CN112343571B - Experimental method capable of realizing dynamic monitoring of deep shale multi-scale hydraulic fractures - Google Patents
Experimental method capable of realizing dynamic monitoring of deep shale multi-scale hydraulic fractures Download PDFInfo
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Abstract
The invention discloses an experimental method capable of realizing dynamic monitoring of deep shale multi-scale hydraulic fractures, which is applied to the technical field of shale hydraulic fracturing development, and particularly comprises the steps of monitoring the opening sequence, the fracture propagation direction and the fracture propagation height of the multi-scale fractures in the deep shale hydraulic fracturing process, the indoor hydraulic fracturing simulation is carried out by determining sample parameters (cement formula, bedding number, natural fracture number and the like) and hydraulic fracturing parameters (pump pressure displacement, perforation arrangement and the like) to obtain monitoring data of multi-scale fracture opening sequence, fracture expansion trend and fracture expansion height in the hydraulic fracturing process, and synchronously comparing and analyzing with a pumping pressure curve, a sample sectioning characteristic and an electron microscope scanning characteristic, and providing technical support for the hydraulic fracturing optimization design of the deep shale.
Description
Technical Field
The invention belongs to the technical field of shale hydraulic fracturing development, and particularly relates to an indoor deep shale hydraulic fracturing experiment technology.
Background
The technology of the shale gas favorable area in China can acquire the resource quantity as high as 21.8 trillion m3At present, the detection rate is only 4.79%, and the resource potential is huge. Areas of Fuling, Wiyang and ChangningThe block has realized the commercial development of middle and shallow layer shale gas with the depth less than 3500m, but the resource amount of the deep layer shale gas (with the depth more than 3500m) is still huge, and the exploration and development work of the deep layer shale in the peripheral blocks of the Tsinging mountain, the south China, the Yongchuan and the pyro stone is gradually carried out at present. Deep shale fracturing mainly refers to the mode and parameters of a middle shallow layer, and finally forms a single fracture form, namely a main fracture is dominant, and multi-scale fractures such as branch fractures and other micro fractures are small in proportion or almost not formed. Along with the increase of the depth of a stratum and the increase of three-dimensional stress, the original seam width of various high-angle natural cracks and horizontal bedding seams/texture seams is narrow, the cracking difficulty is greatly increased, and the development difficulty is also greatly increased, so that the formation of multi-scale cracks by fracturing is realized, the opening sequence, the trend of the expansion cracks and the expansion height of the cracks are researched, the method has important significance, and a solution can be provided for the reconstruction of a deep shale fracturing technology, the optimization of fracturing construction parameters, the proppant type selection and proportion, the reverse discharge after the fracturing and the like.
Disclosure of Invention
In order to solve the technical problems, the invention provides an experimental method for realizing the whole dynamic process of the deep-layer shale multi-scale fracture.
The technical scheme adopted by the invention is as follows: an experimental method for realizing the whole dynamic process of indoor deep shale multiscale fractures comprises the following steps:
s1, preparing a sample;
s2, arranging a resistance strain gauge in the sample;
s3, performing a hydraulic fracturing test on the sample processed in the step S2 to obtain pump pressure data, acoustic emission data and strain data;
s4, sorting the obtained pump pressure data, acoustic emission data and strain data, and drawing a time-strain curve graph, a time-pump pressure curve graph and a time-acoustic emission cumulative count curve graph after eliminating invalid data;
s5, observing a pumping pressure-time curve graph by taking time as a main line, locating a time period of a pumping pressure curve fluctuation area when the curve generates fluctuation, simultaneously observing strain data graphs of all resistance strain gauges, finding out the resistance strain gauge with strain data change in the time period, and determining the position of the hydraulic fracture;
step S5 further includes: analyzing the change degree of the resistance strain gauge, if the change is positive, indicating that the position of the resistance strain gauge is subjected to tensile stress, and if the change is negative, indicating that the position of the resistance strain gauge is subjected to compressive stress; and comparing the position of the resistance strain gauge with the acoustic emission three-dimensional positioning diagram, determining the position of the hydraulic fracture, and judging whether the fracture initiation position is an artificial prefabricated fracture or a sample fracture initiation.
