Shale physical simulation test system for coupling detonation fracturing and flow conductivity test

Abstract

The invention belongs to the field of simulation tests, particularly relates to a shale physical simulation test system for coupling detonation fracturing and flow conductivity testing, and aims to solve the problems that effective means for directly observing and evaluating fracture characteristics and expansion forms after reservoir transformation are lacked, and the detonation fracturing transformation effect cannot be accurately evaluated. The method comprises the following steps: preparing a shale sample with a prefabricated crack, and applying triaxial stress through a warm-pressing assembly; detonation fracturing is carried out by adopting a liquid explosive, and acoustic emission data and scanning imaging are synchronously acquired; injecting fluid under the condition of keeping confining pressure, cooperatively regulating and controlling pressure of a crack inlet and a base inlet, pressurizing after the pressure is balanced, and monitoring stable flow; and calculating the fracture volume, the expansion speed and the fracture conductivity. According to the invention, detonation fracturing dynamic monitoring, multi-physics field coupling simulation and fracture flow guide characteristic quantitative characterization functions are integrated, and multi-dimensional and accurate experimental data support is provided for shale reservoir transformation effect evaluation.

Description

Technical Field

[0001] The invention belongs to the field of simulation tests, and in particular relates to a shale physical simulation test system for coupling detonation fracturing and conductivity testing. Background Art

[0002] Shale oil and gas resources are important replacement resources after conventional energy development. In recent years, with the innovation and large-scale application of reservoir transformation technology, great progress has been made, but the main development areas are still concentrated in shallow reservoirs. Due to the large burial depth of deep reservoirs, high formation pressure and ground temperature, and poor rock brittleness, the existing hydraulic fracturing has a low degree of transformation of deep reservoirs. There are problems such as difficulty in forming fracture networks, poor effective support effect of proppants, and obvious crack creep. The existing hydraulic fracturing methods must be upgraded for the development of deep-ultra-deep shale oil and gas resources. The energy generated by the explosion of explosives can fracture the formation around the wellbore, thereby improving the physical properties of low-permeability reservoirs and increasing the oil and gas recovery rate of low-permeability reservoirs. The explosion production enhancement technology has mainly developed into the following technologies: high-energy gas fracturing, intra-layer explosion, and methane in-situ explosion fracturing.

[0003] The scale of fracture expansion is an important indicator for evaluating the effectiveness of reservoir transformation. At present, it is mainly evaluated indirectly through microseismic monitoring, wide-area electromagnetic method, adding tracers to fracturing fluid, etc., which cannot truly observe the fracture characteristics and expansion morphology after reservoir transformation. In addition, due to the large energy of explosive production enhancement technology, the cost of field tests is high. In order to conduct an economical and effective evaluation of the fracturing effect of explosive production enhancement technology, it has become a feasible means to carry out large-scale indoor reservoir transformation physical simulation experiments.

[0004] Using explosives, especially liquid explosives, to transform reservoirs is a relatively effective means, but there is currently no precedent for large-scale in-situ loading visualization tests. Most of the methods in existing inventions are applied on-site, and laboratory-scale experiments lack fracture characteristics and morphological evolution processes, and their technical details still need to be explored.

[0005] In addition, the conductivity of the fracture network is the most important indicator for evaluating the effect of detonation fracturing. It is usually difficult to obtain in physical simulation tests. Generally, the sample is taken out after the pressure is unloaded to test the conductivity. This will cause the measured conductivity to have a significant error compared with the pressure state, and it is impossible to correctly evaluate the effect of detonation fracturing.

