A method, apparatus, equipment, medium, and product for fracturing and permeability enhancement in unconventional reservoirs.

Abstract

This application discloses a method, apparatus, equipment, medium, and product for fracturing and permeability enhancement in unconventional reservoirs, relating to the field of formation stimulation and fracturing technology for unconventional reservoir resources. The method includes: determining multiple target layers corresponding to the target wellbore based on the geological environment of the target wellbore location; determining the depth and thickness of the unconventional reservoir, and the position and thickness of the top and bottom plates, based on the topographic and geological conditions of the target wellbore location; determining the position of each target point and the corresponding electro-detonation operation energy range based on each target layer, the depth and thickness of the unconventional reservoir, and the position and thickness of the top and bottom plates; and performing electro-detonation operations on the unconventional reservoir to be fractured based on the position of each target point and the corresponding electro-detonation operation energy range. This application can form a multi-layered three-dimensional volumetric fracture network based on different layers and actual rock mass conditions of the unconventional reservoir.

Description

Technical Field

[0001] This application relates to the field of formation stimulation and permeability enhancement technology for unconventional reservoir resources, and in particular to a method, apparatus, equipment, medium and product for fracturing and permeability enhancement of unconventional reservoirs. Background Technology

[0002] Unlike conventional reservoirs, unconventional reservoirs are generally characterized by low porosity, ultra-low permeability, and strong heterogeneity, and the gas occurrence states are complex. For example, coalbed methane mainly exists in the adsorbed state within the micropores of the matrix. This makes commercial gas production impossible through conventional natural energy extraction, necessitating artificial enhancement measures to modify reservoir properties.

[0003] Currently, commonly used fracturing and permeability enhancement technologies include hydraulic fracturing, acid fracturing, and explosive blasting. Although they have all achieved certain permeability enhancement effects, they still have certain shortcomings and limitations. For example, hydraulic fracturing results in a simple fracture network and consumes a large amount of water resources; acid fracturing depends on formation lithology and has a limited scale of modification; and traditional explosives have uncontrollable energy release, high safety risks, and are prone to damage to the wellbore.

[0004] High-intensity electro-detonation technology utilizes the enormous electrical energy stored in a high-voltage capacitor to be transmitted to the discharge electrode via a high-voltage cable within an extremely short time. This energy is then instantaneously released into the liquid medium through the electrode gap, triggering dielectric breakdown and creating a high-temperature, high-pressure plasma channel. The channel rapidly expands, generating a shock wave. The stress value of this shock wave exceeds the compressive or tensile strength of the reservoir, causing it to fracture. As the shock wave propagates further within the reservoir, it facilitates the formation of complex fracture networks in unconventional reservoirs, unblocks gas migration channels, increases reservoir permeability, and enables safe and efficient energy development and utilization.

[0005] For example, in the exploitation of deep-water oil and gas reservoirs using high-intensity electric detonation (EED) technology, high-voltage direct current (VDC) is stored in energy storage capacitors. High-voltage transmission cables transfer this energy to high-voltage electrodes, which then release it instantaneously into the oil and gas reservoir, thus inducing fractures and creating fissures. This can solve problems caused by hydraulic fracturing, acid fracturing, and explosive blasting loosening techniques. However, the discharge electrodes in EED technology release energy in a single manner, failing to create a multi-layered, three-dimensional volumetric fracture network tailored to different strata and rock mass conditions in unconventional reservoirs. This results in an isolated fracture network with poor connectivity, hindering the formation of an effective fracture network, leading to energy waste, poor permeability enhancement, and failing to meet the industrial application requirements for volumetric fracturing-based production enhancement. Summary of the Invention

[0006] The purpose of this application is to provide a fracturing and permeability enhancement method, apparatus, equipment, medium and product for unconventional reservoirs, which can form a multi-layered three-dimensional volumetric fracturing network according to different strata and different rock mass conditions of unconventional reservoirs.

[0007] To achieve the above objectives, this application provides the following solution: In a first aspect, this application provides a fracturing and permeability enhancement method for unconventional reservoirs, comprising: determining multiple target layers corresponding to the target wellbore based on the geological environment of the location of the target wellbore; the target wellbore is the wellbore of the unconventional reservoir production well to be fractured.

[0008] Based on the topographic and geological conditions of the target well location, determine the depth and thickness of the unconventional reservoir, the location and thickness of the unconventional reservoir top plate, and the location and thickness of the unconventional reservoir bottom plate.

[0009] Based on the target wellbore corresponding to each target layer, the depth and thickness of the unconventional reservoir, the position and thickness of the unconventional reservoir top plate, and the position and thickness of the unconventional reservoir bottom plate, determine the position of each target point and the corresponding energy range of the electro-detonation operation when carrying out electro-detonation operation.

[0010] Based on the location of each target point during the electro-detonation operation and the first and second operating energies within the corresponding electro-detonation operation energy range for each target point, electro-detonation operations are performed on the unconventional reservoir to be fractured, in order to achieve fracturing and permeability enhancement of the unconventional reservoir to be fractured; the second operating energy is greater than the first operating energy.

