A high-temperature resistant ceramic proppant for oil wells and its preparation method

Abstract

The application discloses a high-temperature-resistant ceramic oil well proppant and a preparation method thereof. The proppant is prepared by innovative material design and optimized structure ratio, and mechanical properties and thermal properties are obviously improved. The proppant has high strength, high toughness, excellent compression resistance, excellent high-temperature resistance and thermal protection effect. The unique intelligent temperature control system endows the material with temperature self-adaptability and shape memory effect. A multiple coupling system ensures the close combination of components. The synergistic effect of the multistage structure optimizes the performance of the product. The performance advantages are complementary, so that the proppant is a new type of proppant with comprehensive performance and high reliability.

Description

Technical Field

[0001] This invention relates to the field of petroleum extraction technology, specifically to a high-temperature resistant ceramic well proppant and its preparation method. Background Technology

[0002] In the field of oil and gas development, proppant, as a key material for maintaining fractured fissures, directly determines the fracturing effect and oil and gas recovery rate. As oil and gas exploration and development moves towards deeper and ultra-deep formations, traditional proppant can no longer meet the stringent requirements of high-temperature and high-pressure environments. Although existing proppant technology has undergone years of development and improvement, many technical challenges still urgently need to be addressed.

[0003] Currently, the main proppants used in the market include three categories: quartz sand, ceramsite, and resin-coated proppants. Among them, quartz sand proppants are widely used in shallow oil and gas reservoir development due to their wide availability and low cost. However, with the increase in exploration depth, its inherent performance defects have become increasingly prominent. The compressive strength of quartz sand proppants is generally lower than 52 MPa, making them extremely prone to breakage under deep, high-pressure environments, leading to closure of the proppant gaps and severely affecting conductivity. In addition, its temperature resistance is poor; it softens and deforms at temperatures exceeding 150°C, failing to meet the development requirements of deep, high-temperature oil and gas reservoirs.

[0004] While ceramsite proppant has shown improvements in strength and temperature resistance, it still has significant shortcomings. Traditional ceramsite proppant is designed with a single component, resulting in limited performance and difficulty in adapting to the diverse needs under complex formation conditions. Its surface activity is poor, leading to incompatible compatibility with formation fluids and affecting propping effectiveness. Especially under conditions of drastic formation temperature changes, the lack of temperature control capabilities makes it prone to thermal stress cracking. Furthermore, the particle size distribution of existing ceramsite proppant is not optimal, hindering the formation of a suitable packing structure and impacting the stability and conductivity of the propped joints.

[0005] To improve the surface properties of proppants, the industry has developed resin-coated proppants, but this improvement has not fundamentally solved the technical challenges faced in developing deep oil and gas reservoirs. The resin coating layer is prone to aging at temperatures exceeding 180°C, leading to a sharp decline in performance. More seriously, after the resin cures, it easily forms a solidified "caking" phenomenon, severely affecting the conductivity of fractured fissures. Furthermore, due to the lack of effective interface control technology, the bonding strength between the resin layer and the proppant matrix is ​​insufficient, making it prone to peeling off under high temperature and high pressure environments, thus losing its modification effect. Summary of the Invention

[0006] To address or partially address the problems existing in related technologies, this invention provides a high-temperature resistant ceramic proppant for oil wells, comprising the following components by weight: 60-70 parts ceramic substrate, 8-12 parts nano-reinforcing material, 8-12 parts intelligent temperature control material, 12-18 parts bonding system, and 3-8 parts reinforcing fiber.

[0007] Furthermore, the ceramsite substrate includes:

[0008] 45-50 parts of high-purity alumina ceramsite with a purity ≥99.5% and a three-stage particle size distribution, of which 1.2-1.5mm accounts for 30%, 0.8-1.2mm accounts for 50%, and 0.5-0.8mm accounts for 20%.

[0009] 15-20 parts of special silicon carbide ceramic particles with a purity ≥98% and surface doping of 5-8% titanium carbide.

