A shale physical simulation test system for coupled detonation fracturing and conductivity testing

Abstract

The present invention belongs to the field of simulation tests, and specifically relates to a shale physical simulation test system that couples detonation fracturing with conductivity testing, aiming to solve the problems of lack of effective means to directly observe and evaluate the characteristics and expansion morphology of fractures after reservoir transformation, and the inability to accurately evaluate the effect of detonation fracturing. The present invention includes: preparing shale samples with prefabricated fractures, applying triaxial stress through a temperature-pressure assembly; implementing detonation fracturing with liquid explosives, and synchronously collecting acoustic emission data and scanning imaging; injecting fluid while maintaining confining pressure, collaboratively regulating the pressure at the fracture entrance and the base entrance, increasing the pressure after the pressure is balanced and monitoring the stable flow rate; calculating the fracture volume, expansion rate, and fracture conductivity. The present invention integrates the functions of dynamic monitoring of detonation fracturing, multi-physical field coupling simulation, and quantitative characterization of fracture conductivity characteristics, providing multi-dimensional and accurate experimental data support for the evaluation of shale reservoir transformation effects.

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 a crucial successor to conventional energy development. Recent advances in reservoir stimulation technologies and their widespread application have resulted in significant progress, but development remains primarily concentrated in shallow reservoirs. Existing hydraulic fracturing methods have limited success in deep reservoirs due to their great depth, high formation pressure and temperature, and poor rock brittleness. These methods face challenges such as difficulty in forming a fracture network, poor proppant support, and significant fracture creep. Therefore, existing hydraulic fracturing methods require technological upgrades specifically for the development of deep and ultra-deep shale oil and gas resources. The energy generated by explosive detonations can fracture the formation surrounding the wellbore, thereby improving the physical properties and increasing oil and gas recovery rates in low-permeability reservoirs. Explosive stimulation technologies have primarily evolved into the following: high-energy gas fracturing, intra-stratum explosions, and in-situ methane explosion fracturing.

[0003] The scale of fracture expansion is an important indicator for evaluating the effectiveness of reservoir stimulation. Currently, indirect evaluation is mainly carried out on-site through microseismic monitoring, wide-area electromagnetic methods, and the addition of tracers to the fracturing fluid. However, it is impossible to truly observe the fracture characteristics and expansion morphology after reservoir stimulation. In addition, due to the high energy consumption of explosive stimulation technology, the cost of field tests is high. In order to conduct an economical and effective evaluation of the fracture-inducing effect of explosive stimulation technology, conducting large-scale indoor physical simulation experiments of reservoir stimulation has become a feasible means.

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

[0005] Furthermore, the conductivity of the fracture network is the most important indicator for evaluating the effectiveness of detonation fracturing. However, this is often difficult to obtain in physical simulations. Typically, the conductivity is measured after the pressure is unloaded and the sample is removed. This results in significant errors in the measured conductivity compared to the pressure-maintained state, making it difficult to accurately assess the effectiveness of detonation fracturing.

[0006] Based on this, the present invention proposes a shale physical simulation test system that couples detonation fracturing with conductivity testing. Summary of the Invention

[0007] To address the aforementioned problems in the prior art, namely, the lack of effective means to directly observe and evaluate the fracture characteristics and propagation morphology after reservoir stimulation, and the inability to accurately evaluate the effect of detonation fracturing, the present invention provides a shale physical simulation test system that couples detonation fracturing with conductivity testing. The system comprises:

[0008] Multiple shale samples, each shale sample is cut according to a preset size and has prefabricated cracks with different radii and numbers opened in the center of the top surface;

[0009] a temperature and pressure application assembly configured to apply a target temperature, an axial pressure, and a confining pressure to the shale specimen;

[0010] A detonation assembly comprising a polycarbonate tube inserted into a prefabricated crack, a liquid explosive filled in the polycarbonate tube, and an electronic detonator in contact with the liquid explosive;

[0011] A detonation fracturing data monitoring component, comprising 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;