[0006] Based on this, the present invention proposes a shale physical simulation test system for coupling detonation fracturing and conductivity testing. Summary of the invention

[0007] In order to solve the above problems in the prior art, namely, the lack of effective means to directly observe and evaluate the crack characteristics and expansion morphology after reservoir transformation, and the problem of being unable to accurately evaluate the effect of detonation fracturing, the present invention provides a shale physical simulation test system for coupling detonation fracturing and conductivity testing, the system comprising: A plurality of shale samples, each of which is cut according to a preset size and has prefabricated fractures with different radii and numbers opened in the center of the top surface; a temperature and pressure application assembly configured to apply a target temperature, an axial pressure, and a confining pressure to the shale sample; A detonation assembly, comprising a polycarbonate tube inserted into the prefabricated crack, a liquid explosive filled in the polycarbonate tube, and an electronic detonator in contact with the liquid explosive; A detonation fracturing data monitoring component, including a plurality of acoustic emission sensor probes installed on the surface of the shale sample, and a scanning component for imaging the interior of the shale sample after detonation fracturing; A fluid injection assembly is connected to the pressure chamber base and is configured to inject a fluid of set viscosity into the sample under the condition of maintaining the axial pressure and the confining pressure; the base inlet pressure is adjusted to a constant value, and the constant value is set to the hydrostatic pressure of the formation depth corresponding to the confining pressure; The pressure monitoring assembly includes a first sensor for measuring the fluid pressure at the entrance of the prefabricated fracture and a second sensor for measuring the pressure at the entrance of the base; a flow control component configured to increase the fluid pressure at the entrance of the prefabricated fracture according to a set threshold value when the fluid pressure at the entrance of the prefabricated fracture is the same as the pressure at the entrance of the base, and to monitor the stable flow at the outlet of the base; a data processing component configured to calculate the volume and propagation speed of the fracture based on the imaging data and the acoustic emission data generated by the detonation fracturing data monitoring component; The conductivity is calculated based on the steady flow rate, fluid viscosity, shale sample size and pressure difference, where the pressure difference is the difference between the fluid pressure at the entrance of the prefabricated fracture and the pressure at the entrance of the base.

[0008] Furthermore, the data processing component includes: A crack region segmentation module is configured to segment the imaging data into crack regions and matrix regions based on a preset density threshold interval, and generate a binary image; A three-dimensional reconstruction module is configured to convert the binary image into a volume data model through a three-dimensional linear interpolation algorithm to generate a three-dimensional surface mesh model of the fracture network; The volume calculation module is configured to calculate the crack volume based on the three-dimensional surface mesh model using a voxel statistics method.

[0009] Furthermore, the data processing component also includes: The acoustic emission positioning module is configured to calculate the three-dimensional spatial coordinates of the acoustic emission event based on the arrival time difference method according to the geometric coordinates of multiple acoustic emission sensor probes in a preset coordinate system on the surface of the shale sample; align the three-dimensional spatial coordinates with the three-dimensional surface grid model to generate a spatial mapping relationship of the crack extension path; The expansion velocity analysis module is configured to extract the longitudinal wave velocity transition point in the acoustic emission signal and calculate the critical expansion velocity of the crack tip; perform error calibration on the critical expansion velocity through the lead breaking experiment, and correct the calculation model parameters according to the calibration result.

[0010] Further, the temperature and pressure applying assembly includes: a triaxial pressure chamber, an axial loading probe, a confining pressure loading pump and a temperature loading system; The triaxial pressure chamber is connected to a confining pressure loading pump, and the confining pressure loading pump is used to load confining pressure on the shale sample. A shale sample is placed in the triaxial pressure chamber, and an axial loading probe is installed above the top surface of the shale sample, and the axial loading probe is used to load an axial force on the shale sample. The temperature loading system is connected to the triaxial pressure chamber and is used to heat the shale sample to a target temperature.

[0011] Furthermore, the scanning components are arranged on both sides of the triaxial pressure chamber, and the scanning components are connected to a scanning component control system via a line.

[0012] Furthermore, the acoustic emission sensor probe array is installed on the outer surface of the shale sample, and the acoustic emission sensor probe passes through the triaxial pressure chamber and is connected to a multi-channel acoustic emission acquisition system.

[0013] Further, the scanning component is a high-energy accelerator CT scanning system, and the scanning component control system is a high-energy accelerator CT scanning control system; The high energy accelerator CT scanning system includes a ray source and a detector; The ray source and the detector are distributed on both sides of the triaxial pressure chamber. The ray source is used to emit rays to the shale sample, and the detector is used to receive the rays passing through the shale sample and convert them into electrical signals. The high-energy accelerator CT scanning control system acquires the electrical signals and calculates the reconstructed image in combination with the reconstruction algorithm.