[0011] Secondly, this application provides a fracturing and permeation enhancement device for unconventional reservoirs, comprising: a target layer determination module, used to determine multiple target layers corresponding to the target wellbore based on the geological environment of the location of the target wellbore; the target wellbore is the wellbore of the unconventional reservoir production well to be fractured.

[0012] The reservoir parameter determination module is used to determine the depth and thickness of unconventional reservoirs, the location and thickness of the unconventional reservoir top plate, and the location and thickness of the unconventional reservoir bottom plate based on the topographic and geological conditions of the target wellbore location.

[0013] The target point determination module is used to determine the location of each target point and the corresponding energy range of the electro-detonation operation based on the target wellbore, the depth and thickness of the unconventional reservoir, the position and thickness of the unconventional reservoir top plate, and the position and thickness of the unconventional reservoir bottom plate.

[0014] The electro-detonation operation system is used to perform electro-detonation operations on unconventional reservoirs to be fractured, based on the location of each target point and the first and second operating energies within the corresponding electro-detonation operation energy range for each target point, in order to achieve fracturing and permeability enhancement of the unconventional reservoirs to be fractured; the second operating energy is greater than the first operating energy.

[0015] Thirdly, this application provides a computer device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the fracturing and permeability enhancement method for unconventional reservoirs described above.

[0016] Fourthly, this application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the aforementioned fracturing and permeability enhancement method for unconventional reservoirs.

[0017] Fifthly, this application provides a computer program product, including a computer program that, when executed by a processor, implements the aforementioned fracturing and permeability enhancement method for unconventional reservoirs.

[0018] According to the specific embodiments provided in this application, this application has the following technical effects: This application provides a method, apparatus, equipment, medium, and product for fracturing and permeability enhancement of unconventional reservoirs. Based on the target layers corresponding to the target wellbore, the depth and thickness of the unconventional reservoir, the position and thickness of the unconventional reservoir's top plate, and the position and thickness of the unconventional reservoir's bottom plate, this application determines the position of each target point and the corresponding energy range for electro-detonation operations. Based on the position of each target point and the first and second operating energies within the corresponding energy ranges for electro-detonation operations, electro-detonation operations are performed on the unconventional reservoir to be fractured, thereby achieving fracturing and permeability enhancement of the unconventional reservoir. The second operating energy is greater than the first operating energy, which can form a multi-layered three-dimensional volumetric fracture network according to different layers and actual rock mass conditions of the unconventional reservoir. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic flowchart of a fracturing and permeability enhancement method for unconventional reservoirs provided in an embodiment of this application.

[0021] Figure 2 This is a schematic diagram of the structure of an electro-detonation operation system provided in an embodiment of this application, applied to a fracturing and permeability enhancement method for unconventional reservoirs.

[0022] Figure 3 A three-dimensional volumetric fracturing effect diagram provided for an embodiment of this application after fracturing with low energy.

[0023] Figure 4 A three-dimensional volumetric fracturing effect diagram provided for an embodiment of this application after high-energy fracturing.

[0024] Figure 5 A flowchart of an unconventional reservoir multi-level three-dimensional volumetric fracturing, depressurization, and permeation enhancement technology based on high-intensity electric detonation is provided as an embodiment of this application.

[0025] Figure 6 This is a schematic diagram of the functional modules of a fracturing and permeation enhancement device for unconventional reservoirs provided in an embodiment of this application.

[0026] Figure 7 This is a schematic diagram of the structure of a computer device provided in an embodiment of this application.

[0027] Reference numerals: 1-Charging power supply; 2-High-voltage energy storage capacitor bank; 3-Electro-explosion triggering control system; 4-Electrical parameter monitoring device; 5-Cable retraction and deployment self-propelled vehicle; 6-Armored high-voltage transmission cable; 7-High-voltage discharge electrode; 8-Liquid medium; 9-Wellbore perforation; 10-Wellbore casing; 11-Three-dimensional volumetric fracture network; 12-First operation point; 13-Last operation point; 14-Surface cover layer; 15-Reservoir top plate; 16-Unconventional reservoir; 17-Reservoir bottom plate; 18-Micro fracture; 19-Main fracture; 20-Secondary fracture. Detailed Implementation

[0028] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0029] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] In one exemplary embodiment, such as Figure 1 As shown, a fracturing and permeability enhancement method for unconventional reservoirs is provided, including: Step 201: Determining multiple target layers corresponding to the target wellbore based on the geological environment of the target wellbore's location; the target wellbore is the wellbore of the unconventional reservoir to be fractured. Unconventional reservoirs include coalbed methane reservoirs, shale gas reservoirs, or tight oil and gas reservoirs. The production well has sufficient space to accommodate electro-explosive detonation operations.

[0031] Step 202: Based on the topographic and geological conditions of the target well location, determine the depth and thickness of the unconventional reservoir, the location and thickness of the unconventional reservoir top plate, and the location and thickness of the unconventional reservoir bottom plate.

[0032] Step 203: Based on the target layers corresponding to the target wellbore, the depth and thickness of the unconventional reservoir, the position and thickness of the unconventional reservoir top plate, and the position and thickness of the unconventional reservoir bottom plate, determine the position of each target point and the corresponding energy range of the electro-detonation operation when performing electro-detonation operation.

