CN113776931A - Shale visualization fracturing experimental device and method based on DIC technology - Google Patents
Shale visualization fracturing experimental device and method based on DIC technology Download PDFInfo
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- CN113776931A CN113776931A CN202111158233.0A CN202111158233A CN113776931A CN 113776931 A CN113776931 A CN 113776931A CN 202111158233 A CN202111158233 A CN 202111158233A CN 113776931 A CN113776931 A CN 113776931A
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Abstract
The invention discloses a shale visual fracturing experimental device and method based on DIC technology, which are applied to the field of unconventional reservoir transformation and aim at solving the problem that the dynamic expansion process of a shale hydraulic fracturing fracture cannot be effectively observed in the prior art; the invention designs a special shale fixture and optimally designs the structure of the shale fixture, firstly, the shale clamping mode is improved, the rock sample drilling and fixing mode adopted by the prior art is avoided, the clamping mode can more firmly fix the rock sample, and the mechanical property of the rock sample can be ensured not to be interfered; meanwhile, the filling cracks with different approaching angles are manufactured for experiments, so that the interaction mechanism and key influence parameters of the hydraulic cracks and the natural cracks can be effectively obtained; the expansion condition of the fracture in the hydraulic fracturing process is visually and continuously observed through DIC, the expansion mode of the fracture in the hydraulic fracturing process in a real rock stratum can be simulated, the interaction rule of a natural fracture and an artificial fracture is analyzed, and reference is provided for engineering practice.
Description
Technical Field
The invention belongs to the field of oil exploration, and particularly relates to a shale oil and gas unconventional reservoir transformation technology.
Background
Along with the progress of oil exploration and exploitation technology, the exploitation of unconventional oil and gas becomes a hotspot of the current oil industry, shale oil and gas is also paid attention by the majority of researchers due to abundant reserves, and the development of related shale oil blocks is started in China. Therefore, the research on the expansion rule of the cracks in the shale has important significance on shale oil and gas exploitation. However, shale has the characteristics of low porosity and low permeability, the hydrocarbon generation mode of shale is self-generation and self-storage, the ground stress difference of deep shale is large, and the temperature is high, so that the deep shale is difficult to achieve a good cracking effect in a complex environment. The shale is strong in bedding heterogeneity, so that the characteristic that the expansion rule of the cracks in the shale is complex compared with the expansion rule of the cracks in the conventional oil and gas exploitation process is determined, the crack forming mechanism of the complex cracks in the shale is not clear, and particularly the influence mechanism of natural cracks on hydraulic cracks is not clear. The conventional hydraulic fracturing experimental method for researching the shale fracture propagation rule cannot better analyze complex fractures in the shale.
A Digital Image processing system and a numerical calculation system are built in a Digital Image Correlation (DIC) technology, and position information of a marking point in an experimental process can be transmitted to an automatic operation program in the system for processing, so that the purpose of visualization of crack extension in a rock sample is achieved. The lithology of each layer in the shale is complex, and the mechanical properties between the bedding and the bedding are variable, so that the fracture forms are complex and various. In engineering, a series of technical measures are used for improving the complexity of a seam network and improving the shale fracturing modification volume to achieve the purpose of improving the recovery ratio, but the obtained effect is poor, and because deep shale is buried deeply, the existing construction process for improving the complexity of the seam network and improving the shale fracturing modification volume is mainly established on the basis of experience, the interaction mechanism of complex seams and the hydraulic fracture forming mechanism cannot be deeply analyzed and researched, and the existing construction process cannot be improved. Due to the particularity of deep shale, the existing means for monitoring the hydraulic fracture in real time is microseism, but the accuracy is not enough, and the other means is to comprehensively detect various fractures, so that although the fracture expansion condition can be accurately and really reduced, the fracture network is too complex, the fracture expansion rule cannot be analyzed, particularly the interaction mode and rule of the hydraulic fracture and a natural fracture cannot be analyzed, and the position relation between the hydraulic fracture and an artificial fracture cannot be accurately represented when a rock sample is selected, so that the experimental result is more fuzzy. In addition, the existing method for researching the interaction rule between the natural fracture and the artificial fracture is mainly used for predicting by analyzing a stress-strain relation through an indoor model experiment and a numerical simulation experiment, and is lack of persuasion in the aspect of accuracy, and a Digital Image Correlation (DIC) is a lossless, real-time, efficient and full-strain-field surface deformation monitoring means and can realize real-time marking of accurate position change information of the fracture, so that the DIC technology is applied to research of the hydraulic shale fracture expansion rule and has profound research significance, and reference is provided for the new process of the new shale hydraulic fracturing method.