[0012] a fluid injection assembly connected to the pressure chamber base and configured to inject a fluid of set viscosity into the sample while maintaining axial pressure and confining pressure; and adjusting the base inlet pressure to a constant value, wherein the constant value is set to the hydrostatic pressure of the formation depth corresponding to the confining pressure;

[0013] The pressure monitoring assembly includes a first sensor for measuring the fluid pressure at the entrance of the prefabricated crack and a second sensor for measuring the pressure at the entrance of the base;

[0014] a flow control component configured to increase the fluid pressure at the inlet of the prefabricated fracture according to a set threshold value when the fluid pressure at the inlet of the prefabricated fracture is the same as the pressure at the inlet of the base, and to monitor the stable flow rate at the outlet of the base;

[0015] a data processing component configured to calculate the volume and growth rate of the fracture based on the imaging data and acoustic emission data generated by the detonation fracturing data monitoring component;

[0016] The conductivity is calculated based on the steady flow rate, fluid viscosity, shale sample size, and pressure differential, where the pressure differential is the difference between the fluid pressure at the entrance of the prefabricated fracture and the pressure at the base entrance.

[0017] Furthermore, the data processing component includes:

[0018] a crack region segmentation module configured to segment the imaging data into crack regions and matrix regions based on a preset density threshold interval, and generate a binary image;

[0019] a three-dimensional reconstruction module configured to convert the binary image into a volume data model by a three-dimensional linear interpolation algorithm to generate a three-dimensional surface mesh model of the fracture network;

[0020] The volume calculation module is configured to calculate the crack volume based on the three-dimensional surface mesh model using a voxel statistics method.

[0021] Furthermore, the data processing component also includes:

[0022] an acoustic emission positioning module configured to calculate the three-dimensional spatial coordinates of an acoustic emission event based on the geometric coordinates of multiple acoustic emission sensor probes in a preset coordinate system on the surface of the shale sample using a time difference of arrival method; align the three-dimensional spatial coordinates with the three-dimensional surface grid model to generate a spatial mapping relationship of the crack propagation path;

[0023] 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; calibrate the error of the critical expansion velocity through the lead breaking experiment, and correct the calculation model parameters based on the calibration result.

[0024] Furthermore, 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;

[0025] The triaxial pressure chamber is connected to a confining pressure loading pump, which is used to apply confining pressure to the shale sample. The shale sample is placed in the triaxial pressure chamber, and an axial loading probe is installed above the top surface of the shale sample. The axial loading probe is used to apply axial force to the shale sample.

[0026] The temperature loading system is connected to the triaxial pressure chamber and is used to heat the shale sample to a target temperature.

[0027] 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.

[0028] 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.

[0029] Furthermore, 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;

[0030] The high-energy accelerator CT scanning system includes a ray source and a detector;

[0031] 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 obtains the electrical signals and calculates a reconstructed image in combination with a reconstruction algorithm.

[0032] 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.

[0033] Furthermore, the high-energy accelerator CT scanning system and the triaxial pressure chamber are both arranged on the rock sample rotating table.

[0034] Furthermore, the fluid pressure at the entrance of the prefabricated crack and the pressure at the entrance of the base are loaded based on two different pressure pumps.

[0035] Beneficial effects of the present invention:

[0036] Direct observation and evaluation: By simulating the actual on-site detonation fracturing process under laboratory conditions and combining it with an acoustic emission monitoring system and scanning imaging technology, the formation and development of cracks caused by the detonation on the rock sample can be directly observed, providing an intuitive basis for evaluating the reservoir stimulation effect.

[0037] Optimizing detonation parameters: This physical simulation experiment can be used to study the effects of factors such as the radius and number of prefabricated fractures and the amount of liquid explosives on fracture propagation, thereby helping to optimize detonation parameters and improve the effectiveness of deep reservoir reconstruction.

[0038] Reduced field testing costs: Compared to the expensive and complex on-site explosive production increase tests, indoor physical simulation experiments can be repeated multiple times in a more controllable and economical environment, reducing R&D costs and technical risks.

[0039] 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.

[0040] Improved safety: Conducting these experiments in a laboratory setting allows for better control of variables, ensuring operational safety while also reducing environmental impact.

