A rock flexible fracturing system and a fracturing method thereof

Abstract

The application provides a rock flexible fracturing system and a fracturing method thereof. The system comprises a high-pressure servo pump, a low-pressure injection pump, a high-pressure stop valve, a control terminal and a pressure sensor. The high-pressure servo pump and the low-pressure injection pump are connected through the high-pressure stop valve. The high-pressure servo pump is connected with the pressure sensor. Before the high-pressure servo pump is started, the low-pressure injection pump is used to inject fracturing fluid into the high-pressure cylinder of the high-pressure servo pump, so as to discharge the air in the high-pressure cylinder and provide starting pressure for the high-pressure servo pump. The pressure sensor is used to obtain the initial pressure of the high-pressure servo pump when the high-pressure servo pump is injected with the fracturing fluid, and send the initial pressure to the control terminal. The control terminal is used to control the high-pressure stop valve to be closed, control the low-pressure injection pump to be stopped, control the high-pressure servo pump to be started and perform fracturing on the rock sample according to the initial pressure. Based on the above system, the air in the high-pressure cylinder can be discharged by the low-pressure injection pump before fracturing, and the pulse precision of the high-pressure servo pump is improved.

Description

Technical Field

[0001] This specification belongs to the field of rock fracturing technology, and in particular relates to a flexible rock fracturing system and its fracturing method. Background Technology

[0002] Hydraulic fracturing is a widely used method for enhancing oil and gas well production. It involves injecting pressurized fluid into the wellbore at a constant injection rate to disrupt the reservoir through pressure buildup, thereby extracting oil and gas resources. Before hydraulic fracturing, rock fracturing systems are typically used to conduct fracturing experiments on rock samples to obtain their physical properties during the fracturing process, providing a data foundation for hydraulic fracturing. Existing rock fracturing systems are single-pump systems, consisting only of a high-pressure servo pump. The high-pressure servo pump draws fracturing fluid and injects it into a high-pressure cylinder, where the high-pressure servo pump then performs the fracturing. This method cannot adequately purge air from the high-pressure cylinder before fracturing, resulting in poor pulse accuracy of the high-pressure servo pump and making it difficult to obtain accurate rock physical property parameters.

[0003] There is currently no effective solution to the aforementioned technical problems. Summary of the Invention

[0004] This application provides a flexible rock fracturing system and fracturing method, which can improve the accuracy of fracturing control.

[0005] The purpose of this application is to provide a flexible rock fracturing system, which includes at least a high-pressure servo pump, a low-pressure injection pump, a high-pressure shut-off valve, a control terminal, and a pressure sensor. The high-pressure servo pump and the low-pressure injection pump are connected through the high-pressure shut-off valve. The high-pressure servo pump and the pressure sensor are connected. Before the high-pressure servo pump is started, the low-pressure injection pump injects fracturing fluid into the high-pressure cylinder of the high-pressure servo pump to expel air from the high-pressure cylinder and provide starting pressure for the high-pressure servo pump. The pressure sensor acquires the initial pressure of the high-pressure servo pump when fracturing fluid is injected and sends the initial pressure to the control terminal. The control terminal controls the high-pressure shut-off valve to close, the low-pressure injection pump to stop, and the high-pressure servo pump to start and fracture the rock sample based on the initial pressure.

[0006] Furthermore, in another embodiment of the system, the control terminal is used to control the high-pressure shut-off valve to close, control the low-pressure injection pump to stop, and control the high-pressure servo pump to start and fracturing the rock sample based on the initial pressure, including:

[0007] The control terminal is used to detect whether the initial pressure meets the preset start-up conditions;

[0008] If the initial pressure meets the preset start-up conditions, the control terminal sends a stop command to the low-pressure injection pump; the low-pressure injection pump executes the stop command and stops injecting fracturing fluid.

[0009] If the initial pressure meets the preset start-up conditions, the control terminal sends a shut-off command to the high-pressure shut-off valve; the high-pressure shut-off valve executes the shut-off command and performs a shut-off process.

[0010] If the initial pressure meets the preset start-up conditions, the control terminal is also used to send a start-up command to the high-pressure servo pump; the high-pressure servo pump is used to execute the start-up command to fracture the rock sample.

[0011] Furthermore, in another embodiment of the system, the system further includes a high-pressure unloading valve; the high-pressure unloading valve is connected to the high-pressure servo pump.

[0012] Furthermore, in another embodiment of the system, the pressure sensor is also used to acquire the first pulse pressure of the high-pressure servo pump during the pressurization stroke when the high-pressure servo pump is started, and send the first pulse pressure to the control terminal;

[0013] The control terminal is used to detect whether the first pulse pressure is greater than the first pressure threshold; if it is determined that the first pulse pressure is greater than the first pressure threshold, a stop command is sent to the high-pressure servo pump and an opening command is sent to the high-pressure unloading valve; the high-pressure servo pump is used to execute the stop command to stop fracturing the rock sample; the high-pressure unloading valve is used to execute the opening command to open and discharge the fracturing fluid in the high-pressure servo pump.

[0014] Furthermore, in another embodiment of the system, the system further includes a position sensor; the position sensor is connected to the high-pressure servo pump; the position sensor is used to acquire the position information of the high-pressure piston rod in the high-pressure servo pump when the high-pressure servo pump is started, and send the position information to the control terminal.

[0015] Furthermore, in another embodiment of the system, the pressure sensor is also used to acquire the second pulse pressure of the high-pressure servo pump during the decompression stroke when the high-pressure servo pump is started, and send the second pulse pressure to the control terminal; the control terminal is also used to send a high-pressure piston rod stroke adjustment command to the high-pressure servo pump according to the first pulse pressure, the second pulse pressure, and the position information; the high-pressure servo pump is used to execute the high-pressure piston rod stroke adjustment command to adjust the stroke range of the high-pressure piston rod, so as to change the first pulse pressure and / or the second pulse pressure of the high-pressure servo pump.

[0016] Furthermore, in another embodiment of the system, after the stroke range of the high-pressure piston rod is adjusted, the pressure sensor is used to acquire the adjusted first pulse pressure of the high-pressure servo pump and send the adjusted first pulse pressure to the control terminal.

[0017] The control terminal is used to detect whether the adjusted first pulse pressure meets the first pressure range.

[0018] If the adjusted first pulse pressure does not meet the first pressure range, the control terminal is also used to send an opening command to the high-pressure shut-off valve and a start command to the low-pressure injection pump; the high-pressure shut-off valve is used to execute the opening command and perform the opening process; the low-pressure injection pump is used to execute the start command and inject fracturing fluid into the high-pressure cylinder of the high-pressure servo pump.

[0019] Furthermore, in another embodiment of the system, the system further includes a status sensor; the status sensor is connected to the high-pressure servo pump;

[0020] The status sensor is used to acquire the number of pulses of the high-pressure piston rod in the high-pressure servo pump when the high-pressure servo pump is started, and send the number of pulses to the control terminal.

[0021] The control terminal is used to receive the number of pulses and detect whether the number of pulses meets the preset stop condition;

[0022] If the number of pulses meets the preset stopping conditions, the control terminal sends a stop command to the high-pressure servo pump; the high-pressure servo pump executes the stop command to stop fracturing the rock sample.

[0023] Furthermore, in another embodiment of the system, the system further includes a clamping device; the clamping device is connected to the high-pressure servo pump; the clamping device is used to clamp the rock sample.