Disclosure of Invention
In order to solve the technical problems, the invention provides a shale visual fracturing experimental device and method based on DIC technology, which are used for observing the expansion condition of a fracture in a hydraulic fracturing process by using a digital image correlation method (DIC) measuring system, can simulate the expansion mode of the fracture in the hydraulic fracturing process in a real rock stratum, analyze the interaction rule of natural fractures and artificial fractures and provide reference for engineering practice.
One of the technical schemes adopted by the invention is as follows: a shale visualization fracturing experimental apparatus based on DIC technology includes: the device comprises a rock sample clamping system, a stress loading device, a hydraulic applying device and a DIC measuring and analyzing system;
the rock sample clamping system is used for fixing the rock sample, and the rock sample clamping system comprises: the device comprises two stainless steel pressing plates, two organic glass plates, a plurality of fastening devices, two enclosure assemblies and a view window arranged on one of the stainless steel pressing plates; the two enclosure assemblies are respectively arranged on the left side and the right side of the rock sample, and the organic glass plate and the stainless steel pressing plate are sequentially arranged on the front side and the rear side of the rock sample from near to far; reserved hole sites are arranged on the two stainless steel pressing plates, the two organic glass plates and the two enclosure assemblies, and fastening bolts are sequentially inserted into the stainless steel plates, the organic glass plates, the enclosure assemblies, the organic glass plates and the stainless steel plates and are screwed and fixed;
the stress loading device is used for applying stress to the rock sample;
the hydraulic loading device is used for applying hydraulic force to the rock sample to perform fracturing;
the DIC measurement and analysis system is used to analyze fracture changes during hydraulic fracturing.
A rectangular rubber sealing ring is also arranged between the two organic glass plates and the rock sample.
The stress loading device comprises: the hydraulic piston is used for applying stress to the rock sample, and the fixed counterforce device is used for ensuring that the stress applied by the hydraulic piston fully acts in the rock sample.
The hydraulic power applying device includes: annotate liquid mouth, sealed cutting ferrule, stock solution device, hydraulic pump, it is used for injecting the required fracturing fluid of hydraulic fracturing into to the rock specimen to annotate the liquid mouth, sealed cutting ferrule is used for preventing moisture from scattering and disappearing, the stock solution device is used for storing fracturing fluid, the hydraulic pump is used for applying water injection power.
The DIC measurement and analysis system comprises: the system comprises a displacement signal receiving device, a real-time image display device, a host, a strain analysis device and a crack identification and analysis device; the displacement signal receiving device is used for receiving position information of a marking point in a hydraulic fracturing process, the real-time image display device is used for displaying the received position information of the marking point on a screen, the strain analysis device is used for converting the displacement information of the marking point into strain information, the crack identification and analysis device is used for describing and analyzing the change condition of a crack according to the strain information, and the host is used for controlling the displacement signal receiving device, the real-time image display device, the strain analysis device and the crack identification and analysis device to work.
