Fracturing method and apparatus for oil and gas reservoirs or geothermal reservoirs

Abstract

This application discloses a fracturing method, apparatus, equipment, and storage medium for oil and gas reservoirs or geothermal reservoirs, relating to the field of oil and gas well fracturing technology. The method includes: releasing CO2 in a preset state into the target reservoir until the target reservoir reaches a expected pore pressure level, wherein the CO2 released into the target reservoir is in a supercritical state; when the target reservoir reaches the expected pore pressure level, initially fracturing the target reservoir using supercritical CO2 in an impact fracturing device; after the initial impact fracturing of the target reservoir, repeatedly injecting supercritical CO2 into the target reservoir; after each injection of supercritical CO2 into the target reservoir, further fracturing the target reservoir using supercritical CO2 in the impact fracturing device; and after the final impact fracturing of the target reservoir, injecting supercritical CO2 and proppant into the target reservoir to support the fractures. This method can increase the reservoir fracture extension distance and complexity.

Description

Technical Field

[0001] This application relates to the field of oil and gas well fracturing technology, specifically to a fracturing method, apparatus, equipment, and storage medium for oil and gas reservoirs or geothermal reservoirs. Background Technology

[0002] Currently, CO2 fracturing technology in oil and gas field production typically uses liquid CO2 as a pre-fluid for pumping to form a fracture network, followed by conventional hydraulic fracturing operations. This combined fracturing technology leverages the advantages of both CO2 and hydraulic fracturing, enhancing the fracture network while simultaneously improving drainage and increasing oil and gas recovery. However, existing CO2 fracturing technologies primarily use CO2 for drainage enhancement and have limited impact on reservoir fracturing, thus leaving room for further optimization. Therefore, a CO2 fracturing technology with better fracturing performance is needed to achieve full exploitation of reservoir oil and gas. Summary of the Invention

[0003] The purpose of this application is to provide a fracturing method, apparatus, equipment and storage medium for oil and gas reservoirs or geothermal reservoirs, in order to solve the problem of how to design a CO2 fracturing technology with better fracturing effect in the prior art, so as to increase the extension distance and complexity of the fracture generated by fracturing in the target reservoir.

[0004] To achieve the above objectives, a first aspect of this application provides a fracturing method for oil and gas reservoirs or geothermal reservoirs, comprising: continuously injecting CO2 into a production wellbore until the CO2 in the production wellbore reaches a preset state; releasing the preset-state CO2 into a target reservoir until the target reservoir reaches a expected pore pressure level, wherein the CO2 released into the target reservoir is in a supercritical state; when the target reservoir reaches the expected pore pressure level, initially fracturing the target reservoir by impact fracturing with supercritical CO2 in an impact fracturing device; after initially fracturing the target reservoir by impact fracturing, injecting supercritical CO2 into the target reservoir a second time; after the second injection of supercritical CO2 into the target reservoir, further fracturing the target reservoir by impact fracturing with supercritical CO2 in an impact fracturing device; and after the second impact fracturing of the target reservoir, injecting supercritical CO2 and proppant into the target reservoir to support the fractures in the target reservoir.

[0005] In this embodiment of the application, the fracturing method for oil and gas reservoirs or geothermal reservoirs further includes: injecting CO2 into the impact fracturing device until the CO2 in the impact fracturing device reaches a preset pressure value; monitoring the pressure value loss of the impact fracturing device within a preset time period; and, if the pressure value loss does not exceed a preset proportion, performing preliminary and / or secondary impact fracturing of the target reservoir using supercritical CO2 in the impact fracturing device.

[0006] In this embodiment of the application, after the initial impact fracturing of the target reservoir, a secondary injection of supercritical CO2 into the target reservoir is performed, including: at the same time as the initial impact fracturing of the target reservoir ends, a secondary injection of supercritical CO2 into the target reservoir begins.

[0007] In the embodiments of this application, the supercritical CO2 displacement per unit time of the secondary impact fracturing is greater than the supercritical CO2 displacement per unit time of the primary impact fracturing.