[0014] Furthermore, the electronic detonator is connected to an electronic detonator controller, and the electronic detonator controller is used to control the electronic detonator to detonate liquid explosives.

[0015] Furthermore, the high-energy accelerator CT scanning system and the triaxial pressure chamber are both arranged on the rock sample rotating table.

[0016] Furthermore, the fluid pressure at the entrance of the prefabricated fracture and the pressure at the entrance of the base are loaded based on two different pressure pumps respectively.

[0017] Beneficial effects of the present invention: Direct observation and evaluation: By simulating the actual on-site detonation fracturing process under laboratory conditions and combining the acoustic emission monitoring system and scanning imaging technology, the formation and development process of cracks caused by the detonation on the rock sample can be directly observed, providing an intuitive basis for evaluating the reservoir transformation effect.

[0018] Optimizing detonation parameters: This physical simulation experiment can be used to study the effects of different prefabricated fracture radius, number, and amount of liquid explosive on fracture expansion, which helps to optimize detonation parameters and improve the effect of deep reservoir reconstruction.

[0019] Reduce field test costs: Compared with the expensive and complex on-site explosion stimulation tests, indoor physical simulation experiments can be repeated multiple times in a more controllable and economical environment, reducing R&D costs and technical risks.

[0020] Promote technological progress: Through the study of the mechanism of detonation fracturing, we can further promote the development of detonation fracturing technology in the development of deep and ultra-deep shale oil and gas resources, explore new technical details, and improve the overall technical level.

[0021] Improved safety: Conducting these experiments in a laboratory setting allows for better control of variables, ensuring safe operations while also reducing impact on the environment.

[0022] Improved assessment accuracy: The confining pressure and axial pressure are maintained after detonation fracturing to keep the fracture network in an in-situ stress state, avoiding fracture closure or deformation caused by unloading pressure. By actively adjusting the fracture inlet pressure, a controllable pressure gradient is formed to accurately simulate the formation fluid flow and avoid measurement deviations caused by pressure disturbances. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings: Figure 1 It is a schematic diagram of a shale physical simulation test system for coupling detonation fracturing and conductivity testing of the present invention; Figure 2 It is a schematic diagram of various prefabricated fractures in a shale physical simulation test system for coupled detonation fracturing and conductivity testing of the present invention. DETAILED DESCRIPTION

[0024] The present application will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention. It is also necessary to explain that, for ease of description, only the parts related to the relevant invention are shown in the accompanying drawings.

[0025] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0026] The present invention provides a shale physical simulation test system for coupling detonation fracturing and conductivity testing, the system comprising: A plurality of shale samples, each of which is cut according to a preset size and has prefabricated fractures with different radii and numbers opened in the center of the top surface; a temperature and pressure application assembly configured to apply a target temperature, an axial pressure, and a confining pressure to the shale sample; A detonation assembly, comprising a polycarbonate tube inserted into the prefabricated crack, a liquid explosive filled in the polycarbonate tube, and an electronic detonator in contact with the liquid explosive; A detonation fracturing data monitoring component, comprising a plurality of acoustic emission sensor probes 5 installed on the surface of a shale sample, and a scanning component 1 for imaging the interior of the shale sample after detonation fracturing; A fluid injection assembly is connected to the pressure chamber base and is configured to inject a fluid of set viscosity into the sample under the condition of maintaining the axial pressure and the confining pressure; the base inlet pressure is adjusted to a constant value, and the constant value is set to the hydrostatic pressure of the formation depth corresponding to the confining pressure; The pressure monitoring assembly includes a first sensor for measuring the fluid pressure at the entrance of the prefabricated fracture and a second sensor for measuring the pressure at the entrance of the base; a flow control component configured to increase the fluid pressure at the entrance of the prefabricated fracture according to a set threshold value when the fluid pressure at the entrance of the prefabricated fracture is the same as the pressure at the entrance of the base, and to monitor the stable flow at the outlet of the base; a data processing component configured to calculate the volume and propagation speed of the fracture based on the imaging data and the acoustic emission data generated by the detonation fracturing data monitoring component; The conductivity is calculated based on the steady flow rate, fluid viscosity, shale sample size and pressure difference, where the pressure difference is the difference between the fluid pressure at the entrance of the prefabricated fracture and the pressure at the entrance of the base.

