Olivine-based fracturing hydrogen generation integrated proppant, and preparation method and application thereof

Abstract

This invention relates to the field of fracturing technology in oil extraction, specifically disclosing an integrated fracturing and hydrogen generation proppant based on olivine, its preparation method, and its application. The proppant uses olivine as the core particle, with a coating containing a polymer binder, toughening polymer, catalyst aid, and slow-release filler. It possesses both mechanical support and chemical reaction functions: after injection into the fracture, it forms a stable support framework while simultaneously undergoing a controllable serpentinization reaction, continuously generating hydrogen and forming a gas cushion layer within the fracture, effectively inhibiting fracture closure and enhancing fracture wall stability. The proppant provided by this invention has advantages such as high compressive strength, good conductivity retention, controllable hydrogen production, and environmental friendliness, achieving synergy between increased fracturing production and in-situ hydrogen energy utilization.

Description

Technical Field

[0001] This invention relates to the field of fracturing technology in oil extraction, specifically to an integrated fracturing and hydrogen generation proppant based on olivine, its preparation method, and its application. Background Technology

[0002] Unconventional reservoirs (such as shale oil, tight oil, and coalbed methane) generally exhibit extremely low permeability and strong heterogeneity, requiring fracturing technology to create artificial fracture networks to improve fluid flow. Currently, fracturing development of unconventional oil and gas reservoirs commonly employs traditional proppants such as quartz sand, ceramsite, and resin-coated sand. These proppants primarily provide mechanical support but lack chemical activity and energy regulation capabilities, making it difficult to achieve long-term effective fracture conduction. After fracturing operations, formation pressure typically decays rapidly, flowback becomes difficult, and fractures easily close, leading to a significant decrease in production capacity. Summary of the Invention

[0003] This invention provides an integrated fracturing and hydrogen generation proppant based on olivine, its preparation method, and its application. The proppant provided by this invention has advantages such as high compressive strength, good conductivity retention, controllable hydrogen production, and environmental friendliness, achieving synergy between enhanced fracturing production and in-situ hydrogen energy utilization.

[0004] This invention provides an integrated fracturing and hydrogen generation proppant based on olivine, comprising: Peridot particles and a coating covering the surface of the peridot particles; The coating is made of the following components by mass percentage: 55%~65% polymer binder, 18%~22% toughening polymer, 1%~3% catalyst and 16%~20% slow-release filler; the mass ratio of olivine particles to the coating is 25~30:1.

[0005] The proppant provided by this invention has advantages such as high compressive strength, good conductivity, controllable hydrogen production, and environmental friendliness, realizing the synergy between fracturing production enhancement and in-situ hydrogen energy utilization.

[0006] Furthermore, the olivine particles have a particle size of 20 mesh to 70 mesh.

[0007] Furthermore, the thickness of the coating is 10 μm to 30 μm.

[0008] Furthermore, the Fe element content in the olivine particles is 5% to 15% by mass.

[0009] This invention also provides a method for preparing an integrated fracturing and hydrogen generation proppant, comprising the following steps: The peridot is crushed, sieved, washed, and dried to obtain peridot particles. The polymer binder, toughening polymer, catalyst and slow-release filler are mixed and heated and stirred to form a uniform coating slurry; At a temperature of 130℃~160℃, the coating slurry is uniformly sprayed onto the surface of the olivine particles and stirred thoroughly. The coated particles were cooled, dried, and sieved to obtain the modified olivine proppant.

[0010] This invention also provides an application of an integrated fracturing and hydrogen generation proppant in fracturing operations and reservoir pressure maintenance, comprising the following steps: The proppant is mixed with fracturing fluid and pumped into the target formation; The proppant undergoes a serpentinization reaction in the formation environment, continuously generating hydrogen gas; the hydrogen gas forms a gas cushion layer within the fracture to maintain reservoir pressure and inhibit fracture closure.

[0011] Furthermore, the main reaction formula of the serpentinization reaction is: (Mg,Fe)2SiO4+H2O→Mg3Si2O5(OH)4+Mg(OH)2+Fe3O4+H2↑; The reaction byproducts Mg3Si2O5(OH)4 and Mg(OH)2 are deposited on the surface of the crack to form a protective layer, thereby enhancing the stability and lubricity of the crack.

[0012] Furthermore, the mass ratio of the proppant to the fracturing fluid is 1~5:20.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention achieves a synergistic effect of fracturing support and in-situ hydrogen generation through structural innovation and reaction mechanism optimization of olivine proppant, resulting in the following significant technical and economic benefits: This invention provides a dual-function olivine proppant that combines mechanical support with chemical reaction capabilities. While supporting fractures, it continuously releases hydrogen through serpentinization, forming an in-situ gas cushion. This achieves self-compensation and sustained formation pressure, significantly extending the effective cycle of fracturing. The hydrogen generated during the serpentinization process effectively inhibits fracture closure and maintains unobstructed fluid channels within the fractures, thereby improving oil and gas displacement efficiency and recovery. The continuous release of hydrogen can also create localized pressurization zones in the formation, enhancing oil and gas desorption and migration capabilities.