[0008] In this embodiment of the application, the fracturing method for oil and gas reservoirs or geothermal reservoirs further includes: after a secondary injection of supercritical CO2 into the target reservoir, detecting the fracture extension distance of the target reservoir; if the fracture extension distance is greater than a preset distance, performing secondary impact fracturing of supercritical CO2 into the target reservoir at a first displacement rate; if the fracture extension distance is less than or equal to the preset distance, performing secondary impact fracturing of supercritical CO2 into the target reservoir at a second displacement rate; wherein the second displacement rate is less than the first displacement rate.

[0009] In the embodiments of this application, the proppant includes a small molecule guar gum carrying liquid.

[0010] In this embodiment of the application, the target reservoir includes multiple target reservoir segments; the target reservoir is initially subjected to impact fracturing using supercritical CO2 in an impact fracturing device, which includes: lowering the impact fracturing device into the target reservoir; and the impact fracturing device performing supercritical CO2 initial impact fracturing on multiple target reservoir segments in the target reservoir step by step.

[0011] A second aspect of this application provides an oil and gas reservoir fracturing apparatus, comprising: a memory configured to store instructions; and a processor configured to retrieve instructions from the memory and, when executing the instructions, to implement the fracturing method for oil and gas reservoirs or geothermal reservoirs provided in any of the above embodiments.

[0012] The third aspect of this application provides an oil and gas reservoir fracturing device, comprising: a production wellbore for transporting CO2; an impact fracturing device disposed within the production wellbore; a CO2 pumping system for supplying CO2 to the production wellbore; and a monitoring device for monitoring the temperature, pressure, and displacement per unit time of CO2. The oil and gas reservoir fracturing device provided in the second aspect of this application is used to receive data from the monitoring device and control the CO2 pumping system and the impact fracturing device.

[0013] A fourth aspect of this application provides a machine-readable storage medium storing instructions that cause a machine to perform a fracturing method for oil and gas reservoirs or geothermal reservoirs according to any of the preceding embodiments.

[0014] The fracturing method for oil and gas reservoirs or geothermal reservoirs provided in this application combines supercritical CO2 injection, impact fracturing, and proppant pumping to achieve a CO2 composite impact fracturing method for oil and gas reservoirs, resulting in more efficient fracturing. Impact fracturing releases more energy in the fractures, significantly enhancing fracture propagation and allowing the fractures in the target reservoir to extend further and become more complex. This not only helps to more effectively release oil and gas resources from the target reservoir but also demonstrates greater adaptability and superiority in handling complex geological conditions, ensuring better recovery rates in diverse reservoir environments. Attached Figure Description

[0015] The accompanying drawings are provided to further illustrate the embodiments of this application and form part of the specification. They are used together with the following detailed description to explain the embodiments of this application, but do not constitute a limitation on the embodiments of this application. In the drawings:

[0016] Figure 1 The illustration shows a schematic flow diagram of a fracturing method for oil and gas reservoirs or geothermal reservoirs according to an embodiment of this application;

[0017] Figure 2 The illustration shows a schematic flow diagram of another fracturing method for oil and gas reservoirs or geothermal reservoirs according to an embodiment of this application;

[0018] Figure 3 The schematic diagram illustrates the structure of an oil and gas reservoir fracturing device according to an embodiment of this application. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for illustration and explanation of the embodiments of this application and are not intended to limit the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0020] It should be noted that the acquisition, transmission, storage, use, and processing of data in the technical solution of this application all comply with the relevant provisions of national laws and regulations. In the embodiments of this application, certain existing industry solutions such as software, components, and models may be mentioned. These should be considered exemplary, intended only to illustrate the feasibility of implementing the technical solution of this application, and do not imply that the applicant has already used or necessarily used such solutions.

[0021] If the embodiments of this application involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed in this application.

[0022] To address the shortcomings of existing fracturing technologies in terms of fracture extension distance and fracture complexity in target reservoirs, this application provides a fracturing method for oil and gas reservoirs or geothermal reservoirs that employs CO2-based composite impact fracturing. This introduces a dynamic impact effect, effectively fracturing the target reservoir and expanding the fracture network through the shock wave action of high-pressure supercritical CO2. Through multiple impact fracturing operations and continuous CO2 injection, the reservoir permeability is significantly improved, and the complexity and connectivity of the fractures are greatly enhanced.