S6, repeating the positions of the hydraulic fractures at different times obtained in the step S5 to obtain the expansion path of the hydraulic fractures;
s7, carrying out comparative analysis on the expansion path and the time sequence of the hydraulic fracture obtained in the step S6, the position of the shaft and the position of the prefabricated artificial fracture to obtain the opening sequence of the main fracture and the multi-scale fracture of the hydraulic fracture;
s8, keeping observing the strain data of the resistance strain gauge with the strain data changed obtained in the steps S5 and S6 until the data of the resistance strain gauge is stable or the resistance strain gauge is damaged without data, and determining the hydraulic fracture width of the resistance strain gauge;
step S8 specifically includes: if the resistance strain gauge is under tensile stress and the peripheral resistance strain gauges do not change the same, the strain degree is the hydraulic fracture width; if the resistance strain gauge is stressed by compression stress and the peripheral resistance strain gauge has the same change as the resistance strain gauge, the sum of the two strains is the hydraulic fracture width; if the resistance strain gauge is under tensile stress and the change of the peripheral resistance strain gauge is opposite, the difference of the two strains is the hydraulic fracture width.
And S9, determining the height of the crack.
Step S9 specifically includes: if all the strain data change degrees of two layers in the Z direction of a certain crack are small (+/-5 mu epsilon), signals are not monitored in the layers by the acoustic emission three-dimensional positioning diagram, the crack height is positioned between an upper layer and a lower layer, and if the longitudinal layering of the initial sample is more, the monitoring precision of the crack height is higher.
The invention has the beneficial effects that: by adopting the method, indoor hydraulic fracturing simulation can be realized by determining sample parameters (sample properties, layering quantity, natural fracture quantity and the like) and hydraulic fracturing parameters (pumping pressure displacement, perforation arrangement and the like) under the condition of simulating three-way stress of a deep stratum, monitoring data of multi-scale fracture opening sequence, fracture expansion trend and fracture expansion height in the hydraulic fracturing process are obtained, and are synchronously compared and analyzed with a pumping pressure curve, sample sectioning characteristics and electron microscope scanning characteristics, so that technical support is provided for deep shale hydraulic fracturing; in addition, the invention adopts an experimental mode of arranging the resistance strain gauges in layers in the artificial sample, and has the advantages of simple design and convenient operation.
Drawings
FIG. 1 is a schematic diagram of multi-scale fracture opening and strike-in during hydraulic fracturing.
FIG. 2 is a schematic diagram of a prediction layout of a resistive strain gage.
Fig. 3 is a schematic diagram of a matrix method for arranging the resistance strain gauges.
FIG. 4 is a schematic diagram of a dichotomy layout of a resistive strain gage.
Fig. 5 is a schematic diagram of a hydraulic fracturing test.
FIG. 6 is a schematic illustration of hydraulic fracture width;
fig. 6(a) shows a tensile stress condition of the resistance strain gauge, fig. 6(b) shows a compressive stress condition of the resistance strain gauge, and fig. 6(c) shows a tensile stress condition and a compressive stress condition of the resistance strain gauge.
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 is a schematic diagram showing the opening and strike of a multi-scale fracture during hydraulic fracturing. The method comprises the following technical steps:
the first part is sample preparation.
In order to realize the experimental method of the dynamic process of the multi-scale cracks in the indoor deep shale hydraulic fracturing, the method specifically comprises a new method for monitoring the opening sequence, the crack propagation direction and the crack propagation height of the multi-scale cracks in the indoor deep shale hydraulic fracturing process, and the artificial sample is selected as an experimental object. Preparation of artificial sample raw materials are selected from PC52.5R composite portland cement and quartz sand of 40-80 meshes, and the cement: quartz sand: the mass ratio of water is 1: 0.5.
the size of the artificial sample is 300mm multiplied by 300mm or 500mm multiplied by 500mm, the sample bedding surface is manufactured by adopting a layered pouring method, the height of each layer is 1/5 or 1/4 or 1/3 or 1/2 of the sample height, and when layered pouring is carried out, pouring can be carried out according to the real shale bedding surface, for example, the artificial samples with different bedding surface angles are manufactured. In order to simulate the property of the real bedding surface, the cementing property between new and old cement can be changed through different time of layered pouring or barite powder is spread among the bedding surfaces to simulate the real bedding surface.