[0041] Improved assessment accuracy: Maintaining the confining and axial pressures after explosive fracturing keeps the fracture network in an in-situ stress state, preventing fracture closure or deformation due to unloading pressure. By actively adjusting the fracture inlet pressure, a controllable pressure gradient is formed, accurately simulating formation fluid flow and avoiding measurement deviations caused by pressure disturbances. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Other features, objects and advantages of the present application will become more apparent upon reading the detailed description of non-limiting embodiments made with reference to the following drawings:

[0043] Figure 1 This is a schematic diagram of a shale physical simulation test system for coupled detonation fracturing and conductivity testing according to the present invention;

[0044] Figure 2 This is a schematic diagram of multiple prefabricated fractures in a shale physical simulation test system for coupled detonation fracturing and conductivity testing of the present invention. DETAILED DESCRIPTION

[0045] The present application will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are intended only to illustrate the relevant invention and are not intended to limit the invention. It should also be noted that, for ease of description, only portions relevant to the relevant invention are shown in the accompanying drawings.

[0046] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this 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.

[0047] The present invention provides a shale physical simulation test system for coupling detonation fracturing and conductivity testing, the system comprising:

[0048] Multiple shale samples, each shale sample is cut according to a preset size and has prefabricated cracks with different radii and numbers opened in the center of the top surface;

[0049] a temperature and pressure application assembly configured to apply a target temperature, an axial pressure, and a confining pressure to the shale specimen;

[0050] A detonation assembly comprising a polycarbonate tube inserted into a prefabricated crack, a liquid explosive filled in the polycarbonate tube, and an electronic detonator in contact with the liquid explosive;

[0051] A detonation fracturing data monitoring component includes a plurality of acoustic emission sensor probes 5 installed on the surface of the shale sample and a scanning component 1 for imaging the interior of the shale sample after detonation fracturing;

[0052] a fluid injection assembly connected to the pressure chamber base and configured to inject a fluid of set viscosity into the sample while maintaining axial pressure and confining pressure; and adjusting the base inlet pressure to a constant value, wherein the constant value is set to the hydrostatic pressure of the formation depth corresponding to the confining pressure;

[0053] The pressure monitoring assembly includes a first sensor for measuring the fluid pressure at the entrance of the prefabricated crack and a second sensor for measuring the pressure at the entrance of the base;

[0054] a flow control component configured to increase the fluid pressure at the inlet of the prefabricated fracture according to a set threshold value when the fluid pressure at the inlet of the prefabricated fracture is the same as the pressure at the inlet of the base, and to monitor the stable flow rate at the outlet of the base;

[0055] a data processing component configured to calculate the volume and growth rate of the fracture based on the imaging data and acoustic emission data generated by the detonation fracturing data monitoring component;

[0056] The conductivity is calculated based on the steady flow rate, fluid viscosity, shale sample size, and pressure differential, where the pressure differential is the difference between the fluid pressure at the entrance of the prefabricated fracture and the pressure at the base entrance.

[0057] 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:

[0058] Multiple shale samples, each shale sample is cut according to a preset size and has prefabricated cracks with different radii and numbers opened in the center of the top surface;

[0059] like Figure 2 As shown, in this embodiment, the shale sample is cut into a cylinder with a size of Φ500 mm×1000 mm. The prefabricated cracks include two types of 8 different cracks:

[0060] Category 1: Figure 2 As shown in the four shale specimens in the upper part, a crack was 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 specimen.

[0061] The second category: Figure 1 As shown in the four shale specimens in the lower part, two cracks were prefabricated with diameters of Φ1 mm, Φ5 mm, Φ10 mm, and Φ16 mm, respectively, and the height was half the height of the shale specimens, which was 500 mm.

[0062] 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;

[0063] The triaxial pressure chamber 3 is connected to a confining pressure loading pump 8, which is used to apply confining pressure to 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 apply axial force to the shale sample.

[0064] 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.

[0065] In this embodiment, the scanning components 1 in the detonation fracturing data monitoring component are arranged on both sides of the triaxial pressure chamber 3 , and the scanning components 1 are connected to the scanning component control system 10 via a line.