[0023] Figure 1 This illustration schematically shows a flow diagram of a fracturing method for oil and gas reservoirs or geothermal reservoirs according to an embodiment of this application. Figure 1 As shown in the figure, this application provides a fracturing method for oil and gas reservoirs or geothermal reservoirs, which may include the following steps:

[0024] S102 continuously injects CO2 into the production shaft until the CO2 in the production shaft reaches a preset state;

[0025] S104 releases CO2 in a preset state into the target reservoir until the target reservoir reaches the expected pore pressure level, wherein the CO2 released into the target reservoir is in a supercritical state;

[0026] S106 initially impacts and fractures the target reservoir by using supercritical CO2 in the impact fracturing device when the target reservoir reaches the expected pore pressure level.

[0027] After the initial impact fracturing of the target reservoir, S108 injects supercritical CO2 into the target reservoir a second time.

[0028] After a secondary injection of supercritical CO2 into the target reservoir, S110 uses supercritical CO2 in the impact fracturing device to perform secondary impact fracturing of the target reservoir.

[0029] After secondary impact fracturing of the target reservoir, S112 injects supercritical CO2 and proppant into the target reservoir to support the fractures.

[0030] The fracturing method for oil and gas reservoirs or geothermal reservoirs provided in this application first increases the fluid pressure and pore pressure of the target reservoir by injecting supercritical CO2 into it, thereby increasing the permeability of the target reservoir and helping to open natural microfractures, reducing the minimum principal stress of the reservoir rock, and making subsequent fracturing operations more efficient. Once the target reservoir reaches the expected pore pressure level, the target reservoir is initially fracturing using supercritical CO2 in an impact fracturing device. Due to its unique rheological properties, supercritical CO2 has stronger permeability and dissolving capacity, enabling it to effectively penetrate into microfractures. The impact fracturing device can cause supercritical CO2 to impact the target reservoir in the form of high-pressure dynamic shock waves, thereby instantaneously fracturing the formation and forming new fractures, while simultaneously expanding the scale of existing fractures. This dynamic impact effect not only significantly increases the complexity of the fracture network but also promotes fracture expansion over a larger area, forming larger flow channels, thereby effectively improving the permeability of the target reservoir. After the initial impact fracturing of the target reservoir, supercritical CO2 is injected a second time to further expand the size of the existing fractures. A large amount of supercritical CO2 flows into the formation fractures, utilizing its dissolution and permeability properties to further propel the fractures deeper and wider. This process not only promotes vertical fracture development but also fosters interconnection between fractures, forming a more complex fracture network structure. To ensure sufficient fracture development, a second impact fracturing is subsequently performed on the target reservoir, utilizing the cumulative effect of multiple impacts to further expand and complicate the fracture network. Multiple impacts not only increase the number of fractures but also improve their distribution, ensuring uniform reservoir stimulation. After the second impact fracturing, supercritical CO2 and proppant are injected into the target reservoir to ensure the fractures remain stable and do not close during production. The expansion of the fracture network is crucial for improving the productivity of oil and gas wells, especially in low-permeability and tight reservoirs, where the size and complexity of fractures directly affect reservoir recoverability and oil and gas flow efficiency. The fracturing method for oil and gas reservoirs or geothermal reservoirs provided in this application combines supercritical CO2 injection, impact fracturing, and proppant pumping to achieve a CO2 composite impact fracturing method for oil and gas reservoirs, resulting in more efficient fracturing. Impact fracturing releases more energy in the fractures, significantly enhancing fracture propagation. This not only helps to more effectively release oil and gas resources from the target reservoir but also demonstrates greater adaptability and superiority in handling complex geological conditions, ensuring better recovery rates in diverse reservoir environments. Simultaneously, proppant injection enables fracture support and CO2 storage, bringing sustainable production enhancement benefits to oil and gas field development.

[0031] Understandably, CO2 enters a supercritical state when the temperature exceeds 31.1 degrees Celsius and the pressure exceeds 7.38 MPa. In step S102, the temperature and pressure of the CO2 injected into the production wellbore are higher than those required for CO2 to enter a supercritical state, ensuring that in step S104, CO2 is released into the target reservoir in a supercritical state. The expected pore pressure level in step S104 can be, for example, 90% to 95% of the formation fracturing pressure of the target reservoir. The impact fracturing device in step S106 can have a built-in venting channel. When the supercritical CO2 exceeds the pressure threshold of the impact fracturing device, the venting channel automatically opens, generating a high-pressure dynamic shock wave towards the target reservoir.

