooling and solution treatment: the solution treatment temperature is 350~470℃, and the time is 0.5~6h, and the bar is immediately placed in tap water for cooling after solution treatment: the aging temperature is 90~180℃, and the aging time is 6~48h.

[0052] This invention is not limited to this process route; equivalent performance can also be obtained through other different process schemes.

[0053] The high-strength soluble aluminum alloy of this invention is mainly used in unconventional shale oil and gas extraction tools. After processing and hot working, the corresponding tools can be obtained, and it also has the mechanical and corrosion properties required for fracturing tools.

[0054] The mining tool is preferably a fracturing ball, ball seat, or bridge plug, and more preferably a bridge plug.

[0055] Note: The term "corrosion performance" used in this invention has the same meaning as terms such as corrosion rate, corrosion speed, and corrosion behavior. This invention uses the weight loss method to evaluate the corrosion performance of the alloy. Specifically, within a certain time period (preferably 1, 2, 4, 6, 8 hours, etc.), the difference between the alloy's mass before corrosion (mg) and its mass after corrosion (mg) is divided by the product of the alloy's surface area and time. The final unit is mg·cm³. -2 ·h -1 .

[0056] Compared with the prior art, the present invention has the following beneficial effects:

[0057] According to the preparation method of the present invention, the soluble aluminum alloy material obtained by the above-mentioned heat treatment and deformation process is simple, low-cost, and has a high production yield. It can not only improve the microstructure, distribution, size, and morphology of the second phase in the alloy, but also refine the grains through the deformation process, improve the second phase of the Al-Zn-Mg-Cu alloy, thereby improving the mechanical and corrosion properties of the alloy.

[0058] In addition, large-scale soluble fracturing tools, such as bridge plugs, can be manufactured through traditional semi-continuous casting, electromagnetic casting / stirring, and heat treatment processes.

[0059] Furthermore, according to the high-strength soluble aluminum alloy of the present invention, by controlling the type (M) and amount of alloying elements, the alloy is activated, thereby effectively regulating the corrosion rate of the alloy and meeting the requirements of different downhole service conditions. In addition, the high-strength soluble aluminum alloy of the present invention can be completely dissolved in KCl solution, and the resulting corrosion products are discharged with the flowback fluid after downhole operations, without causing blockage.

[0060] In summary, as demonstrated by the preparation method of this invention, by controlling different heat treatment and deformation process parameters, the internal structure of the alloy becomes uniform and fine, effectively improving the overall performance of the alloy. Through the alloy design and process control of this invention, a high-strength soluble aluminum alloy material with excellent mechanical and corrosion properties is ultimately obtained.

[0061] The soluble Al-Zn-Mg-Cu alloy prepared by this invention has a short process flow and the obtained alloy has excellent strength-plasticity balance. It has a fast dissolution rate and can be fully dissolved downhole without the need for secondary drilling. Therefore, the Al-Zn-Mg-Cu soluble aluminum alloy of this invention has broad application prospects in the field of oil and gas extraction. Attached Figure Description

[0062] Figure 1 This is a scanned image of the alloy in the as-cast state in Example 1.

[0063] Figure 2 for Figure 1 A magnified partial photograph.

[0064] Figure 3 The image shows the microstructure of the Al-8Zn-1.5Mg-1.7Cu-0.15Y-0.15Sc-1Ga-0.8Sn-0.4In alloy after solution treatment in Example 4.

[0065] Figure 4 The image shows the microstructure of the Al-10Zn-2.5Mg-1.5Cu-0.15Sc-0.8Ga-0.8In alloy in Example 5 after homogenization treatment at 450 °C for 10 h. Detailed Implementation

[0066] The present invention will be described in detail below with reference to the accompanying drawings and embodiments, as follows:

[0067] Example 1: Preparation of the alloy Al-11Zn-3Mg-1.5Cu-0.15Zr-0.15Ti-1Ga-0.4In-0.4Sn

[0068] All the aluminum alloy raw materials in the above proportions are added to a crucible and melted in a pit-type resistance furnace at 710~730℃. After all the raw materials have melted, they are left to stand for 15~20 minutes to remove slag and stir. Then, they are refined and the melt is electromagnetically treated at 700~720℃ with a current of 10A, a frequency of 50Hz, and a time of 5min. After the electromagnetic treatment, the melt is immediately gravity-cast into a mold to finally obtain an ingot with a soluble aluminum alloy composition of Al-11Zn-3Mg-1.5Cu-0.15Zr-0.15Ti-1Ga-0.4In-0.4Sn. The ingot was solution treated at 470℃ for 4 hours, then immediately cooled in tap water at room temperature, and then aged at 120℃ for 24 hours to obtain the T6 state alloy Al-11Zn-3Mg-1.5Cu-0.15Zr-0.15Ti-1Ga-0.4In-0.4Sn, thus obtaining the aluminum alloy of the present invention.