[0066] 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;

[0067] The high energy accelerator CT scanning system includes a ray source 4 and a detector 12;

[0068] 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.

[0069] The array of acoustic emission sensor probes 5 in the detonation fracturing data monitoring assembly is installed on the outer surface of the shale sample. 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 .

[0070] The electronic detonator in the detonation assembly is connected to an electronic detonator controller 7 , and the electronic detonator controller 7 is used to control the electronic detonator to detonate the liquid explosive.

[0071] The high-energy accelerator CT scanning system and the triaxial pressure chamber 3 are both arranged on the rock sample rotating platform 2 .

[0072] The fluid pressure at the inlet of the prefabricated crack and the pressure at the base inlet configured by the flow control component are loaded based on two different pressure pumps respectively.

[0073] In this embodiment, the data processing component includes:

[0074] a crack region segmentation module configured to segment the imaging data into crack regions and matrix regions based on a preset density threshold interval, and generate a binary image;

[0075] a three-dimensional reconstruction module configured to convert the binary image into a volume data model by a three-dimensional linear interpolation algorithm to generate a three-dimensional surface mesh model of the fracture network;

[0076] Volume calculation module, configured to calculate the crack volume based on a 3D surface mesh model using voxel statistics V c .

[0077] 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).

[0078] V c = N v × v 0;

[0079] in, N v is the number of crack voxels, v 0 is the actual volume of a single voxel.

[0080] The data processing component also includes:

[0081] an acoustic emission positioning module configured to calculate the three-dimensional spatial coordinates of the acoustic emission event based on the geometric coordinates of the plurality of acoustic emission sensor probes 5 in a preset coordinate system on the surface of the shale sample using a time difference of arrival method; align the three-dimensional spatial coordinates with the three-dimensional surface grid model to generate a spatial mapping relationship of the fracture propagation path;

[0082] 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; calibrate the error of the critical expansion velocity through the lead breaking experiment, and correct the calculation model parameters based on the calibration result.

[0083] In this embodiment, the Geiger iterative algorithm based on time difference of arrival is used to solve the acoustic emission events to obtain the three-dimensional positioning of the rupture position.

[0084] In this embodiment, a shale physical simulation test system for coupled detonation fracturing and conductivity testing has the following workflow:

[0085] Step S1: cutting the shale according to a preset size to obtain multiple shale samples, and creating prefabricated cracks of different radius and number at the center of the top surface of each shale sample;

[0086] Step S2, placing a polycarbonate tube in the prefabricated crack, and injecting a set amount of liquid explosive into the polycarbonate tube;

[0087] 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. The length of the liquid explosive column is selected to be 30 mm.

[0088] 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 through orthogonal experiment optimization.

[0089] 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, and stable rheological properties, and is highly operable and safe during the actual construction process.

[0090] The filling amount of liquid explosive inside the sample is calculated by the following formula:

[0091] ;

[0092] 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).

[0093] Step S3, installing an electronic detonator in the polycarbonate tube, wherein the electronic detonator is in contact with the liquid explosive; after the electronic detonator is installed, sealing the prefabricated crack;

[0094] Among them, the outer diameter of the electronic detonator is selected to be 0.9 mm, and the anchoring agent is selected as the filling material to seal the prefabricated cracks, and the filling length is 10 mm; 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.

[0095] Step S4: select one of the sealed shale samples, evenly install acoustic emission sensor probes 5 on its surface, and perform initial debugging using a multi-channel acoustic emission monitoring system;

[0096] In this embodiment, the rock sample filled with liquid explosives and electronic detonators is evenly attached to the acoustic emission sensor probe 5, and the multi-channel acoustic emission monitoring system is initially debugged to check the correctness of the acoustic emission channel threshold and amplitude settings.