[0032] In some embodiments of this application, the fracturing method for oil and gas reservoirs or geothermal reservoirs may further include:

[0033] Microseismic testing is used to detect fracture size before fracturing in order to determine the design size of fracturing fractures in the target reservoir.

[0034] After step S110, if the fracture size of the target reservoir has not reached the design size of the fracturing fracture, supercritical CO2 is repeatedly injected into the target reservoir, and the target reservoir is fracturing by impacting the supercritical CO2 in the impact fracturing device until the fracture size of the target reservoir reaches the design size of the fracturing fracture, then step S112 is executed.

[0035] In some embodiments of this application, the proppant in step S112 includes a small molecule guar gum carrying solution.

[0036] Small molecule guar gum can serve as an excellent proppant-carrying fluid, playing a role in proppant carrying and filling in fractures, ensuring that fractures remain stable and do not close during production. Injecting CO2 in combination with small molecule guar gum proppant-carrying fluid into the target reservoir helps to evenly distribute the proppant-carrying fluid in the fracture network, further enhancing the reservoir's permeability and conductivity, ultimately achieving the goal of reservoir stimulation and maximizing the production efficiency of oil and gas wells.

[0037] In some embodiments of this application, the fracturing method for oil and gas reservoirs or geothermal reservoirs further includes:

[0038] Inject CO2 into the impact fracturing device until the CO2 in the impact fracturing device reaches the preset pressure value;

[0039] Monitor the pressure loss of the impact fracturing device within a preset time period;

[0040] Under the condition that the pressure loss does not exceed a preset ratio, the target reservoir is subjected to initial and / or secondary impact fracturing using supercritical CO2 in the impact fracturing device.

[0041] The above steps can be used to verify whether the sealing and impact performance of the impact fracturing device meet the requirements, thus demonstrating the reliability of the impact fracturing device, ensuring the success of subsequent fracturing steps, and effectively avoiding construction failures or safety accidents caused by impact fracturing device malfunctions.

[0042] Understandably, the preset pressure value can be, for example, higher than the pressure value required for impact fracturing. The preset time period can be, for example, 5 minutes, and the preset percentage can be, for example, 5%.

[0043] In some embodiments of this application, step S108 includes: simultaneously with the completion of the initial impact fracturing of the target reservoir, starting a secondary injection of supercritical CO2 into the target reservoir.

[0044] This allows the high-pressure state of the target reservoir to be maintained after initial impact fracturing. By relying on the low viscosity and high diffusivity of supercritical CO2, the reservoir is encouraged to undergo shear-type fracturing, which then expands and accumulates, connecting natural fractures to form complex fractures. This further drives the fluids within the formation, expands the existing fractures, better alters the reservoir's permeability, increases the flow channels for oil and gas, and improves the recovery rate.

[0045] In some embodiments of this application, the supercritical CO2 displacement per unit time in the secondary impact fracturing in step S110 is greater than the supercritical CO2 displacement per unit time in the initial impact fracturing in step S106.

[0046] The rate of supercritical CO2 discharge per unit time directly affects the pressure it exerts on the target reservoir. By increasing the rate of supercritical CO2 discharge per unit time during secondary impact fracturing, the supercritical CO2 can exert greater pressure on the target reservoir. This allows the secondary impact fracturing to continue propagating fractures along new stress paths, particularly connecting and extending previously formed microfractures, and increasing the number of new fractures, thereby expanding the coverage of the fracture network.

[0047] See Figure 2 In some embodiments of this application, the fracturing method for oil and gas reservoirs or geothermal reservoirs further includes:

[0048] S202. After injecting supercritical CO2 into the target reservoir for the second time, detect the fracture extension distance of the target reservoir.

[0049] S204. When the fracture extension distance is greater than a preset distance, a second impact fracturing of supercritical CO2 is performed on the target reservoir at a first displacement rate; when the fracture extension distance is less than or equal to the preset distance, a second impact fracturing of supercritical CO2 is performed on the target reservoir at a second displacement rate; wherein the second displacement rate is less than the first displacement rate.

[0050] If the fracture extension distance in the target reservoir does not reach the preset distance, it indicates that the supercritical CO2 displacement per unit time during the initial impact fracturing is too small and insufficient to extend the fractures in the target reservoir to the ideal distance. Therefore, the supercritical CO2 displacement per unit time should be increased during the secondary impact fracturing to increase the pressure of supercritical CO2 on the target reservoir during the secondary impact fracturing process, thereby allowing the fractures in the target reservoir to extend further.