In order to more accurately simulate the real situation of deep shale and simulate the opening and communication of multi-scale fractures during hydraulic fracturing, when artificial samples are prepared in a layering mode, oatmeal is adopted to simulate micro fractures in a real reservoir, A4 paper sheet is adopted to simulate medium fractures in the real reservoir, cardboard sheet is adopted to simulate thick fractures in the real reservoir, the coarse fractures can be randomly distributed in the samples or distributed among the samples at different angles with the samples, and the spatial positions of the prefabricated artificial fractures are recorded.
The shaft is embedded in the center of the artificial sample, and the water outlet of the shaft can be blocked by dough or a paperboard before embedding, so that cement slurry is prevented from being poured into the shaft and blocking the shaft. And when the shaft is embedded, the shaft position is guaranteed to be reasonable, and the shaft position is recorded.
It is also possible to change the sample parameters by changing them, including: sample properties, number of layers, number of natural fractures, etc., different samples were prepared.
The second part is an arrangement of resistive strain gauges.
In order to monitor the opening sequence, the crack propagation direction and the crack propagation height of the multi-scale cracks in the deep shale hydraulic fracturing process, high-precision resistance strain gauges are arranged on the artificial sample in a layering mode, and the arrangement positions of the resistance strain gauges can refer to the following three methods.
1. And (4) prediction method.
As shown in FIG. 2, the fracture initiation position and propagation direction of the fracture are predicted according to the position of the shaft, the distribution of the loading stress and the position of the artificial pre-fabricated fracture, and measuring points are arranged at the corresponding positions.
2. Matrix method
As shown in FIG. 3, an appropriate matrix is selected according to the size of the sample to arrange the resistance strain gauges, for example, a matrix of 10 × 10 can be selected for a 300mm × 300mm × 300mm artificial sample to arrange the resistance strain gauges, and the method comprehensively monitors the initiation of the multi-scale cracks, the propagation direction of the cracks and the propagation height of the cracks.
3. Dichotomy
As shown in fig. 4, a measuring point of a resistance strain gauge is arranged at the bottom of the shaft, measuring points are arranged at the middle points of connecting lines of the measuring points and the sample boundaries except the shaft direction, measuring points are arranged in the middle of the two measuring points, a new measuring point is electrically arranged in the middle of the measuring point of the new measuring point and the measuring point at the bottom of the shaft, and the position of the measuring point at the bottom of the shaft is continuously approached until a new resistance strain gauge cannot be arranged due to the size of the space.
The method comprises the following steps of:
1. selection of resistance strain gauge:
in a batch of resistance strain gauges with the same resistance strain gauge sensitivity K, the resistance strain gauges with shape defects of resistance wire grids, and defects of bubbles, mildew spots, rusty spots and the like in the resistance strain gauges are removed. And measuring the resistance value R of the resistance strain gauge by using a resistance gear of a digital multimeter, selecting the resistance strain gauge with the resistance value within the range of 120/350 +/-0.5 omega for standby, and recording the resistance value and the sensitivity coefficient of the gauge.
2. And (3) measuring point positioning:
the position and direction of the resistance strain gauge pasting have great influence on the strain measurement, the resistance strain gauge must be accurately pasted on a measuring point, and the pasting direction must be the strain direction to be measured. In order to meet the requirements, a cross line is drawn on the test piece by using a steel plate ruler and a drawing needle, the cross point of the cross line is aligned with the position of a measuring point, and the longer line is consistent with the strain measuring direction.
3. Treatment of the surface of the test piece:
removing surface cement on the patch position of the sample by using tools such as a file, coarse sandpaper and the like, polishing the surface cement into 45-degree crossed lines by using fine sandpaper, then cleaning the patch position by using forceps to pick up a degreasing cotton ball stained with acetone/absolute ethyl alcohol until the cotton ball is white, and ensuring that the surface can not be contacted with hands.