[0014] The reaction products enhance the structural stability of the fracture. The reaction byproducts serpentine and magnesium hydroxide deposit on the fracture surface to form a dense protective layer, which can improve the structural stability and lubricity of the fracture wall, reduce post-compression closure and conductivity decay, and extend the effective service life of the proppant.

[0015] The coating's rate-controlled design ensures safety and controllable reaction. Optimized coating thickness and composition enable slow-release regulation of the serpentine reaction, preventing rapid reactions or airlocks in the early stages of fracturing. This ensures smooth injection of fracturing fluid and uniform distribution of proppant, enhancing operational safety and controllability.

[0016] The material is widely available, low in cost, and easy to scale up. Olivine resources are abundant and inexpensive, and the preparation process is simple. It can be rapidly converted and industrialized on the basis of existing fracturing proppant production lines, which has significant economic and promotional advantages.

[0017] Environmentally friendly with zero carbon emissions, this reaction system also offers clean energy benefits. It does not produce greenhouse gases such as CO2, making the process clean and environmentally friendly. The generated hydrogen can be recovered through the wellbore for use as a clean energy source, providing energy replenishment to oil and gas fields or supplying energy externally, achieving the dual benefits of fracturing production enhancement and hydrogen energy development. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 The XRD results are for the modified olivine proppant.

[0020] Figure 2 SEM and microscopic mechanism analysis of modified olivine proppant are shown in the figure. In the figure, a is the dissolution pit formed on the fracture surface of olivine particles in the early stage of reaction; b is the cross-sectional view of the reaction products replacing and filling the microcracks inside the olivine particles; c is the polyhedral deep dissolution pit developed on the surface of olivine particles; d is a local magnified view of the area in the box in c, showing the dense crystal morphology of the product layer; e is the pyramidal dissolution pit developed on the surface of olivine particles; f is the papillary product layer and serpentine adhesion morphology formed on the surface of olivine particles in the later stage of reaction. Detailed Implementation

[0021] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise specified, the experimental methods described in the embodiments of the present invention are conventional methods, and the materials and reagents used in the following embodiments are commercially available unless otherwise specified.

[0022] Example 1: An integrated fracturing and hydrogen generation proppant based on olivine, its preparation method and application.

[0023] 1. Prop composition and formulation Core particles: Olivine ore is used as raw material. After being crushed in stages by a PE-60×100 jaw crusher (Hebi Metallurgical Machinery and Instrument Factory), the resulting particles are classified by particle size using a ZS-200 standard vibrating screen (Xinxiang Gaofu Machinery Co., Ltd.). Olivine particles with a particle size of 45±25 mesh are selected as core particles of proppant to support cracks.

[0024] Coating material: Polymer binder: thermosetting phenolic resin, used to provide adhesion to the surface of olivine particles and improve the temperature stability of the coating; Toughening polymers: polyacrylamide (PAM) and polyvinylpyrrolidone (PVP) enhance the coating's toughness and crack resistance; Catalytic promoter: Nickel oxide (NiO), used to regulate Fe in olivine. 2+ The oxidation rate is increased, thus improving the efficiency of the serpentinization reaction; Slow-release filler: Bentonite, used to improve coating density, abrasion resistance and high-temperature stability.

[0025] The mass ratio of olivine core particles to coating is 28:1, and the coating accounts for 3.4% of the total proppant mass. This ensures effective coating of the olivine particle surface without affecting the crack conductivity. 2. Proppant Preparation

[0026] Raw material pretreatment: The olivine is crushed and sieved to the target particle size range (45±25 mesh). The particles are washed with deionized water to remove dust and impurities from the surface. Then, they are placed in a constant temperature drying oven and dried at 105±5℃ for 3.5±0.5 h until the moisture content is less than 0.5%, thus obtaining dried olivine particles.

[0027] Coating preparation: The thermosetting phenolic resin, PAM, PVP, NiO, and bentonite were mixed in a weight percentage ratio of 60%:10%:10%:2%:18%. Specifically, 600 g of thermosetting phenolic resin, 100 g of PAM, 100 g of PVP, 20 g of NiO, and 180 g of bentonite were accurately weighed. The above components were mixed and heated and stirred until a uniform coating slurry was formed. This slurry was used for coating olivine particles, so that the coating mass accounted for 3.4% of the total proppant mass.

