High-strength magnesium alloy dissolvable bridge plug material and preparation method thereof

Abstract

The application provides a high-strength magnesium alloy soluble bridge plug material and a preparation method thereof. a Al b Zn c Ni d X e ; wherein the X is graphene GNP or nanometer carbon tube CNT; a, b, c, d and e respectively represent the mass fraction of each element, the range of b is 3-9%, the range of c is 0.7-1%, the range of d is 0.01-0.3%, the range of e is 0.05-2.5%, and a+b+c+d+e=100%. After ball milling, powder metallurgy, heat treatment and aging treatment, the required alloy material is obtained. The finished product of the material has high strength, contains trace carbon, forms a carbon-metal primary cell, can realize faster dissolution in an electrolyte, and the downhole tool prepared by using the material can be dissolved automatically after service, so that subsequent flowback, drilling and milling processes are omitted, construction efficiency is improved, cost is saved, and energy consumption is reduced.

Description

Technical Field

[0001] The present invention relates to the preparation of magnesium alloy materials in the field of metal materials, in particular to a high-strength magnesium alloy soluble bridge plug material and a preparation method thereof. Background Art

[0002] In recent years, the development of unconventional energy sources such as tight gas, tight oil, and shale gas has received increasing attention. Staged fracturing technology for horizontal wells has been widely used, leading to the large-scale adoption of drillable bridge plugs and large-diameter bridge plugs. However, conventional tools require secondary drill pipe removal, a time-consuming, costly, and energy-intensive process. Consequently, self-dissolving materials and tools are gaining increasing popularity in energy extraction.

[0003] Magnesium alloys offer a range of advantages, including low density, high specific strength, high specific stiffness, excellent electromagnetic shielding, machinability, and ease of recycling. They are widely used in aerospace, marine, automotive, and electronics industries. Furthermore, magnesium alloys have low electrode potentials, are chemically active, and are susceptible to corrosion in most solutions. This characteristic makes them suitable for the manufacture of fracturing and isolation tools used in oil and gas production. While commercial magnesium alloys typically have excellent mechanical properties, they dissolve slowly and cannot be used directly as soluble materials. Therefore, alloy designs based on traditional magnesium alloys are necessary.

[0004] However, existing soluble magnesium alloys primarily improve their solubility by forming corrosion electrodes with elements such as Cu, Ni, and Fe. The relatively small electrode potential difference between these elements and Mg results in a low corrosion rate for these soluble magnesium alloys, as well as low strength, which cannot meet the practical needs of oil and gas production tools. A magnesium alloy with both high strength and a high corrosion rate is needed to meet the demands of the oil and gas industry. Summary of the Invention

[0005] In light of this, the present invention aims to provide a high-strength magnesium alloy soluble bridge plug material and its preparation method, ensuring excellent mechanical properties and rapid dissolution in solutions with low electrolyte content. The magnesium alloy material produced using the method described herein exhibits high strength and rapid dissolution, and can be widely used in the production of downhole fracturing tool components, such as fracturing balls, ball seats, packers, and bridge plugs.

[0006] The object of the present invention is achieved through the following technical solutions:

[0007] <First Aspect>

[0008] A high-strength magnesium alloy soluble bridge plug material, the soluble bridge plug material is composed of: Mg a Al b Znc Ni d X e ; Wherein, X is graphene GNP or carbon nanotube CNT; a, b, c, d, e represent the mass fraction of each element, b ranges from 3-9%, c ranges from 0.7-1%, d ranges from 0.01-0.3%, e ranges from 0.05-2.5%, a+b+c+d+e=100%.

[0009] The mass ratio of X to Ni is 5:1-1:10.