[0033] Step 204: Based on the location of each target point during the electro-detonation operation and the first and second operating energies in the electro-detonation operation energy range corresponding to each target point, electro-detonation operation is performed on the unconventional reservoir to be fractured, so as to achieve fracturing and permeability enhancement of the unconventional reservoir to be fractured; the second operating energy is greater than the first operating energy.

[0034] In another exemplary embodiment of this application, an electric detonation operation system is used to perform electric detonation operations on unconventional reservoirs to be fractured, based on the location of each target point during the electric detonation operation and the first and second operating energies in the electric detonation operation energy range corresponding to each target point.

[0035] In another exemplary embodiment of this application, the electro-detonation operation system includes a charging power supply 1, a high-voltage energy storage capacitor bank 2, an electro-detonation trigger control system 3, and a high-voltage discharge electrode 7 connected in sequence. The circuit of the electro-detonation operation system is integrated and controlled by the electro-detonation trigger system. The charging power supply 1 is used to charge the high-voltage energy storage capacitor bank 2; the high-voltage energy storage capacitor bank 2 is used to store high-voltage electricity, and the high-voltage energy storage capacitor bank 2 supports variable capacitance adjustment to control the energy released in a single operation. The high-voltage discharge electrode 7 is arranged at the electro-detonation operation position in the target reservoir section. The high-voltage discharge electrode 7 is used to instantaneously release the electrical energy stored in the high-voltage energy storage capacitor when the control circuit of the electro-detonation trigger system is in the connected state, so as to convert the electrical energy into shock wave energy, thermal energy, and mechanical energy. Using the electro-detonation operation system, based on the position of each target point during the electro-detonation operation and the first and second operating energies in the electro-detonation operation energy range corresponding to each target point, electro-detonation operation is performed on the unconventional reservoir to be fractured. Specifically, the high-voltage discharge electrode 7 is arranged at the current target point and immersed in the liquid medium 8 in the target wellbore. Liquid medium 8 is formation water produced in the wellbore or artificially injected clean water.

[0036] Based on the first working energy corresponding to the current target location, set the first capacitance value of the high-voltage energy storage capacitor bank 2.

[0037] Turn on the charging power supply 1 to charge the high-voltage energy storage capacitor bank 2 until the high-voltage energy storage capacitor bank 2 reaches the preset voltage value.

[0038] The wireless remote control terminal sends trigger signals to the electric explosion trigger control system 3 multiple times to complete multiple small energy inductions at the current target point.

[0039] Based on the second working energy corresponding to the current target location, set the second capacitance value of the high-voltage energy storage capacitor bank 2.

[0040] Turn on the charging power supply 1 to charge the high-voltage energy storage capacitor bank 2 until the high-voltage energy storage capacitor bank 2 reaches the preset voltage value.

[0041] The system sends multiple trigger signals to the electric detonation trigger control system 3 via a wireless remote control terminal to complete the high-energy fracturing of the current target location.

[0042] Determine whether the fracturing and permeability enhancement effect at the current target location has achieved the expected results.

[0043] If the expected result is achieved, update the current target location and return to the steps of placing the high-voltage discharge electrode 7 at the current target location and immersing the high-voltage discharge electrode 7 in the liquid medium 8 inside the target wellbore.

[0044] If the expected results are not achieved, the process returns to the step of setting the first capacitance value of the high-voltage energy storage capacitor bank 2 based on the first working energy corresponding to the current target point, until the fracturing and permeation enhancement effects corresponding to all target points reach the expected levels. Once the fracturing and permeation enhancement effects corresponding to all target points have reached the expected levels, a three-dimensional volumetric fracture network 11 is formed. The remote wireless control terminal sends a trigger command to the electric explosion trigger control system 3 from a safe distance, realizing human-machine separation operation and ensuring the safety of construction personnel.

[0045] In practical applications, the electric detonation triggering control system 3 can adjust the capacitance of the high-voltage energy storage capacitor bank 2 and control the on / off state of the entire circuit. The electric detonation triggering control system 3 has a built-in automated operating program; the automated operating program can automatically adjust the charging voltage, discharge frequency and cycle number according to the set timing logic, automatically execute the control process of switching from small energy induction to large energy fracturing, and automatically control the on / off of the charging power supply 1 and the sending of trigger signals, without the need for frequent manual intervention.

[0046] In practical applications, the electric detonation system also includes: an armored high-voltage transmission cable 6, through which the electric detonation triggering control system 3 is connected to the high-voltage discharge electrode 7. The armored high-voltage transmission cable 6 is used to transmit electrical energy from the high-voltage energy storage capacitor bank 2 to the high-voltage electrode.

[0047] In practical applications, the electric detonation system also includes a position adjustment device, which is used to adjust the length of the armored high-voltage transmission cable 6. Specifically, the position adjustment device is a cable retraction and deployment self-propelled vehicle 5, which is drivable. The armored high-voltage transmission cable 6 is coiled on the cable retraction and deployment self-propelled vehicle 5, which can control the retraction and deployment speed of the armored high-voltage transmission cable 6, thereby adjusting the arrangement position of the high-voltage discharge electrode 7. When the production well is a horizontal well, the cable retraction and deployment self-propelled vehicle 5 is used to pull the armored high-voltage transmission cable 6 and the high-voltage discharge electrode 7 to move within the horizontal well section. With the coordination of the surface winch's retraction and deployment control, the electrode can be precisely positioned in unconventional reservoirs.