The invention also provides a shale visual fracturing experiment method based on the DIC technology, which comprises the following steps:
s1: preparing a shale rock sample, and drilling a hydraulic hole in the center of the rock sample;
s2: placing the enclosing components on two sides of the rock sample, pre-clamping the rock sample provided with the enclosing components by using an organic glass plate after combustion, then placing the pre-clamped rock sample between the front stainless steel pressing plate and the rear stainless steel pressing plate, finally inserting the fastening devices into the stainless steel plate, the organic glass plate, the rock sample enclosing components, the organic glass plate and the stainless steel plate in sequence, and screwing and fixing;
s3: starting a hydraulic piston by using the stress loading device, and applying required stress on the rock plate test piece by using the hydraulic piston so as to load the boundary force of the rock plate test piece;
s4: starting a hydraulic pump through a hydraulic applying device, applying required hydraulic power to the rock plate test piece through a hydraulic hole, and performing a hydraulic fracturing experiment;
s5: the change of the displacement of the marking point in the hydraulic fracturing process is obtained through the displacement signal receiving device, then the strain information in the experimental process can be obtained through the strain analysis device, the strain information is analyzed and processed through the crack identification and analysis device, and finally the crack information in the hydraulic fracturing process is displayed in a display through the image display device, so that the purpose of visualizing the real-time change of the crack is achieved.
When the rock sample is prepared, drilling a reserved hole in the center of the rock sample and preparing a vertical crack which vertically penetrates through the reserved hole to serve as an artificial crack.
When the rock sample is prepared, white paint is sprayed on one side of the rock sample displacement information to be observed, and black speckles are sprayed after the white paint is fully dried.
The rock sample height is all greater than rock sample clamping system.
Includes preparing a plurality of rock samples of different approach angle filling cracks.
The invention has the beneficial effects that: the experimental device, especially the sample clamp, adopts a unique plane sealing mode, a special rectangular sealing ring clamping groove is designed on the front glass panel, and the highest pressure resistance of the experiment can reach 20 MPa; secondly, introducing a DIC test system to carry out dynamic real-time observation on the crack propagation process; finally, quantitative analysis is carried out on the mutual interference mechanism of the hydraulic fracture and the natural fracture by using the experimental device; the invention has the following advantages:
1. compared with the mode of fixing the rock sample by drilling in the prior art, the rock sample clamping mode is improved, the rock sample fixing method can more stably fix the rock sample and ensure that the mechanical property of the rock sample is not interfered;
2. the heights of the prepared rock samples are all larger than that of the clamping device assembly, so that the situation that the rock samples are deformed to be lower than that of the clamping device assembly due to compression and the pressure cannot be continuously applied to the rock samples is avoided;
3. the method adopts a linear cutting mode to make clear filling cracks on the shale sample, adopts different fillers to fill, and carries out experiments by making filling cracks with different approaching angles, aiming at obtaining the interaction mode and interaction rule of the hydraulic cracks and natural cracks and factors influencing the interaction mode and interaction rule of the hydraulic cracks and natural cracks;
4. in the invention, the transparent organic glass plate is adopted for pre-clamping in the rock sample clamping process, so that the observation is convenient, and the deformation condition of the sample in the crack propagation process is captured in real time by the front-mounted camera; a rectangular rubber sealing ring is arranged between the sample and the front glass panel, so that higher sealing and buffering effects can be achieved;
5. the invention utilizes a digital image correlation method (DIC) measuring system to observe the expansion condition of the fracture in the hydraulic fracturing process, and provides a shale hydraulic fracture expansion real-time visual observation method; the method can simulate the expansion mode of the fracture in the hydraulic fracturing process in a real rock stratum, analyze the interaction rule of the natural fracture and the artificial fracture, and provide reference for engineering practice.