[0010] <Second Aspect>

[0011] A method for preparing the high-strength magnesium alloy soluble bridge plug material according to claim 1, comprising the following steps:

[0012] S1. Preparation of nickel / X composite powder: After X is activated, it is added to a nickel-containing solution and stirred evenly, and then sodium hypophosphite is added. The mixture is further stirred, filtered, and dried to obtain a nickel / X composite powder;

[0013] S2. Ball milling: Calculate and weigh the raw materials according to the predetermined alloy composition and perform ball milling, wherein Ni and X are added in the form of nickel / X composite powder;

[0014] S3, hot pressing and sintering: hot pressing and sintering the powder obtained by ball milling;

[0015] S4, hot extrusion: hot extruding the obtained sintered material at a certain temperature to obtain an alloy rod;

[0016] S5. Aging treatment: The alloy bars are aged at a certain temperature.

[0017] Step S1 specifically comprises: after activating X, adding it to a mixture of nickel chloride, ammonium chloride, sodium citrate and boric acid and stirring, adding sodium hypophosphite after uniformity, further stirring, filtering and drying to obtain nickel / X composite powder.

[0018] In step S2, the ball milling speed is 50-400 r / min, the ball-to-material ratio is 1:3-5:1, and the ball milling time is 0.5-8 h.

[0019] In step S3, the sintering temperature is 300-500° C., the sintering pressure is 7-12 MPa, and the sintering time is 0.5-4 h.

[0020] In step S3, hot pressing sintering is performed using a vacuum hot pressing furnace.

[0021] In step S4, the hot extrusion temperature is 300-500° C., and the hot extrusion ratio ranges from 10-30.

[0022] Step S5 is aging treatment, with a temperature range of 200-450° C. and a time of 20-50 hours.

[0023] The application of the high-strength magnesium alloy soluble bridge plug material in aerospace, ocean, automobile, and electronics also falls within the protection scope of the present invention.

[0024] The present inventors discovered that only a mass ratio of graphene (GNP) or carbon nanotubes (CNT) to nickel within the range of 5:1-1:10 can achieve good mechanical properties and a high dissolution rate. This is because the graphene (GNP) or carbon nanotubes (CNT) provide mechanical reinforcement and form a galvanic cell, while nickel forms a good interface between the graphene (GNP) or carbon nanotubes (CNT) and major elements such as Mg and Al. The synergistic effect of the two can achieve the effects of improving mechanical properties and dissolution rate.

[0025] If the content of graphene (GNP) or carbon nanotube (CNT) is too high, there is a problem of non-wetting with the main elements, and thus the interface conduction function of the load and the electrochemical effect of the primary battery cannot be exerted.

[0026] The content of graphene (GNP) or carbon nanotube (CNT) is too low, and the graphene (GNP) or carbon nanotube (CNT) reinforcement and interface effect are not obvious, so the role of graphene (GNP) or carbon nanotube (CNT) cannot be played.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. Since graphene (GNP) or carbon nanotubes (CNT) with high modulus and mechanical properties are used as the reinforcement phase and the Ni layer is used as the interface transition, the composite material of the present invention has high mechanical strength and good plasticity;

[0029] 2. At the same time, because graphene (GNP) or carbon nanotubes (CNT) have a large specific surface area, they can form a large number of primary cells. The strong electrochemical effect can make the material dissolve quickly in the salt solution, which is easy to mass-produce. It is suitable for processing plugging tools used in the fracturing process of oil and gas fields. The tools can dissolve by themselves after the service is completed, eliminating the subsequent flowback and milling processes and improving the application efficiency.

[0030] 3. The purpose of adding graphene (GNP) or carbon nanotubes (CNT) in the present invention is to utilize the high specific area of ​​graphene (GNP) or carbon nanotubes (CNT) to form a good load transfer effect. At the same time, the high specific area of ​​graphene (GNP) or carbon nanotubes (CNT) enables the reinforcement phase to still form a large number of Mg / GNP and Mg / CNT interfaces and galvanic cells at a lower content, thereby solving the problems of low mechanics and low dissolution rate of the composite material.

[0031] 4. The addition of Ni in the present invention is different from the role of Ni in traditional magnesium alloys. In the present invention, Ni is coated on the surface of graphene (GNP) or carbon nanotubes (CNT). The Ni layer can not only serve as a reinforcing element in the traditional sense, but also serves as an interface transition layer between graphene (GNP) or carbon nanotubes (CNT), Mg, Al and other major elements, thereby solving the interface bonding problem between graphene (GNP) or carbon nanotubes (CNT) and elements such as Mg and Al.

