A corrosion and scale inhibition proppant and preparation method thereof

Abstract

The present invention belongs to the field of petroleum and natural gas engineering fracturing technology, specifically relating to a corrosion- and scale-inhibiting proppant and its preparation method. The proppant comprises a spherical skeleton with through-holes and a solid corrosion- and scale-inhibiting agent. The solid corrosion- and scale-inhibiting agent is filled in the through-holes and forms a corrosion- and scale-inhibiting coating on the surface of the spherical skeleton. The fracturing proppant prepared by the present invention has a breakage rate of less than 6% at a temperature of 80°C and a closure pressure of 35 MPa, and simultaneously performs the functions of corrosion inhibition, scale inhibition, and propping up formation fractures.

Description

Technical Field

[0001] The invention belongs to the technical field of petroleum and natural gas engineering fracturing, and particularly relates to a corrosion and scale inhibition proppant and a preparation method thereof. Background Art

[0002] Hydraulic fracturing is a key method for increasing oil and gas production during field development. This technology involves injecting a fracturing fluid loaded with proppants into the fractures created by the fracturing process. The proppants then fill the fractures, creating stable pathways for oil and gas flow. However, when fresh water or other media carried by the fracturing fluid enter the proppant layer, high concentrations of dissolved substances or incompatibility with the formation water can easily cause salt deposition, reducing the proppant's conductivity. Scale inhibitors injected into the wellbore only reach the vertical sections, failing to reach the horizontal sections where the proppant is laid. Furthermore, wellbores are often exposed to corrosion and scaling risks due to produced acidic gases and highly saline formation water. Acidic gases (H2S and CO2) chemically corrode downhole tubing and equipment, while highly saline formation water can easily cause scaling on the wellbore's inner walls. This can further lead to under-scale corrosion, severely reducing recovery efficiency and even causing wellbore equipment failure, forcing production to cease. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to overcome the shortcomings of the existing technology and, through technological innovation, provide a corrosion-inhibiting and scale-inhibiting proppant and a preparation method thereof, which can simultaneously solve the problems of easy scaling of the proppant laying layer and corrosion scaling of the wellbore, and can effectively reduce manpower and material costs.

[0004] In order to solve the technical problem, the technical solution of the present invention is:

[0005] The first technical purpose of the present invention is to provide a corrosion and scale inhibition proppant, which comprises a spherical skeleton with through holes and a solid corrosion and scale inhibition agent; wherein,

[0006] The spherical skeleton with through holes is a ceramic particle, and the outer radius R of the spherical skeleton with through holes is 212.5-850 μm, and the inner radius r is 64-425 μm;

[0007] The solid corrosion and scale inhibitor is filled in the through hole and forms a corrosion and scale inhibitor coating with a thickness of δ of 20 to 80 μm on the surface of the spherical skeleton;

[0008] The particle size D of the corrosion and scale inhibition proppant is 465-1860 μm, and the relationship among the particle size D, the outer radius R of the spherical skeleton, the inner radius r of the spherical skeleton, and the thickness δ of the corrosion and scale inhibition coating is r=(0.3-0.5)R, and D=2(R+δ).

[0009] It should be noted that the proppant particle size D range is the most common specification for oilfield fracturing proppants based on the sieve mesh size in standard Q / SY 17125-2009; r = (0.3~0.5) The design purpose of R is to allow the spherical skeleton with through holes to retain compressive strength while the through holes can load more corrosion and scale inhibitors.

[0010] Optionally, the spherical skeleton with through holes comprises raw material components in the following proportions:

[0011] Al2O3 powder 60~80wt%, MgO powder 3~14wt%, Fe2O3 powder 1~10%, TiO2 powder 1~8wt%, CaCO3 powder 2~8wt%, SiO2 powder 3~7wt%.

[0012] Optionally, the solid corrosion and scale inhibitor comprises raw material components in the following proportions:

[0013] Adsorption material 40~50wt%, corrosion and scale inhibitor 20~40wt%, resin 20~35wt%, antioxidant 0.1~1.0wt%.

[0014] Furthermore, the particle size of the Al2O3 powder is 1~10μm; the particle size of the MgO powder is 1~5μm; the particle size of the Fe2O3 powder is 1~5μm; the particle size of the TiO2 powder is 0.5~2μm; the particle size of the CaCO3 powder is 1~8μm; and the particle size of the SiO2 powder is 1~10μm.

[0015] Furthermore, the adsorption material is selected from any one of diatomaceous earth, kaolin, carboxymethyl cellulose, corn starch, and wheat starch; the corrosion and scale inhibitor is selected from any one of polyaspartic acid and polyepoxysuccinic acid; the resin is selected from any one of epoxy resin and phenolic resin; and the antioxidant is selected from bisphenol A phosphite.