[0048] In practical applications, the high-voltage discharge electrode 7 is positioned at the target location. Specifically, an armored high-voltage transmission cable 6 of appropriate length is configured according to the depth of the target location, and the high-voltage discharge electrode 7 is transported to the target location using a position adjustment device. The length of the armored high-voltage transmission cable 6 is segmented and adapted according to the location of the target location. The cable energy loss during the electric detonation operation is related to the cable current and cable resistance. By selecting the shortest suitable cable length that meets the operating depth, and optimizing the cable length to reduce the impedance loss of the transmission line while meeting the lowering depth requirements, the energy transmission efficiency is improved, thereby increasing the effective energy output of the high-voltage discharge electrode 7.

[0049] In practical applications, the electric detonation operation system also includes: a cable tractor; the cable tractor is connected to the high-voltage discharge electrode 7 assembly, and is used to overcome frictional resistance in horizontal or highly deviated well sections, and to move the electrode to the predetermined fracturing target point, so as to achieve flexible adjustment and precise positioning of the operation position.

[0050] In practical applications, the electric detonation operation system also includes a boost rectifier, which has a voltage regulation function and is used to adjust the voltage output by the charging power supply 1 to a preset high voltage DC value according to the rated parameters of the high voltage energy storage capacitor bank 2 or the energy requirements set in the operation.

[0051] In practical applications, the electric detonation system also includes: a rigid support assembly (such as a sucker rod or an insulating rod), an armored high-voltage transmission cable 6 and a high-voltage discharge electrode 7, which are fixed to the rigid support assembly by clips or clamps. The weight and rigidity of the rigid support assembly are used to assist in lowering the electrode and prevent the cable from bending or knotting inside the wellbore.

[0052] In another exemplary embodiment of this application, determining whether the fracturing and permeability enhancement effect corresponding to the current target point has achieved the expected result specifically includes: Obtain the fracturing parameters; determine whether the fracturing and permeability enhancement effect has achieved the expected results based on the fracturing parameters.

[0053] In another exemplary embodiment of this application, the electric detonation operation system further includes: an electrical parameter monitoring device 4, used to monitor fracturing parameters; the fracturing parameters include: voltage and current signals during the transient discharge of the high-voltage discharge electrode 7. The electrical parameter monitoring device 4 is disposed between the electric detonation triggering control system 3 and the high-voltage electrode, used to monitor the transient voltage and transient current signals during each discharge process in real time or quasi-real time, and to determine the energy release characteristics of a single electric detonation operation based on the signals.

[0054] In another exemplary embodiment of this application, the electric blasting operation system further includes: a micro-vibration sensor for monitoring fracturing parameters; the fracturing parameters are: ground vibration signals.

[0055] In practical applications, the electric blasting operation system also includes a fracturing effect monitoring module, which includes microseismic sensors and strain monitoring units deployed downhole or on the surface. These are used to collect ground vibration signals and rock deformation data under the action of shock waves in real time, so as to provide feedback and determine the current energy range.

[0056] In practical applications, the electric detonation system also includes an operation effect evaluation unit, which can evaluate the effectiveness of a single fracturing operation (whether the expected effect is achieved) based on the discharge current waveform (obtained from the current signal), the voltage drop curve (obtained from the voltage signal), and the monitored formation feedback signal through a built-in algorithm. When the evaluation result does not reach the preset threshold, the system automatically generates a supplementary fracturing command.

[0057] In practical applications, when the production well is a vertical well, it passes sequentially through the unconventional reservoir roof, the unconventional reservoir, and the unconventional reservoir floor. When the production well is horizontal, its spatial location is within the unconventional reservoir, with the unconventional reservoir roof above it and the unconventional reservoir floor below it.

[0058] like Figure 2 As shown, this application also provides a more specific embodiment, employing an electro-detonation operation system to perform electro-detonation operations on unconventional reservoirs to be fractured. The electro-detonation operation system is installed on the surface overburden layer 14, and a well casing 10 is installed inside the production well. Well casing perforations 9 or slots are pre-drilled at corresponding positions in the unconventional reservoir 16, reservoir top plate 15, and reservoir bottom plate 17. The shock wave energy and plasma jet generated by the high-voltage discharge electrode 7 are directionally released into the formation through the well casing perforations 9 or slots, achieving directional pressure relief of the unconventional reservoir 16, reservoir top plate 15, and reservoir bottom plate 17. Figure 5As shown, the process includes: measuring operating conditions and cable adaptation; device placement and positioning; conducting the first stage: low-energy induction; completing the predetermined number of operations and switching energy power; conducting the second stage: high-energy fracturing; completing the predetermined number of operations; monitoring and evaluating the effectiveness; if good, moving to the next operation point; if not, supplementing the number of operations and conducting the first stage: low-energy induction again. Specific steps include: S1. Before the operation begins, firstly, the geological environment of the wellbore where the unconventional reservoir horizontal well is located is measured to determine the multiple unconventional reservoir target layers traversed by the wellbore. Then, based on the topographic and geological conditions of the wellbore, the depth and thickness of the unconventional reservoir 16 to be fractured, as well as the position and thickness of the reservoir top plate 15 and reservoir bottom plate 17 are determined. Based on the multiple unconventional reservoir target layers traversed by the wellbore, the depth and thickness of the unconventional reservoir 16 to be fractured, and the position and thickness of the reservoir top plate 15 and reservoir bottom plate 17, several target points for electro-detonation operations are determined. The spacing between each target operation point is reasonably determined so that the electro-detonation operation position can effectively cover all formations that need to be fractured, and finally the positions of the various target points for fracture and the energy range of the electro-detonation operation are locked.