[0032] 5. The magnesium alloy material prepared using the composition and process described in the present invention has high strength as the finished product and contains trace amounts of carbon, forming a carbon-metal primary cell, which can achieve faster dissolution in the electrolyte. It is suitable for processing and preparing soluble downhole tools used in the fracturing process of oil and gas fields. The downhole tools prepared using this material can dissolve by themselves after the service ends, eliminating subsequent backflow, drilling and milling processes, greatly improving construction efficiency, saving construction costs, and reducing energy consumption. DETAILED DESCRIPTION

[0033] The present invention will be described in detail below with reference to the examples. The following examples will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that those skilled in the art may make several adjustments and improvements without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0034] In the following examples and comparative examples:

[0035] The tensile strength (MPa), yield strength (MPa), elongation (%), corrosion rate (mg / cm 2 / h) for testing.

[0036] The tensile strength (MPa), yield strength (MPa) and elongation (%) were tested according to the GB / T228-09 metal room temperature tensile test method.

[0037] Corrosion rate (mg / cm 2 The alloy samples were characterized using a weight loss test (weight loss / h): 10*10*3 mm alloy samples were cut using wire cutting, polished, cleaned with anhydrous ethanol, and blown dry. Finally, the samples were weighed using an analytical balance (1 / 10,000). The weighed samples were immersed in a 3 wt% NaCl solution for 5 hours. The ratio of the solution volume to the surface area of ​​the immersed sample was 35 ml / cm. 2The corroded specimens were placed in a chromic acid solution to remove corrosion products from the sample surface. Finally, the samples were cleaned with alcohol, blown dry, and weighed again. Five parallel samples of each alloy were tested, and the average of the multiple measurements was used to calculate the corrosion rate of the alloy.

[0038] The preparation method of the nickel / GNP composite powder or nickel / CNT composite powder is as follows:

[0039] The GNPs or CNTs are activated and added to a mixture of nickel chloride, ammonium chloride, sodium citrate and boric acid, stirred until uniform, and sodium hypophosphite is added, followed by further stirring, filtering and drying to obtain nickel / GNP composite powder.

[0040] The specific steps of GNP or CNT activation are as follows: (1) Add GNP or CNT powder to 100 g / L sodium hydroxide solution, stir for 30 minutes, and then wash with deionized water until neutral to remove oil from the surface. (2) Add the deoiled GNP or CNT powder to a beaker containing 15% HNO3 solution, stir the solution at 90°C for 60 minutes, and then wash with deionized water until neutral to roughen the surface. (3) Add the roughened GNP or CNT powder to 10 g / L SnCl2 solution, stir at room temperature for 10 minutes, and then wash with deionized water until neutral to sensitize the surface. (4) Add the sensitized GNP or CNT powder to 0.02 g / L PbCl2 solution, stir at room temperature for 10 minutes, and then wash with deionized water until neutral to obtain activated GNP or CNT powder.

[0041] Example 1

[0042] Mg-4Al-0.9Zn-0.1Ni-0.6GNP alloy

[0043] The desired amount of GNPs was weighed, dispersed, activated, and then added to a mixture of nickel chloride, ammonium chloride, sodium citrate, and boric acid, stirring until uniform. Sodium hypophosphite was added, stirred further, filtered, and dried to obtain a nickel / GNP composite powder. Other alloying materials, such as Mg and Al, were weighed and added to a ball mill. Milling balls were added at a 1:1 ratio of balls to material, and the mill was milled under Ar protection at a speed of 50 r / min for 8 hours. After milling, the resulting powder was formed into a blank under protective atmosphere and transferred to a vacuum hot press furnace. The sintering pressure was 10 MPa, the sintering temperature was 300°C, and the sintering time was 2 hours. The sintered material was processed into cylinders and extruded at a temperature of 350°C, a speed of 5 mm / s, and an extrusion ratio of 10. After extrusion, the rods were aged at 200°C for 48 hours.