[0051] Understandably, the fracture extension distance in the target reservoir can be determined through microseismic detection, and the preset distance can be selected within, for example, between 50 and 70 meters. The supercritical CO2 emission rate of the secondary impact fracturing can be greater than that of the primary impact fracturing to achieve better fracture extension.

[0052] In some embodiments of this application, the target reservoir includes multiple target reservoir segments;

[0053] Step S106 may include:

[0054] The impact fracturing device is lowered into the target reservoir;

[0055] The impact fracturing device performs supercritical CO2 initial impact fracturing on multiple target reservoir sections in the target reservoir step by step.

[0056] The above steps allow the impact fracturing device to perform supercritical CO2 preliminary impact fracturing on multiple target reservoir sections in a single run-in process. Operators can perform fracturing operations section by section according to the specific conditions of the target reservoir, without repeatedly pulling the impact fracturing device. This multi-stage construction method not only improves construction efficiency and reduces operation time, but also reduces the risks of downhole operations. When supercritical CO2 fluid is continuously pumped into the device and pressurized, the pressure inside the tubing gradually rises until it exceeds the designed fracturing pressure. At this point, the high-pressure nozzles inside the impact fracturing device automatically open, and supercritical CO2 is injected into the surrounding reservoir rock, forming a dynamic shock wave. This shock wave can instantly fracture the formation, forming a new fracture network and expanding existing fractures, greatly improving reservoir permeability.

[0057] The following describes, by way of example, a fracturing process for an oil and gas reservoir or a geothermal reservoir, based on the fracturing method for oil and gas reservoirs provided in the embodiments of this application.

[0058] Before CO2 injection can commence, a comprehensive geological exploration and reservoir assessment are necessary. Detailed reservoir analysis yields crucial information, including geological characteristics, reserves, porosity, and permeability. These parameters will guide subsequent fracturing design, ensuring effective reservoir modification and increased oil and gas production during the fracturing process.

[0059] Well site preparation is carried out before formal construction. If necessary, a liquid CO2 storage tank of appropriate capacity will be selected according to the construction design requirements to ensure a continuous supply of liquid CO2 during construction. Buffer tanks are used to balance the flow rate and pressure of liquid CO2 to prevent fluctuations during pumping. In addition, fracturing trucks and other conventional fracturing equipment, such as high-pressure pumps and sand mixing trucks, are also arranged at the well site. To ensure smooth construction, the positioning and connection of all equipment are carried out in accordance with the construction design and safety specifications to avoid any unnecessary delays or safety hazards during pumping.

[0060] After the equipment is ready, the next step is to connect the various components to the manifold. In this step, the liquid CO2 storage tank is connected to the buffer tank via a dedicated pipeline, and then the buffer tank is connected to the fracturing pump to ensure that the liquid CO2 can be injected into the formation at a stable flow rate and pressure. In addition, the high-pressure manifold needs to be connected to the wellhead, and pressure tests must be performed on both the manifold and the wellhead. The purpose of the pressure test is to ensure that the entire system will not leak or burst during the pumping of liquid CO2. This test is usually conducted under conditions higher than the operating pressure to ensure safety and reliability in actual operation.

[0061] A thorough overhaul and cleaning of the wellbore is necessary to ensure it remains unobstructed. This includes removing any blockages or deposits that could hinder CO2 injection. Additionally, the wellhead equipment must be inspected and maintained to ensure it meets the technical requirements for CO2 pumping and can withstand high-pressure CO2 injection. After all equipment connections and pressure tests are completed, liquid CO2 injection can begin according to the predetermined fracturing design. A CO2 injection scheme is designed based on geological and wellbore conditions, specifying parameters such as injection rate, injection cycle, and pumping pressure, before supercritical CO2 is injected into the target reservoir.