[0024] The purpose of this application embodiment is to provide a flexible rock fracturing method, which is applied to the flexible rock fracturing system and includes:

[0025] The control terminal receives preset startup conditions;

[0026] The low-pressure injection pump injects fracturing fluid into the high-pressure cylinder of the high-pressure servo pump;

[0027] The pressure sensor acquires the initial pressure of the high-pressure servo pump and sends the initial pressure to the control terminal;

[0028] The control terminal detects whether the initial pressure meets the preset start-up conditions;

[0029] If the initial pressure meets the preset start-up conditions, the control terminal sends a stop command to the low-pressure injection pump, a close command to the high-pressure shut-off valve, and a start command to the high-pressure servo pump.

[0030] The low-pressure injection pump receives and executes a stop command to stop injecting fracturing fluid.

[0031] The high-pressure shut-off valve receives and executes the closing command to perform the closing process;

[0032] The high-pressure servo pump receives and executes the start command to fracturing the rock sample. Attached Figure Description

[0033] To more clearly illustrate the embodiments of this specification, the accompanying drawings used in the embodiments will be briefly introduced below. The drawings described below are only some embodiments recorded in this specification. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of the rock flexible fracturing system provided in the embodiments of this specification;

[0035] Figure 2 This is a schematic diagram of the high-pressure servo pump provided in the embodiments of this specification;

[0036] Figure 3 This is a schematic diagram of the confined pressure vessel and true triaxial pressurization system provided in the embodiments of this specification;

[0037] Figure 4 This specification provides a schematic diagram of the structure of a specific flexible rock fracturing system as an embodiment.

[0038] Figure 5 A schematic flowchart of a flexible rock fracturing method provided for embodiments of this specification;

[0039] Figure 6 A schematic flowchart of a flexible rock fracturing method provided for embodiments of this specification;

[0040] Figure 7 This is a schematic diagram of the structure of a flexible rock fracturing device provided in the embodiments of this specification;

[0041] Figure 8 A schematic diagram of one embodiment of the server structure provided in this specification;

[0042] Figure 9 This is a schematic diagram of a square wave provided for an embodiment of this specification;

[0043] Figure 10 This is a schematic diagram of a sine wave provided for an embodiment of this specification;

[0044] Figure 11 This is a schematic diagram of a triangular wave provided for an embodiment of this specification;

[0045] Figure 12 This is a schematic diagram of the ramp waveform provided in the embodiments of this specification;

[0046] Figure 13 This is a schematic diagram of the step-by-step boost waveform provided for the embodiments of this specification. Detailed Implementation

[0047] To enable those skilled in the art to better understand the technical solutions in this specification, the technical solutions in the embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this specification, and not all embodiments. Based on the embodiments in this specification, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this specification.

[0048] Hydraulic fracturing is a widely used method for enhancing oil and gas well production. It involves injecting pressurized fluid into the wellbore at a constant injection rate to disrupt the reservoir through pressure buildup, thereby extracting oil and gas resources. Before hydraulic fracturing, rock fracturing systems are typically used to conduct fracturing experiments on rock samples to obtain their physical properties during the fracturing process, providing a data foundation for hydraulic fracturing. However, existing rock fracturing systems are single-pump systems, consisting only of a high-pressure servo pump. The servo pump draws fracturing fluid and injects it into a high-pressure cylinder, which then performs the fracturing. This method fails to adequately purge air from the high-pressure cylinder before fracturing, resulting in poor pulse accuracy from the servo pump and making it difficult to obtain accurate rock physical property parameters.

[0049] Geothermal energy is a renewable "green energy" with significant application value and strong competitiveness. Compared with new energy sources such as solar, wind, and nuclear power, it has advantages such as high efficiency, stability, and no seasonal or diurnal limitations. The main type of geothermal resource is hot dry rock. Enhanced Geothermal Systems (EGS) are one of the current methods for mining hot dry rock and are widely used in hot dry rock geothermal development projects. The main technical means for mining hot dry rock is also hydraulic fracturing. However, considering the disadvantages of existing hot dry rock hydraulic fracturing, such as consuming large amounts of water resources, frequent microseismic events, high fracturing pressure, and uniform fracture morphology, it seriously restricts the development and utilization of hot dry rock.

[0050] In view of the above-mentioned problems in existing methods and the specific reasons for these problems, this application proposes a rock flexible fracturing system and fracturing method that can use a low-pressure injection pump to expel air from a high-pressure servo pump, improve the pulse accuracy of the high-pressure servo pump, and thus obtain more accurate fracturing results.

[0051] See Figure 1 As shown in the figure, this specification proposes a flexible rock fracturing system. The system includes: a high-pressure servo pump 1, a low-pressure injection pump 3, a high-pressure shut-off valve 2, a control terminal 5, and a pressure sensor 4; the high-pressure servo pump 1 and the low-pressure injection pump 3 are connected via the high-pressure shut-off valve 2; the high-pressure servo pump 1 and the pressure sensor 4 are connected; before the high-pressure servo pump 1 is started, the low-pressure injection pump 3 injects fracturing fluid into the high-pressure cylinder of the high-pressure servo pump 1 to expel air from the high-pressure cylinder and provide starting pressure for the high-pressure servo pump 1; the pressure sensor 4 acquires the initial pressure of the high-pressure servo pump 1 when fracturing fluid is injected and sends the initial pressure to the control terminal 5; the control terminal 5 controls the high-pressure shut-off valve 2 to close, the low-pressure injection pump 3 to stop, and the high-pressure servo pump 1 to start and fracture the rock sample based on the initial pressure.

[0052] In some embodiments, the high-pressure servo pump, the low-pressure injection pump, and the high-pressure shut-off valve are connected by pipelines; the low-pressure injection pump can also be used to purge air from the pipelines.

[0053] In some embodiments, before fracturing begins, fracturing fluid is injected into the high-pressure servo pump using a low-pressure injection pump to expel air from the high-pressure cylinder and pipeline. This achieves the following technical effects: (1) Preventing air bubbles from affecting fluid flow: Air bubbles may cause unstable fluid flow, thus affecting the repeatability and accuracy of the fracturing experiment; by expelling air, air bubbles can be prevented from affecting fluid flow; (2) Preventing pressure changes in the pipeline: If air is present in the pipeline, its high compressibility will cause changes in the pipeline pressure, thus affecting the fracturing experiment; expelling air can maintain stable pressure conditions in the pipeline, ensuring the controllability of the fracturing experiment; (3) Improving the accuracy of the fracturing experiment: In pulsed hydraulic fracturing experiments, even tiny air bubbles may adversely affect the experimental results (e.g., causing unstable pulse pressure); by expelling air, the purity of the fracturing medium can be ensured, thereby improving the accuracy of the experimental results. Therefore, by expelling air from the high-pressure cylinder and pipeline beforehand, the pulse accuracy of the high-pressure servo pump can be improved, thus improving the accuracy of the fracturing experiment.