[0016] The second technical purpose of the present invention is to provide a method for preparing the corrosion and scale inhibition proppant as described above, comprising the following steps:

[0017] Step 1: Add Al2O3 powder, MgO powder, Fe2O3 powder, TiO2 powder, CaCO3 powder, and SiO2 powder in a ball mill according to a certain proportion and mill for 24 hours to obtain a spherical skeleton powder. Place the spherical skeleton powder in a blender, add a binder, and stir to obtain a uniform mixture.

[0018] Step 2: The uniform mixture obtained in step 1 is placed in a spherical shell mold with a central cylindrical core and pressed to obtain spherical skeleton particles with through holes, and the spherical skeleton particles with through holes are placed in a drying oven and dried for 2 hours;

[0019] Step 3: Place the spherical skeleton particles with through holes after drying in step 2 into an electric furnace and sinter at 1200-1400° C. for 1-2 hours to obtain a spherical skeleton with through holes, and cool it for later use;

[0020] Step 4: The adsorbent material and the corrosion and scale inhibitor are mixed uniformly in a stirred tank according to a proportion to obtain a mixture A, and then the resin and the antioxidant are added to the mixture A and mixed uniformly to obtain a mixture B;

[0021] Step 5: Heat the mixture B in step 4 in a reactor until it is molten at a temperature of 120-140°C;

[0022] Step 6: Add a curing agent to the molten state in step 5 and mix well to obtain a mixture C;

[0023] Step 7: Immerse the spherical skeleton with through holes obtained in step 3 in a coupling agent and then fish it out. Then, evenly spread it in a flat mold with multiple spherical pits, ensuring that each proppant skeleton falls into a spherical pit. Then, evenly pour the mixture C obtained in step 6 onto the flat mold, ensuring that the mixture C completely fills each spherical pit. After naturally cooling at room temperature until completely solidified, demold the finished product, which is the corrosion and scale inhibition proppant.

[0024] Optionally, in step 1, the mass ratio of the Al2O3 powder, MgO powder, Fe2O3 powder, TiO2 powder, CaCO3 powder and SiO2 powder is (60~80):(3~14):(1~10):(1~8):(2~8):(3~7).

[0025] Optionally, in step 1, the binder is polyvinyl alcohol, and the amount of the binder added is 4-6% of the mass of the spherical skeleton powder.

[0026] Optionally, in step 2, the cylindrical radius of the central cylindrical core is 64-425 μm, and the radius of the spherical shell mold is 212.5-850 μm.

[0027] Optionally, in step 4, the mass ratio of the adsorption material, corrosion and scale inhibitor, resin and antioxidant is (40-50): (20-40): (20-35): (0.1-1.0).

[0028] Optionally, in step 6, the curing agent is any one of ethylenediamine, diethylenetriamine, and triethylenetetramine, and the added amount of the curing agent is 5-20% of the mass of the resin.

[0029] Optionally, in step 7, the coupling agent is a silane-silane coupling agent; the silane-silane coupling agent is any one of γ-glycidyloxypropyltrimethoxysilane, γ-methacryloyloxyethoxysilane, and vinyltriethoxysilane; and the radius of the spherical pit in the flat mold is 232.5~930 μm.

[0030] Compared with the prior art, the advantages of the present invention are:

[0031] 1) The corrosion-inhibiting and scale-inhibiting proppant disclosed in the present invention comprises a spherical skeleton with through holes and a solid corrosion-inhibiting and scale-inhibiting agent. The solid corrosion-inhibiting and scale-inhibiting agent is filled in the through holes and forms a corrosion-inhibiting and scale-inhibiting coating on the surface of the spherical skeleton, which can effectively prevent the deposition of salt scale on the proppant paving layer. The design of the spherical skeleton with through holes can significantly increase the load capacity compared with the traditional surface coating method, and the skeleton can protect the solid corrosion-inhibiting and scale-inhibiting agent in the through holes, thereby overcoming the risk of losing the corrosion-inhibiting and scale-inhibiting performance after the surface coating falls off, so that the active ingredients can be released continuously and stably, and the action period is significantly extended. When the solid corrosion-inhibiting and scale-inhibiting agent in the subsequent through holes fully exerts its performance and degrades, the remaining spherical skeleton with through holes has an open channel structure, and its conductivity is significantly better than that of the traditional solid proppant, thereby realizing the secondary utilization value of enhanced conductivity performance.