[0027] In order to more clearly explain the shale physical simulation test system for coupling detonation fracturing and conductivity testing of the present invention, the following is combined with Figure 1 Each component in the embodiment of the present invention is described in detail as follows: A plurality of shale samples, each of which is cut according to a preset size and has prefabricated fractures with different radii and numbers opened in the center of the top surface; like Figure 2 As shown, in this embodiment, the shale sample is cut into a cylinder with a size of Φ500 mm×1000 mm, and the prefabricated cracks include two types of 8 different cracks: Category 1: Figure 2 As shown in the four shale samples in the upper part, one fracture was prefabricated, with diameters of Φ1 mm, Φ5 mm, Φ10 mm, and Φ16 mm, respectively, and the height was half the height of the shale sample, which was 500 mm; The second category: Figure 1 As shown in the four shale samples in the lower part, two cracks were prefabricated, with diameters of Φ1 mm, Φ5 mm, Φ10 mm, and Φ16 mm, respectively, and a height of 500 mm, which is half the height of the shale samples.

[0028] See also Figure 1 , the temperature and pressure applying assembly includes: a triaxial pressure chamber 3, an axial loading probe 6, a confining pressure loading pump 8 and a temperature loading system 9; The triaxial pressure chamber 3 is connected to a confining pressure loading pump 8, and the confining pressure loading pump 8 is used to load confining pressure on the shale sample. A shale sample is placed in the triaxial pressure chamber 3, and an axial loading probe 6 is installed above the top surface of the shale sample. The axial loading probe 6 is used to load an axial force on the shale sample. The temperature loading system 9 is connected to the triaxial pressure chamber 3 and is used to heat the shale sample to a target temperature.

[0029] In this embodiment, the scanning assembly 1 in the detonation fracturing data monitoring assembly is arranged on both sides of the triaxial pressure chamber 3, and the scanning assembly 1 is connected to the scanning assembly control system 10 through a line.

[0030] The scanning component 1 is a high-energy accelerator CT scanning system, and the scanning component control system 10 is a high-energy accelerator CT scanning control system; The high energy accelerator CT scanning system comprises a ray source 4 and a detector 12; The ray source 4 and the detector 12 are distributed on both sides of the triaxial pressure chamber 3. The ray source 4 is used to emit rays to the shale sample, and the detector 12 is used to receive the rays passing through the shale sample and convert them into electrical signals. The high-energy accelerator CT scanning control system obtains the electrical signals and calculates the reconstructed image in combination with the reconstruction algorithm.

[0031] The acoustic emission sensor probes 5 array in the detonation fracturing data monitoring assembly are installed on the outer surface of the shale sample, and the acoustic emission sensor probes 5 pass through the triaxial pressure chamber 3 and are connected to the multi-channel acoustic emission acquisition system 11 .

[0032] The electronic detonator in the detonation assembly is connected to the electronic detonator controller 7, and the electronic detonator controller 7 is used to control the electronic detonator to detonate the liquid explosive.

[0033] The high energy accelerator CT scanning system and the triaxial pressure chamber 3 are both arranged on the rock sample rotating table 2 .

[0034] The fluid pressure at the entrance of the prefabricated crack and the pressure at the entrance of the base configured by the flow control assembly are loaded based on two different pressure pumps respectively.

[0035] In this embodiment, the data processing component includes: A crack region segmentation module is configured to segment the imaging data into crack regions and matrix regions based on a preset density threshold interval, and generate a binary image; A three-dimensional reconstruction module is configured to convert the binary image into a volume data model through a three-dimensional linear interpolation algorithm to generate a three-dimensional surface mesh model of the fracture network; Volume calculation module, configured to calculate the crack volume based on a 3D surface mesh model using voxel statistics V c .

[0036] Among them, the preset density threshold range (between 0 and 255) marks the crack area as white (pixel value 255) and the matrix area as black (pixel value 0).