4. Pasting the resistance strain gauge:
(1) pasting the resistance strain gauge: note that the front and back surfaces of the resistance strain gauge (the surface from which the lead wires are led out is the front surface) are separated, the front surface of the resistance strain gauge is attached to a transparent adhesive tape, and then a layer of adhesive (502 adhesive) is uniformly and thinly coated on the attachment surface of the resistance strain gauge. After one minute, when the glue is sticky, correcting the direction (the positioning line of the resistance strain gauge is aligned with the cross line of the cross line, the wire winding direction of the resistance grid is consistent with the direction of the longer line in the cross line) to ensure that the center of the resistance grid is aligned with the cross point, and rolling for 1-2 minutes in one direction by hands.
(2) And (3) checking after the resistance strain gauge is pasted: after the resistance strain gauge is attached, the resistance strain gauge is checked to have the phenomena of no bubble, warping, degumming and the like, and then the resistance grade of a universal meter is used for checking whether the resistance strain gauge has the phenomena of short circuit, open circuit and sudden change of resistance (caused by uneven adhesion of the resistance strain gauge), if the phenomena occur, the accuracy of measurement is influenced, and the resistance strain gauge is attached again at this time.
5. Fixing a lead:
because the lead-out wire of the resistance strain gauge is thin, particularly the connection strength of the lead-out wire and the resistance wire of the resistance strain gauge is low, the lead-out wire and the resistance wire of the resistance strain gauge are easy to break by pulling, and transition is needed. The lead is a transition line for transmitting the sensing information of the resistance strain gauge to the testing instrument, one end of the lead is connected with the outgoing line of the resistance strain gauge, and the other end of the lead is connected with the testing instrument.
(1) Binding of the binding post:
the function of the binding post is to connect the lead wire of the resistance strain gauge with the lead wire connected into the strain gauge. The binding post is pressed on the position to be adhered by tweezers, then a drop of glue is dripped on the edge of the binding post, and after one minute, the binding post is adhered on the test piece.
(2) Welding: and welding the lead-out wire of the resistance strain gauge and the lead wire on the wiring terminal together by using an electric iron.
The welding key points are as follows: the connection points must be soldered by soldering tin to ensure the quality requirement of the electrical conductivity of the test circuit, and the size of the soldering points should be uniform and not too large and not have insufficient soldering. And after the welding is finished, the resistance is checked by using a universal meter to ensure the smoothness of all lines.
6. Manufacturing a moisture-proof layer:
the resistance strain gauge must have sufficient insulation in a humid environment, and once the resistance strain gauge is affected with moisture, the resistance value of the resistance strain gauge is unstable, so that the strain cannot be accurately measured. The moisture barrier may be formed by mixing a portion of epoxy CH31A with a portion of CH31B and then applying the moisture barrier formulation to the resistive strain gage (including the exposed portion of the lead) or silicone rubber to the resistive strain gage and then checking the insulation with a multimeter. The moisture barrier typically cures for 24 hours.
The third section is the experimental section.
After the artificial sample is prepared and maintained for 28 days, performing a hydraulic fracturing test according to the determined hydraulic fracturing parameters (pump pressure displacement, perforation arrangement and the like); of course, in the specific experimental process, hydraulic fracturing parameters (pump pressure displacement, perforation arrangement and the like) can be changed according to needs, and the positions, the crack propagation paths, the crack widths and the like of the opened cracks of different hydraulic fracturing parameters are different.
As shown in fig. 5, the experimental procedure was:
(1) and accurately recording the bedding surface of the artificial sample, the shape and the spatial position of the prefabricated artificial crack.
(2) And (3) putting the prepared sample into a true triaxial loading chamber, and arranging 2 acoustic emission probes on each diagonal line of 4 end surfaces of the hydraulic fracturing sample so as to effectively monitor the internal crack cracking information of the sample.
(3) The red tracer is added into the fracturing fluid, a hydraulic fracturing channel is observed by splitting a sample after a test is facilitated, and the loading of a simulated three-dimensional ground stress condition is completed by adopting a true triaxial physical model testing machine.