Drawings
FIG. 1 is an experimental set-up according to the present invention provided in an embodiment of the present invention;
FIG. 2 is a rock sample clamping system provided in an embodiment of the present invention;
FIG. 3 is a stress loading apparatus according to an embodiment of the present invention;
FIG. 4 is a hydraulic force applying apparatus provided in accordance with an embodiment of the present invention;
FIG. 5 is a schematic diagram of a DIC measurement and analysis system according to an embodiment of the present invention;
FIG. 6 is a detailed view of a rock sample at an approach angle of 45 degrees provided by an embodiment of the invention;
FIG. 7 is a detail view of a rock sample with an approach angle of 30 degrees provided by an embodiment of the invention;
FIG. 8 is a detailed view of a rock sample at an approach angle of 15 provided by an embodiment of the invention;
fig. 9 is a cloud chart of maximum principal strain obtained by the apparatus when the rock sample approach angle provided by the embodiment of the present invention is 45 °;
fig. 10 is a cloud chart of maximum principal strain obtained by the apparatus when the rock sample approach angle provided by the embodiment of the invention is 30 °;
fig. 11 is a cloud chart of maximum principal strain obtained by the device when the rock sample approach angle provided by the embodiment of the invention is 15 °;
reference numerals: 1 is a rock sample clamping system, 101 is a stainless steel pressing plate, 102 is a plexiglass plate, 103 is a view window, 104 is a fastening device, 105 is a containment assembly, 106 is a rock sample, 2 is a stress loading device, 201 is a hydraulic piston, 202 is a fixed counterforce device, 3 is a hydraulic force applying device, 301 is a liquid injection port, 302 is a sealing clamping sleeve, 303 is a liquid storage device, 304 is a hydraulic pump, 4 is a DIC measurement and analysis system, and 401 is a positionA signal receiving device, 402 a real-time image display device, 403 a strain analysis device, 404 a crack recognition and analysis device, 5 a detail drawing of a rock sample with an approximate angle of 45 degrees, 501 a maximum stress sigma 1502 is the maximum stress σ 2503 is a filling crack, 504 is a hydraulic hole, 505 is a hydraulic crack, 6 is a detail diagram of a rock sample with an approach angle of 30 degrees, 601 is the maximum stress sigma 1602 is the maximum stress σ 2603 is a filling crack, 604 is a hydraulic hole, 7 is a detail diagram of a rock sample with an approach angle of 15 degrees, 701 is a maximum stress sigma1And 702 is the maximum stress σ2The numeral 703 denotes a pack fracture, 704 denotes a hydraulic hole, and 705 denotes a hydraulic fracture.
Detailed Description
In order to facilitate the understanding of the technical contents of the present invention by those skilled in the art, the present invention will be further explained with reference to the accompanying drawings.
Fig. 1 shows a shale hydraulic fracturing experimental apparatus of the present invention, which includes: the device comprises a rock sample clamping system 1, a stress loading device 2, a hydraulic force applying device 3 and a DIC measuring and analyzing system 4.
As shown in fig. 2, the rock sample clamping system 1 includes: a stainless steel pressure plate 101, a plexiglas plate 102, a view window 103, a fastening device 104, and a containment assembly 105. The stainless steel pressure plate 101 is configured to protect and secure the rock sample 106, the plexiglass plate 102 is configured to protect the rock sample 106 from external interference, the viewing window 103 is configured to facilitate viewing of macroscopic representations of the rock sample 106 during hydraulic fracturing, the fastening device 104 is configured to secure various components, and the containment assembly 105 is configured to protect the rock sample 106.
As shown in fig. 3, the stress applying device 2 includes: a hydraulic piston 201, and a fixed reaction device 202. The hydraulic piston 201 is configured to apply a stress. The fixed reaction device 202 is configured to ensure that the force applied to the rock sample 106 by the hydraulic piston is sufficient to act in the rock sample 106.
The hydraulic power applying apparatus 3 is shown in fig. 4, and includes: the liquid injection port 301, the sealing sleeve 302, the liquid storage device 303 and the hydraulic pump 304. The injection port 301 is configured to inject a fracturing fluid required for hydraulic fracturing into the rock sample 106, specifically, through a hydraulic hole of the rock sample, the sealing sleeve 302 is configured to prevent moisture loss, the liquid storage device 303 is configured to store the fracturing fluid, the hydraulic pump 304 is configured to apply a water injection power, and a water injection rate is controlled.
The DIC measurement and analysis system 4 is shown in FIG. 5 and comprises: a displacement signal receiving device 401, a real-time image display device 402, a host computer, a strain analysis device 403 and a crack recognition and analysis device 404. The displacement signal receiving device 401 is configured to receive position information of a marker point in a hydraulic fracturing process, the real-time image display device 402 is configured to display the received position information of the marker point on a screen for visualization, the host computer is configured to control the computers to work in coordination with each other, the strain analysis device 403 is configured to convert the displacement information of the marker point into strain information, and the fracture identification and analysis device 404 is configured to trace and analyze the change condition of the fracture according to the strain information.