[0037] V c = N v × v 0 ; in, N v is the number of crack voxels, v 0 is the actual volume of a single voxel.

[0038] The data processing component also includes: The acoustic emission positioning module is configured to calculate the three-dimensional spatial coordinates of the acoustic emission event based on the arrival time difference method according to the geometric coordinates of the multiple acoustic emission sensor probes 5 in the preset coordinate system on the surface of the shale sample; align the three-dimensional spatial coordinates with the three-dimensional surface grid model to generate a spatial mapping relationship of the crack extension path; The expansion velocity analysis module is configured to extract the longitudinal wave velocity transition point in the acoustic emission signal and calculate the critical expansion velocity of the crack tip; perform error calibration on the critical expansion velocity through the lead breaking experiment, and correct the calculation model parameters according to the calibration result.

[0039] In this embodiment, the Geiger iterative algorithm based on arrival time difference is used to solve the acoustic emission events to obtain the three-dimensional positioning of the rupture position.

[0040] In this embodiment, a shale physical simulation test system for coupling detonation fracturing and conductivity testing has the following working process: Step S1, cutting the shale according to a preset size to obtain a plurality of shale samples, and opening prefabricated cracks of different radius sizes and numbers at the center of the top surface of each shale sample; Step S2, placing a polycarbonate tube in the prefabricated crack, and injecting a set amount of liquid explosive into the polycarbonate tube; In this embodiment, the outer diameter of the polycarbonate tube is selected to be 1 mm, and one end of the polycarbonate tube away from the top surface of the shale sample is sealed to prevent leakage of liquid explosives, and the length of the liquid explosive column is selected to be 30 mm.

[0041] The liquid explosive is compounded by nitromethane-based materials, amine compounds (such as ethylenediamine) and polymer thickeners (such as cellulose acetate) in a specific synergistic ratio, and its formula components and ratio relationship are determined by orthogonal experimental optimization.

[0042] The amount of liquid explosive is calculated and determined based on the prefabricated crack parameters (crack width, crack length) and the critical explosion diameter of the liquid explosive (1-5mm) to ensure that the explosion threshold concentration of the liquid explosive is reached in the prefabricated crack; the liquid explosive has the characteristics of stable chemical properties, insolubility in water, stable rheology, etc., and has high operability and safety in the actual construction process.

[0043] The filling amount of liquid explosive inside the sample is calculated by the following formula: ; in M is the mass of liquid explosive; r is the relative density of the prepared liquid explosive; F is the diameter of the prefabricated crack; L is the length of the prefabricated crack; K D is the correction factor for critical charge diameter; or is the safety factor (take 1.2-2.0).

[0044] Step S3, loading an electronic detonator into the polycarbonate tube, wherein the electronic detonator is in contact with the liquid explosive; after loading the electronic detonator, sealing the prefabricated crack; Among them, the outer diameter of the electronic detonator is selected to be 0.9mm, and the anchoring agent is selected as the filling material to seal the prefabricated cracks, and the filling length is 10mm; the electronic detonator and the anchoring agent are selected as the initiation method and the filling material respectively, mainly considering their safety, and the liquid explosive can be safely and successfully detonated under the premise of clarifying the critical detonation velocity and initiation diameter.

[0045] Step S4, selecting one of the sealed shale samples, evenly installing acoustic emission sensor probes 5 on its surface, and performing initial debugging through a multi-channel acoustic emission monitoring system; In this embodiment, the rock sample filled with liquid explosives and electronic detonators is evenly pasted on the acoustic emission sensor probe 5, and the multi-channel acoustic emission monitoring system is used for initial debugging to check the correctness of the acoustic emission channel threshold and amplitude setting.