[0032] 2) The solid corrosion and scale inhibitor in the present invention forms a corrosion and scale inhibitor coating on the surface of the spherical skeleton, which can effectively reduce the breakage rate of the proppant; the solid corrosion and scale inhibitor coating on the surface of the proppant can prevent the spherical skeleton from directly contacting the inner wall of the pipeline, and can effectively reduce the erosion and wear of the pipeline equipment; bisphenol A phosphite can prevent the thermal decomposition reaction and oxidation reaction of epoxy resin and phenolic resin caused by changes in ambient temperature, changes in light and contact with air, and effectively improve the stability of epoxy resin and phenolic resin in high temperature and high pressure environment; polyaspartic acid or polyepoxysuccinic acid has good biodegradability and will not cause pollution to water bodies, soil and other environments. At the same time, the preparation process is simple, the cost is low and it has a high cost performance.

[0033] 3) The silane coupling agent in the present invention has two groups with different properties, one forming a covalent bond with SiO2 in the spherical skeleton with through holes, and the other undergoing copolymerization reaction with the resin, which can significantly enhance the bonding strength between the spherical skeleton and the solid corrosion and scale inhibitor.

[0034] 4) The proppant disclosed in the present invention has three functions: corrosion inhibition, scale inhibition, and support for formation fractures. After injecting it into the formation, the subsequent process of adding corrosion and scale inhibitors can be omitted, effectively reducing time and economic costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0036] Figure 1 It is a two-dimensional longitudinal cross-section of the corrosion and scale inhibition proppant of the present invention.

[0037] Figure 2 This is a three-dimensional diagram of a longitudinal section of 1 / 2 of the corrosion and scale inhibition proppant of the present invention.

[0038] Figure 3 It is a two-dimensional cross-sectional view of the corrosion and scale inhibition proppant of the present invention.

[0039] Figure 4 This is a three-dimensional diagram of a horizontal cross-section of 1 / 2 of the corrosion and scale inhibition proppant of the present invention.

[0040] Figure 5 This is a three-dimensional diagram of a 1 / 4 transverse section of the corrosion and scale inhibition proppant of the present invention. DETAILED DESCRIPTION

[0041] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0042] The term "embodiment" is used herein specifically to describe any embodiment as "exemplary," and should not be construed as superior or preferable to other embodiments. Performance indicators in the embodiments of this application were tested using conventional testing methods in the art, unless otherwise specified. It should be understood that the terms used in this application are intended solely to describe specific implementations and are not intended to limit the disclosure herein.

[0043] Unless otherwise specified, the technical and scientific terms used herein have the same meanings as commonly understood by ordinary technicians in the technical field to which this application belongs; other experimental methods and technical means not specifically specified in this application refer to experimental methods and technical means commonly used by ordinary technicians in this field.

[0044] In order to better illustrate the content of the present application, numerous specific details are provided in the specific examples below. It should be understood by those skilled in the art that without certain specific details, the present application can be implemented equally. In the embodiments, some methods, means, instruments, equipment etc. well known to those skilled in the art are not described in detail, so as to highlight the purport of the present application. Under the premise of not conflicting, the technical features disclosed in the embodiments of the present application can be combined in any way, and the technical scheme obtained belongs to the content disclosed in the embodiments of the present application.

[0045] The invention discloses a corrosion and scale inhibition proppant and a preparation method thereof.

[0046] For a better understanding of the present invention, the present invention is further specifically described below through the following examples, but it should not be understood as limiting the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above invention content are also considered to fall within the scope of protection of the present invention.

[0047] Example 1

[0048] A method for preparing a corrosion and scale inhibition proppant comprises the following steps:

[0049] Step 1: Add Al2O3 powder, MgO powder, Fe2O3 powder, TiO2 powder, CaCO3 powder, and SiO2 powder in a ball mill according to a certain proportion and mill for 24 hours to obtain a spherical skeleton powder. Place the spherical skeleton powder in a blender, add a binder, and stir to obtain a uniform mixture.

[0050] Step 2: The uniform mixture obtained in step 1 is placed in a spherical shell mold with a central cylindrical core and pressed to obtain spherical skeleton particles with through holes, and the spherical skeleton particles with through holes are placed in a drying oven and dried for 2 hours;

[0051] Step 3: Place the spherical skeleton particles with through holes after drying in step 2 into an electric furnace and sinter at 1400° C. for 2 hours to obtain a spherical skeleton with through holes, and cool it for later use;

[0052] Step 4: The adsorbent material and the corrosion and scale inhibitor are mixed uniformly in a stirred tank according to a proportion to obtain a mixture A, and then the resin and the antioxidant are added to the mixture A and mixed uniformly to obtain a mixture B;

[0053] Step 5: heating the mixture B in step 4 to a molten state in a reactor at a heating temperature of 140°C;

[0054] Step 6: Add a curing agent to the molten state in step 5 and mix well to obtain a mixture C;

[0055] Step 7: Immerse the spherical skeleton with through holes obtained in step 3 in a coupling agent and then fish it out. Then, evenly spread it in a flat mold with multiple spherical pits, ensuring that each proppant skeleton falls into a spherical pit. Then, evenly pour the mixture C obtained in step 6 onto the flat mold, ensuring that the mixture C completely fills each spherical pit. After naturally cooling at room temperature until completely solidified, demold the finished product, which is the corrosion and scale inhibition proppant.