[0054] In some embodiments, see Figure 2 As shown, Figure 2This is a schematic diagram of a high-pressure servo pump, also known as a high-pressure servo pulse pump. Specifically, it includes: an outlet 201, an injection port 202, an upper limit of the high-pressure piston 203, a high-pressure cylinder 204, a low-friction sealing assembly 205, a high-pressure piston rod 206, a lower limit of the high-pressure piston 207, a servo motor 208, a precision lead screw 209, a transmission device 210, and a mounting base 211. The low-pressure injection pump injects fracturing fluid into the high-pressure cylinder 204 through the injection port 202, expelling air from the high-pressure cylinder 204 and the pipeline. The servo motor 208 controls the precision lead screw 209, which in turn drives the high-pressure piston rod 206 to move along the axis (vertical direction) of the high-pressure cylinder 204. Inside the high-pressure cylinder 204, the high-pressure piston rod 206 performs a reciprocating stroke between the upper limit of the high-pressure piston 203 and the lower limit of the high-pressure piston 207, pressurizing the fracturing fluid and thus hydraulically fracturing the rock sample. The low-friction sealing assembly 205 seals the high-pressure cylinder 204 to prevent fracturing fluid leakage and minimize frictional energy loss. After fracturing is completed, the fracturing fluid is discharged through the outlet 201. A midpoint exists between the upper limit 203 and lower limit 207 of the high-pressure piston. When the high-pressure piston rod 206 moves between this midpoint and the upper limit 203, it is called the "pressurization stroke," which pressurizes the rock sample. When the high-pressure piston rod 206 moves between this midpoint and the lower limit 207, it is called the "depressurization stroke," which depressurizes the rock sample. Both the outlet 201 and the injection port 202 are equipped with sealing collars to prevent fracturing fluid leakage. The transmission device 210 is connected to the high-pressure piston rod 206. The outlet 201 is connected to the clamping device. The lower limit 207 of the high-pressure piston in the high-pressure servo pump can be connected to the control terminal via a data cable to transmit data; alternatively, the high-pressure servo pump can send data to the control terminal wirelessly without a data cable connection. Specifically, the injection port 202 is connected to the low-pressure injection pump through the first channel, the high-pressure piston lower limit 207 is connected to the control terminal through the second channel (data line), and the outlet 201 is connected to the bearing device through the third channel.

[0055] In some embodiments, the system further includes a supply tank for holding fracturing fluid. This application uses a flexible medium as the fracturing fluid, such as liquid nitrogen or supercritical carbon dioxide. Compared to water-based fracturing fluids, flexible media offer the following advantages: they can penetrate any micro-space larger than their molecular size, facilitating micro-fracture formation; after fracturing, they are easily flowed back, causing minimal damage to the reservoir. The supply tank is connected to the low-pressure injection pump and the high-pressure servo pulse pump via pipelines. Specifically, the supply tank is connected to the injection port of the high-pressure servo pulse pump. The supply tank is made of metal, possessing low-temperature and high-pressure resistance characteristics. An insulation layer is provided in the supply tank to keep the flexible medium warm. The fracturing method in this application is flexible fracturing, which also belongs to pulsed hydraulic fracturing.

[0056] In some embodiments, the control terminal is used to control the high-pressure shut-off valve to close, the low-pressure injection pump to stop, and the high-pressure servo pump to start and fracturing the rock sample based on the initial pressure, including:

[0057] The control terminal is used to detect whether the initial pressure meets the preset start-up conditions;

[0058] If the initial pressure meets the preset start-up conditions, the control terminal sends a stop command to the low-pressure injection pump; the low-pressure injection pump executes the stop command and stops injecting fracturing fluid.

[0059] If the initial pressure meets the preset start-up conditions, the control terminal sends a shut-off command to the high-pressure shut-off valve; the high-pressure shut-off valve executes the shut-off command and performs a shut-off process.

[0060] If the initial pressure meets the preset start-up conditions, the control terminal is also used to send a start-up command to the high-pressure servo pump; the high-pressure servo pump is used to execute the start-up command to fracture the rock sample.

[0061] In some embodiments, the preset start-up condition can be that the initial pressure is greater than a second pressure threshold (e.g., 5 MPa) and remains constant. When the initial pressure is greater than the second pressure threshold and remains constant, it indicates that the high-pressure cylinder is filled with sufficient fracturing fluid to provide kinetic energy for hydraulic fracturing. When the initial pressure is greater than the second pressure threshold and remains constant, the initial pressure serves as the start-up pressure, enabling the high-pressure servo pump to reach the target pressure (i.e., meet the first pressure range) more quickly, thus satisfying the user's requirements.

[0062] In some embodiments, the high-pressure shut-off valve is in a closed state during fracturing, thus isolating the high-pressure servo pump from the low-pressure injection pump and preventing excessive fracturing fluid from entering the high-pressure servo pump and causing interference. A pilot valve control chip is installed on the high-pressure shut-off valve, which executes opening or closing commands sent by the control terminal to control the high-pressure shut-off valve to open or close.

[0063] In some embodiments, the system further includes a clamping device; the clamping device is connected to the high-pressure servo pump; the clamping device is used to clamp the rock sample; the rock sample may be a rock outcrop (granite, dolomite, etc.), a cubic rock block cut from an artificial rock sample (cement), etc.

[0064] In some embodiments, the system further includes a vent valve. A vent valve is installed between the bearing device and the high-pressure servo pump. The high-pressure pulse pump and the low-pressure injection pump are connected via pipelines. When the low-pressure injection pump injects fracturing fluid into the high-pressure cylinder of the high-pressure servo pump, the vent valve is open, and air in the high-pressure cylinder and the pipeline is discharged from the vent valve. The vent valve closes when the initial pressure meets preset start-up conditions.

[0065] In some embodiments, the system further includes a true triaxial confining pressure vessel (hereinafter referred to as the confining pressure vessel), a true triaxial pressurization system, a holding device, and a rock sample placed inside the confining pressure vessel. The confining pressure vessel and the true triaxial pressurization system are used to provide confining pressure (stress) to the rock sample. The confining pressure vessel can hold 100 mm... 3 Up to 400mm 3 It can process rock samples of various sizes and also has a heating function, with a maximum heating temperature of 400°C.

[0066] In a specific scenario example, see Figure 3 As shown, the confining pressure vessel includes a top plate (pressure plate), side plates, and a bottom plate. The side length of the top plate, side plates, and bottom plate is equal to 400mm, and there is a circular hole with a diameter Φ equal to 20mm on the top plate. Pipelines pass through the circular hole, and fracturing fluid is injected through the pipelines. The top plate (pressure plate), side plates, and bottom plate are combined to form a confining pressure chamber, where the rock sample and clamping device are located. An interface is connected to a high-pressure servo pump. A confining pressure vessel valve is installed between the interface and the confining pressure vessel to control the injection of fracturing fluid. A true triaxial pressurization system is connected to the confining pressure vessel to apply triaxial stress (X-axis, Y-axis, Z-axis stress) to the rock sample. The true triaxial pressurization system also includes a pressure relief valve; if the triaxial stress is too high, the pressure relief valve opens to reduce the pressure. The true triaxial pressurization system is connected to a control terminal, whose display screen shows the system's operating waveform (S), pulse period (T), and pulse pressure (P).

[0067] In some embodiments, the system further includes a check valve. A check valve is installed between the high-pressure shut-off valve and the low-pressure injection pump, controlling the unidirectional flow of the liquid. The fracturing fluid can only flow from the low-pressure injection pump to the high-pressure servo pump via the check valve, but cannot flow from the high-pressure servo pump to the low-pressure injection pump.

[0068] In some embodiments, the system further includes a power module connected to the high-voltage servo pump to supply power to the high-voltage servo pump.