(4) And after the three-dimensional ground stress loading is finished, keeping the ground stress condition unchanged for two hours, so that the inside of the sample is uniformly stressed. And connecting the lead with a strain gauge and a computer, and performing self-checking and zero clearing treatment on the channels to ensure that the channels are smooth. And starting the hydraulic fracturing pump pressure system, the acoustic emission monitoring system and the strain data acquisition system, and synchronously acquiring the pump pressure data, the acoustic emission data and the strain data in real time by a computer.
(5) And after the fracturing test is finished, stopping the hydraulic fracturing pump pressure system, the acoustic emission monitoring system and the strain data acquisition system, and unloading the true triaxial physical model testing machine to 0 stably.
(6) And (4) disassembling the sample, loading each surface of the sample, directly observing and recording, and shooting by adopting a digital camera.
(7) Sectioning a fracturing sample, describing a hydraulic migration channel in the sample by observing a red tracer in fracturing fluid, and mastering a hydraulic fracture expansion rule.
(8) And sampling and polishing the sample on the fracture path, and performing scanning analysis on an electron microscope.
(9) And comprehensively comparing the strain data, the pumping pressure curve and the acoustic emission monitoring data to obtain information such as crack initiation positions, crack propagation directions, crack propagation heights and the like. The specific data analysis procedure is as follows.
And (3) data analysis step:
the obtained strain data, acoustic emission data and pump pressure data are sorted, invalid data are eliminated, time and strain, time and pump pressure and time and acoustic emission accumulated counting curve graphs can be drawn, and acoustic emission data can be used for drawing a three-dimensional positioning graph.
And secondly, observing a drawn pumping pressure-time curve graph by taking time as a main line, and when a pumping pressure curve generates fluctuation, indicating that hydraulic cracks are generated inside the sample, and positioning the time of a fluctuation area of the pumping pressure curve. And simultaneously observing the strain data graphs of all the resistance strain gauges, finding the resistance strain gauge with the strain data changed in the time period, analyzing the change degree of the resistance strain gauge, and indicating that the position of the resistance strain gauge is subjected to tensile stress when the change degree is positive and indicating that the position of the resistance strain gauge is subjected to compressive stress when the change degree is negative. And comparing the position of the resistance strain gauge with the acoustic emission three-dimensional positioning diagram, determining the position of the hydraulic fracture, and judging whether the fracture initiation position is an artificial prefabricated fracture or a sample fracture initiation.
And thirdly, continuously observing the fluctuation of the pumping pressure curve, repeating the step II, and sequentially obtaining the positions of the hydraulic fractures at different time, thereby obtaining the expansion path of the hydraulic fractures.
Fourthly, comparing and analyzing the extension path and the time sequence of the hydraulic fracture obtained in the third step with the position of the shaft and the position of the prefabricated artificial fracture to obtain the opening sequence of the main fracture and the multi-scale fracture of the hydraulic fracture.
And fifthly, when obtaining the resistance strain gauges with the strain data change of the pump pressure fluctuation in the steps II and III, keeping observing the strain data of the resistance strain gauges until the data is stable or the resistance strain gauges are damaged and have no data:
if the resistance strain gauge is subjected to tensile stress and the peripheral resistance strain gauges do not change in the same way, the strain degree is the hydraulic fracture width, as shown in fig. 6(a), the area between two vertical dotted lines represents a fracture area, the distance between the two vertical dotted lines represents the fracture width, the fracture is a tension fracture, the fracture area is tensile stress, and the periphery of the fracture is compressive stress, namely the resistance strain gauge shown in fig. 6(a) is subjected to tensile stress;
if the resistance strain gauge is under compressive stress and the peripheral resistance strain gauge has the same variation (i.e. the peripheral resistance strain gauge is under compressive stress), the sum of the two strains is the hydraulic fracture width, as shown in fig. 6 (b);
if the resistance strain gauge is under tensile stress and the change of the peripheral resistance strain gauge is opposite (i.e. the peripheral resistance strain gauge is under compressive stress), the difference between the two strains is the hydraulic fracture width, as shown in fig. 6 (c).