[0056] The masses of the Al2O3 powder, MgO powder, Fe2O3 powder, TiO2 powder, CaCO3 powder and SiO2 powder are 65g, 10g, 8g, 6g, 6g and 5g respectively. The particle size of the Al2O3 powder is 1~10μm; the particle size of the MgO powder is 1~5μm; the particle size of the Fe2O3 powder is 1~5μm; the particle size of the TiO2 powder is 0.5~2μm; the particle size of the CaCO3 powder is 1~8μm; and the particle size of the SiO2 powder is 1~10μm.

[0057] The binder is polyvinyl alcohol, and the amount of the binder is 5g.

[0058] The cylindrical radius of the central cylindrical core is 180 μm, and the radius of the spherical shell mold is 450 μm.

[0059] The adsorption material, corrosion and scale inhibitor, resin, and antioxidant are diatomaceous earth, polyaspartic acid, epoxy resin, and bisphenol A phosphite, respectively, and the masses of the adsorption material, corrosion and scale inhibitor, resin, and antioxidant are 40g, 30g, 29.7g, and 0.3g, respectively.

[0060] The curing agent is ethylenediamine, and the amount of the curing agent is 6g.

[0061] The coupling agent is a silane-silane coupling agent; the silane-silane coupling agent is γ-glycidyloxypropyltrimethoxysilane.

[0062] The radius of the spherical pits of the flat plate mold is 520 μm.

[0063] The corrosion and scale inhibition proppant obtained according to the above scheme has a solid corrosion and scale inhibition loading rate of 30.2%.

[0064] Example 2

[0065] A method for preparing a corrosion and scale inhibition proppant comprises the following steps:

[0066] Step 1: Add Al2O3 powder, MgO powder, Fe2O3 powder, TiO2 powder, CaCO3 powder, and SiO2 powder in a ball mill according to a certain proportion and mill for 24 hours to obtain a spherical skeleton powder. Place the spherical skeleton powder in a blender, add a binder, and stir to obtain a uniform mixture.

[0067] Step 2: The uniform mixture obtained in step 1 is placed in a spherical shell mold with a central cylindrical core and pressed to obtain spherical skeleton particles with through holes, and the spherical skeleton particles with through holes are placed in a drying oven and dried for 2 hours;

[0068] Step 3: Place the spherical skeleton particles with through holes after drying in step 2 into an electric furnace and sinter at 1400° C. for 2 hours to obtain a spherical skeleton with through holes, and cool it for later use;

[0069] Step 4: The adsorbent material and the corrosion and scale inhibitor are mixed uniformly in a stirred tank according to a proportion to obtain a mixture A, and then the resin and the antioxidant are added to the mixture A and mixed uniformly to obtain a mixture B;

[0070] Step 5: heating the mixture B in step 4 to a molten state in a reactor at a heating temperature of 140°C;

[0071] Step 6: Add a curing agent to the molten state in step 5 and mix well to obtain a mixture C;

[0072] Step 7: Immerse the spherical skeleton with through holes obtained in step 3 in a coupling agent and then fish it out. Then, evenly spread it in a flat mold with multiple spherical pits, ensuring that each proppant skeleton falls into a spherical pit. Then, evenly pour the mixture C obtained in step 6 onto the flat mold, ensuring that the mixture C completely fills each spherical pit. After naturally cooling at room temperature until completely solidified, demold the finished product, which is the corrosion and scale inhibition proppant.

[0073] The masses of the Al2O3 powder, MgO powder, Fe2O3 powder, TiO2 powder, CaCO3 powder and SiO2 powder are 70g, 5g, 8g, 6g, 6g and 5g respectively. The particle size of the Al2O3 powder is 1~10μm; the particle size of the MgO powder is 1~5μm; the particle size of the Fe2O3 powder is 1~5μm; the particle size of the TiO2 powder is 0.5~2μm; the particle size of the CaCO3 powder is 1~8μm; and the particle size of the SiO2 powder is 1~10μm.

[0074] The binder is polyvinyl alcohol, and the amount of the binder is 5g.

[0075] The cylindrical radius of the central cylindrical core is 180 μm, and the radius of the spherical shell mold is 450 μm.

[0076] The adsorption material, corrosion and scale inhibitor, resin, and antioxidant are diatomaceous earth, polyaspartic acid, epoxy resin, and bisphenol A phosphite, respectively, and the masses of the adsorption material, corrosion and scale inhibitor, resin, and antioxidant are 40g, 30g, 29.7g, and 0.3g, respectively.