[0046] Step S5, placing the shale sample with the acoustic emission sensor probe 5 installed in the triaxial pressure chamber 3, and applying temperature and axial force to the shale sample: Step S51, placing the shale sample into the triaxial pressure chamber 3, and passing the acoustic emission sensor probe 5 through the triaxial pressure chamber 3 to connect with the multi-channel acoustic emission acquisition system 11; Step S52, connecting the electronic detonator controller 7, the confining pressure loading pump 8 and the temperature loading system 9, checking the sealing of the pipeline, and after the inspection, closing the triaxial pressure chamber 3 through the operating console and placing it on the rock sample rotating table 2; Step S53, the triaxial pressure chamber 3 is pressurized by injecting hydraulic oil through the confining pressure loading pump 8 to increase the pressure to the target confining pressure value; at the same time, the shale sample is heated by the temperature loading system 9 with a temperature gradient of 5°C / min. After heating to the target temperature, the temperature is maintained at a constant temperature; Step S54, applying axial force to the shale sample based on the initial loading speed through the axial loading probe 6. When the axial loading probe 6 is close to the triaxial pressure chamber 3, the initial loading speed is changed to the first preset speed. After the axial pressure is loaded to the target value, the constant pressure is maintained.

[0047] Wherein, the initial loading speed is 2 mm / min, and the first preset speed is 200 N / s.

[0048] Step S6, detonating the liquid explosive to detonate the shale sample, scanning and imaging the shale sample through the scanning component, and recording the acoustic emission channel signal during the rupture process: Step S61, detect the airtightness of the triaxial pressure chamber 3. When the airtightness meets the requirements, the electronic detonator controller 7 is used to control the electronic detonator to detonate the liquid explosive to perform detonation initiation of the shale sample; the multi-channel acoustic emission acquisition system 11 is turned on to record the acoustic emission channel signals during the rupture of the shale sample.

[0049] Step S62: After the shale sample is destroyed, the ray source 4 is turned on to scan and image the shale sample.

[0050] Step S7, maintaining the confining pressure of the triaxial pressure chamber 3 s 3 and axial pressure s 1 , pass clean water with a viscosity of 1 cP through the base of the triaxial pressure chamber 3, and control the pressure at the base connection to be a constant value P 0 ,in P 0 < s 3 And the value is confining pressure s 3 The hydrostatic pressure corresponding to the depth of the formation; Step S8, monitoring the fluid pressure at the iron pipe access port at the prefabricated crack P 1 ,when P 1 = P 0 When adjusting the inlet pressure ΔP = P 1 - P 0 =1-5MPa and maintain P 0 Constant, monitor the stable flow rate at the base outlet Q 0 ; Step S9, according to the formula Calculating Fracture Network Conductivity CF ; Where α is the crack network shape correction factor; m is the fluid viscosity; L is the length of the shale sample; D is the diameter of the shale sample.

[0051] Step S10, unload the axial force and cool down, remove the acoustic emission sensor probe 5, disassemble the electronic detonator, take pictures of the destroyed rock sample, organize the acquired data, jump to step S4, select other sealed shale samples, until all shale samples are tested.

[0052] Unload the axial force and cool down, remove the acoustic emission sensor probe 5, and disassemble the electronic detonator. The specific steps are as follows: Unload the axial force of the axial loading probe 6, close the temperature loading system 9, return the hydraulic oil to the confining pressure loading pump 8, cool the triaxial pressure chamber 3 to room temperature, open the triaxial pressure chamber 3, remove the acoustic emission sensor probe 5, and disassemble the electronic detonator.

[0053] Among them, the acquired data include CT scanning data, acoustic emission data and fracture network conductivity data.

[0054] In step S10, before jumping to step S4, the amount of liquid explosive for the shale sample of the next test is corrected according to the fracture volume and conductivity of the shale sample of the current test, and the method is as follows: Calculate the difference between the fracture volume of the shale sample in this test and the target volume ΔV , the difference between the conductivity and the target conductivity ΔQ ,according to ΔV and ΔQ The multiple relationship of the weight distribution priority mode is determined according to different priority modes. ΔV and ΔQ The weight is calculated by comprehensive scoring to obtain the adjustment direction of the amount of liquid explosive, and the adjustment amount is calculated according to the comprehensive scoring; The adjustment direction includes increasing or decreasing the charge amount; the priority mode includes a conductivity priority mode, a fracture volume priority mode and a balanced mode; when ΔQ ≥2 ΔV When , it is determined to be the flow capacity priority mode, and the weight classification strategy is: , ; in, and are the normalized deviations of conductivity and fracture volume, k is the sensitivity coefficient, and its value range is [3, 5]. is the conductivity weight, is the fracture volume weight; Through comprehensive scoring calculation, the adjustment direction of liquid explosive quantity is obtained as follows: ; in, S For the comprehensive rating, is the target flow capacity, is the target volume.