[0069] In some embodiments, the system further includes a pressure regulating valve. The pressure regulating valve is connected to the low-pressure injection pump. The user can manually control the pressure regulating valve to reduce the pressure inside the low-pressure injection pump, ensuring experimental safety.

[0070] In some embodiments, the system further includes a pressure gauge connected to a high-pressure servo pump for collecting and displaying the pressure inside the high-pressure servo pump.

[0071] In some embodiments, the system further includes a high-pressure unloading valve connected to the high-pressure servo pump. The high-pressure unloading valve is also connected to a supply tank. A pilot valve control chip is installed on the high-pressure unloading valve, which executes opening or closing commands sent by the control terminal to control the high-pressure unloading valve to open or close.

[0072] In some embodiments, after the high-pressure servo pump is started, the high-pressure piston rod reciprocates between the upper and lower limits of the high-pressure piston, pressurizing the fracturing fluid and thus hydraulically fracturing the rock sample. There is a midpoint between the upper and lower limits of the high-pressure piston. When the high-pressure piston rod moves between this midpoint and the upper limit, it is called the "pressurization stroke," which pressurizes the rock sample. The maximum pressure during the pressurization stroke (when the high-pressure piston rod is at the very front of the forward stroke) is called the first pulse pressure. When the high-pressure piston rod moves between the midpoint and the lower limit, it is called the "decompression stroke," which depressurizes the rock sample. The minimum pressure during the decompression stroke is called the second pulse pressure (when the high-pressure piston rod is at the very rear of the backward stroke). The first pulse pressure is greater than the second pulse pressure.

[0073] In some embodiments, the pressure sensor is further configured to acquire the first pulse pressure of the high-pressure servo pump during the pressurization stroke when the high-pressure servo pump is started, and send the first pulse pressure to the control terminal; the control terminal is configured to detect whether the first pulse pressure is greater than a first pressure threshold; if it is determined that the first pulse pressure is greater than the first pressure threshold, a stop command is sent to the high-pressure servo pump, and an opening command is sent to the high-pressure unloading valve; the high-pressure servo pump is configured to execute the stop command to stop fracturing the rock sample; the high-pressure unloading valve is configured to execute the opening command to open and discharge the fracturing fluid in the high-pressure servo pump.

[0074] In some embodiments, the first pressure threshold can be set to 30 MPa. When the first pulse pressure exceeds the first pressure threshold, it indicates that the pressure inside the high-pressure cylinder is too high, posing a safety hazard, and therefore immediate unloading is required. At this time, the high-pressure servo pump stops operating, stops fracturing the rock sample, the high-pressure unloading valve opens, and the fracturing fluid in the high-pressure cylinder of the high-pressure servo pump flows back to the supply tank through the pipeline.

[0075] In some embodiments, the system further includes a position sensor; the position sensor is connected to the high-pressure servo pump; the position sensor is used to acquire the position information of the high-pressure piston rod in the high-pressure servo pump when the high-pressure servo pump is started, and to send the position information to the control terminal.

[0076] In some embodiments, the pressure sensor is further configured to acquire the second pulse pressure of the high-pressure servo pump during the decompression stroke when the high-pressure servo pump is started, and send the second pulse pressure to the control terminal; the control terminal is further configured to send a high-pressure piston rod stroke adjustment command to the high-pressure servo pump according to the first pulse pressure, the second pulse pressure, and the position information; the high-pressure servo pump is configured to execute the high-pressure piston rod stroke adjustment command to adjust the stroke range of the high-pressure piston rod, so as to change the first pulse pressure and / or the second pulse pressure of the high-pressure servo pump.

[0077] In some embodiments, the control terminal receives a first pressure range and a second pressure range input by the user in advance; the first pressure range is used to match the first pulse pressure, and the second pressure range is used to match the second pulse pressure.

[0078] In some embodiments, when the high-pressure servo pump is started, the control terminal is used to establish a correspondence between position information and a first pulse pressure, and a correspondence between position information and a second pulse pressure.

[0079] In some embodiments, if the first pulse pressure is higher than the upper limit of the first pressure range (and less than or equal to the first pressure threshold), it indicates that the first pulse pressure is too high. The control terminal extracts the maximum distance that the high-pressure piston rod can move forward (push stroke) from the position information. Based on the correspondence between the upper limit of the first pressure range, the position information, and the first pulse pressure, the target distance that the high-pressure piston rod can move forward can be obtained. The maximum distance is subtracted from the target distance to obtain the reduced distance that the high-pressure piston rod should move forward after adjustment. Then, a high-pressure piston rod stroke adjustment command is generated (the high-pressure piston rod stroke adjustment command is used to indicate the reduced distance that the high-pressure piston rod should move forward after adjustment). The high-pressure piston rod stroke adjustment command is sent to the high-pressure servo pump to reduce the distance that the high-pressure piston rod moves forward during the pressurization stroke (reduce the push stroke) to reduce the first pulse pressure.

[0080] In some embodiments, if the first pulse pressure is lower than the lower limit of the first pressure range, it indicates that the first pulse pressure is too low. The control terminal extracts the maximum distance that the high-pressure piston rod can move forward (push stroke) from the position information. Based on the upper limit of the first pressure range, the correspondence between the position information and the first pulse pressure, the target distance that the high-pressure piston rod can move forward can be obtained. The target distance is subtracted from the maximum distance to obtain the increased distance that the high-pressure piston rod can move forward after adjustment. Then, a high-pressure piston rod stroke adjustment command is generated (the high-pressure piston rod stroke adjustment command is used to indicate the increased distance that the high-pressure piston rod can move forward after adjustment). The high-pressure piston rod stroke adjustment command is sent to the high-pressure servo pump to increase the distance that the high-pressure piston rod can move forward during the pressurization stroke (increase the push stroke) to increase the first pulse pressure.

[0081] In some embodiments, if the second pulse pressure is higher than the upper limit of the second pressure range, it indicates that the second pulse pressure is too high. The control terminal extracts the maximum distance that the high-pressure piston rod can move backward (reverse stroke) from the position information. Based on the correspondence between the upper limit of the second pressure range, the position information, and the second pulse pressure, the target distance that the high-pressure piston rod can move backward can be obtained. The target distance is subtracted from the maximum distance to obtain the increased distance that the high-pressure piston rod should move backward after adjustment. Then, a high-pressure piston rod stroke adjustment command is generated (the high-pressure piston rod stroke adjustment command is used to indicate the increased distance that the high-pressure piston rod should move backward after adjustment). The high-pressure piston rod stroke adjustment command is sent to the high-pressure servo pump to increase the distance that the high-pressure piston rod moves backward during the decompression stroke (increase the reverse stroke) to reduce the second pulse pressure.

[0082] In some embodiments, if the second pulse pressure is lower than the lower limit of the second pressure range, it indicates that the second pulse pressure is too low. The control terminal extracts the maximum distance that the high-pressure piston rod can move backward (reverse stroke) from the position information. Based on the correspondence between the lower limit of the second pressure range, the position information, and the second pulse pressure, the target distance that the high-pressure piston rod can move backward can be obtained. The maximum distance is subtracted from the target distance to obtain the reduced distance that the high-pressure piston rod should move backward after adjustment. Then, a high-pressure piston rod stroke adjustment command is generated (the high-pressure piston rod stroke adjustment command is used to indicate the reduced distance that the high-pressure piston rod should move backward after adjustment). The high-pressure piston rod stroke adjustment command is sent to the high-pressure servo pump to reduce the distance that the high-pressure piston rod moves backward during the decompression stroke (reduce the reverse stroke) in order to increase the second pulse pressure.