[0077] The curing agent is ethylenediamine, and the amount of the curing agent is 6g.

[0078] The coupling agent is a silane-silane coupling agent; the silane-silane coupling agent is γ-glycidyloxypropyltrimethoxysilane.

[0079] The radius of the spherical pit of the flat plate mold is 500 μm.

[0080] The corrosion and scale inhibition proppant obtained according to the above scheme has a solid corrosion and scale inhibition loading rate of 25.3%.

[0081] Example 3

[0082] A method for preparing a corrosion and scale inhibition proppant comprises the following steps:

[0083] Step 1: Add Al2O3 powder, MgO powder, Fe2O3 powder, TiO2 powder, CaCO3 powder, and SiO2 powder in a ball mill according to a certain proportion and mill for 24 hours to obtain a spherical skeleton powder. Place the spherical skeleton powder in a blender, add a binder, and stir to obtain a uniform mixture.

[0084] Step 2: The uniform mixture obtained in step 1 is placed in a spherical shell mold with a central cylindrical core and pressed to obtain spherical skeleton particles with through holes, and the spherical skeleton particles with through holes are placed in a drying oven and dried for 2 hours;

[0085] Step 3: Place the spherical skeleton particles with through holes after drying in step 2 into an electric furnace and sinter at 1400° C. for 2 hours to obtain a spherical skeleton with through holes, and cool it for later use;

[0086] Step 4: The adsorbent material and the corrosion and scale inhibitor are mixed uniformly in a stirred tank according to a proportion to obtain a mixture A, and then the resin and the antioxidant are added to the mixture A and mixed uniformly to obtain a mixture B;

[0087] Step 5: heating the mixture B in step 4 to a molten state in a reactor at a heating temperature of 140°C;

[0088] Step 6: Add a curing agent to the molten state in step 5 and mix well to obtain a mixture C;

[0089] Step 7: Immerse the spherical skeleton with through holes obtained in step 3 in a coupling agent and then fish it out. Then, evenly spread it in a flat mold with multiple spherical pits, ensuring that each proppant skeleton falls into a spherical pit. Then, evenly pour the mixture C obtained in step 6 onto the flat mold, ensuring that the mixture C completely fills each spherical pit. After naturally cooling at room temperature until completely solidified, demold the finished product, which is the corrosion and scale inhibition proppant.

[0090] The masses of the Al2O3 powder, MgO powder, Fe2O3 powder, TiO2 powder, CaCO3 powder and SiO2 powder are 65g, 10g, 8g, 6g, 6g and 5g respectively. The particle size of the Al2O3 powder is 1~10μm; the particle size of the MgO powder is 1~5μm; the particle size of the Fe2O3 powder is 1~5μm; the particle size of the TiO2 powder is 0.5~2μm; the particle size of the CaCO3 powder is 1~8μm; and the particle size of the SiO2 powder is 1~10μm.

[0091] The binder is polyvinyl alcohol, and the amount of the binder is 5g.

[0092] The cylindrical radius of the central cylindrical core is 135 μm, and the radius of the spherical shell mold is 450 μm.

[0093] The adsorption material, corrosion and scale inhibitor, resin, and antioxidant are diatomaceous earth, polyaspartic acid, epoxy resin, and bisphenol A phosphite, respectively, and the masses of the adsorption material, corrosion and scale inhibitor, resin, and antioxidant are 40g, 40g, 19.8g, and 0.2g, respectively.

[0094] The curing agent is ethylenediamine, and the amount of the curing agent is 4g.

[0095] The coupling agent is a silane-silane coupling agent; the silane-silane coupling agent is γ-glycidyloxypropyltrimethoxysilane.

[0096] The radius of the spherical pits of the flat plate mold is 520 μm.

[0097] The corrosion and scale inhibition proppant obtained according to the above scheme has a solid corrosion and scale inhibition loading rate of 24.7%.

[0098] Example 4

[0099] A method for preparing a corrosion and scale inhibition proppant comprises the following steps:

[0100] Step 1: Add Al2O3 powder, MgO powder, Fe2O3 powder, TiO2 powder, CaCO3 powder, and SiO2 powder in a ball mill according to a certain proportion and mill for 24 hours to obtain a spherical skeleton powder. Place the spherical skeleton powder in a blender, add a binder, and stir to obtain a uniform mixture.