[0069] Scanning images and magnified images of the alloy in the as-cast state in Example 1 are shown below. Figure 1 and Figure 2 .

[0070] The corrosion rate and mechanical properties of the alloy obtained in Example 1 were tested.

[0071] Corrosion rate

[0072] To simulate different environments during oil extraction, the corrosion rate of the alloy was studied under conditions of 93℃ and 3% KCl. The corrosion rate was tested using the weight loss method. Specific results are shown in Table 1.

[0073] Mechanical property testing

[0074] Mechanical property testing was conducted according to national standards, with a strain rate of 10. -3 / s.

[0075] The obtained mechanical properties are shown in Table 1.

[0076] Example 2: Alloy Al-10Zn-2.4Mg-1.3Cu-0.15Sc-1.2Ga

[0077] All the aluminum alloy raw materials in the above proportions were added to a crucible and melted in a pit-type resistance furnace at 700~720℃. After all the raw materials were melted, the mixture was allowed to stand for 15~20 minutes to remove slag and stir, and then refined. The melt was then subjected to electromagnetic treatment at 700~710℃ with a current of 50A, a frequency of 50Hz, and a time of 2 minutes. After the electromagnetic treatment, the melt was immediately gravity-cast into a mold to obtain an ingot with a soluble aluminum alloy composition of Al-10Zn-2.4Mg-1.3Cu-0.15Sc-1.2Ga. The ingot was subjected to solution treatment at 470℃ for 2 hours, followed by immediate cooling in tap water at room temperature, and then aging treatment at 120℃ for 24 hours to obtain the T6 state alloy Al-10Zn-2.4Mg-1.3Cu-0.15Sc-1.2Ga, thus obtaining the aluminum alloy of this invention.

[0078] The obtained aluminum alloy was subjected to corrosion rate and mechanical property tests, using the same methods as in Example 1.

[0079] The results are shown in Table 1.

[0080] Example 3: Al-8Zn-1.8Mg-1.3Cu-0.15Er-1.2Ga-0.8Sn

[0081] All the aluminum alloy raw materials in the above proportions were added to a crucible and melted in a pit-type resistance furnace at 700~720℃. After all the raw materials were melted, the mixture was allowed to stand for 15~20 minutes to remove slag and stir, and then refined. The melt was then subjected to electromagnetic treatment at 700~720℃ with a current of 20A, a frequency of 5Hz, and a time of 10min. After the electromagnetic treatment, the melt was immediately gravity-cast into a mold to obtain an ingot with a soluble aluminum alloy composition of Al-8Zn-1.8Mg-1.3Cu-0.15Er-1.2Ga-0.8Sn. The ingot was subjected to solution treatment at 470℃ for 1 h, and then immediately cooled in tap water at room temperature. It was then subjected to aging treatment at 120℃ for 24 h to obtain the T6 state alloy Al-8Zn-1.8Mg-1.3Cu-0.15Er-1.2Ga-0.8Sn, thus obtaining the aluminum alloy of this invention.

[0082] The obtained aluminum alloy was subjected to corrosion rate and mechanical property tests, using the same methods as in Example 1. The results are shown in Table 1.

[0083] Example 4: Alloy Al-8Zn-1.5Mg-1.7Cu-0.15Y-0.15Sc-1Ga-0.8Sn-0.4In

[0084] All the aluminum alloy raw materials in the above proportions are added to a crucible and melted in a pit-type resistance furnace at 700~720℃. After all the raw materials have melted, they are left to stand for 15~20 minutes to remove slag and stir. Then, they are refined and electromagnetically treated at 680~720℃ with a current of 10A, a frequency of 25Hz, and a time of 5min. After the electromagnetic treatment, the melt is immediately gravity-cast into a mold to obtain an ingot with a soluble aluminum alloy composition of Al-8Zn-1.5Mg-1.7Cu-0.15Y-0.15Sc-1Ga-0.8Sn-0.4In. The ingot was solution treated at 470℃ for 2 hours, then immediately cooled in tap water at room temperature, and then aged at 120℃ for 24 hours to obtain the T6 state alloy Al-8Zn-1.5Mg-1.7Cu-0.15Y-0.15Sc-1Ga-0.8Sn-0.4In, thus obtaining the aluminum alloy of the present invention.