The specific working process of the displacement signal receiving device 401 is as follows: the position information of the black speckles obtained by the high-speed camera is transmitted to the displacement signal receiving device 401, the black speckles are equivalent to artificial mark points, and the deformation of the whole sample is propagated by the high-speed camera through a built-in algorithm by comparing the displacement change conditions of the black speckles on 2 continuous photos.
The invention prepares different samples with approach angles of 45 degrees, 30 degrees and 15 degrees, and the following description is given by the approach angle of 45 degrees:
a rock sample required for the experiment as shown in FIG. 6 was prepared, the dimension of the rock sample 5 was 240X 150X 30mm, a hydraulic hole 504 having a diameter of 3mm was drilled at the center of the specimen by a high-precision drill, and a hydraulic fracture having a half-fracture length of 10mm and a width of 0.5mm was prepared by wire cutting. Two through-cracks 20mm long and 1.5mm wide and 45 ° to the horizontal were cut symmetrically at 25mm in the hydraulic hole 504 by wire cutting and filled with gypsum to simulate the filled crack 503.
The filling material is mainly used for simulating natural cracks with different cementing strength characteristics, and common filling materials can also comprise cement mortar, high-grade cement and the like.
And (3) putting the prepared rock sample 106 into a high-temperature oven to be dried for 24 hours at a high temperature of 120 ℃ until the sample is fully dried, spraying white paint on one side of the rock sample displacement information to be observed, and spraying black speckles which are easy to be shot by a high-speed camera after the white paint is fully dried.
The organic glass plate 102 is pre-fixed on two sides of the prepared rock sample 106, hole positions of the organic glass plate are enabled to be aligned with hole positions of the rock sample enclosure assembly 105, then the combined body is placed between the front stainless steel pressing plate and the rear stainless steel pressing plate 101, and the hole positions are also enabled to be aligned, the fastening device 104 is sequentially inserted into the stainless steel plate 101, the organic glass plate 102, the rock sample enclosure assembly 105, the organic glass plate 102 and the stainless steel plate 101, and the parts are fastened and fixed together.
The hydraulic piston 201 is fully contacted with the rock sample 106, the hydraulic piston 201 is absolutely vertical to the side face of the rock sample 106, the contact end is positioned in the center of the stress surface of the rock sample 106 so as to ensure uniform stress, the stress loading device 2 is used for starting the hydraulic piston 201, and the required maximum stress and minimum stress are applied to the rock plate test piece through the hydraulic piston 201, so that the boundary force loading of the rock plate test piece can be realized.
The hydraulic pump 304 is started by the hydraulic power applying device 3, the hydraulic pump 304 gives a certain pressure to the fracturing fluid stored in the fluid storage device 303, and applies a required hydraulic pressure to the rock sample 106 through the fluid injection port 301, so that the water flow speed is uniform, and the flow rate of the water flow is kept consistent within unit time. The device thus enters the hydraulic fracturing stage in preparation for further fracturing experiments.
Through the displacement signal receiving device 401, the change of the displacement of the marking point in the hydraulic fracturing process can be obtained, then the strain information in the experimental process can be obtained through the strain analysis device 402, the strain information can be analyzed and processed through the fracture identification and analysis device 403, and finally the fracture information in the hydraulic fracturing process is displayed in a display through the image display device 404, so that the purpose of visualizing the real-time change of the fracture is achieved.