[0059] S2. Determine the required length of the armored high-voltage transmission cable 6 based on the location of the target point. Under the premise of meeting the working depth, select the shortest suitable length as much as possible, or connect the segments according to the location of the target point to reduce the resistance consumption of the armored high-voltage transmission cable 6 during long-distance transmission.

[0060] S3. A reverse fracturing method is adopted, starting from the reservoir bottom plate 17, sequentially passing through the unconventional reservoir 16, and finally completing the operation at the reservoir top plate 15. The first operation point 12 is at the bottom of the horizontal well, and the last operation point 13 is at the top of the horizontal well. The high-voltage discharge electrode 7 is connected to the armored high-voltage transmission cable 6, and the armored high-voltage transmission cable 6 is wound up in the cable winding and unwinding vehicle 5. The high-voltage discharge electrode 7 is positioned at the first target point by winding and unwinding the length of the armored high-voltage transmission cable 6. The wellbore or at least the target point is filled with liquid medium 8 (clean water) to ensure that the conditions for the electrohydraulic effect are met. The charging power supply 1, the boost rectifier, the high-voltage energy storage capacitor bank 2, the electric detonation trigger control system 3, and the electrical parameter monitoring device 4 are connected, and the remote wireless control terminal is connected to complete the operation preparation.

[0061] S4. Adjust the capacitance value of the high-voltage energy storage capacitor bank 2 required for this operation according to the energy range of the electric detonation operation at the first target point. A smaller capacitance value allows the electric detonation system to release less energy. It primarily functions in the near-wellbore region. The capacitance value can be calculated using the following formula, where the preset voltage value U is typically 14kV: Turn on the charging power supply 1 to charge the high-voltage energy storage capacitor bank 2 until the preset voltage value is reached, and the system enters the standby state.

[0062] S5. The operator sends a trigger signal to the electric explosion trigger control system 3 through the wireless remote control terminal. The electric explosion trigger control system 3 turns on the circuit, and the electrical energy stored in the high-voltage energy storage capacitor bank 2 is instantly transmitted to the downhole high-voltage discharge electrode 7 through the armored high-voltage transmission cable 6.

[0063] S6. Perform cyclic electric detonation operation, repeating S5 until the predetermined number of operations is reached, forming microcracks 18, such as... Figure 3 As shown.

[0064] S7. Adjust the required capacitance value for this operation to a larger value based on the energy range of the electro-detonation operation at the first target point. This will allow the electro-detonation system to release more energy, primarily affecting the distant well area. Turn on the charging power supply 1 to charge the high-voltage energy storage capacitor bank 2 until the preset voltage value is reached, and the system enters the standby state.

[0065] S8. Repeat S5 until the predetermined number of operations are reached, forming primary crack 19 and secondary crack 20, as follows. Figure 4 As shown.

[0066] S9. Analyze the discharge waveform in real time using the electrical parameter monitoring device 4, or monitor the formation response using a microseismic sensor; if the monitoring data shows that the reservoir fracture development is not as expected, return to S4; if it shows that an effective breakthrough has been formed, end the operation at the current energy level and proceed to S10.

[0067] S10. Control the cable retraction and deployment speed of the self-propelled vehicle 5, adjust the length of the armored high-voltage transmission cable 6 in the well, and place the high-voltage discharge electrode 7 to the next target point for operation. Repeat steps S4-S9 again to complete the operation at all target points. Multi-level operations were carried out on the unconventional reservoir 16, reservoir top plate 15, and reservoir bottom plate 16 to complete the construction of the three-dimensional volumetric fracture network 11.

[0068] In this embodiment, the energy loss via the armored high-voltage transmission cable 6 can be calculated using the following formula: In the formula, E C Energy lost in the cable; I C R is the cable current, i.e., the discharge current. C The resistance of the cable is Ω.

[0069] In this embodiment, the energy output to the high-voltage discharge electrode 7 via the armored high-voltage transmission cable 6 during liquid dielectric breakdown is: In the formula, E D The effective energy output by the high-voltage discharge electrode. This is the discharge current of the high-voltage electrode. This is the discharge resistor for the high-voltage electrode.