[0044] The Mg-4Al-0.9Zn-0.1Ni-0.6GNP alloy obtained by the above steps has a room temperature tensile strength of 359 MPa, a yield strength of 304 MPa, and an elongation of 10.2%. The corrosion rate in 3% KCl solution at 93°C is about 63 mg / cm 2 / h.

[0045] Example 2

[0046] Mg-3Al-1Zn-0.01Ni-0.1CNT alloy

[0047] The desired amount of CNT powder was weighed and dispersed, activated, and then added to a mixture of nickel chloride, ammonium chloride, sodium citrate, and boric acid, stirring until uniform. Sodium hypophosphite was added, stirred further, filtered, and dried to obtain a nickel / CNT composite powder. Other alloying materials, such as Mg and Al, were weighed and added to a ball mill. Milling balls were added at a 5:1 ratio of balls to material, and Ar was applied to the mill at a speed of 400 rpm for 8 hours. After milling, the resulting powder was formed into a blank under a protective atmosphere and transferred to a vacuum hot press furnace. The sintering pressure was 12 MPa, the sintering temperature was 400°C, and the sintering time was 4 hours. The sintered material was processed into cylinders and extruded at a temperature of 500°C, a speed of 1 mm / s, and an extrusion ratio of 30. After extrusion, the rods were aged at 350°C for 25 hours.

[0048] The Mg-3Al-1Zn-0.01Ni-0.1X alloy obtained by the above steps has a room temperature tensile strength of 392 MPa, a yield strength of 348 MPa, and an elongation of 7.78%. At 93°C, the corrosion rate in 3% KCl solution is about 78 mg / cm 2 / h.

[0049] Example 3

[0050] Mg-9Al-0.7Zn-0.3Mn-0.05GNP alloy

[0051] The desired amount of GNPs was weighed, dispersed, and activated, then added to a mixture of nickel chloride, ammonium chloride, sodium citrate, and boric acid, stirred. Sodium hypophosphite was added after uniform mixing, and further stirring, filtration, and drying were performed to obtain a nickel / GNP composite powder. Other alloying materials, such as Mg and Al, were weighed and added to a ball mill. Milling balls were added at a 1:3 ratio of balls to material, and the mill was operated under a gas shield at a speed of 300 rpm for 4 hours. After milling, the resulting powder was formed into a blank under a protective atmosphere and transferred to a vacuum hot press furnace at a sintering pressure of 10 MPa, a sintering temperature of 500°C, and a sintering time of 0.5 hours. The sintered material was processed into cylinders and extruded at a temperature of 340°C, a speed of 2 mm / s, and an extrusion ratio of 20. After extrusion, the rods were aged at 450°C for 36 hours.

[0052] The Mg-9Al-0.7Zn-0.3Mn-0.05GNP alloy obtained by the above steps has a room temperature tensile strength of 378MPa, a yield strength of 333MPa, and an elongation of 11.78%. The corrosion rate in 3% KCl solution at 93°C is about 69mg / cm 2 / h.

[0053] Comparative Example 1

[0054] Mg-4Al-0.9Zn-0.1Ni-0.6 graphite alloy

[0055] The difference between this comparative example and Example 1 is that GNPs are replaced by graphite powder.

[0056] The Mg-4Al-0.9Zn-0.1Ni-0.6 graphite alloy obtained by the above steps has a room temperature tensile strength of 215 MPa, a yield strength of 128 MPa, and an elongation of 3.4%. At 93°C, the corrosion rate in 3% KCl solution is about 47 mg / cm 2 / h.

[0057] Comparative Example 2

[0058] Mg-3Al-1Zn-0.01Ni-1 CNT alloy

[0059] The difference between this comparative example and Example 2 is that the CNT content is increased and the mass ratio of Ni to X is 1:100.