[0083] In some embodiments, four rock samples can be pre-cut from the target area, and triaxial stress (σ) can be set using a confined pressure vessel and a true triaxial pressurization system. h =6,σ H =6,σ v =6, σ hσ represents the stress along the x-axis. H σ represents the stress along the y-axis. v (Representing z-axis stress), the temperature was set at 25℃, and a constant injection rate (30ml / min) was set. Three rock samples were subjected to conventional hydraulic fracturing experiments using liquid water as the fracturing fluid until the rock samples fractured. The fracture pressures P1, P2, and P3 of these three rock samples in the conventional hydraulic fracturing experiments were recorded, and the average fracture value Pb = (P1 + P2 + P3) / 3 was calculated. The upper limit of the first pressure range was set to 90% * Pb, and the lower limit of the first pressure range was set to 80% * Pb. Then, a fourth rock sample was subjected to fracturing experiments based on flexible fracturing fluid using the rock flexible fracturing system described in this application, under the same triaxial pressure conditions as the conventional hydraulic fracturing experiments.

[0084] In some embodiments, the upper limit of the second pressure range can be set to 0.5 MPa, and the lower limit of the second pressure range can be set to 0.1 MPa.

[0085] In some embodiments, after the stroke range of the high-pressure piston rod is adjusted, the pressure sensor is used to acquire the adjusted first pulse pressure of the high-pressure servo pump and send the adjusted first pulse pressure to the control terminal.

[0086] The control terminal is used to detect whether the adjusted first pulse pressure meets the first pressure range.

[0087] If the adjusted first pulse pressure does not meet the first pressure range, the control terminal is also used to send an opening command to the high-pressure shut-off valve and a start command to the low-pressure injection pump; the high-pressure shut-off valve is used to execute the opening command and perform the opening process; the low-pressure injection pump is used to execute the start command and inject fracturing fluid into the high-pressure cylinder of the high-pressure servo pump.

[0088] In some embodiments, if the distance the high-pressure piston rod moves forward during the pressurization stroke has been adjusted to its maximum value, but the first pulse pressure is still less than the lower limit of the first pressure range, it indicates that there is a leak of fracturing fluid in the high-pressure servo pump, and the insufficient fracturing fluid prevents it from providing a sufficient first pulse pressure. At this time, the control terminal sends an opening command to the high-pressure shut-off valve and a start command to the low-pressure injection pump; the high-pressure shut-off valve executes the opening command and performs the opening process; the low-pressure injection pump executes the start command and injects fracturing fluid again into the high-pressure cylinder of the high-pressure servo pump to replenish the leaked fracturing fluid and increase the first pulse pressure of the high-pressure servo pump. When the first pulse pressure is greater than or equal to the lower limit of the first pressure range, the high-pressure shut-off valve is closed, and the low-pressure injection pump is shut down.

[0089] In some embodiments, the system further includes a status sensor; the status sensor is connected to the high-pressure servo pump;

[0090] The status sensor is used to acquire the number of pulses of the high-pressure piston rod in the high-pressure servo pump when the high-pressure servo pump is started, and send the number of pulses to the control terminal.

[0091] The control terminal is used to receive the number of pulses and detect whether the number of pulses meets the preset stop condition;

[0092] If the number of pulses meets the preset stopping conditions, the control terminal sends a stop command to the high-pressure servo pump; the high-pressure servo pump executes the stop command to stop fracturing the rock sample.

[0093] In some embodiments, the number of pulses is equal to the number of times the high-pressure piston rod completes one full stroke. The control terminal is used to receive a preset stop condition input by the user (e.g., number of pulses = 1000 times), and then when the pulse count obtained by the status sensor is equal to 1000 times, it considers whether the pulse count meets the preset stop condition, stops the fracturing of the rock sample, and ends the experiment.

[0094] In some embodiments, the control terminal includes a display device (e.g., a display screen) that can display information such as the first pulse pressure, the second pulse pressure, position information, pulse count, and amplitude in real time.

[0095] In some embodiments, the high-pressure servo pump and the low-pressure control pump are combined to generate different pulse waveforms. The high-pressure servo pump performs fracturing according to a preset pulse waveform.

[0096] In some embodiments, the system can mainly generate two types of pulse waveforms: single pressure pulse waveforms and multi-stage boost pulse waveforms;

[0097] Single-pressure pulse waveforms mainly include single-pressure sine waves, single-pressure square waves, single-pressure triangular waves, and single-pressure oblique waves. In flexible rock fracturing systems, servo motors, high-pressure cylinders, high-pressure piston rods, and precision lead screws work in tandem. By changing the speed, direction, and braking timing of the servo motor, the precision lead screw controls the movement of the high-pressure piston rod within the high-pressure cylinder, thus generating different single-pressure pulse waveforms; specifically, Figure 9 A waveform diagram representing a single pressure square wave. Figure 10 A waveform diagram representing a single-pressure sine wave. Figure 11 A waveform diagram representing a single pressure triangular wave. Figure 12 A waveform diagram representing a single pressure ramp;

[0098] Multi-stage pressure boosting pulse waveforms mainly include multi-stage pressure boosting sine waves, multi-stage pressure boosting square waves, multi-stage pressure boosting triangular waves, and multi-stage pressure boosting oblique waves. The control terminal, in conjunction with the high-pressure servo pump and the low-pressure injection pump, can generate a step-by-step pressure boosting scheme combining multiple multi-stage pressure boosting pulse waveforms, or a step-by-step pressure boosting scheme with a single multi-stage pressure boosting pulse waveform. Taking the step-by-step pressure boosting scheme with a single multi-stage pressure boosting pulse waveform as an example, before the fracturing experiment, the multi-stage pressure boosting scheme can be set through the control terminal. Taking a pressure boost of 2 MPa each time as an example, the first pressure range is set to [8 MPa, 10 MPa]. After 1000 pulses, the control terminal will open the high-pressure shut-off valve and drive the low-pressure injection pump to replenish fracturing fluid to the high-pressure servo pump to increase the first pulse pressure. When the first pulse pressure reaches 10 MPa-12 MPa, the high-pressure shut-off valve is closed, and another 1000 pulses are performed. This pressure boosting process is then repeated until the rock sample fractures. Figure 13 The diagram shows the step-by-step pressure increase waveform corresponding to the multi-stage pressure increase triangular wave. The pressure of the first pulse is increased by replenishing fluid with a low-pressure injection pump and increasing the injection rate of the low-pressure injection pump to achieve pressure increase. After each pressure increase, the triangular wave waveform is continuously subjected to fracturing for 1000 times, and then the pressure is increased again. The above process is repeated until the fracturing experiment ends.

[0099] In some embodiments, different pulse waveforms with the same amplitude will produce different impact pressures. For example, square waves can generate more rapid hydraulic shocks, inducing the formation of complex fractures, while sine waves can produce relatively smooth pressure changes, which is beneficial for generating fractures of a single morphology. By utilizing different types of pulse waveforms, multi-scale fractures can be effectively created, improving the permeability of oil and gas and achieving different fracturing effects.