[0062] After the injection of liquid CO2 is completed, the wellbore pressure is monitored. By observing pressure changes within the wellbore, operators can determine the effect of liquid CO2 on the reservoir and the reservoir's response. In particular, it is necessary to observe the pressure drop and recovery to assess the formation's fracture state and fluid flowback capacity. Specifically, a pressure drop indicates that liquid CO2 has successfully entered the reservoir, and the reservoir can absorb the liquid CO2 for subsequent fracture impact and fracturing stimulation. Furthermore, the pressure drop trend is consistent with the formation's absorption capacity, and there is no excessively rapid drop (an excessively rapid drop may indicate formation leakage or other problems). A reasonable and moderate pressure drop indicates that the reservoir has undergone sufficient stress, forming new fractures or expanding existing ones. Subsequently, the pressure recovery curve is used to determine whether liquid CO2 is flowback within the formation. If some liquid CO2 begins to flowback, it means that a reservoir fracture network has formed and has fluid conductivity, thus confirming that the pressure recovery is as expected. If the pressure drop and recovery are as expected, it indicates that the reservoir has achieved the desired stimulation effect, and subsequent fracturing operations can continue.

[0063] Test the impact fracturing device by continuously injecting liquid CO2 fracturing fluid into it; after the pressure reaches the design pressure value, stop the injection and observe the pressure value change in the impact fracturing device; if the pressure value loss does not exceed 5% within 5 minutes, the impact requirement is met.

[0064] In the formation section requiring fracturing, perforation guns are used to create holes in the wellbore to allow subsequent fracturing fluid to enter the formation. The impact fracturing device is then lowered into the target section and secured using the working tubing. Supercritical CO2 fluid is pumped into the device and continuously pressurized. When the pressure inside the fracturing string exceeds the engineering design pressure, the nozzle of the impact fracturing device is opened. The supercritical CO2 fluid enters the formation through the perforation holes, dynamically impacting and fracturing the formation to form complex fractures and increase the seepage channels for oil and gas.

[0065] Subsequently, supercritical CO2 was injected a second time into the target reservoir. The impact fracturing device was then pressure tested, with liquid CO2 fracturing fluid continuously injected. Once the pressure reached the design pressure, injection was stopped, and the pressure change within the impact fracturing device was observed. If the pressure loss did not exceed 5% within 5 minutes, the impact requirement was met. In the target formation section requiring fracturing, perforations were created again in the wellbore using a perforating gun to allow subsequent fracturing fluid to enter the formation. The impact fracturing device was then lowered into the target formation using the work tubing and secured. Supercritical CO2 fluid was pumped into the device and continuously pressurized. When the pressure within the fracturing string exceeded the engineering design pressure, the nozzle of the impact fracturing device was opened. The supercritical CO2 fluid entered the formation through the perforations, dynamically impacting the formation a second time, increasing the fracture size, and forming a highly efficient oil flow channel.

[0066] A large-volume CO2 pump was injected again to maintain the open state of the fracture under high pressure and high speed. Small molecule guar gum was injected along with sand and fluid into the deep formation microfractures and fractures generated by impact fracturing to increase the migration distance of the proppant, form support in the fractures, and maintain the conductivity of the artificial fractures after impact.

[0067] The fracturing method for oil and gas reservoirs or geothermal reservoirs provided in this application can further improve reservoir stimulation and oil and gas production. This method introduces a dynamic impact effect, effectively fracturing the reservoir and expanding the fracture network through the shock wave action of high-pressure supercritical CO2. Through multiple impact fracturing operations and continuous CO2 injection, the reservoir permeability is significantly improved, and the complexity and connectivity of the fractures are greatly enhanced. This method overcomes the limitations of traditional CO2 fracturing, further improving the proppant migration distance and fracture support effect, ensuring the long-term unobstructed flow channels for oil and gas. This method not only significantly improves the reservoir fracturing stimulation effect but also achieves permanent CO2 sequestration while reducing water consumption, making an important contribution to the sustainable development of the petroleum industry and the achievement of global carbon neutrality goals.

[0068] This application also provides an oil and gas reservoir fracturing apparatus, including a memory and a processor. The memory is configured to store instructions; the processor is configured to retrieve instructions from the memory and, when executing the instructions, to implement the fracturing method for oil and gas reservoirs or geothermal reservoirs provided in any of the above embodiments.

[0069] See Figure 3 This application also provides an oil and gas reservoir fracturing device, including: a production wellbore 302, an impact fracturing device 304, a CO2 injection system 306, a monitoring device 308, and the aforementioned oil and gas reservoir fracturing device 310.