[0085] The obtained aluminum alloy was subjected to corrosion rate and mechanical property tests, using the same methods as in Example 1.

[0086] The results are shown in Table 1.

[0087] Example 5: Al-10Zn-2.5Mg-1.5Cu-0.15Sc-0.15Zr-0.8Ga-0.8In

[0088] All the aluminum alloy raw materials in the above proportions are added to a crucible and melted in a pit-type resistance furnace at 700~720℃. After all the raw materials have melted, they are left to stand for 15~20 minutes to remove slag and stir. Then, they are refined and electromagnetically treated at 680~720℃ with a current of 20A, a frequency of 10Hz, and a time of 5min. After the electromagnetic treatment, the melt is immediately gravity-cast into a mold to obtain an ingot with a soluble aluminum alloy composition of Al-10Zn-2.5Mg-1.5Cu-0.15Sc-0.15Zr-0.8Ga-0.8In. The ingot was homogenized at 450 °C for 10 h, and then the alloy was extruded at 400 °C with an extrusion ratio of 9. After that, it was solution treated at 470 °C for 3 h and aged at 120 °C for 24 h to obtain the final extruded bar alloy Al-10Zn-2.5Mg-1.5Cu-0.15Sc-0.15Zr-0.8Ga-0.8In, which is the aluminum alloy of the present invention.

[0089] The obtained aluminum alloy was subjected to corrosion rate and mechanical property tests, using the same methods as in Example 1.

[0090] The results are shown in Table 1.

[0091] The obtained aluminum alloy was subjected to corrosion rate and mechanical property tests, using the same methods as in Example 1.

[0092] The results are shown in Table 1.

[0093] Example 6: Al-11Zn-1.5Mg-1.0Cu-0.1Sc-0.6Ga-0.6In-0.5Sn

[0094] All the aluminum alloy raw materials in the above proportions are added to a crucible and melted in a pit-type resistance furnace at 700~720℃. After all the raw materials have melted, the mixture is allowed to stand for 15~20 minutes to remove slag and stir. Then, it is refined and the melt is subjected to electromagnetic treatment at 680~720℃ with a current of 40A, a frequency of 25Hz, and a time of 10min. After the electromagnetic treatment, it is immediately gravity-cast into a mold to finally obtain an ingot with a soluble aluminum alloy composition of Al-11Zn-1.5Mg-1.0Cu-0.1Sc-0.6Ga-0.6In-0.5Sn. The ingot was homogenized at 440 °C for 16 h, then the alloy was extruded at 400 °C with an extrusion ratio of 4, followed by solution treatment at 470 °C for 2 h and aging treatment at 120 °C for 20 h to obtain T6-state extruded bar alloy Al-11Zn-1.5Mg-1.0Cu-0.1Sc-0.6Ga-0.6In-0.5Sn, thus obtaining the aluminum alloy of the present invention.

[0095] The obtained aluminum alloy was subjected to corrosion rate and mechanical property tests, using the same methods as in Example 1.

[0096] The results are shown in Table 1.

[0097] Example 7: Al-9Zn-2.5Mg-2.0Cu-0.15Y-1.2Ga-0.5In-0.5Sn

[0098] All the aluminum alloy raw materials in the above proportions are added to a crucible and melted in a pit-type resistance furnace at 700~720℃. After all the raw materials have melted, they are left to stand for 15~20 minutes to remove slag and stir. Then, they are refined and the melt is electromagnetically treated at 680~720℃ with a current of 80A, a frequency of 30Hz, and a time of 15min. After the electromagnetic treatment, the melt is immediately gravity-cast into a mold to finally obtain an ingot with a soluble aluminum alloy composition of Al-9Zn-2.5Mg-2.0Cu-0.15Y-1.2Ga-0.5In-0.5Sn. The ingot was homogenized at 450 °C for 20 h, and then the alloy was extruded at 390 °C with an extrusion ratio of 4. After that, it was solution treated at 470 °C for 1 h and aged at 120 °C for 24 h to obtain the T6-state extruded bar alloy Al-9Zn-2.5Mg-2.0Cu-0.15Y-1.2Ga-0.5In-0.5Sn, which is the aluminum alloy of the present invention.