[0100] The flexible rock fracturing system provided in this application allows for real-time control of the first and second pulse pressures during fracturing, ensuring they meet user requirements and improving fracturing control accuracy. It automatically stops the experiment and initiates unloading when the pressure is too high or a safety risk exists, guaranteeing experimental safety. By utilizing pulsed loading, rock samples are degraded, reducing fracturing initiation pressure and forming a complex fracture network, effectively modifying hot, dry rock reservoirs while reducing the occurrence of earthquakes, thus facilitating construction.

[0101] In some embodiments, the flexible rock fracturing system can provide the following experimental parameters:

[0102] Pressure range: 1-100MPa;

[0103] The pulse count range is 0-990,000 times;

[0104] Pressure gauge accuracy: Class 1.6;

[0105] Sensor accuracy: 0.25 grade; the sensor includes a position sensor, a pressure sensor, and a status sensor;

[0106] Pulse frequency range: 1-20Hz;

[0107] Experimental medium: Flexible fracturing medium;

[0108] Number of tests: 1;

[0109] Accuracy: ±0.5% FS;

[0110] Pulse waveforms: sine wave, square wave, triangle wave, ramp wave;

[0111] Control method: Controlled by a control terminal.

[0112] In a specific scenario example, see Figure 4 As shown, Figure 4 This is a schematic diagram of a specific flexible rock fracturing system. The flexible rock fracturing system includes: a high-pressure servo pump 1, a high-pressure shut-off valve 2, a low-pressure injection pump 3, a pressure sensor 4, a control terminal 5, a check valve 6, a pressure regulating valve 7, a supply tank 8, a high-pressure unloading valve 9, a pressure gauge 10, a power module 11, a status sensor 12, a position sensor 13, a vent valve 14, and a clamping device 15. The control terminal 5 includes an alarm module 51 and a pressure compensation module 52. The alarm module 51 generates an early warning message when the first pulse pressure does not conform to the first pressure range and / or the second pulse pressure does not conform to the pressure operating range. The pressure compensation module adjusts the first pulse pressure to make it conform to the first pressure range and also adjusts the second pulse pressure to make it conform to the second pressure range. The high-pressure shut-off valve 2 isolates the high-pressure servo pump 1 and the low-pressure injection pump 3 during fracturing. When the first pulse pressure collected by the pressure sensor 4 is too high, the high-pressure unloading valve 9 opens, and the fracturing fluid in the high-pressure servo pump 1 flows back to the supply tank 9 through the pipeline.

[0113] This application also proposes a flexible rock fracturing method, which is applied to a flexible rock fracturing system, and the method includes:

[0114] S1: Obtain 100mm 3 Granite outcrops are used as rock samples; supercritical carbon dioxide is injected into the supply tank as fracturing fluid; the rock samples are connected to the clamping device.

[0115] S2: The control terminal receives the user input of the first pressure range ([10.5MPa, 11.5MPa]), the second pressure range ([0.1, 0.5]), the pulse frequency (1Hz), the pulse waveform (sine wave), the pulse starting pressure (11MPa), the amplitude (11MPa), the stop condition (number of pulses = 1000 times), the start condition (initial pressure is greater than 5MPa and remains unchanged), and the first pressure threshold (30MPa);

[0116] S3: The control terminal starts the power supply module, which supplies power to the high-pressure servo pump; it opens the high-pressure shut-off valve and the vent valve, and closes the high-pressure unloading valve.

[0117] S4: The low-pressure injection pump starts, injecting fracturing fluid into the high-pressure cylinder of the high-pressure servo pump, and venting the air in the high-pressure cylinder and pipeline through the vent valve, and providing starting pressure for the high-pressure servo pump; the pressure sensor obtains the initial pressure of the high-pressure servo pump when fracturing fluid is injected, and sends the initial pressure to the control terminal;

[0118] S5: The control terminal detects whether the initial pressure meets the start-up conditions; if the initial pressure meets the start-up conditions, the control terminal sends a stop command to the low-pressure injection pump; the low-pressure injection pump executes the stop command and stops injecting fracturing fluid; if the initial pressure meets the start-up conditions, the control terminal sends a closing command to the high-pressure shut-off valve and the vent valve; the high-pressure shut-off valve and the vent valve close; the control terminal also sends a start command to the high-pressure servo pump; the high-pressure servo pump executes the start command, generates a pulse wave based on the pulse frequency (1Hz), pulse waveform (sine wave), and amplitude (11MPa) to fracture the rock sample; and performs amplitude correction on the high-pressure piston rod to make the actual amplitude equal to 11MPa;

[0119] S6: The pressure sensor acquires the first pulse pressure and the second pulse pressure, and sends the first pulse pressure and the second pulse pressure to the control terminal; the position sensor acquires the position information of the high-pressure piston rod, and sends the position information to the control terminal; the status sensor acquires the number of pulses, and sends the number of pulses to the control terminal; the control terminal includes an early warning module and a pressure compensation module;

[0120] S7: The control terminal detects whether the first pulse pressure is greater than the first pressure threshold; if it is determined that the first pulse pressure is greater than the first pressure threshold, a stop command is sent to the high-pressure servo pump and an opening command is sent to the high-pressure unloading valve; the high-pressure servo pump executes the stop command and stops fracturing the rock sample; the high-pressure unloading valve opens to discharge the fracturing fluid in the high-pressure servo pump to reduce the pressure in the high-pressure servo pump.

[0121] S8: The control terminal detects whether the first pulse pressure meets the first pressure range and whether the second pulse pressure meets the second pressure range. If the first pulse pressure does not meet the first pressure range, the warning module generates a prompt message and displays it on the control terminal screen. The pressure compensation module generates a high-pressure piston rod stroke adjustment command based on the position information and the first pressure range, and sends the high-pressure piston rod stroke adjustment command to the high-pressure servo pump. The high-pressure servo pump changes the forward distance of the high-pressure piston rod during the pressurization stroke according to the high-pressure piston rod stroke adjustment command, so that the first pulse pressure meets the first pressure range. If the second pulse pressure does not meet the second pressure range, the warning module generates a prompt message and displays it on the control terminal screen. The pressure compensation module generates a high-pressure piston rod stroke adjustment command based on the position information and the second pressure range, and sends the high-pressure piston rod stroke adjustment command to the high-pressure servo pump. The high-pressure servo pump changes the backward distance of the high-pressure piston rod during the depressurization stroke according to the high-pressure piston rod stroke adjustment command, so that the second pulse pressure meets the second pressure range.

[0122] S9: The control terminal detects whether the adjusted first pulse pressure meets the first pressure range; if it is determined that the adjusted first pulse pressure is less than the lower limit of the first pressure range, the control terminal also sends an opening command to the high-pressure shut-off valve and a start command to the low-pressure injection pump; the high-pressure shut-off valve opens; the low-pressure injection pump executes the start command and injects fracturing fluid into the high-pressure cylinder of the high-pressure servo pump; the control terminal detects again whether the first pulse pressure meets the first pressure range; if it is determined that the first pulse pressure meets the first pressure range, the high-pressure shut-off valve closes and the low-pressure injection pump stops injecting fracturing fluid.