[0028] Coating treatment: The prepared olivine particles were preheated to 150℃, and the coating slurry was uniformly sprayed onto the surface of the olivine particles using a vertical high-speed mixer. During the spraying process, the mixer speed was set to 300 rpm, and continuous stirring was performed for 30 minutes to ensure that the coating evenly covered the particle surface. The spraying system used an adjustable nozzle atomization device to form fine mist droplets, thereby ensuring uniform adhesion of the coating to the particle surface. After spraying, stirring was continued for 10 minutes to ensure that the coating fully adhered to the particle surface and was evenly distributed.

[0029] Drying and sieving: The coated olivine particles were naturally cooled to 50°C, then placed in a constant temperature drying oven and dried at 80°C for 120 minutes to remove surface moisture and stabilize the coating structure. After drying, the particles were sieved using a stainless steel vibrating screen with a mesh size of 40 mesh to obtain modified olivine proppant with uniform particle size that meets the requirements.

[0030] 3. Preparation process control and performance evaluation indicators The Fe content in the raw material olivine is strictly controlled within the range of 5% to 15%. This range not only ensures sufficient hydrogen production sources and magnetite byproduct formation space for the serpentinization reaction, but also maintains the mechanical stability of the olivine crystal structure, avoiding increased particle brittleness due to excessive iron content.

[0031] During the coating process, the coating thickness is precisely controlled within 20±10 μm by adjusting the inkjet volume of the atomizing device and the speed of the mixer. This thickness range aims to balance the controllability of the modification reaction rate and provide high-temperature wear-resistant protection to prevent premature failure due to an excessively thin coating.

[0032] By adjusting the content of the catalyst NiO, the initial hydrogen production rate of the modified particles under simulated reservoir conditions was maintained at 0.001 mol H2 / (mol olivine·h). After 24 h, the reaction entered a steady state, ensuring long-term and controllable release of hydrogen, so as to exert the self-pressurization function and avoid the initial gas lock effect.

[0033] The prepared proppant needs to pass a breakage rate test under closure pressure. The overall breakage rate should be <5% under a high closure pressure of 70 MPa. This indicator is used to verify the coating's repair effect on olivine surface defects and its ability to optimize the stress distribution of the packing system.

[0034] 4. Performance Testing and Result Analysis To verify the comprehensive performance of the olivine proppant of this invention, its mechanical strength, conductivity, thermal stability and hydrogen production reaction characteristics were systematically tested and compared with conventional ceramsite and quartz sand proppants.

[0035] 4.1 Compressive strength and breakage rate test According to the "SY / T 5108—2014 Evaluation Method for Fracturing Proppant Performance", the hydraulic crusher was used for testing under a high closure pressure of 70 MPa. The results are shown in Table 1.

[0036] Table 1. Test results of compressive strength and breakage rate The average fracture pressure of a single particle of the modified olivine proppant is 16±1.8 MPa. Although the strength of a single particle is limited, after modification with a high-temperature coating, the coating effectively repairs the surface defects of the particles and optimizes the contact stress distribution. As a result, the breakage rate of the stacked system under a high closure pressure of 70 MPa is only 3.2±0.6%, which is significantly lower than the 6.5% of ceramsite of the same specification and the 9.2% of quartz sand, demonstrating excellent deep bearing capacity.

[0037] 4.2 Flow diversion capacity test The conductivity was tested at 150℃ and 15 MPa closure pressure according to the "SY / T 6302—2016 Evaluation Method for the Conductivity of Fracturing Proppant". The results are shown in Table 2.

[0038] Table 2 Results of the flow guiding capacity test The modified olivine proppant maintained 86.4% of its conductivity relative to the initial value after 72 hours of operation under a closure pressure of 15 MPa, which is significantly higher than that of ceramsite (70%) and quartz sand (55%). This indicates that the material has better crush resistance and crack conductivity retention under long-term closure pressure.

[0039] 4.3 In-situ hydrogen production performance test Reaction kinetics tests were conducted under simulated reservoir conditions (120℃, 15 MPa, water-rock ratio 10:1) to monitor hydrogen production. The results are shown in Table 3.

[0040] Table 3. Results of in-situ hydrogen production performance tests The results showed that the hydrogen production process using the modified olivine proppant was stable and controllable, with a cumulative hydrogen production of approximately 0.44 mmol·g. -1 (≈0.09 mol H2 / mol olivine) can still react continuously under 15 MPa conditions, indicating that olivine proppant has good formation adaptability and reaction stability.

[0041] 4.4 Analysis of Reaction Products To verify the physicochemical evolution of the proppant under actual working conditions, the modified olivine proppant was mixed with fracturing fluid (mass ratio of proppant to fracturing fluid was 3:20) and placed in a simulated formation environment (150℃, 70 MPa, simulated formation water) for hydrothermal reaction experiments to simulate its dynamic service process after entering the formation with the fracturing fluid (the main reaction formula of the serpentinization reaction of the modified olivine proppant is: (Mg,Fe)2SiO4+H2O→Mg3Si2O5(OH)4+Mg(OH)2+Fe3O4+H2↑).