[0099] The obtained aluminum alloy was subjected to corrosion rate and mechanical property tests, using the same methods as in Example 1.

[0100] The results are shown in Table 1.

[0101] Example 8: Al-10Zn-3.0Mg-1.5Cu-0.05Ti-0.15Sc-1.0Ga-0.8In-0.6Sn

[0102] All the aluminum alloy raw materials in the above proportions are added to a crucible and melted in a pit-type resistance furnace at 700~720℃. After all the raw materials have melted, the mixture is allowed to stand for 15~20 minutes to remove slag and stir. Then, it is refined and the melt is subjected to electromagnetic treatment at 680~720℃ with a current of 100A, a frequency of 20Hz, and a time of 10min. After the electromagnetic treatment is completed, it is immediately gravity-cast into a mold to finally obtain an ingot with a soluble aluminum alloy composition of Al-10Zn-3.0Mg-1.5Cu-0.05Ti-0.15Sc-1.0Ga-0.8In-0.6Sn. The ingot was homogenized at 350 °C for 12 h, then the alloy was extruded at 410 °C with an extrusion ratio of 4, followed by solution treatment at 470 °C for 3 h and aging treatment at 120 °C for 24 h to obtain a T6-state extruded bar alloy Al-10Zn-3.0Mg-1.5Cu-0.05Ti-0.15Sc-1.0Ga-0.8In-0.6Sn, thus obtaining the aluminum alloy of this invention.

[0103] Comparative Example 1: Al-11Zn-3.0Mg-1.5Cu-0.15Sc

[0104] All the aluminum alloy raw materials in the above proportions were added to a crucible and melted in a pit-type resistance furnace at 700~720℃. After all the raw materials were melted, the mixture was allowed to stand for 15~20 minutes to remove slag and stir, and then refined. The melt was then subjected to electromagnetic treatment at 680~720℃ with a current of 50A, a frequency of 20Hz, and a time of 10min. Immediately after the electromagnetic treatment, the melt was gravity-cast into a mold to obtain an ingot with a soluble aluminum alloy composition of Al-11Zn-3.0Mg-1.5Cu-0.15Sc. The ingot was homogenized at 460℃ for 12 h, and then the alloy was extruded at 420℃ with an extrusion ratio of 4. After that, it was solution treated at 470℃ for 1 h and aged at 120℃ for 24 h to obtain T6-state extruded bar alloy Al-11Zn-3.0Mg-1.5Cu-0.15Sc.

[0105] Comparative Example 2: Al-10Zn-2.0Mg-1.2Cu-0.10Ti

[0106] All the aluminum alloy raw materials in the above proportions were added to a crucible and melted in a pit-type resistance furnace at 700~720℃. After all the raw materials were melted, the mixture was allowed to stand for 15~20 minutes to remove slag and stir, and then refined. The melt was then subjected to electromagnetic treatment at 680~720℃ with a current of 100A, a frequency of 20Hz, and a time of 10min. Immediately after the electromagnetic treatment, the melt was gravity-cast into a mold to obtain an ingot with a soluble aluminum alloy composition of Al-10Zn-2.0Mg-1.2Cu-0.10Ti. The ingot was homogenized at 460℃ for 12 h, and then the alloy was extruded at 420℃ with an extrusion ratio of 8. After that, it was solution treated at 470℃ for 1 h and aged at 120℃ for 24 h to obtain T6-state extruded bar alloy Al-10Zn-2.0Mg-1.2Cu-0.10Ti.

[0107] The obtained aluminum alloy was subjected to corrosion rate and mechanical property tests, using the same methods as in Example 1.

[0108] The results are shown in Table 1.

[0109] Table 1 shows the mechanical and corrosion properties of all alloys in the examples.