Sixthly, if the change degree of all strain data of two layers in the Z direction of a certain crack is small, and the acoustic emission three-dimensional positioning diagram does not monitor signals in the layers, the distance between the two layers of the crack can be judged to expand in the Z direction, and the crack height can be obtained, and if the number of layers is large, the crack height is more accurate. The strain data has small change degree, specifically, before and after 2% of the limit of the resistance strain gauge, the value of the embodiment is +/-5 mu epsilon, mu represents micrometer, and epsilon represents strain.
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. An experimental method for realizing dynamic monitoring of indoor deep shale multiscale hydraulic fractures is characterized by comprising the following steps:
s1, preparing a sample;
s2, arranging a resistance strain gauge in the sample;
s3, performing a hydraulic fracturing experiment on the sample processed in the step S2 to obtain pump pressure data, acoustic emission data and strain data;
s4, sorting the obtained pump pressure data, acoustic emission data and strain data, and drawing a time-strain curve graph, a time-pump pressure curve graph and a time-acoustic emission cumulative count curve graph after eliminating invalid data;
s5, observing a time-pump pressure curve chart by taking time as a main line, locating a time period of a pump pressure curve fluctuation area when the curve generates a fluctuation, simultaneously observing the time-strain curve charts of all resistance strain gauges, finding out the resistance strain gauge with strain data changed in the time period, and determining the hydraulic fracture position by combining the time-acoustic emission accumulated counting curve chart;
s6, repeating the positions of the hydraulic fractures at different times obtained in the step S5 to obtain the expansion path of the hydraulic fractures;
s7, carrying out comparative analysis on the expansion path and the time sequence of the hydraulic fracture obtained in the step S6, the position of the shaft and the position of the prefabricated artificial fracture to obtain the opening sequence of the main fracture and the multi-scale fracture of the hydraulic fracture;
s8, keeping observing the strain data of the resistance strain gauge with the strain data changed obtained in the steps S5 and S6 until the data of the resistance strain gauge is stable or the resistance strain gauge is damaged without data, and determining the hydraulic fracture width of the resistance strain gauge;
and S9, determining the height of the crack.
2. The experimental method for realizing dynamic monitoring of indoor deep shale multi-scale hydraulic fractures as claimed in claim 1, wherein step S5 further comprises: and analyzing the change degree of the resistance strain gauge with the change of the strain data, if the time-strain curve graph of the resistance strain gauge is changed to be positive, indicating that the position of the resistance strain gauge with the change of the strain data is subjected to tensile stress, and if the time-strain curve graph of the resistance strain gauge is changed to be negative, indicating that the position of the resistance strain gauge with the change of the strain data is subjected to compressive stress.
3. The experimental method for realizing dynamic monitoring of indoor deep shale multi-scale hydraulic fractures according to claim 2, wherein the step S8 is specifically as follows: if the resistance strain gauge with the changed strain data is subjected to tensile stress and the peripheral resistance strain gauges are not changed in the same way, the strain degree of the resistance strain gauge with the changed strain data is the hydraulic fracture width of the resistance strain gauge; if the resistance strain gauge with the changed strain data is subjected to compressive stress and the peripheral resistance strain gauges have the same change as the resistance strain gauge, the sum of the two strains is the hydraulic fracture seam width; if the resistance strain gauge with the changed strain data is subjected to tensile stress and the change of the peripheral resistance strain gauges is opposite, the difference of the strain of the resistance strain gauge and the strain of the peripheral resistance strain gauge is the hydraulic fracture seam width.
4. The experimental method for realizing dynamic monitoring of indoor deep shale multi-scale hydraulic fractures as claimed in claim 1, wherein step S9 specifically comprises: if the change degree of all strain data of a certain two sub-layers in the longitudinal direction of a certain crack is small, and the acoustic emission three-dimensional positioning diagram does not monitor signals in the two sub-layers, the distance between the two sub-layers of the crack is judged to be longitudinally expanded, and the crack height is obtained.