[0123] S10: When the high-pressure servo pump is started, the status sensor acquires the number of pulses of the high-pressure piston rod in the high-pressure servo pump and sends the pulse count to the control terminal; the control terminal checks whether the pulse count meets the stop condition (whether it reaches 1000 times); if it is determined that the pulse count meets the stop condition, the control terminal sends a stop command to the high-pressure servo pump; the high-pressure servo pump stops fracturing the rock sample; or, when the first pulse pressure and the second pulse pressure are equal to 0 (indicating that the rock sample has been fractured), the control terminal sends a stop command to the high-pressure servo pump; the high-pressure servo pump stops fracturing the rock sample;

[0124] S11: The control terminal plots a pressure-time curve based on the first pulse pressure and the second pulse pressure; the pressure-time curve can be used to guide fracturing operations in the target area and provide a data basis for fracturing operations in the target area.

[0125] In some embodiments, the control terminal can also plot a curve of pulse pressure versus pulse number, which can indicate at which pulse the rock sample fractured.

[0126] Based on the above embodiments, this application also proposes a flexible rock fracturing method, see reference. Figure 5 As shown, the rock flexible fracturing method is applied to a rock flexible fracturing system, and the method includes:

[0127] S501: The control terminal receives the preset start conditions;

[0128] S502: The low-pressure injection pump injects fracturing fluid into the high-pressure cylinder of the high-pressure servo pump;

[0129] S503: The pressure sensor acquires the initial pressure of the high-pressure servo pump and sends the initial pressure to the control terminal;

[0130] S504: The control terminal detects whether the initial pressure meets the preset start-up conditions;

[0131] S505: When it is determined that the initial pressure meets the preset start-up conditions, the control terminal sends a stop command to the low-pressure injection pump, a close command to the high-pressure shut-off valve, and a start command to the high-pressure servo pump.

[0132] S506: The low-pressure injection pump receives and executes a stop command to stop injecting fracturing fluid;

[0133] S507: The high-pressure shut-off valve receives and executes a shut-off command to perform a shut-off process;

[0134] S508: The high-pressure servo pump receives and executes the start command to fracturing the rock sample.

[0135] Based on the above embodiments, this application also proposes a flexible rock fracturing method, see reference. Figure 6 As shown, the rock flexible fracturing method is applied to a control terminal, and the method includes:

[0136] S601: Receive initial pressure;

[0137] S602: Detect whether the initial pressure meets the preset start-up conditions;

[0138] S603: If the initial pressure meets the preset start-up conditions, a stop command is sent to the low-pressure injection pump, a close command is sent to the high-pressure shut-off valve, and a start command is sent to the high-pressure servo pump.

[0139] This application also provides an embodiment of a flexible rock fracturing device, see reference. Figure 7As shown, the flexible rock fracturing device is applied to the control terminal and specifically includes the following modules: receiving module 701, detection module 702, and sending module 703.

[0140] The receiving module 701 is used to receive the initial pressure.

[0141] The detection module 702 is used to detect whether the initial pressure meets the preset start-up conditions.

[0142] The sending module 703 is used to send a stop command to the low-pressure injection pump, a close command to the high-pressure shut-off valve, and a start command to the high-pressure servo pump when the initial pressure meets the preset start conditions.

[0143] It should be noted that the units, devices, or modules described in the above embodiments can be implemented by computer chips or physical entities, or by products with certain functions. For ease of description, the above devices are described by dividing them into various modules according to their functions. Of course, in implementing this specification, the functions of each module can be implemented in one or more software and / or hardware, or the module that implements the same function can be implemented by a combination of multiple sub-modules or sub-units, etc. The device embodiments described above are merely illustrative. For example, the division of units is only a logical functional division, and there may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection between the devices or units shown or discussed can be through some interfaces, and the indirect coupling or communication connection between devices or units can be electrical, mechanical, or other forms.

[0144] This specification also provides a computer storage medium for a rock flexible fracturing method. The computer storage medium stores computer program instructions, which, when executed by a processor, perform the following: receiving an initial pressure; detecting whether the initial pressure meets preset start-up conditions; and, if the initial pressure meets the preset start-up conditions, sending a stop command to a low-pressure injection pump, a close command to a high-pressure shut-off valve, and a start command to a high-pressure servo pump.

[0145] In this embodiment, the storage medium includes, but is not limited to, Random Access Memory (RAM), Read-Only Memory (ROM), cache, hard disk drive (HDD), or memory card. The memory can be used to store computer program instructions. The network communication unit can be an interface configured according to standards specified in the communication protocol for network connection communication.

[0146] In this embodiment, the specific functions and effects implemented by the program instructions stored in the computer storage medium can be explained in comparison with other implementation methods, and will not be repeated here.

[0147] This specification also provides a server, including a processor and a memory for storing processor-executable instructions. In a specific implementation, the processor can perform the following steps according to the instructions: receiving an initial pressure; detecting whether the initial pressure meets preset startup conditions; and, if it is determined that the initial pressure meets the preset startup conditions, sending a stop command to a low-pressure injection pump, sending a shut-off command to a high-pressure shut-off valve, and sending a start command to a high-pressure servo pump.

[0148] To execute the above instructions more accurately, please refer to... Figure 8 As shown in the embodiments of this specification, another specific server is also provided, wherein the server includes a network communication port 801, a processor 802, and a memory 803. The above structures are connected by internal cables so that the various structures can perform specific data interaction.

[0149] Specifically, the network communication port 801 can be used to receive initial pressure.

[0150] The processor 802 can be used to detect whether the initial pressure meets the preset start-up conditions; if it is determined that the initial pressure meets the preset start-up conditions, it sends a stop command to the low-pressure injection pump, a shut-off command to the high-pressure shut-off valve, and a start command to the high-pressure servo pump.

[0151] The memory 803 can be used to store the corresponding instruction program.

[0152] In this embodiment, the network communication port 801 can be a virtual port bound to different communication protocols, thereby enabling the sending or receiving of different data. For example, the network communication port can be a port responsible for web data communication, a port responsible for FTP data communication, or a port responsible for email data communication. Furthermore, the network communication port can also be a physical communication interface or communication chip. For example, it can be a wireless mobile network communication chip, such as GSM or CDMA; it can also be a Wi-Fi chip; or it can be a Bluetooth chip.

[0153] In this embodiment, the processor 802 can be implemented in any suitable manner. For example, the processor can take the form of a microprocessor or processor and a computer-readable medium storing computer-readable program code (e.g., software or firmware) executable by the (micro)processor, logic gates, switches, application-specific integrated circuits (ASICs), programmable logic controllers, and embedded microcontrollers, etc. This specification is not limiting.

[0154] In this embodiment, the memory 803 may include multiple layers. In a digital system, anything that can store binary data can be a memory. In an integrated circuit, a circuit with storage function but no physical form is also called a memory, such as RAM, FIFO, etc. In a system, a storage device with a physical form is also called a memory, such as a memory stick, TF card, etc.

[0155] While this specification provides the steps of operation for the methods described in the embodiments or flowcharts, more or fewer steps may be included based on conventional or non-inventive means. The order of steps listed in the embodiments is merely one possible order of execution among many steps and does not represent the only possible order. In actual device or client product execution, the methods shown in the embodiments or drawings may be executed sequentially or in parallel (e.g., in a parallel processor or multi-threaded processing environment, or even a distributed data processing environment). The terms "comprising," "including," or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, product, 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 a process, method, product, or apparatus. Without further limitations, the presence of other identical or equivalent elements in a process, method, product, or apparatus that includes said elements is not excluded. The terms "first," "second," etc., are used to denote names and do not indicate any particular order.