[0110]

[0111] All embodiments and comparative examples of this invention demonstrate that Al-Zn-Mg-Cu alloys, with Zn, Mg, and Cu as main elements, exhibit excellent mechanical properties. Specifically, the tensile strength of the aluminum alloys is 300–750 MPa, the yield strength is 280–720 MPa, and the elongation is 0.5–9%; however, regarding corrosion rate, the alloys of Examples 1–8 exhibit corrosion rates of 20–185 mg·cm⁻¹ in a 3% KCl solution at 93°C. -2 ·h -1 In contrast, the alloys of Comparative Examples 1 and 2 exhibited corrosion rates significantly lower than those of the present invention in a 3% KCl solution at 93°C, at only 0.3 and 1.4 mg·cm⁻¹, respectively. -2 ·h -1The corrosion rate is significantly lower than that of the present invention. This indicates that, under the same process conditions, compared to the Al-Zn-Mg-Cu-N alloy composition of the comparative example, the high-strength soluble aluminum alloy obtained by the composition ratio designed in this invention, namely Al-Zn-Mg-Cu-M or Al-Zn-Mg-Cu-MN, can effectively regulate the corrosion rate of the alloy by controlling the alloying element M (at least one of Ga, In, and Sn) and its addition amount, thereby activating the alloy. Furthermore, by adding Ga, In, and Sn to the Al-Zn-Mg-Cu-M alloy system, different second phases such as Ga5Mg2, Al3Sn, and Mg3In can be formed, which promote corrosion. These phases form electrical couples with the matrix, which can exacerbate pitting and intergranular corrosion. At the same time, due to their low solubility in the Al matrix, the continuous distribution of the second phase at the grain boundaries provides channels for the penetration of corrosive media, thus intensifying the corrosion behavior. For this reason, the high-strength soluble aluminum alloy of the present invention can be completely dissolved in KCl solution, and the resulting corrosion products are discharged with the flowback fluid after downhole operations. Even at this corrosion rate, in actual operations, the corrosion products formed can also be discharged with the flowback fluid after downhole operations without causing blockages, thus meeting the requirements of different downhole service conditions. Therefore, the high-strength soluble aluminum alloy of the present invention exhibits excellent corrosion resistance.

[0112] In summary, as can be seen from the data of the embodiments and comparative examples in Table 1 above, while maintaining the required mechanical properties, by adding some other elements M and N (especially M) from this invention to the Al-Zn-Mg-Cu alloy, and by using heat treatment and deformation processes, the relationship between the mechanical properties and corrosion properties of the Al-Zn-Mg-Cu alloy can be coordinated. In other words, the high-strength soluble aluminum alloy of this invention can achieve a synergistic match between strength and corrosion rate.

[0113] In addition, Figure 1 , Figure 2 As can be seen from the figure, the composition consists of an α-Al matrix phase, AlZnMgCu, Mg2Sn, and a second phase composed of other elements. This demonstrates that the preparation method of the present invention, by changing the alloy composition and heat treatment process, can not only improve the microstructure, distribution, size, and morphology of the second phase in the alloy, but also refine the grains through deformation processes, thereby improving the second phase of the Al-Zn-Mg-Cu alloy and enhancing its mechanical and corrosion properties. Furthermore, due to differences in the composition, morphology, size, distribution, and content of the second phase in different embodiments, the potentials of the Al matrix and the second phase differ, resulting in different potential differences and ultimately different corrosion rates. Therefore, the alloy of the present invention achieves excellent mechanical and corrosion properties by forming a harmonious relationship between composition, process, microstructure, and properties.

[0114] in addition, Figure 3 The microstructure of the Al-8Zn-1.5Mg-1.7Cu-0.15Y-0.15Sc-1Ga-0.8Sn-0.4In alloy after solution treatment is shown in Example 4. From the figure, it can be seen that AlMgSn and AlZnMgCuGaIn phases are formed. During the corrosion process, they preferentially corrode at the grain boundaries, thereby increasing the corrosion rate.

[0115] Figure 4 The microstructure of the Al-10Zn-2.5Mg-1.5Cu-0.15Sc-0.15Zr-0.8Ga-0.8In alloy in Example 5 after homogenization treatment at 450 °C for 10 h is shown. In addition to the second phase identical to that in Example 3, an Al(Ss, Zr) phase was observed, which plays a strengthening role.

[0116] In summary, the soluble Al-Zn-Mg-Cu alloy prepared by this invention has a short process flow, and the obtained alloy has excellent strength-plasticity balance, fast dissolution rate and can be fully dissolved downhole without the need for secondary drilling. Therefore, the Al-Zn-Mg-Cu soluble aluminum alloy of this invention has broad application prospects in the field of oil and gas extraction.