[0060] The Mg-3Al-1Zn-0.01Ni-1 CNT alloy obtained by the above steps has a room temperature tensile strength of 185 MPa, a yield strength of 98 MPa, and an elongation of 4.22%. The corrosion rate in 3% KCl solution at 93°C is about 54 mg / cm 2 / h.

[0061] Comparative Example 3

[0062] Mg-9Al-0.7Zn-0.3Mn-0.05GNP alloy

[0063] The difference between this comparative example and Example 3 is that the aging treatment time is adjusted from 25 hours to 55 hours.

[0064] The Mg-9Al-0.7Zn-0.3Mn-0.05GNP alloy obtained by the above steps has a room temperature tensile strength of 202 MPa, a yield strength of 135 MPa, and an elongation of 5.36%. The corrosion rate in 3% KCl solution at 93°C is about 49 mg / cm 2 / h.

[0065] Comparative Example 4

[0066] Mg-9Al-0.7Zn-0.3Mn-0.05GNP alloy

[0067] The difference between this comparative example and Example 3 is that the aging treatment temperature is adjusted from 450°C to 150°C.

[0068] The Mg-9Al-0.7Zn-0.3Mn-0.05GNP gold obtained by the above steps has a room temperature tensile strength of 216MPa, a yield strength of 147MPa, and an elongation of 4.74%. At 93°C, the corrosion rate in 3% KCl solution is about 58mg / cm 2 / h.

[0069] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various variations or modifications within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A high-strength magnesium alloy soluble bridge plug material, characterized in that: The magnesium alloy soluble bridge plug material is composed of: Mg a Al b Zn c Ni d X e ; Wherein, X is graphene GNP or carbon nanotube CNT; a, b, c, d, e represent the mass fraction of each element, b ranges from 3-9%, c ranges from 0.7-1%, d ranges from 0.01-0.3%, e ranges from 0.05-2.5%, a+b+c+d+e=100%; The mass ratio of X to Ni is 5:1-1:10; The high-strength magnesium alloy soluble bridge plug material is prepared by a method comprising the following steps: S1. Preparation of nickel / X composite powder: After X is activated, it is added to a nickel-containing solution and stirred evenly, and then sodium hypophosphite is added. The mixture is further stirred, filtered, and dried to obtain a nickel / X composite powder; S2. Ball milling: Calculate and weigh the raw materials according to the predetermined alloy composition and perform ball milling, wherein Ni and X are added in the form of nickel / X composite powder; S3, hot pressing and sintering: hot pressing and sintering the powder obtained by ball milling; S4, hot extrusion: hot extruding the obtained sintered material at a certain temperature to obtain an alloy rod; S5, aging treatment: The alloy bar is subjected to aging treatment at a certain temperature; the aging treatment in step S5 has a temperature range of 200-450° C. and a time of 20-50 hours.

2. The high-strength magnesium alloy soluble bridge plug material according to claim 1, characterized in that: Step S1 specifically comprises: after activating X, adding it to a mixture of nickel chloride, ammonium chloride, sodium citrate and boric acid and stirring, adding sodium hypophosphite after uniformity, further stirring, filtering and drying to obtain nickel / X composite powder.

3. The high-strength magnesium alloy soluble bridge plug material according to claim 1, characterized in that: In step S2, the ball milling speed is 50-400 r / min, the ball-to-material ratio is 1:3-5:1, and the ball milling time is 0.5-8 h.

4. The high-strength magnesium alloy soluble bridge plug material according to claim 1, characterized in that: In step S3, the sintering temperature is 300-500° C., the sintering pressure is 7-12 MPa, and the sintering time is 0.5-4 h.

5. The high-strength magnesium alloy soluble bridge plug material according to claim 1, characterized in that: In step S3, hot pressing sintering is performed using a vacuum hot pressing furnace.

6. The high-strength magnesium alloy soluble bridge plug material according to claim 1, characterized in that: In step S4, the hot extrusion temperature is 300-500° C., and the hot extrusion ratio ranges from 10-30.

7. Use of the high-strength magnesium alloy soluble bridge plug material according to any one of claims 1 to 6 in the fields of aerospace, ocean, automobile, and electronics.