[0010] Furthermore, the nano-reinforcing material includes:

[0011] 6-8 parts of silane coupling agent modified nano-alumina, with a particle size of 20-50 nm and a specific surface area ≥200 m². 2 / g;

[0012] Plasma-activated nano-silicon carbide, 2-4 parts, with a particle size of 30-70 nm and a purity ≥99%.

[0013] Furthermore, the intelligent temperature control material includes:

[0014] 4-5 parts of low-temperature phase change material, potassium nitrate based, with a phase change temperature of 334℃;

[0015] 1-2 parts of high-temperature phase change material, potassium sulfate based, with a phase change temperature of 1069℃;

[0016] 3-5 parts of shape memory alloy, nickel-titanium based, with a phase transformation temperature of 400-500℃.

[0017] Furthermore, the bonding system includes:

[0018] 8-12 parts of modified PLA main binder with a molecular weight of 150,000-200,000, and 2-3 wt% grafted maleic anhydride;

[0019] 2-4 parts of PCL toughening component, with a molecular weight of 80,000-100,000;

[0020] Two parts of the composite coupling agent.

[0021] Furthermore, the reinforcing fibers include:

[0022] Surface-oxidized carbon fiber 2-4 parts, with a length of 3-5 mm and a tensile strength ≥3500 MPa;

[0023] 1-4 parts of silanized glass fiber, with a length of 3-4 mm and a diameter of 8-12 μm.

[0024] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit the scope of this application.

[0025] Beneficial technical effects of the present invention:

[0026] This invention's proppant achieves significant improvements in mechanical and thermal properties through innovative material design and optimized structural ratios. It not only possesses high strength, high toughness, and excellent compressive strength, but also exhibits outstanding high-temperature resistance and thermal protection. Its unique intelligent temperature control system endows the material with temperature adaptability and shape memory effects, while the multi-coupling system ensures tight bonding between components. The synergistic effect of the multi-level structure optimizes product performance, and the complementary advantages of various properties make it a novel proppant material with comprehensive performance and high reliability. Detailed Implementation

[0027] The alternative embodiments of this application will now be described in more detail. While alternative embodiments of this application have been described, it should be understood that this application can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to make this application more thorough and complete, and to fully convey the scope of this application to those skilled in the art.

[0028] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The singular forms “a,” “the,” and “the” used in this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0029] This invention application provides a high-temperature resistant ceramic proppant oil well proppant, comprising the following components by weight: 60-70 parts of ceramic substrate, 8-12 parts of nano-reinforcing material, 8-12 parts of intelligent temperature control material, 12-18 parts of bonding system, and 3-8 parts of reinforcing fiber.

[0030] The high-temperature resistant ceramic proppant for oil wells has the following characteristics:

[0031] 1. High strength and high temperature resistance

[0032] Using high-purity alumina (≥99.5%) and silicon carbide (≥98%) ceramsite as the base material, it provides excellent mechanical strength.

[0033] The three-stage particle size distribution design (1.2-1.5mm, 0.8-1.2mm, 0.5-0.8mm) ensures the optimal packing density of the particles.

[0034] Titanium carbide doping (5-8%) on the silicon carbide surface further enhances wear resistance and thermal conductivity.

[0035] 2. Nano-enhancing effect

[0036] Nano-alumina modified with a silane coupling agent has a large specific surface area (≥200m²). 2 / g), significantly improves interfacial adhesion.

[0037] Plasma-activated nano-silicon carbide provides additional enhancements, improving overall performance.

[0038] Nanoscale dispersion significantly improves the mechanical properties and thermal stability of materials.

[0039] 3. Intelligent temperature control function

[0040] Employing a dual-phase change material system:

[0041] Low-temperature phase change materials (334℃) provide thermal regulation in the mid-temperature range.

[0042] High-temperature phase change materials (1069℃) ensure thermal protection under extreme high-temperature conditions.