[0097] Step S5: Place the shale sample equipped with the acoustic emission sensor probe 5 into the triaxial pressure chamber 3, and apply temperature and axial force to the shale sample:

[0098] 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;

[0099] Step S52: Connect the electronic detonator controller 7, the confining pressure loading pump 8, and the temperature loading system 9, and check the sealing of the pipelines. After the inspection is completed, close the triaxial pressure chamber 3 through the control console and place it on the rock sample rotating table 2;

[0100] Step S53: The triaxial pressure chamber 3 is pressurized with hydraulic oil by the confining pressure loading pump 8 to a target confining pressure value; at the same time, the shale sample is heated by the temperature loading system 9 at a temperature gradient of 5°C / min. After heating to the target temperature, the temperature is maintained constant.

[0101] In step S54, an axial force is applied 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.

[0102] Wherein, the initial loading speed is 2 mm / min, and the first preset speed is 200 N / s.

[0103] Step S6: detonate the liquid explosive to detonate the shale sample, scan and image the shale sample through the scanning component, and record the acoustic emission channel signal during the fracture process:

[0104] In step S61, the airtightness of the triaxial pressure chamber 3 is detected. When the airtightness meets the requirements, the electronic detonator controller 7 is used to control the electronic detonator to detonate the liquid explosive to detonate the shale sample; the multi-channel acoustic emission acquisition system 11 is turned on to record the acoustic emission channel signals during the shale sample rupture process.

[0105] Step S62: After the shale sample is destroyed, the ray source 4 is turned on to scan and image the shale sample.

[0106] Step S7: Maintain the confining pressure of the triaxial pressure chamber 3 s 3 and axial pressure s 1. Introduce 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, where P 0< s 3 and the value is confining pressure s 3 hydrostatic pressure corresponding to the depth of the formation;

[0107] Step S8: monitoring the fluid pressure at the iron pipe access port at the prefabricated crack P 1. When P 1= P 0, adjust the inlet pressure to ΔP = P 1- P 0=1-5MPa and maintain P 0 constant, monitor the stable flow rate of the base outlet Q 0;

[0108] Step S9, according to the formula Calculating fracture network conductivity CF ;

[0109] Where α is the crack network shape correction coefficient; m is the fluid viscosity; L is the length of the shale sample; D is the diameter of the shale sample.

[0110] In step S10, the axial force is unloaded and the temperature is lowered. The acoustic emission sensor probe 5 is removed, the electronic detonator is disassembled, the rock sample after destruction is photographed, the acquired data is sorted, and the process is skipped to step S4 to select other sealed shale samples until all shale samples are tested.

[0111] 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:

[0112] 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.

[0113] The acquired data include CT scan data, acoustic emission data and fracture network conductivity data.

[0114] 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:

[0115] 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 judged, and according to different priority modes, the ΔV and ΔQ Weight, and through comprehensive score calculation, obtain the liquid explosive amount adjustment direction, and obtain the adjustment amount according to the comprehensive score calculation;

[0116] 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;

[0117] when ΔQ≥2 ΔV When , it is determined to be the flow conduction capacity priority mode, and the weight classification strategy is:

[0118] , ;

[0119] 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 crack volume weight;

[0120] Through comprehensive scoring calculation, the adjustment direction of liquid explosive quantity is obtained as follows:

[0121] ;

[0122] in, S For the comprehensive rating, is the target flow capacity, is the target volume.

[0123] when ΔV ≥2 ΔQ When , it is determined to be the fracture volume priority mode, and the weight classification strategy is:

[0124] , ;

[0125] and , which is calculated as follows:

[0126] ; .

[0127] 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.

[0128] Through comprehensive scoring calculation, the adjustment direction of liquid explosive quantity is obtained as follows:

[0129] ;

[0130] like S >0: The flow conductivity needs to be improved or the crack volume needs to be controlled, and the charge amount should be adjusted to increase;

[0131] like S <0: It is necessary to suppress crack expansion or optimize diversion efficiency, and the charge amount should be adjusted to decrease.

[0132] To increase or decrease the charge amount, adjust the amount , which is calculated as follows:

[0133] ;in, a It is a preset coefficient with an initial value of 0.1.

[0134] This invention achieves dynamic optimization of the testing process through a test-evaluation-parameter correction cycle. After each test, core parameters (charge amount) are automatically adjusted based on quantitative analysis, forming an adaptive testing system. This effectively improves the iterative efficiency of test data and provides a standardized operating framework for continuous testing of multiple samples.