[0101] Step 2: The uniform mixture obtained in step 1 is placed in a spherical shell mold with a central cylindrical core and pressed to obtain spherical skeleton particles with through holes, and the spherical skeleton particles with through holes are placed in a drying oven and dried for 2 hours;

[0102] Step 3: Place the spherical skeleton particles with through holes after drying in step 2 into an electric furnace and sinter at 1400° C. for 2 hours to obtain a spherical skeleton with through holes, and cool it for later use;

[0103] Step 4: The adsorbent material and the corrosion and scale inhibitor are mixed uniformly in a stirred tank according to a proportion to obtain a mixture A, and then the resin and the antioxidant are added to the mixture A and mixed uniformly to obtain a mixture B;

[0104] Step 5: heating the mixture B in step 4 to a molten state in a reactor at a heating temperature of 140°C;

[0105] Step 6: Add a curing agent to the molten state in step 5 and mix well to obtain a mixture C;

[0106] Step 7: Immerse the spherical skeleton with through holes obtained in step 3 in a coupling agent and then fish it out. Then, evenly spread it in a flat mold with multiple spherical pits, ensuring that each proppant skeleton falls into a spherical pit. Then, evenly pour the mixture C obtained in step 6 onto the flat mold, ensuring that the mixture C completely fills each spherical pit. After naturally cooling at room temperature until completely solidified, demold the finished product, which is the corrosion and scale inhibition proppant.

[0107] The masses of the Al2O3 powder, MgO powder, Fe2O3 powder, TiO2 powder, CaCO3 powder and SiO2 powder are 65g, 10g, 8g, 6g, 6g and 5g respectively. The particle size of the Al2O3 powder is 1~10μm; the particle size of the MgO powder is 1~5μm; the particle size of the Fe2O3 powder is 1~5μm; the particle size of the TiO2 powder is 0.5~2μm; the particle size of the CaCO3 powder is 1~8μm; and the particle size of the SiO2 powder is 1~10μm.

[0108] The binder is polyvinyl alcohol, and the amount of the binder is 5g.

[0109] The cylindrical radius of the central cylindrical core is 135 μm, and the radius of the spherical shell mold is 450 μm.

[0110] The adsorption material, corrosion inhibitor, resin and antioxidant are diatomaceous earth, polyaspartic acid, epoxy resin and bisphenol A phosphite, and the masses of the adsorption material, corrosion inhibitor, resin and antioxidant are 40g, 25g, 34.6g and 0.4g respectively.

[0111] The curing agent is ethylenediamine, and the amount of the curing agent is 7g.

[0112] The coupling agent is a silane-silane coupling agent; the silane-silane coupling agent is γ-glycidyloxypropyltrimethoxysilane.

[0113] The radius of the spherical pits of the flat plate mold is 520 μm.

[0114] The corrosion and scale inhibition proppant obtained according to the above scheme has a solid corrosion and scale inhibition loading rate of 19.7%.

[0115] Comparative Example 1

[0116] As described in Example 1, the difference is that the masses of the adsorption material, corrosion and scale inhibitor, resin, and antioxidant are 40g, 40g, 19.8g, and 0.2g respectively, and the curing agent is ethylenediamine, and the amount of curing agent is 4g.

[0117] Comparative Example 2

[0118] As described in Example 1. The difference is that the masses of the adsorbent material, corrosion and scale inhibitor, resin, and antioxidant are 40g, 25g, 34.6g, and 0.2g respectively, and the curing agent is ethylenediamine, and the amount of the curing agent is 7g.

[0119] To further demonstrate the beneficial effects of the present invention and to facilitate a better understanding of the present invention, the following conventional indicator data further illustrates the technical features disclosed in the present invention, but should not be construed as limiting the present invention. Other improvements made by those skilled in the art based on the above invention without inventive steps are also deemed to fall within the scope of protection of the present invention.

[0120] (1) Breakage rate test

[0121] According to SY / T 5108-2014 "Test Method for Proppant Performance for Hydraulic Fracturing and Gravel Packing Operations", the breakage rates of corrosion and scale inhibition proppants and spherical skeletons with through holes were tested at a temperature of 80°C and a closing pressure of 35 MPa. The test results are shown in Table 1.

[0122] (2) Conductivity test

[0123] According to SY / T 6302-2019 "Test method for conductivity of fracturing proppants", the corrosion and scale inhibition proppant and the spherical skeleton with through holes were tested at a temperature of 25°C and a proppant concentration of 10 kg / m 2 , the flow conductivity under the closing pressure of 35MPa, the test results are shown in Table 1.