[0043] Nickel-titanium based shape memory alloys offer reversible deformation capabilities in the 400-500℃ temperature range, increasing the material's adaptability.

[0044] 4. Optimized bonding system

[0045] The modified PLA main binder has a high molecular weight (150,000-200,000), providing good mechanical properties. Maleic anhydride graft modification (2-3 wt%) improves interfacial compatibility.

[0046] PCL toughening components significantly improve toughness and prevent brittle fracture.

[0047] Composite coupling agents further enhance interfacial bonding.

[0048] 5. Fiber synergistic reinforcement

[0049] Surface-oxidized carbon fiber possesses ultra-high tensile strength (≥3500MPa), providing significant reinforcement. Silanized glass fiber provides supplementary reinforcement and improves the material's toughness.

[0050] The dual-fiber system forms a three-dimensional network structure, providing multi-dimensional reinforcement.

[0051] In one embodiment of this invention application, the ceramsite substrate includes:

[0052] 45-50 parts of high-purity alumina ceramsite with a purity ≥99.5% and a three-stage particle size distribution, of which 1.2-1.5mm accounts for 30%, 0.8-1.2mm accounts for 50%, and 0.5-0.8mm accounts for 20%.

[0053] 15-20 parts of special silicon carbide ceramic particles with a purity ≥98% and surface doping of 5-8% titanium carbide.

[0054] In one embodiment of this invention application, the nano-reinforcing material comprises:

[0055] 6-8 parts of silane coupling agent modified nano-alumina, with a particle size of 20-50 nm and a specific surface area ≥200 m². 2 / g;

[0056] Plasma-activated nano-silicon carbide, 2-4 parts, with a particle size of 30-70 nm and a purity ≥99%.

[0057] In one embodiment of this invention application, the intelligent temperature control material includes:

[0058] 4-5 parts of low-temperature phase change material, potassium nitrate based, with a phase change temperature of 334℃;

[0059] 1-2 parts of high-temperature phase change material, potassium sulfate based, with a phase change temperature of 1069℃;

[0060] 3-5 parts of shape memory alloy, nickel-titanium based, with a phase transformation temperature of 400-500℃.

[0061] In one embodiment of this invention application, the bonding system includes:

[0062] 8-12 parts of modified PLA main binder with a molecular weight of 150,000-200,000, and 2-3 wt% grafted maleic anhydride;

[0063] 2-4 parts of PCL toughening component, with a molecular weight of 80,000-100,000;

[0064] Two parts of the composite coupling agent.

[0065] In one embodiment of this invention application, the reinforcing fiber comprises:

[0066] Surface-oxidized carbon fiber 2-4 parts, with a length of 3-5 mm and a tensile strength ≥3500 MPa;

[0067] 1-4 parts of silanized glass fiber, with a length of 3-4 mm and a diameter of 8-12 μm.

[0068] For clarity, the following examples will be used to provide a detailed description.

[0069] Example 1:

[0070] By weight, it includes the following components:

[0071] 1. 60 parts of expanded clay substrate:

[0072] - 45 parts of high-purity alumina ceramic particles (purity 99.5%, 30% 1.2-1.5mm, 50% 0.8-1.2mm, and 20% 0.5-0.8mm)

[0073] - 15 parts of special silicon carbide ceramic particles (98% purity, 5% titanium carbide surface doping)

[0074] 2. 8 parts of nano-reinforcing materials:

[0075] - 6 parts of silane coupling agent modified nano-alumina (particle size 20nm, specific surface area 200m²) 2 / g)-Plasma-activated nano-silicon carbide, 2 portions (particle size 30nm, purity 99%)

[0076] 3. 8 portions of intelligent temperature control material:

[0077] - 4 parts of low-temperature phase change material (potassium nitrate based, phase change temperature 334℃)

[0078] - 1 part of high-temperature phase change material (potassium sulfate based, phase change temperature 1069℃)