The invention also provides a specific experimental method, which comprises the following steps:
s1: preparing a shale rock sample with the size of 240 multiplied by 150 multiplied by 30mm, drilling a hydraulic hole penetrating through the rock sample at the center of the rock sample, preparing a vertical crack vertically penetrating through a reserved hole as an artificial crack, spraying white paint on one side of the rock sample displacement information to be observed, and spraying black speckles which are easy to be shot by a high-speed camera after the white paint is fully dried in the air;
s2: placing the enclosure assembly on two sides of the rock sample to play a role in protection, placing the organic glass plates on two sides of the rock sample and the enclosure assembly, paying attention to enable the organic glass plates to be aligned with reserved hole sites of the enclosure assembly, then installing stainless steel plates on the outer sides of the organic glass plates, sequentially inserting fastening bolts into the stainless steel plates, the organic glass plates and the enclosure assembly, and screwing and fixing the stainless steel plates and the organic glass plates to ensure that all the parts are tightly fixed together;
s3: starting a hydraulic piston by using the stress loading device, and applying required stress on the rock plate test piece by using the hydraulic piston so as to load the boundary force of the rock plate test piece;
s4: starting a hydraulic pump through a hydraulic applying device, and applying required hydraulic power to the rock plate test piece through a hydraulic hole, so that the device enters a hydraulic fracturing stage and can continue to perform a fracturing experiment; a hole position matched with the hydraulic hole is arranged in the center of the view window 103;
s5: through the displacement signal receiving device, the change of the displacement of the marking point in the hydraulic fracturing process can be obtained, then the strain information in the experimental process can be obtained through the strain analysis device, the strain information can be analyzed and processed through the crack identification and analysis device, and finally the crack information in the hydraulic fracturing process is displayed in a display through the image display device, so that the purpose of visualizing the real-time change of the crack is achieved.
Fig. 9 is a cloud of the maximum main tensile strain obtained by the device when the approach angle of the rock sample is 45 degrees, and it can be seen from fig. 9 that the central fracture is initiated first, the hydraulic fracture extends to the filling fracture after initiation, the extending direction of the hydraulic fracture deflects before the hydraulic fracture and the filling fracture meet, and the hydraulic fracture and the filling fracture meet in an approximately vertical form. After the hydraulic fracture intersects the pack fracture, the hydraulic fracture continues to extend, but the hydraulic fracture continues to deflect in a direction opposite to that before the hydraulic fracture intersects the pack fracture.
Fig. 10 is a cloud chart of maximum main tensile strain obtained by the device when the rock sample approach angle is 30 °, and as can be seen from fig. 10, two ends of a hydraulic fracture first start to crack and uniformly extend towards the horizontal direction along with Time, but the right-side fracture extension speed is obviously higher than that of the left side, when the right-side hydraulic fracture extends to the position of the right-side filling fracture at Time of 68.43s, the filling fracture starts to have obvious strain, then the left-side filling fracture has strain, and finally the hydraulic fracture penetrates through the filling fracture to a lower degree.
Fig. 11 is a cloud chart of the maximum main tensile strain obtained by the device when the rock sample approach angle is 15 °, and as can be seen from Time 233.67s and Time 276.27s, at first, at the initial stage of fracturing, a significant strain appears in the left-side filled fracture, and as the hydraulic power continues to be applied, a significant tensile strain appears in the right-side filled fracture, but as Time goes on, the right-side hydraulic fracture reaches the filled fracture first, but does not penetrate the filled fracture.
According to the invention, the influence of natural cracks on the expansion rule of the artificial cracks can be analyzed by obtaining the maximum tensile strain cloud charts with different approach angles as shown in FIGS. 9-11.
It will be appreciated by those of ordinary skill in the art that the embodiments described herein are intended to assist the reader in understanding the principles of the invention and are to be construed as being without limitation to such specifically recited embodiments and examples. Various modifications and alterations to this invention will become apparent to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.
Claims (10)
1. The utility model provides a shale visual fracturing experimental apparatus based on DIC technique which characterized in that includes: the device comprises a rock sample clamping system, a stress loading device, a hydraulic applying device and a DIC measuring and analyzing system;
the rock sample clamping system is used for fixing the rock sample, and the rock sample clamping system comprises: the device comprises two stainless steel pressing plates, two organic glass plates, a plurality of fastening devices, two enclosure assemblies and a view window arranged on one of the stainless steel pressing plates; the two enclosure assemblies are respectively arranged on the left side and the right side of the rock sample, and the organic glass plate and the stainless steel pressing plate are sequentially arranged on the front side and the rear side of the rock sample from near to far; reserved hole sites are arranged on the two stainless steel pressing plates, the two organic glass plates and the two enclosure assemblies, and fastening bolts are sequentially inserted into the stainless steel plates, the organic glass plates, the enclosure assemblies, the organic glass plates and the stainless steel plates and are screwed and fixed;
the stress loading device is used for applying stress to the rock sample;
the hydraulic loading device is used for applying hydraulic force to the rock sample to perform fracturing;
the DIC measurement and analysis system is used to analyze fracture changes during hydraulic fracturing.