[0124] Table 1 Breakage rate test results of Examples 1 to 4

[0125]

[0126] As can be seen from Table 1, the corrosion-inhibiting and scale-inhibiting proppants and spherical skeletons with through-holes produced by the fracturing proppant preparation method provided by the present invention meet the industry standard for quartz sand proppants at a pressure of 35 MPa. The corrosion-inhibiting and scale-inhibiting proppants have a lower crushing rate than the spherical skeletons with through-holes, while the spherical skeletons with through-holes have a higher conductivity than the corrosion-inhibiting and scale-inhibiting proppants. A comparison of the corrosion-inhibiting and scale-inhibiting proppants prepared in Examples 1 and 2, and 1 and 3, shows that the thicker the corrosion-inhibiting and scale-inhibiting coating on the spherical skeleton surface, the lower the crushing rate. While the outer radius R remains unchanged, the smaller the inner radius r, the stronger the proppant's crushing resistance. However, the conductivity of each example does not change significantly. The spherical skeletons with through-holes have a much higher conductivity than the corrosion-inhibiting and scale-inhibiting proppants, indicating that the conductivity of the remaining skeleton will be significantly improved after the solid corrosion-inhibiting and scale-inhibiting agent in the through-holes dissolves and falls off.

[0127] (3) Corrosion inhibition performance test

[0128] According to the national standard GB / 10124-88 "Laboratory uniform corrosion test method for metal materials" and the Chinese petroleum industry standard SY / T 5273-2014 "Performance index and evaluation method of corrosion inhibitor for oilfield produced water treatment" as reference standards, the corrosion inhibition rate of N80 steel with the corrosion and scale inhibition proppant prepared in Example 1 at 7d and 30d was tested. The test temperature was 80℃, the CO2 partial pressure was 2MPa, and the Cl - The concentration was 20,000 mg / L, and each liter of test solution contained 2 g of proppant. No proppant was added to the blank group.

[0129] (IV) Scale inhibition performance test

[0130] According to the standard Q / SY 126-2014 "Technical Specifications for Corrosion and Scale Inhibitors for Oilfield Water Treatment", the scale inhibition rate of the corrosion and scale inhibitor proppant prepared in Example 1 was tested at 7 days and 30 days. The test temperature was 80°C, and 2 g of proppant was contained in each liter of the test solution. No proppant was added to the blank group.

[0131] Table 2 Test results of corrosion inhibition rate and scale inhibition rate of Examples 1-4 and Comparative Examples 1-2

[0132]

[0133] Table 2 shows that the corrosion and scale inhibition proppant of the present invention exhibits excellent corrosion and scale inhibition performance at 80°C. Both the corrosion inhibition and scale inhibition rates are improved over the 30-day experimental period compared to the 7-day experimental period. Examples 1-4 show that the corrosion and scale inhibition rates of the corrosion and scale inhibition proppant decrease in sequence, indicating that the more solid corrosion and scale inhibitor loaded into the proppant, the better the corrosion and scale inhibition performance. A comparison of Example 1, Comparative Example 1, and Comparative Example 2 shows that a higher proportion of solid corrosion and scale inhibitor in the solid corrosion and scale inhibitor improves the performance.

[0134] (V) Erosion resistance test

[0135] The erosion depth of proppant on N80 steel was tested according to ASTM G76-18, "Standard Test Method for Conducting Erosion Tests by Solid Particle Impingement Using Gas Jets." The test conditions were an impact velocity of 20 m / s, an impact angle of 30°, a particle mass flow rate of 2 g / min, and a test duration of 20 minutes.

[0136] Table 3 Erosion depth test results of Examples 1-4 and Comparative Examples 1-2

[0137]

[0138] From the erosion depth results in Table 3, it can be seen that the erosion depth of the corrosion-inhibiting and scale-inhibiting proppant on N80 steel is greatly reduced compared with the spherical skeleton with through holes; from the comparison of the corrosion-inhibiting and scale-inhibiting proppant prepared in Example 1 and Example 2, and Example 1 and Comparative Example 1, it can be seen that the thicker the solid corrosion-inhibiting and scale-inhibiting coating layer on the surface, the lower the erosion damage to N80 steel, and the higher the resin content in the solid corrosion-inhibiting and scale-inhibiting agent, the lower the erosion damage to N80 steel.

[0139] The above test results show that the fracturing proppant prepared by the present invention has the functions of corrosion inhibition, scale inhibition and crack propping, which can effectively reduce the cost of oil and gas production, and significantly reduces the erosion damage to the pipe compared with ordinary ceramic proppants.

[0140] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A corrosion and scale inhibition proppant, characterized in that: The corrosion and scale inhibition proppant comprises a spherical skeleton with through holes and a solid corrosion and scale inhibition agent; The spherical skeleton with through holes is a ceramic particle, and the outer radius R of the spherical skeleton with through holes is 212.5-850 μm, and the inner radius r is 64-425 μm; The solid corrosion and scale inhibitor is filled in the through hole and forms a corrosion and scale inhibitor coating with a thickness of δ of 20 to 80 μm on the surface of the spherical skeleton; The particle size D of the corrosion and scale inhibition proppant is 465-1860 μm, and the relationship among the particle size D, the outer radius R of the spherical skeleton, the inner radius r of the spherical skeleton, and the thickness δ of the corrosion and scale inhibition coating is r=(0.3-0.5)R, and D=2(R+δ); The spherical skeleton with through holes comprises raw material components in the following proportions: Al2O3 powder 60~80wt%, MgO powder 3~14wt%, Fe2O3 powder 1~10%, TiO2 powder 1~8wt%, CaCO3 powder 2~8wt%, SiO2 powder 3~7wt%; The solid corrosion and scale inhibitor comprises raw material components in the following proportions: Adsorption material 40-50wt%, corrosion and scale inhibitor 20-40wt%, resin 20-35wt%, antioxidant 0.1-1.0wt%, the sum of the percentages of the raw material components is 100wt%.