[0070] The purpose of this application is to provide a multi-level, three-dimensional volumetric fracturing and permeation enhancement technology for unconventional reservoirs based on high-intensity electro-explosion. It aims to construct a complex three-dimensional fracture network within unconventional reservoirs through energy cascade control and multi-point electro-explosion operations, achieving low-damage, high-efficiency pressure relief and permeation enhancement. This method is not only safe and effective but also environmentally friendly and economical, achieving permeability enhancement for unconventional reservoirs and improving the effective exploitation of unconventional energy sources such as coalbed methane, shale gas, and tight oil. The fracturing and permeation enhancement method for unconventional reservoirs provided in this application comprises five parts. The first part is operational condition measurement and planning: measuring the wellbore environment of the unconventional reservoir production well, determining multiple target unconventional reservoir layers traversed by the wellbore and their corresponding top and bottom plate positions, and planning several target electro-explosion operation points. The second part is system layout and environment construction: configuring armored high-voltage transmission cables of appropriate length according to the target layer depth, using a position adjustment device to deliver high-voltage discharge electrodes to the first target point, and ensuring that the high-voltage discharge electrodes are immersed in the liquid medium. The third part is the fracturing initiation operation: The high-voltage energy storage capacitor bank is adjusted to its first energy state (corresponding to a smaller capacitance value or lower charging voltage, used to generate high-frequency, low-energy shock waves to activate natural weak surfaces in the rock mass without creating a pulverizing zone) via an electro-explosive triggering control system. After charging, the high-voltage discharge electrode is triggered to release energy in the liquid medium, generating shock waves that act on the near-wellbore area and repeating this cycle a predetermined number of times at the current location to induce initial microcracks within the reservoir. The fourth part is the expansion and mesh-building operation: The high-voltage energy storage capacitor bank is adjusted to its second energy state (corresponding to a larger capacitance value or higher charging voltage, used to generate low-frequency, high-energy shock waves and strong cavitation bubble pulsations, enabling deep fracture extension and three-dimensional communication). The energy released in a single operation in the second energy state is greater than that in the first energy state. The high-voltage discharge electrode is controlled to release high-energy shock waves, driving the initial microcracks to extend into the far-wellbore area. The fifth part is multi-layer fracturing: After completing the work at the current target point, the high-voltage discharge electrode is moved to the next target point using the position adjustment device. The third, fourth and fifth parts are repeated until the fracturing work at all predetermined layers is completed.

[0071] The core technology of this application adopts an "energy cascade control" and "multi-point coordination" mode: First, the electrode is precisely delivered to the target layer via a cable-driven self-propelled vehicle; second, a cyclical operation of "small energy induction - large energy expansion" is executed, first using high-frequency, low-energy shock waves to induce initial microcracks in the near-wellbore zone to avoid the formation of a pulverization zone, and then switching to a low-frequency, high-energy mode to drive the fracture to extend deeper; finally, based on feedback from electrical parameters or microseismic monitoring, the operating parameters are automatically adjusted and the electrode is moved to complete the fracturing of multiple layers throughout the well section. This application can effectively construct complex three-dimensional volumetric fracture networks in unconventional reservoirs, and has significant advantages such as no water-sensitive damage, controllable operating range, adaptability to horizontal wells and multi-thin reservoirs, and being green, safe, and efficient.

[0072] This application charges a high-voltage energy storage capacitor bank with a charging power supply, stores high-voltage electrical energy in the capacitor bank, and releases the electrical energy instantaneously in a liquid medium through a high-voltage discharge electrode. It utilizes the strong shock wave generated by the electrohydraulic effect and the cavitation bubble pulsation physical mechanism to create fractures. In the operational mode, the position of the high-voltage discharge electrode is adjusted and arranged by a self-propelled vehicle using cable retraction and deployment, enabling multi-level operations from the bottom to the top of unconventional reservoirs, achieving a full-coverage operational effect.

[0073] By utilizing the variable capacitance regulation function of high-voltage energy storage capacitor banks, combined with the precise control of discharge energy and pulse time intervals by an electric detonation triggering control system, a cyclical operation mode of high-frequency low-energy induction and low-frequency high-energy expansion is achieved, ultimately completing a three-dimensional volumetric fracture network and realizing the fracturing and permeability enhancement effect in unconventional reservoirs. This method requires no large amounts of water resources, provides precisely controllable energy release, produces no harmful byproducts, and does not pollute the environment. It possesses technological advantages such as being green, safe, economical, and efficient, which is beneficial for resource extraction in unconventional reservoirs.

[0074] This application primarily utilizes the liquid-phase discharge principle of high-intensity electro-detonation to break down the liquid medium and generate plasma channels. The energy from the expansion of these plasma channels then generates shock waves that act on unconventional reservoirs, their top and bottom plates. By adjusting the capacitance of the high-voltage energy storage capacitor bank to a relatively small value, high-frequency, low-energy fracturing initiation is first implemented, with the control system outputting a low-energy, high-frequency current. Using the generated weak shock waves, with peak impact stress slightly exceeding the tensile strength of the rock, repeated fatigue loading is applied to the surrounding rock mass, activating natural micro-fractures and bedding, forming radial initial directional micro-fractures without creating a rock fragmentation zone. Then, by adjusting the capacitance of the high-voltage energy storage capacitor bank to a larger value, low-frequency, high-energy fracture widening and network formation are implemented again, adjusting the system to a high-energy, low-frequency mode to release high-energy shock waves. These high-energy shock waves propagate at high speed along the previously formed initial directional cracks, driving the micro-fractures to extend deeper into the reservoir, forming main fractures. These main fractures are interconnected by secondary fractures, forming a complex three-dimensional fracture network.