2. The shale visual fracturing experimental device based on DIC technology of claim 1, wherein a rectangular rubber sealing ring is further arranged between the two organic glass plates and the rock sample.
3. The shale visualization fracturing experimental apparatus based on DIC technology as claimed in claim 1, wherein the stress loading device comprises: the hydraulic piston is used for applying stress to the rock sample, and the fixed counterforce device is used for ensuring that the stress applied by the hydraulic piston fully acts in the rock sample.
4. The shale visualization fracturing experimental device based on DIC technology as claimed in claim 1, wherein the hydraulic force applying device comprises: annotate liquid mouth, sealed cutting ferrule, stock solution device, hydraulic pump, it is used for injecting the required fracturing fluid of hydraulic fracturing into to the rock specimen to annotate the liquid mouth, sealed cutting ferrule is used for preventing moisture from scattering and disappearing, the stock solution device is used for storing fracturing fluid, the hydraulic pump is used for applying water injection power.
5. The shale visualization fracturing experimental facility based on DIC technology of claim 1, wherein the DIC measurement and analysis system comprises: the system comprises a displacement signal receiving device, a real-time image display device, a host, a strain analysis device and a crack identification and analysis device; the displacement signal receiving device is used for receiving position information of a marking point in a hydraulic fracturing process, the real-time image display device is used for displaying the received position information of the marking point on a screen, the strain analysis device is used for converting the displacement information of the marking point into strain information, the crack identification and analysis device is used for describing and analyzing the change condition of a crack according to the strain information, and the host is used for controlling the displacement signal receiving device, the real-time image display device, the strain analysis device and the crack identification and analysis device to work.
6. A shale visualization fracturing experiment method based on DIC technology is characterized by comprising the following steps:
s1: preparing a shale rock sample, and drilling a hydraulic hole in the center of the rock sample;
s2: placing the enclosing components on two sides of the rock sample, pre-clamping the rock sample provided with the enclosing components by using an organic glass plate after combustion, then placing the pre-clamped rock sample between the front stainless steel pressing plate and the rear stainless steel pressing plate, finally inserting the fastening devices into the stainless steel plate, the organic glass plate, the rock sample enclosing components, the organic glass plate and the stainless steel plate in sequence, and screwing and fixing;
s3: starting a hydraulic piston by using the stress loading device, and applying required stress on the rock plate test piece by using the hydraulic piston so as to load the boundary force of the rock plate test piece;
s4: starting a hydraulic pump through a hydraulic applying device, applying required hydraulic power to the rock plate test piece through a hydraulic hole, and performing a hydraulic fracturing experiment;
s5: the change of the displacement of the marking point in the hydraulic fracturing process is obtained through the displacement signal receiving device, then the strain information in the experimental process can be obtained through the strain analysis device, the strain information is analyzed and processed through the crack identification and analysis device, and finally the crack information in the hydraulic fracturing process is displayed in a display through the image display device, so that the purpose of visualizing the real-time change of the crack is achieved.
7. The shale visualization fracturing experiment method based on DIC technology as claimed in claim 6, wherein the rock sample is prepared by drilling a reserved hole in the center of the rock sample and preparing a vertical fracture vertically crossing the reserved hole as an artificial fracture.
8. The shale visualization fracturing experiment method based on DIC technology of claim 7, wherein during preparation of the rock sample, the method further comprises spraying white paint on one side of the rock sample where the rock sample displacement information needs to be observed, and spraying black speckles after the white paint is fully dried.
9. The shale visualization fracturing experiment method based on DIC technology of claim 8, wherein the heights of the rock samples are all larger than the height of the rock sample clamping system.
10. The shale visualization fracturing experiment method based on DIC technology as claimed in claim 9, which comprises preparing a plurality of rock samples with different approach angles to fill the fracture.
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