[0070] The production wellbore 302 is used to transport CO2; the impact fracturing device 304 is located inside the production wellbore 302; the CO2 pumping system is used to transport CO2 into the production wellbore 302; the monitoring device 308 is used to monitor the temperature, pressure, and displacement per unit time of CO2; the oil and gas reservoir fracturing device 310 is used to receive the data from the monitoring device 308 and control the CO2 pumping system 306 and the impact fracturing device 304.

[0071] This application also provides a machine-readable storage medium storing instructions that cause a machine to perform the fracturing method for oil and gas reservoirs or geothermal reservoirs described above.

[0072] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0073] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0074] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0075] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0076] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0077] Memory may include non-persistent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0078] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0079] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0080] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A fracturing method for oil and gas reservoirs or geothermal reservoirs, characterized in that, include: CO2 is continuously injected into the wellbore until the CO2 in the wellbore reaches a preset state. The CO2 in the preset state is released into the target reservoir until the target reservoir reaches the expected pore pressure level, wherein the CO2 released into the target reservoir is in a supercritical state; When the target reservoir reaches the expected pore pressure level, the target reservoir is initially subjected to impact fracturing using supercritical CO2 in an impact fracturing device. After the initial impact fracturing of the target reservoir, supercritical CO2 is injected into the target reservoir a second time; After the secondary injection of supercritical CO2 into the target reservoir, the target reservoir is subjected to secondary impact fracturing using supercritical CO2 in the impact fracturing device. After the secondary impact fracturing of the target reservoir, supercritical CO2 and proppant are injected into the target reservoir to support the fractures.

2. The method of claim 1, wherein, Also includes: CO2 is injected into the impact fracturing device until the CO2 in the impact fracturing device reaches a preset pressure value; Monitor the pressure loss of the impact fracturing device within a preset time period; If the pressure loss does not exceed a preset ratio, the target reservoir is subjected to initial and / or secondary impact fracturing using supercritical CO2 within the impact fracturing device.

3. The method of claim 1, wherein, The step of injecting supercritical CO2 into the target reservoir a second time after the initial impact fracturing of the target reservoir includes: Simultaneously with the completion of the initial impact fracturing of the target reservoir, a secondary injection of supercritical CO2 into the target reservoir begins.

4. The method of claim 1, wherein, The rate of discharge of supercritical CO2 per unit time during the secondary impact fracturing is greater than that during the primary impact fracturing.

5. The method of claim 4, wherein, Also includes: After the secondary injection of supercritical CO2 into the target reservoir, the fracture extension distance of the target reservoir is detected; If the fracture extension distance is greater than a preset distance, the secondary impact fracturing of supercritical CO2 is performed on the target reservoir at a first displacement. When the fracture extension distance is less than or equal to the preset distance, the secondary impact fracturing of supercritical CO2 is performed on the target reservoir at a second displacement rate; wherein the second displacement rate is less than the first displacement rate.

6. The method of claim 1, wherein, The proppant comprises a small molecule guar gum-carrying liquid.

7. The method of claim 1, wherein, The target reservoir includes multiple target reservoir segments; The preliminary impact fracturing of the target reservoir using supercritical CO2 within an impact fracturing device includes: The impact fracturing device is lowered into the target reservoir; The impact fracturing device performs supercritical CO2 initial impact fracturing on multiple target reservoir sections in the target reservoir step by step.

8. An oil and gas reservoir fracturing apparatus, characterized by, include: The memory is configured to store instructions; The processor is configured to retrieve the instructions from the memory and, when executing the instructions, to implement the fracturing method for oil and gas reservoirs or geothermal reservoirs according to any one of claims 1 to 7.

9. An oil and gas reservoir fracturing apparatus, characterized by, include: Mining shafts are used to transport CO2. An impact fracturing device is installed inside the wellbore. A CO2 pumping system for supplying CO2 into the wellbore; The monitoring device is used to monitor the temperature, pressure, and emission rate of CO2 per unit time. The oil and gas reservoir fracturing device according to claim 8 is used to receive data from the monitoring device and control the CO2 injection system and the impact fracturing device.

10. A machine-readable storage medium, characterized in that, The machine-readable storage medium stores instructions for causing the machine to perform a fracturing method for oil and gas reservoirs or geothermal reservoirs according to any one of claims 1 to 7.

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