[0042] XRD results ( Figure 1 The results show that serpentine (Mg3Si2O5(OH)4) and magnesium hydroxide (Mg(OH)2) generated by the reaction of modified olivine proppant are deposited on the surface of particles and microcracks to form a protective layer, thereby enhancing the stability and lubrication of cracks. This new biophase system has high structural continuity and effectively repairs the original physical defects of olivine.

[0043] SEM and micromechanical analysis results show that the modified olivine proppant enters the target formation under the carrying force of fracturing fluid, and its microstructural evolution logic is as follows: Active triggering and controlled dissolution ( Figure 2 (a, c, e): In the early stages of the reaction, formation fluids preferentially induce dissolution at stress concentration points and fracture surfaces on the olivine surface, forming characteristic polyhedral and pyramidal dissolution pits. The existence of these dissolution pits proves that the particle surface has extremely high chemical activity, providing core sites for the in-situ growth of subsequent products.

[0044] In-situ sealing and chemical suturing Figure 2 (b) As the serpentinization reaction continues, the generated hydrogen gas creates a hydrogen cushion layer for self-pressurization, while solid products permeate into the particle interior. Cross-sectional analysis shows that the originally developed microcracks are gradually replaced and filled by new biological phases, achieving a "chemical stitching" of the particle core and fundamentally eliminating stress concentration caused by physical defects.

[0045] Product solidification and strong adhesion: In the later stages of the reaction, a dense crystalline product layer evolves on the surface ( Figure 2 d) and papillary morphology ( Figure 2 (f). Even under the scouring of complex fluid environments, the generated products remain firmly attached. This protective barrier works synergistically with the generated hydrogen cushion layer to effectively maintain reservoir pressure and inhibit fracture closure.

[0046] The above results show that, compared with traditional proppant, the olivine proppant of the present invention exhibits a 10% to 30% increase in compressive strength and a 16% to 31% increase in conductivity retention under simulated formation closure pressure. It also has controllable in-situ hydrogen production and self-pressurization functions, and the coating reaction is controllable, safe and reliable, avoiding early gas lock during construction. In terms of thermal stability, chemical activity and environmental friendliness, it is significantly superior to existing ceramsite and quartz sand proppants.

[0047] Although preferred embodiments of the invention have been described, those skilled in the art, once they have learned the basic inventive concept, can make other changes and modifications to these embodiments.

[0048] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. An olivine-based fracturing hydrogen-producing integrated proppant, characterized in that, include: Peridot particles and a coating covering the surface of the peridot particles; The coating is made of the following components by weight percentage: 55%~65% polymer binder, 18%~22% toughening polymer, 1%~3% catalyst and 16%~20% slow-release filler; The mass ratio of the olivine particles to the coating is 25~30:

1.

2. The fracturing hydrogen generation integrated proppant of claim 1, wherein, The olivine particles have a particle size of 20-70 mesh.

3. The fracturing hydrogen generation integrated proppant of claim 1, wherein, The thickness of the coating is 10 μm to 30 μm.

4. The fracturing hydrogen generation integrated proppant of claim 1, wherein, The Fe content in the olivine particles is 5% to 15% by mass.

5. The method of producing the fracturing hydrogen generation integrated proppant according to any one of claims 1 to 4, characterized in that, Includes the following steps: The peridot is crushed, sieved, washed, and dried to obtain peridot particles. The polymer binder, toughening polymer, catalyst and slow-release filler are mixed and heated and stirred to form a uniform coating slurry; At a temperature of 130℃~160℃, the coating slurry is uniformly sprayed onto the surface of the olivine particles and stirred thoroughly. The coated particles were cooled, dried, and sieved to obtain the modified olivine proppant.

6. The use of the fracturing-hydrogen generation integrated proppant according to any one of claims 1-4 in fracturing operation and reservoir pressure maintenance, characterized in that, Includes the following steps: The proppant is mixed with fracturing fluid and pumped into the target formation; The proppant undergoes a serpentinization reaction in the formation environment, continuously generating hydrogen gas; the hydrogen gas forms a gas cushion layer within the fracture to maintain reservoir pressure and inhibit fracture closure.

7. Use according to claim 6, characterized in that, The main reaction formula of the serpentinization reaction is: (Mg,Fe)2SiO4+H2O→Mg3Si2O5(OH)4+Mg(OH)2+Fe3O4+H2↑; The reaction byproducts Mg3Si2O5(OH)4 and Mg(OH)2 are deposited on the surface of the crack to form a protective layer, thereby enhancing the stability and lubricity of the crack.

8. Use according to claim 6, characterized in that, The mass ratio of the proppant to the fracturing fluid is 1~5:20.

Images