[0079] - 3 parts shape memory alloy (nickel-titanium based, phase transformation temperature 400℃)

[0080] 4. Adhesive system (12 parts):

[0081] - 8 parts of modified PLA main binder (molecular weight 150,000, grafted maleic anhydride 2wt%)

[0082] - 2 parts of PCL toughening component (molecular weight 80,000)

[0083] - 2 parts of composite coupling agent

[0084] 5. Reinforcing fibers (3 parts):

[0085] - Two parts of surface-oxidized carbon fiber (3mm in length, tensile strength 3500MPa)

[0086] - One piece of silanized glass fiber (3mm in length, 8μm in diameter)

[0087] Example 2:

[0088] By weight, it includes the following components:

[0089] 1. 65 parts of expanded clay substrate:

[0090] - 47.5 parts of high-purity alumina ceramsite (purity 99.5%, 30% 1.2-1.5mm, 50% 0.8-1.2mm, and 20% 0.5-0.8mm)

[0091] - 17.5 parts of special silicon carbide ceramic particles (98% purity, 6.5% surface-doped titanium carbide)

[0092] 2. 10 parts of nano-reinforcing material:

[0093] - 7 parts of silane coupling agent modified nano-alumina (particle size 35nm, specific surface area 200m²) 2 / g)-Plasma-activated nano-silicon carbide 3 parts (particle size 50nm, purity 99%)

[0094] 3. 10 portions of intelligent temperature control material:

[0095] - 4.5 parts of low-temperature phase change material (potassium nitrate based, phase change temperature 334℃)

[0096] - 1.5 parts of high-temperature phase change material (potassium sulfate based, phase change temperature 1069℃)

[0097] - 4 parts of shape memory alloy (nickel-titanium based, phase transformation temperature 450℃)

[0098] 4. Adhesive system (15 parts):

[0099] - 10 parts modified PLA main binder (molecular weight 175,000, grafted maleic anhydride 2.5wt%) - 3 parts PCL toughening component (molecular weight 90,000)

[0100] - 2 parts of composite coupling agent

[0101] 5.5 parts reinforcing fiber:

[0102] - Surface-oxidized carbon fiber, 3 parts (4mm in length, tensile strength 3500MPa)

[0103] - 2.5 parts of silanized glass fiber (3.5 mm in length, 10 μm in diameter)

[0104] Example 3:

[0105] By weight, it includes the following components:

[0106] 1. 70 parts of expanded clay substrate:

[0107] - 50 parts of high-purity alumina ceramsite (99.5% purity, 30% 1.2-1.5mm, 50% 0.8-1.2mm, and 20% 0.5-0.8mm)

[0108] - 20 parts of special silicon carbide ceramic particles (98% purity, 8% surface doped with titanium carbide)

[0109] 2. 12 parts of nano-reinforcing material:

[0110] - 8 parts of silane coupling agent modified nano-alumina (particle size 50nm, specific surface area 200m²) 2 / g)-Plasma-activated nano-silicon carbide, 4 portions (particle size 70nm, purity 99%)

[0111] 3. 12 portions of intelligent temperature control material:

[0112] - 5 parts of low-temperature phase change material (potassium nitrate based, phase change temperature 334℃)

[0113] - Two parts of high-temperature phase change material (potassium sulfate based, phase change temperature 1069℃)

[0114] - 5 parts of shape memory alloy (nickel-titanium based, phase transformation temperature 500℃)

[0115] 4. Adhesive system (18 parts):

[0116] - 12 parts of modified PLA main binder (molecular weight 200,000, grafted maleic anhydride 3wt%)

[0117] -4 parts of PCL toughening component (molecular weight 100,000)

[0118] - 2 parts of composite coupling agent

[0119] 5. 8 parts reinforcing fiber:

[0120] - Surface-oxidized carbon fiber, 4 parts (5mm in length, tensile strength 3500MPa)

[0121] - 4 parts of silanized glass fiber (4 mm in length, 12 μm in diameter)

[0122] Test Example 1. High Temperature Stability Test

[0123] Objective: To verify the physical and chemical stability of proppant under extreme high-temperature conditions and ensure its reliability in high-temperature conditions in oil wells.