2. The corrosion and scale inhibition proppant according to claim 1, characterized in that: The particle size of the Al2O3 powder is 1~10μm; the particle size of the MgO powder is 1~5μm; the particle size of the Fe2O3 powder is 1~5μm; the particle size of the TiO2 powder is 0.5~2μm; the particle size of the CaCO3 powder is 1~8μm; and the particle size of the SiO2 powder is 1~10μm.

3. The corrosion and scale inhibition proppant according to claim 1, characterized in that: The adsorption material is selected from any one of diatomaceous earth, kaolin, carboxymethyl cellulose, corn starch, and wheat starch; the corrosion and scale inhibitor is selected from any one of polyaspartic acid and polyepoxysuccinic acid; the resin is selected from any one of epoxy resin and phenolic resin; and the antioxidant is bisphenol A phosphite.

4. A method for preparing the corrosion and scale inhibition proppant according to claim 1, characterized in that: The following steps are involved: Step 1: ball-mill Al2O3 powder, MgO powder, Fe2O3 powder, TiO2 powder, CaCO3 powder, and SiO2 powder to obtain spherical skeleton powder, place the spherical skeleton powder in a blender, add a binder, and stir to obtain a uniform mixture; Step 2: placing the uniform mixture obtained in step 1 into a spherical shell mold with a central cylindrical core and pressing to obtain spherical skeleton particles with through holes, and then drying the spherical skeleton particles with through holes; Step 3: Place the spherical skeleton particles with through holes after drying in step 2 into an electric furnace and sinter at 1200-1400° C. for 1-2 hours to obtain a spherical skeleton with through holes, and cool it for later use; Step 4: The adsorbent material and the corrosion and scale inhibitor are mixed uniformly in a stirred tank according to a proportion to obtain a mixture A, and then the resin and the antioxidant are added to the mixture A and mixed uniformly to obtain a mixture B; Step 5: Heat the mixture B in a reactor until it is molten at a temperature of 120-140°C; then add a curing agent and mix well to obtain a mixture C; Step 6: Immerse the spherical skeleton with through holes obtained in step 3 in a coupling agent, and then evenly spread it on a flat mold with multiple spherical pits, ensuring that each proppant skeleton falls into a spherical pit. Then, pour the mixture C evenly onto the flat mold to ensure that the mixture C completely fills each spherical pit. After naturally cooling at room temperature until completely solidified, demold the finished product to obtain the corrosion and scale inhibition proppant.

5. The method for preparing the corrosion and scale inhibition proppant according to claim 4, characterized in that: In step 1, the mass ratio of Al2O3 powder, MgO powder, Fe2O3 powder, TiO2 powder, CaCO3 powder and SiO2 powder is (60~80):(3~14):(1~10):(1~8):(2~8):(3~7).

6. The method for preparing the corrosion and scale inhibition proppant according to claim 4, characterized in that: In step 1, the binder is polyvinyl alcohol, and the amount of the binder added is 4-6% of the mass of the spherical skeleton powder.

7. The method for preparing the corrosion and scale inhibition proppant according to claim 4, characterized in that: In step 2, the cylindrical radius of the central cylindrical core is 64-425 μm, and the radius of the spherical shell mold is 212.5-850 μm.

8. The method for preparing the corrosion and scale inhibition proppant according to claim 4, characterized in that: In step 4, the mass ratio of the adsorption material, corrosion and scale inhibitor, resin and antioxidant is (40-50): (20-40): (20-35): (0.1-1.0).

9. The method for preparing the corrosion and scale inhibition proppant according to claim 4, characterized in that: In step 5, the curing agent is selected from any one of ethylenediamine, diethylenetriamine, and triethylenetetramine, and the added amount of the curing agent is 5-20% of the mass of the resin.

10. The method for preparing the corrosion and scale inhibition proppant according to claim 4, characterized in that: In step 6, the coupling agent is a silane-silane coupling agent; the silane-silane coupling agent is any one of γ-glycidyloxypropyltrimethoxysilane, γ-methacryloyloxyethoxysilane, and vinyltriethoxysilane; and the radius of the spherical pit of the flat mold is 232.5~930 μm.

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