[0075] The capacitance value of the high-voltage energy storage capacitor bank in this application can be adjusted according to the actual needs of the project, and is not limited to a specific capacitance value. This allows for continuous adjustment of the energy released by electro-detonation from low to medium energy, and from medium to high energy. The effect of electro-detonation operations is achieved in both near-wellbore and far-wellbore areas. Repeated operations enhance the effect and propagation range of the shock wave, expanding fracture formation, particularly beneficial for complex fracture networks in unconventional reservoirs.

[0076] This application utilizes a self-propelled cable retraction vehicle to move and control the cable retraction and adjustment of the high-voltage discharge electrode position, enabling multi-level, multi-point operations on unconventional reservoirs, reservoir top plates, and reservoir bottom plates. Multi-level electro-explosion operations can connect the fracture network formed by the unconventional reservoir from deep to shallow, achieving a fully covered three-dimensional volumetric fracture network. This results in pressure relief and permeability enhancement of the unconventional reservoir, improving the energy extraction efficiency of the unconventional reservoir.

[0077] Based on the same inventive concept, this application also provides a fracturing and permeation enhancement device for unconventional reservoirs for implementing the aforementioned fracturing and permeation enhancement method for unconventional reservoirs. The solution provided by this device is similar to the solution described in the above method. Therefore, the specific limitations of one or more embodiments of the fracturing and permeation enhancement device for unconventional reservoirs provided below can be found in the limitations of the fracturing and permeation enhancement method for unconventional reservoirs described above, and will not be repeated here.

[0078] In one exemplary embodiment, such as Figure 6 As shown, a fracturing and permeation enhancement device for unconventional reservoirs is provided, comprising: a target layer determination module, used to determine multiple target layers corresponding to the target wellbore based on the geological environment of the location of the target wellbore; the target wellbore is the wellbore of the unconventional reservoir production well to be fractured.

[0079] The reservoir parameter determination module is used to determine the depth and thickness of unconventional reservoirs, the location and thickness of the unconventional reservoir top plate, and the location and thickness of the unconventional reservoir bottom plate based on the topographic and geological conditions of the target wellbore location.

[0080] The target point determination module is used to determine the location of each target point and the corresponding energy range of the electro-detonation operation based on the target wellbore, the depth and thickness of the unconventional reservoir, the position and thickness of the unconventional reservoir top plate, and the position and thickness of the unconventional reservoir bottom plate.

[0081] The electro-detonation operation system is used to perform electro-detonation operations on unconventional reservoirs to be fractured, based on the location of each target point and the first and second operating energies within the corresponding electro-detonation operation energy range for each target point, in order to achieve fracturing and permeability enhancement of the unconventional reservoirs to be fractured; the second operating energy is greater than the first operating energy.

[0082] In one exemplary embodiment, a computer device is provided, which may be a server or a terminal, and its internal structure diagram may be as follows. Figure 7 As shown, the computer device includes a processor, memory, input / output (I / O) interfaces, and a communication interface. The processor, memory, and I / O interfaces are connected via a system bus, and the communication interface is also connected to the system bus via the I / O interfaces. The processor provides computational and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system, computer programs, and a database. The internal memory provides the environment for the operating system and computer programs in the non-volatile storage media to run. The database stores fracturing and permeation enhancement data for unconventional reservoirs. The I / O interfaces allow the processor to exchange information with external devices. The communication interface allows communication with external terminals via a network connection. When the computer program is executed by the processor, it implements a fracturing and permeation enhancement method for unconventional reservoirs.

[0083] Those skilled in the art will understand that Figure 7 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0084] In one exemplary embodiment, a computer device is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the above-described method embodiments.

[0085] In one exemplary embodiment, a computer-readable storage medium is provided storing a computer program that, when executed by a processor, implements the above-described method embodiments.

[0086] In one exemplary embodiment, a computer program product is provided, including a computer program that, when executed by a processor, implements the above-described method embodiments.

[0087] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of the relevant data must comply with relevant regulations.

[0088] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments described above. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM).

[0089] The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, etc., and are not limited to these.

[0090] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0091] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for fracturing and permeability enhancement in unconventional reservoirs, characterized in that, The fracturing and permeability enhancement method for unconventional reservoirs includes: Based on the geological environment of the target wellbore's location, multiple target strata corresponding to the target wellbore are determined; the target wellbore is the wellbore where the unconventional reservoir development well to be fractured is located. Based on the topographic and geological conditions of the target well location, determine the depth and thickness of the unconventional reservoir, the location and thickness of the unconventional reservoir top plate, and the location and thickness of the unconventional reservoir bottom plate. Based on the target wellbore corresponding to each target layer, the depth and thickness of the unconventional reservoir, the position and thickness of the unconventional reservoir top plate, and the position and thickness of the unconventional reservoir bottom plate, determine the position of each target point and the corresponding energy range of the electro-detonation operation when carrying out electro-detonation operation. Based on the location of each target point during the electro-detonation operation and the first and second operating energies within the corresponding electro-detonation operation energy range for each target point, electro-detonation operations are performed on the unconventional reservoir to be fractured, in order to achieve fracturing and permeability enhancement of the unconventional reservoir to be fractured; the second operating energy is greater than the first operating energy.