[0124] Experimental steps:

[0125] Sample preparation:

[0126] Product of this invention: Take 3 groups of support agent samples from Example 2, 50 grams per group.

[0127] Commercially available products (control group): 50 grams of each of the three groups of common commercially available ceramic proppant samples were taken.

[0128] Thermogravimetric analysis (TGA):

[0129] Under nitrogen protection, the sample was gradually heated from room temperature to 1200℃, and the mass change at different temperatures was recorded to determine the heat resistance limit.

[0130] High-temperature immersion test:

[0131] The samples were placed in high-temperature furnaces at 334℃, 500℃, 800℃ and 1069℃ respectively, and heated for 24 hours.

[0132] After heating, the sample was removed, the mass loss was recorded, and its morphological changes and structural integrity were observed.

[0133] X-ray diffraction (XRD) analysis:

[0134] XRD analysis was performed on the samples after high-temperature treatment to detect changes in crystal phase and assess chemical stability.

[0135] Experimental data:

[0136]

[0137] Results analysis:

[0138] TGA mass loss rate: At all temperatures, the mass loss rate of the product of this invention is lower than that of commercially available products, especially at high temperatures (800°C and 1069°C), where the difference is significant.

[0139] Mass loss after immersion: The product of this invention exhibits less mass loss after high-temperature immersion, indicating its better high-temperature stability.

[0140] Crystal phase change: The crystal phase change of the product of this invention under high temperature treatment is less than that of commercially available products, thus maintaining better structural integrity.

[0141] Test Example 2. Mechanical Strength Test

[0142] Objective: To evaluate the compressive and tensile strength of proppant under high-temperature conditions to ensure its load-bearing capacity and stability in oil wells.

[0143] Experimental steps:

[0144] Sample preparation:

[0145] Product of the present invention: Propionate sample of Example 2, which was treated at room temperature and 800°C respectively.

[0146] Commercially available products (control group): Commercially available ceramsite proppant samples of the same standard size were prepared and treated at room temperature and 800°C, respectively.

[0147] Compressive strength test:

[0148] A universal testing machine was used to test the compressive strength of the samples before and after treatment, and the maximum load-bearing capacity was recorded.

[0149] Tensile strength test:

[0150] For the reinforcing fiber portion, its tensile strength at room temperature and 800°C was determined using a tensile testing machine.

[0151] Data recording and analysis:

[0152] Compare the compressive and tensile strengths at different temperatures to evaluate the high-temperature mechanical properties of the material.

[0153] Experimental data:

[0154]

[0155] Results analysis:

[0156] Compressive strength: At 800℃, the compressive strength of the product of this invention decreased from 150MPa to 135MPa, a decrease of only 10%; while the commercially available product decreased from 130MPa to 110MPa, a decrease of about 15.4%, indicating that the product of this invention has better high-temperature load-bearing capacity.

[0157] Tensile strength: At 800℃, the tensile strength of the product of the present invention decreased from 3600MPa to 3300MPa, a decrease of about 8.3%; the commercially available product decreased from 3200MPa to 2800MPa, a decrease of about 12.5%, indicating that the product of the present invention maintains higher tensile strength at high temperatures.

[0158] Experimental Example 3. Thermal Control Performance Test

[0159] Objective: To verify the role of intelligent temperature control materials in proppant, evaluate their phase change temperature and heat absorption / release capacity, and ensure effective temperature regulation in oil wells.

[0160] Experimental steps:

[0161] Sample preparation:

[0162] Product of this invention: Example 2 contains 3 sets of proppant samples containing intelligent temperature control materials.

[0163] Commercially available products (control group): Three groups of commercially available ceramsite proppant samples without intelligent temperature control materials were taken.