[0055] when ΔV ≥2 ΔQ When , it is determined to be the fracture volume priority mode, and the weight classification strategy is: , ; and , which is calculated as: ; .

[0056] The other cases are balanced modes, and the weight classification strategy is that the weight assigned to the conductivity is equal to the weight assigned to the fracture volume, both of which are 0.5.

[0057] Through comprehensive scoring calculation, the adjustment direction of liquid explosive quantity is obtained as follows: ; like S >0: It is necessary to improve the conductivity or control the crack volume, and the charge amount is adjusted to increase; like S <0: It is necessary to suppress crack expansion or optimize diversion efficiency, and the charge amount should be adjusted to reduce.

[0058] To increase or decrease the charge, adjust the amount , which is calculated as: ;in, a It is the preset coefficient, and its initial value is 0.1.

[0059] The present invention realizes dynamic optimization of the test process through a cycle mechanism of test-evaluation-parameter correction. After each test, the core parameters (charge amount) are automatically adjusted based on quantitative analysis to form an adaptive test system, which effectively improves the iteration efficiency of test data and provides a standardized operation framework for continuous testing of multiple samples.

[0060] Three priority mode judgment mechanisms are innovatively proposed. Through the dynamic weight allocation strategy, directional optimization can be carried out for specific engineering needs (such as conductivity enhancement or crack expansion control), and the balance adjustment of dual indicators can be achieved. Normalized deviation calculation eliminates dimensional differences, making the collaborative analysis of different physical quantities scientifically comparable.

[0061] A charge adjustment algorithm based on quantitative scoring is constructed to convert the multi-dimensional deviations between the test results and the target values ​​into actionable adjustment instructions. Through the coupling of the sensitivity coefficient and the preset coefficient, the direction of parameter adjustment is guaranteed to be correct, and the risk of over-correction is avoided through progressive adjustment, which significantly improves the stability of parameter optimization.

[0062] In the description of the present invention, the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings, which are only for the convenience of description, and do not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0063] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0064] The term "comprise" or any other similar term is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus / device that includes a list of elements includes not only those elements but also other elements not expressly listed, or also includes elements inherent to such process, method, article, or apparatus / device.

[0065] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A shale physical simulation test system for coupled detonation fracturing and conductivity testing, characterized in that: The system includes: A plurality of shale samples, each of which is cut according to a preset size and has prefabricated fractures with different radii and numbers opened in the center of the top surface; a temperature and pressure application assembly configured to apply a target temperature, an axial pressure, and a confining pressure to the shale sample; A detonation assembly, comprising a polycarbonate tube inserted into the prefabricated crack, a liquid explosive filled in the polycarbonate tube, and an electronic detonator in contact with the liquid explosive; A detonation fracturing data monitoring component, including a plurality of acoustic emission sensor probes installed on the surface of the shale sample, and a scanning component for imaging the interior of the shale sample after detonation fracturing; A fluid injection assembly is connected to the pressure chamber base and is configured to inject a fluid of set viscosity into the sample under the condition of maintaining the axial pressure and the confining pressure; the base inlet pressure is adjusted to a constant value, and the constant value is set to the hydrostatic pressure of the formation depth corresponding to the confining pressure; The pressure monitoring assembly includes a first sensor for measuring the fluid pressure at the entrance of the prefabricated fracture and a second sensor for measuring the pressure at the entrance of the base; a flow control component configured to increase the fluid pressure at the entrance of the prefabricated fracture according to a set threshold value when the fluid pressure at the entrance of the prefabricated fracture is the same as the pressure at the entrance of the base, and to monitor the stable flow at the outlet of the base; a data processing component configured to calculate the volume and propagation speed of the fracture based on the imaging data and the acoustic emission data generated by the detonation fracturing data monitoring component; The conductivity is calculated based on the steady flow rate, fluid viscosity, shale sample size and pressure difference, where the pressure difference is the difference between the fluid pressure at the entrance of the prefabricated fracture and the pressure at the entrance of the base.