2. The fracturing and permeability enhancement method for unconventional reservoirs according to claim 1, characterized in that, An electric detonation system is used to perform electric detonation operations on unconventional reservoirs to be fractured, based on the location of each target point and the first and second operating energies within the electric detonation energy range corresponding to each target point.

3. The fracturing and permeability enhancement method for unconventional reservoirs according to claim 2, characterized in that, The electro-detonation operation system includes a charging power supply, a high-voltage energy storage capacitor bank, an electro-detonation triggering control system, and a high-voltage discharge electrode connected in sequence. Using this system, electro-detonation operations are performed on the unconventional reservoir to be fractured, based on the location of each target point and the first and second operating energies within the corresponding electro-detonation energy range for each target point. Specifically: Place the high-voltage discharge electrode at the current target location and immerse the high-voltage discharge electrode in the liquid medium inside the target wellbore; Based on the first working energy corresponding to the current target location, set the first capacitance value of the high-voltage energy storage capacitor bank; Turn on the charging power to charge the high-voltage energy storage capacitor bank until the high-voltage energy storage capacitor bank reaches the preset voltage value. The system sends trigger signals to the electric explosion triggering control system multiple times via a wireless remote control terminal to induce multiple small energy movements at the current target location. Based on the second working energy corresponding to the current target location, set the second capacitance value of the high-voltage energy storage capacitor bank; Turn on the charging power to charge the high-voltage energy storage capacitor bank until the high-voltage energy storage capacitor bank reaches the preset voltage value. The wireless remote control terminal sends trigger signals to the electric explosion triggering control system multiple times to complete the high-energy fracturing of the current target point. Determine whether the fracturing and permeability enhancement effect at the current target location has achieved the expected results; If the expected result is achieved, update the current target point and return to the steps of placing the high-voltage discharge electrode at the current target point and immersing the high-voltage discharge electrode in the liquid medium inside the target wellbore. If the expected results are not achieved, return to the step of setting the first capacitance value of the high-voltage energy storage capacitor bank based on the first working energy corresponding to the current target point, until the fracturing and permeation enhancement effects corresponding to all target points reach the expected results.

4. The fracturing and permeability enhancement method for unconventional reservoirs according to claim 3, characterized in that, To determine whether the fracturing and permeability enhancement effect at the current target location has achieved the expected results, the following steps are taken: Obtain the fracturing parameters; The effectiveness of fracturing and permeability enhancement is determined based on the fracturing parameters.

5. The fracturing and permeability enhancement method for unconventional reservoirs according to claim 4, characterized in that, The electric detonation system also includes an electrical parameter monitoring device for monitoring fracturing parameters, which include voltage and current signals during the transient discharge of the high-voltage discharge electrode.

6. The fracturing and permeability enhancement method for unconventional reservoirs according to claim 4, characterized in that, The electric blasting operation system also includes: a micro-vibration sensor for monitoring fracturing parameters; the fracturing parameters are: ground vibration signals.

7. A fracturing and permeability enhancement device for unconventional reservoirs, characterized in that, The fracturing and permeation enhancement device for unconventional reservoirs includes: The target stratum determination module is used to determine multiple target strata corresponding to the target wellbore based on the geological environment of the location of the target wellbore; the target wellbore is the wellbore where the unconventional reservoir development well to be fractured is located. The reservoir parameter determination module is used to determine the depth and thickness of unconventional reservoirs, the location and thickness of the unconventional reservoir top plate, and the location and thickness of the unconventional reservoir bottom plate based on the topographic and geological conditions of the target wellbore location. The target point determination module is used to determine the location of each target point and the corresponding energy range of the electro-detonation operation based on the target wellbore, the depth and thickness of the unconventional reservoir, the position and thickness of the unconventional reservoir top plate, and the position and thickness of the unconventional reservoir bottom plate. The electro-detonation operation system is used to perform electro-detonation operations on unconventional reservoirs to be fractured, based on the location of each target point and the first and second operating energies within the corresponding electro-detonation operation energy range for each target point, in order to achieve fracturing and permeability enhancement of the unconventional reservoirs to be fractured; the second operating energy is greater than the first operating energy.

8. A computer device, comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that the processor executes the computer program to implement the fracturing and permeability enhancement method for unconventional reservoirs as described in any one of claims 1-6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the computer program implements the fracturing and permeation enhancement method for unconventional reservoirs as described in any one of claims 1-6.

10. A computer program product, comprising a computer program, characterized in that, When executed by a processor, the computer program implements the fracturing and permeation enhancement method for unconventional reservoirs as described in any one of claims 1-6.

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