[0164] Differential scanning calorimetry (DSC):

[0165] The phase transition temperature and latent heat of low-temperature phase change materials (potassium nitrate-based), high-temperature phase change materials (potassium sulfate-based), and shape memory alloys (nickel-titanium-based) were determined.

[0166] Thermal cycling test:

[0167] The sample was subjected to 10 thermal cycles (heated to the phase transition temperature and then cooled) to observe the stability of its heat absorption / release capacity.

[0168] Data recording and analysis:

[0169] Record the phase transition temperature and latent heat changes for each thermal cycle to assess the repeatability and reliability of the smart temperature control material.

[0170] Experimental data:

[0171]

[0172]

[0173] Results analysis:

[0174] Phase change temperature and latent heat: After 10 thermal cycles, the phase change temperature and latent heat value of the intelligent temperature control material in the product of this invention remain almost unchanged (the change does not exceed 1℃ and 1J / g), showing excellent thermal control performance and repeatability; while commercially available products cannot achieve temperature regulation function because they do not contain intelligent temperature control material.

[0175] Thermal management capability: The product of this invention can effectively absorb or release heat at different temperature stages, maintaining the temperature stability of the oil well environment, while commercially available products lack this function and cannot regulate the temperature.

[0176] Summarize

[0177] Through three key experiments—high-temperature stability testing, mechanical strength testing, and thermal control performance testing—the data shows that:

[0178] High temperature stability:

[0179] The product of this invention exhibits a lower mass loss rate than commercially available products at all test temperatures, and demonstrates superior stability, especially at high temperatures (800℃ and 1069℃).

[0180] The crystal phase changes are less pronounced than those of commercially available products, maintaining better structural integrity.

[0181] Mechanical strength:

[0182] The product of this invention exhibits higher compressive and tensile strengths than commercially available products under high-temperature conditions, demonstrating stronger load-bearing capacity and stability.

[0183] Thermal control performance:

[0184] The product of this invention achieves effective temperature regulation and thermal management capabilities by incorporating intelligent temperature control materials, a function that commercially available products cannot achieve.

[0185] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications and improvements made without departing from the spirit of the present invention are within the scope of protection claimed by the present invention.

Claims

1. A high temperature resistant ceramic proppant, characterized in that, By weight parts include the following components: ceramsite base material 65 parts, nano reinforced material 10 parts, intelligent temperature control material 10 parts, bonding system 15 parts and reinforcing fiber 5.5 parts; wherein: The ceramsite base material includes: high-purity alumina ceramsite 47.5 parts, with purity ≥ 99.5%, with three-level particle size distribution, wherein 1.2-1.5mm accounts for 30%, 0.8-1.2mm accounts for 50%, and 0.5-0.8mm accounts for 20%; Special silicon carbide ceramsite 17.5 parts, with purity ≥ 98%, surface doped titanium carbide 6.5%; The nano reinforced material includes: silane coupling agent modified nano alumina 7 parts, with particle size of 35nm, specific surface area ≥ 200m² / g; Plasma activated nano silicon carbide 3 parts, with particle size of 50nm, purity ≥ 99%; The intelligent temperature control material includes: potassium nitrate-based low-temperature phase change material 4.5 parts, with phase change temperature 334℃; Potassium sulfate-based high-temperature phase change material 1.5 parts, with phase change temperature 1069℃; Nickel-titanium-based shape memory alloy 4 parts, with phase change temperature 450℃; The bonding system includes: modified PLA main binder 10 parts, with molecular weight of 175,000, grafted maleic anhydride 2.5wt%; PCL toughening component 3 parts, with molecular weight of 90,000; Composite coupling agent 2 parts; The reinforcing fiber includes: surface oxidized carbon fiber 3 parts, with length of 4mm, tensile strength ≥ 3500MPa; Silanized glass fiber 2.5 parts, with length of 3.5mm, diameter of 10μm.

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