Claims

1. A high-strength soluble aluminum alloy material for shale oil and gas extraction tools, characterized in that, The aluminum alloy composition is Al-Zn-Mg-Cu-M, with each element expressed as a mass percentage: Zn: 4.0~12.0 wt.%, Mg: 1.0~5.0 wt.%, Cu: 0.5~4.0 wt.%; M is at least one of Ga, In, and Sn, wherein Ga: 0.1~4.0 wt.%, In: 0.1~4.0 wt.%, Sn: 0.1~4.0 wt.%; The balance is Al; The aluminum alloy has a tensile strength of 300-750 MPa, a yield strength of 280-720 MPa, and an elongation of 0.5-9%; the alloy has a corrosion rate of 20-185 mg·cm⁻¹ in a 3% KCl solution at 93°C. -2 ·h -1 .

2. The high-strength soluble aluminum alloy material according to claim 1, characterized in that, The alloy has a tensile strength of 400-750 MPa, a yield strength of 300-720 MPa, and an elongation of 1.5-8.5%; the alloy exhibits a corrosion rate of 50-180 mg·cm⁻¹ in a 3% KCl solution at 93°C. -2 ·h -1 .

3. The high-strength soluble aluminum alloy material according to claim 1, characterized in that, The elements of the aluminum alloy, expressed as mass percentages, are: Zn: 6.0~10.0 wt.%, Mg: 2.0~4.0 wt.%, Cu: 1.0~3.0 wt.%; M is at least one of Ga, In, and Sn, with Ga: 0.5~3.0 wt.%, In: 0.5~2.0 wt.%, and Sn: 0.5~2.0 wt.%. The balance is Al.

4. The high-strength soluble aluminum alloy material according to claim 1, characterized in that, The aluminum alloy may also contain nitrogen (N), which is at least one of Sc, Zr, Ti, Er, and Y, with each element expressed as a mass percentage: Sc: 0.01~0.5 wt.%, Zr: 0.01~0.5 wt.%, Ti: 0.01~0.5 wt.%, Er: 0.01~0.5 wt.%, Y: 0.01~0.5 wt.%.

5. The high-strength soluble aluminum alloy material according to claim 4, characterized in that, M is at least one of Ga, In, and Sn, with Ga: 0.5~3.0 wt.%, In: 0.5~2.0 wt.%, Sn: 0.5~2.0 wt.%; N is at least one of the elements Sc, Zr, Ti, Er, and Y, wherein Sc: 0.1~0.4 wt.%, Zr: 0.1~0.4 wt.%, Ti: 0.1~0.4 wt.%, Er: 0.1~0.4 wt.%, and Y: 0.1~0.4 wt.%.

6. A method for preparing a high-strength soluble aluminum alloy according to any one of claims 1 to 5, characterized in that, The steps are as follows: All raw materials for the aluminum alloy as designed above are placed in a crucible and melted in a pit-type resistance furnace at 700~750℃. After all raw materials have melted, the mixture is allowed to stand for 15~20 minutes for slag removal and stirring, followed by refining. Then, the melt is subjected to electromagnetic treatment at 680~720℃: current 10~100A, frequency 5~50Hz, time 1~30min. After the electromagnetic treatment, the melt is immediately gravity-cast into a mold to obtain the corresponding ingot. The obtained ingot is then subjected to solution treatment at 350~470℃ for 0.5~6h. After the solution treatment, the ingot is immediately placed in tap water for cooling. The water-cooled ingot is then subjected to aging treatment at 90~180℃ for 6~48h to obtain the high-strength soluble aluminum alloy of this invention.

7. The method for preparing high-strength soluble aluminum alloy material according to claim 6, characterized in that, Alternatively, after obtaining the ingot, it can be subjected to homogenization and air cooling sequentially: the homogenization temperature is 330~450℃, and the time is 6~24h; then, the air-cooled ingot is subjected to hot extrusion, wherein the preheating temperature of the obtained ingot, extrusion die, and extrusion cylinder is the same as the extrusion temperature, the sample preheating time is 1.5~2.0h, the extrusion die and extrusion cylinder preheating time is 4~6h, the extrusion temperature is 350~440℃, the extrusion ratio is 4:1~9:1, and the bar obtained after extrusion is immediately placed in tap water for cooling and solution treatment: the solution treatment temperature is 350~470℃, and the time is 0.5~6h; immediately after solution treatment, it is placed in tap water for cooling: the aging temperature is 90~180℃, and the aging time is 6~48h.

8. Using the aluminum alloy of any one of claims 1 to 5, or the aluminum alloy obtained by the preparation method of claim 6 or 7, in unconventional shale oil and gas extraction tools, wherein the extraction tools are fracturing balls, ball seats, or bridge plugs.

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