[0156] Those skilled in the art will also know that, besides implementing the controller using purely computer-readable program code, the same functions can be achieved by logically programming the method steps, making the controller function as logic gates, switches, application-specific integrated circuits (ASICs), programmable logic controllers (PLCs), and embedded microcontrollers. Therefore, such a controller can be considered a hardware component, and the devices within it used to implement various functions can also be considered structures within that hardware component. Alternatively, the devices used to implement various functions can be considered as both software modules implementing the method and structures within a hardware component.

[0157] This specification can be described in the general context of computer-executable instructions that are executed by a computer, such as program modules. Generally, program modules include routines, programs, objects, components, data structures, classes, etc., that perform a specific task or implement a specific abstract data type. This specification can also be practiced in distributed computing environments, where tasks are performed by remote processing devices connected via a communication network. In distributed computing environments, program modules can reside in local and remote computer storage media, including storage devices.

[0158] As can be seen from the above description of the embodiments, those skilled in the art can clearly understand that this specification can be implemented by means of software plus necessary general-purpose hardware platforms. Based on this understanding, the technical solutions of this specification can essentially be embodied in the form of a software product. This computer software product can be stored in a storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, mobile terminal, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments of this specification.

[0159] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on its differences from other embodiments. This specification can be used in numerous general-purpose or special-purpose computer system environments or configurations. Examples include: personal computers, server computers, handheld or portable devices, tablet devices, multiprocessor systems, microprocessor-based systems, set-top boxes, programmable electronic devices, network PCs, minicomputers, mainframe computers, and distributed computing environments including any of the above systems or devices, etc.

[0160] Although this specification has been described by way of examples, those skilled in the art will recognize that many variations and modifications are possible without departing from the spirit of this specification, and it is intended that the appended claims cover such variations and modifications without departing from the spirit of this specification.

Claims

1. A flexible rock fracturing system, characterized in that, The system includes at least a high-pressure servo pump, a low-pressure injection pump, a high-pressure shut-off valve, a control terminal, and a pressure sensor; The high-pressure servo pump and the low-pressure injection pump are connected via the high-pressure shut-off valve; The high-pressure servo pump is connected to the pressure sensor; Before the high-pressure servo pump is started, the low-pressure injection pump is used to inject fracturing fluid into the high-pressure cylinder of the high-pressure servo pump to purge the air in the high-pressure cylinder and provide starting pressure for the high-pressure servo pump. The pressure sensor is used to acquire the initial pressure when the high-pressure servo pump is injected with fracturing fluid, and to send the initial pressure to the control terminal; The control terminal is used to control the high-pressure shut-off valve to close, the low-pressure injection pump to stop, and the high-pressure servo pump to start and fracture the rock sample based on the initial pressure.

2. The system according to claim 1, characterized in that, The control terminal is used to control the high-pressure shut-off valve to close, the low-pressure injection pump to stop, and the high-pressure servo pump to start and fracturing the rock sample based on the initial pressure, including: The control terminal is used to detect whether the initial pressure meets the preset start-up conditions; If the initial pressure meets the preset start-up conditions, the control terminal sends a stop command to the low-pressure injection pump; the low-pressure injection pump executes the stop command and stops injecting fracturing fluid. If the initial pressure meets the preset start-up conditions, the control terminal sends a shut-off command to the high-pressure shut-off valve; the high-pressure shut-off valve executes the shut-off command and performs a shut-off process. If the initial pressure meets the preset start-up conditions, the control terminal is also used to send a start-up command to the high-pressure servo pump; the high-pressure servo pump is used to execute the start-up command to fracture the rock sample.

3. The system according to claim 1, characterized in that, The system also includes a high-pressure unloading valve; the high-pressure unloading valve is connected to the high-pressure servo pump.

4. The system according to claim 3, characterized in that, The pressure sensor is also used to acquire the first pulse pressure of the high-pressure servo pump during the pressurization stroke when the high-pressure servo pump is started, and to send the first pulse pressure to the control terminal. The control terminal is used to detect whether the first pulse pressure is greater than the first pressure threshold. If the first pulse pressure is determined to be greater than the first pressure threshold, a stop command is sent to the high-pressure servo pump and an open command is sent to the high-pressure unloading valve; the high-pressure servo pump is used to execute the stop command to stop fracturing the rock sample; the high-pressure unloading valve is used to execute the open command to open and discharge the fracturing fluid in the high-pressure servo pump.

5. The system according to claim 4, characterized in that, The system also includes a position sensor; the position sensor is connected to the high-pressure servo pump; the position sensor is used to acquire the position information of the high-pressure piston rod in the high-pressure servo pump when the high-pressure servo pump is started, and send the position information to the control terminal.

6. The system according to claim 5, characterized in that, The pressure sensor is also used to acquire the second pulse pressure of the high-pressure servo pump during the decompression stroke when the high-pressure servo pump is started, and to send the second pulse pressure to the control terminal. The control terminal is also used to send a high-pressure piston rod stroke adjustment command to the high-pressure servo pump according to the first pulse pressure, the second pulse pressure, and the position information; The high-pressure servo pump is used to execute high-pressure piston rod stroke adjustment commands to adjust the stroke range of the high-pressure piston rod, thereby changing the first pulse pressure and / or the second pulse pressure of the high-pressure servo pump.

7. The system according to claim 6, characterized in that, After adjusting the stroke range of the high-pressure piston rod, the pressure sensor is used to acquire the adjusted first pulse pressure of the high-pressure servo pump and send the adjusted first pulse pressure to the control terminal. The control terminal is used to detect whether the adjusted first pulse pressure meets the first pressure range. If the adjusted first pulse pressure does not meet the first pressure range, the control terminal is also used to send an opening command to the high-pressure shut-off valve and a start command to the low-pressure injection pump; the high-pressure shut-off valve is used to execute the opening command and perform the opening process; the low-pressure injection pump is used to execute the start command and inject fracturing fluid into the high-pressure cylinder of the high-pressure servo pump.

8. The system according to claim 1, characterized in that, The system also includes a status sensor; the status sensor is connected to the high-pressure servo pump. The status sensor is used to acquire the number of pulses of the high-pressure piston rod in the high-pressure servo pump when the high-pressure servo pump is started, and send the number of pulses to the control terminal. The control terminal is used to receive the number of pulses and detect whether the number of pulses meets the preset stop condition; If the number of pulses meets the preset stopping conditions, the control terminal sends a stop command to the high-pressure servo pump; the high-pressure servo pump executes the stop command to stop fracturing the rock sample.

9. The system according to claim 1, characterized in that, The system also includes a clamping device; the clamping device is connected to the high-pressure servo pump; the clamping device is used to clamp the rock sample.

10. A method for flexible rock fracturing, characterized in that, The method is applied to the rock flexible fracturing system according to any one of claims 1-9, comprising: The control terminal receives preset startup conditions; The low-pressure injection pump injects fracturing fluid into the high-pressure cylinder of the high-pressure servo pump; The pressure sensor acquires the initial pressure of the high-pressure servo pump and sends the initial pressure to the control terminal; The control terminal detects whether the initial pressure meets the preset start-up conditions; If the initial pressure meets the preset start-up conditions, the control terminal sends a stop command to the low-pressure injection pump, a close command to the high-pressure shut-off valve, and a start command to the high-pressure servo pump. The low-pressure injection pump receives and executes a stop command to stop injecting fracturing fluid. The high-pressure shut-off valve receives and executes the closing command to perform the closing process; The high-pressure servo pump receives and executes the start command to fracturing the rock sample.

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