5. The experimental method for realizing dynamic monitoring of the indoor deep shale multi-scale hydraulic fracture as claimed in claim 1, wherein the sample of step S1 is prepared by layering, specifically: the method comprises the steps of simulating micro cracks in a real reservoir by using oatmeal, simulating medium cracks in the real reservoir by using A4 paper, simulating coarse cracks in the real reservoir by using cardboard sheets, randomly distributing the simulated micro cracks, the simulated medium cracks and the simulated coarse cracks in a sample or distributing the simulated micro cracks, the simulated medium cracks and the simulated coarse cracks among the samples at different angles with the sample, and recording the spatial position of the prefabricated artificial cracks.
6. The experimental method for realizing dynamic monitoring of indoor deep shale multi-scale hydraulic fractures as claimed in claim 5, wherein step S5 further comprises: and judging whether the crack is an artificial prefabricated crack or a crack initiated by a sample according to the initiation position.
7. The experimental method for realizing dynamic monitoring of indoor deep shale multi-scale hydraulic fractures as claimed in claim 1, wherein step S2 specifically comprises:
s21, determining the arrangement position of the resistance strain gauge in the sample layering to obtain a measuring point to be pasted;
s22, selecting a resistance strain gauge;
s23, measuring the strain direction;
s24, processing the surface of the test piece;
s25, pasting the resistance strain gauge on the measuring point, wherein the pasting direction is the measured strain direction;
and S26, connecting the lead-out wire of the resistance strain gauge with a test instrument by adopting a lead.
8. The experimental method for realizing the dynamic monitoring of the indoor deep shale multi-scale hydraulic fracture as claimed in claim 7, wherein the step S1 adopts one of the following three methods to determine the arrangement position of the resistance strain gauge in the sample layering:
the prediction method comprises the following steps: predicting the crack initiation position and the expansion direction of the crack according to the position of the shaft, the distribution of the loading stress and the position of the artificial prefabricated crack, and arranging measuring points at the corresponding positions;
matrix method: selecting a proper matrix according to the size of the sample to arrange the resistance strain gauge;
bisection method: and arranging measuring points of the resistance strain gauges at the bottom of the shaft, arranging measuring points at the middle points of connecting lines of the measuring points and the sample boundaries except the shaft direction, arranging measuring points in the middle of the two measuring points, and arranging new measuring points at the middle points of the currently arranged measuring points and the measuring points at the bottom of the shaft, wherein the new measuring points are continuously close to the positions of the measuring points at the bottom of the shaft until new resistance strain gauges cannot be arranged due to the size of space.
9. The experimental method for realizing dynamic monitoring of the indoor deep shale multiscale hydraulic fractures as claimed in claim 8, further comprising manufacturing a moisture barrier layer on the adhered resistance strain gauge.
10. The experimental method for realizing dynamic monitoring of indoor deep shale multi-scale hydraulic fractures as claimed in claim 9, wherein the moisture barrier is formed by mixing epoxy resin, one part of CH31A and one part of CH 31B.
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| CN113216947B (en) * | 2021-05-17 | 2023-01-13 | 中国石油大学(华东) | Horizontal well fracturing process crack height determination method based on monitoring well distributed optical fiber strain monitoring |
| CN113256780B (en) * | 2021-07-06 | 2021-11-19 | 广州中望龙腾软件股份有限公司 | Dynamic sectioning method of tool body, intelligent terminal and storage device |
| CN113702157B (en) * | 2021-08-30 | 2022-03-25 | 中国石油大学(华东) | True triaxial fracture test crack propagation dynamic monitoring method based on distributed optical fiber strain monitoring |
| CN113914841B (en) * | 2021-10-14 | 2022-12-13 | 中国科学院武汉岩土力学研究所 | Shale visual fracturing experimental device and method |
| CN115600425B (en) * | 2022-11-07 | 2023-05-02 | 中国科学院武汉岩土力学研究所 | Shale compressibility evaluation device and method based on vermiculite thermal expansion fracturing |
| CN117147321B (en) * | 2023-10-30 | 2024-02-20 | 新疆泰齐石油科技有限公司 | Method and device for representing crack morphology of experimental rock sample |
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