2. A shale physical simulation test system for coupled detonation fracturing and conductivity testing according to claim 1, characterized in that: The data processing component includes: A crack region segmentation module is configured to segment the imaging data into crack regions and matrix regions based on a preset density threshold interval, and generate a binary image; A three-dimensional reconstruction module is configured to convert the binary image into a volume data model through a three-dimensional linear interpolation algorithm to generate a three-dimensional surface mesh model of the fracture network; The volume calculation module is configured to calculate the crack volume based on the three-dimensional surface mesh model using a voxel statistics method.

3. A shale physical simulation test system for coupled detonation fracturing and conductivity testing according to claim 2, characterized in that: The data processing component also includes: The acoustic emission positioning module is configured to calculate the three-dimensional spatial coordinates of the acoustic emission event based on the arrival time difference method according to the geometric coordinates of multiple acoustic emission sensor probes in a preset coordinate system on the surface of the shale sample; align the three-dimensional spatial coordinates with the three-dimensional surface grid model to generate a spatial mapping relationship of the crack extension path; The expansion velocity analysis module is configured to extract the longitudinal wave velocity transition point in the acoustic emission signal and calculate the critical expansion velocity of the crack tip; perform error calibration on the critical expansion velocity through the lead breaking experiment, and correct the calculation model parameters according to the calibration result.

4. The shale physical simulation test system for coupling detonation fracturing and conductivity testing according to claim 1, characterized in that: The temperature and pressure application assembly includes: a triaxial pressure chamber, an axial loading probe, a confining pressure loading pump and a temperature loading system; The triaxial pressure chamber is connected to a confining pressure loading pump, and the confining pressure loading pump is used to load confining pressure on the shale sample. A shale sample is placed in the triaxial pressure chamber, and an axial loading probe is installed above the top surface of the shale sample, and the axial loading probe is used to load an axial force on the shale sample. The temperature loading system is connected to the triaxial pressure chamber and is used to heat the shale sample to a target temperature.

5. The shale physical simulation test system for coupling detonation fracturing and conductivity testing according to claim 1, characterized in that: The scanning components are arranged on both sides of the triaxial pressure chamber, and the scanning components are connected to a scanning component control system through a line.

6. A shale physical simulation test system for coupled detonation fracturing and conductivity testing according to claim 5, characterized in that: The acoustic emission sensor probe array is installed on the outer surface of the shale sample, and the acoustic emission sensor probe passes through the triaxial pressure chamber and is connected to a multi-channel acoustic emission acquisition system.

7. The shale physical simulation test system for coupling detonation fracturing and conductivity testing according to claim 5, characterized in that: The scanning component is a high-energy accelerator CT scanning system, and the scanning component control system is a high-energy accelerator CT scanning control system; The high energy accelerator CT scanning system includes a ray source and a detector; The ray source and the detector are distributed on both sides of the triaxial pressure chamber. The ray source is used to emit rays to the shale sample, and the detector is used to receive the rays passing through the shale sample and convert them into electrical signals. The high-energy accelerator CT scanning control system acquires the electrical signals and calculates the reconstructed image in combination with the reconstruction algorithm.

8. The shale physical simulation test system for coupled detonation fracturing and conductivity testing according to claim 1, characterized in that: The electronic detonator is connected to an electronic detonator controller, and the electronic detonator controller is used to control the electronic detonator to detonate liquid explosive.

9. The shale physical simulation test system for coupling detonation fracturing and conductivity testing according to claim 7, characterized in that: The high-energy accelerator CT scanning system and the triaxial pressure chamber are both arranged on the rock sample rotating table.

10. The shale physical simulation test system for coupled detonation fracturing and conductivity testing according to claim 1, characterized in that: The fluid pressure at the entrance of the prefabricated crack and the pressure at the base entrance are loaded based on two different pressure pumps.

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