[0135] An innovative three-priority mode determination mechanism is proposed. Through a dynamic weight allocation strategy, this approach enables targeted optimization for specific engineering needs (such as enhanced conductivity or crack propagation control) while also achieving a balanced adjustment of dual indicators. Normalized deviation calculation eliminates dimensional differences, making the collaborative analysis of different physical quantities scientifically comparable.

[0136] A charge adjustment algorithm based on quantitative scoring was constructed, converting multi-dimensional deviations between test results and target values ​​into actionable adjustment instructions. By coupling sensitivity coefficients with preset coefficients, the correct direction of parameter adjustment was ensured while overcorrection risk was avoided through progressive adjustment, significantly improving the stability of parameter optimization.

[0137] In the description of the present invention, terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings. These are intended solely for ease of description and are not intended to indicate or imply that the device or component described must have, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not intended to indicate or imply relative importance.

[0138] Furthermore, it should be noted that, in the description of the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0139] The term "comprise" or any other similar term is intended to cover non-exclusive inclusion such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0140] Thus far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art may make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will fall within the scope of protection 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: Multiple shale samples, each shale sample is cut according to a preset size and has prefabricated cracks 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 specimen; A detonation assembly comprising a polycarbonate tube inserted into a 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 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 connected to the pressure chamber base and configured to inject a fluid of set viscosity into the sample while maintaining axial pressure and confining pressure; and adjusting the base inlet pressure to a constant value, wherein 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 crack 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 inlet of the prefabricated fracture according to a set threshold value when the fluid pressure at the inlet of the prefabricated fracture is the same as the pressure at the inlet of the base, and to monitor the stable flow rate at the outlet of the base; a data processing component configured to calculate the volume and growth rate of the fracture based on the imaging data and acoustic emission data generated by the detonation fracturing data monitoring component; Calculating conductivity based on steady flow rate, fluid viscosity, shale sample size, and pressure differential, where the pressure differential is the difference between the fluid pressure at the entrance of the prefabricated fracture and the pressure at the base entrance; According to the fracture volume and conductivity of the shale sample in this test, the amount of liquid explosives in the shale sample of the next test is modified; 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 judged, and according to different priority modes, the ΔV and ΔQ Weight, and through comprehensive scoring calculation, get the liquid explosive amount adjustment direction; 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 the flow conductivity priority mode is ΔV ≥2 ΔQ When , it is determined to be the crack volume priority mode, and other cases are the balanced mode.

2. The 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 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 configured to convert the binary image into a volume data model by 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. The 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: an acoustic emission positioning module configured to calculate the three-dimensional spatial coordinates of an acoustic emission event based on the geometric coordinates of multiple acoustic emission sensor probes in a preset coordinate system on the surface of the shale sample using a time difference of arrival method; align the three-dimensional spatial coordinates with the three-dimensional surface grid model to generate a spatial mapping relationship of the crack propagation 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; calibrate the error of the critical expansion velocity through the lead breaking experiment, and correct the calculation model parameters based on the calibration result.

4. The shale physical simulation test system for coupled 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, which is used to apply confining pressure to the shale sample. The shale sample is placed in the triaxial pressure chamber, and an axial loading probe is installed above the top surface of the shale sample. The axial loading probe is used to apply axial force to 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 coupled 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 via a line.

6. The 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 coupled 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 obtains the electrical signals and calculates a reconstructed image in combination with a 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 explosives.

9. The shale physical simulation test system for coupled 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.

11. The shale physical simulation test system for coupled detonation fracturing and conductivity testing according to claim 1, characterized in that: The weight classification strategy for the diversion capacity priority mode is: ， ； in, and are the normalized deviations of conductivity and fracture volume, k is the sensitivity coefficient, is the conductivity weight, is the crack 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; The fracture volume priority mode weight classification strategy is: ， ； Through comprehensive scoring calculation, the adjustment direction of liquid explosive quantity is obtained as follows: ； like S >0: The flow conductivity needs to be improved or the crack volume needs to be controlled, and the charge amount should be 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 decrease.

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