CN116879068A - Shock wave rock breaking experiment method for simulating stratum environment - Google Patents
Shock wave rock breaking experiment method for simulating stratum environment Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/32—Investigating strength properties of solid materials by application of mechanical stress by applying repeated or pulsating forces
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/02—Details
Abstract
The invention provides a shock wave broken rock experimental method for simulating stratum environment, which comprises the following steps: s1, preprocessing a rock sample to form a rock sample with a cube structure; s2, drilling a reserved hole in the rock sample, and installing a shaft in the reserved hole; s3, placing the rock sample into a triaxial pulse type shock wave fracturing rock experiment system, loading stress in the horizontal X-axis direction, stress in the horizontal Y-axis direction and stress in the vertical direction on the rock sample, and heating the rock sample; s4, calibrating crack extension by a crack extension calibration method, and placing a shock wave generator into a shaft; s5, performing shock wave operation fracturing on the rock sample through a shock wave generator; s6, repeating the step S5 until the crack breaks through the boundary of the rock sample and no new crack is generated; s7, recording the fracturing radius and the crack expansion form, and drilling a sampling hole on the rock sample and sampling; s8, comparing and analyzing the sampling result to obtain the change condition of the pore-penetration parameter of the rock sample and the change condition of the mechanical parameter of the rock sample.
Description
Technical Field
The invention relates to the technical field of rock mechanics experiments, in particular to a shock wave rock breaking experiment method for simulating stratum environment.
Background
The pulse type controllable shock wave rock breaking technology is based on a high-power electric pulse technology and discharge plasma, converts electric energy and chemical energy into mechanical energy, repeatedly generates shock waves in a controllable area by means of repeated operation of a pulse power driving source, and achieves good application effects in aspects of oil and gas well blocking removal, fracturing, permeability improvement and the like as an emerging reservoir reconstruction technology. As an emerging reservoir reconstruction technology, the pulse type controllable shock wave fracturing technology has a series of advantages of low energy consumption, high efficiency, low cost, safety, environmental protection, high operation efficiency, easiness in control and the like compared with the conventional fracturing technology.
The actual reservoir is in a deep stratum, and the reservoir bears higher ground stress and a certain temperature environment, so that the rupture characteristics of the actual reservoir can be truly reflected by taking the ground stress and the temperature into consideration of pulse-type controllable shock wave test research. And adopt bulky rock just can comparatively simulate the reservoir fracture characteristic accurately, bulky rock length width height is one meter at least, therefore heavy, difficult operation, and the controllable shock wave that does not have at present and send fracturing rock physical simulation experimental scheme suitable for bulky rock, has consequently influenced the smooth going on of controllable shock wave transformation reservoir.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a shock wave rock breaking experimental method for simulating stratum environment.
The technical scheme for solving the technical problems is as follows: a shock wave broken rock experimental method for simulating stratum environment, comprising:
s1, preprocessing a rock sample to form a rock sample with a cube structure;
s2, drilling a reserved hole in the rock sample, and installing a shaft in the reserved hole;
s3, placing the rock sample into a triaxial pulse type shock wave fracturing rock experiment system, loading stress in the horizontal X-axis direction, stress in the horizontal Y-axis direction and stress in the vertical direction on the rock sample, and heating the rock sample;
s4, calibrating crack extension by a crack extension calibration method, and placing a shock wave generator into a shaft;
s5, performing shock wave operation fracturing on the rock sample through a shock wave generator;
s6, repeating the step S5 until the crack breaks through the boundary of the rock sample and no new crack is generated;
s7, recording the fracturing radius and the crack expansion form, and drilling a sampling hole on the rock sample and sampling;
s8, comparing and analyzing the sampling result to obtain the change condition of the pore-penetration parameter of the rock sample and the change condition of the mechanical parameter of the rock sample.
The technical scheme of the invention has the beneficial effects that: the method is suitable for large-volume rock, can simulate the shock wave fracturing reservoir process under real stratum environment (high temperature and high pressure) and well shaft conditions (casing, well cementation and perforation), is convenient for observing the pulse controllable shock wave fracturing rock crack extension rule, realizes the pulse controllable shock wave fracturing rock physical simulation experiment of a large-scale rock sample (2 m multiplied by 1 m) under the condition of approaching the true triaxial stress of the stratum, and realizes the organic unification of indoor experimental conditions and site construction parameters. The structure is reasonable in setting, easy to operate, high in safety, capable of greatly improving the efficiency of the experimental process and providing accurate experimental results. And (3) respectively carrying out multipoint sampling on the rock sample and the sleeve before and after the experiment, comparing and analyzing the influence of the shock wave fracturing on the rock mechanical parameters and the metal performance of the sleeve, recognizing the relation between the crack extension rule after the fracturing and the shock wave operation times, verifying the technical safety of the pulse controllable shock wave reservoir reconstruction, and providing data support for the field test of the pulse controllable shock wave reservoir reconstruction technology.
Further, the step of drilling and sampling a sample hole in a rock sample comprises: the sampling holes are all positioned on the same straight line, the straight lines formed by sampling for many times are uniformly distributed in the circumference of the reserved hole, the distance between every two adjacent sampling holes in the sampling holes is 25cm-35cm, and the distance between any sampling hole and the reserved hole is larger than 25cm.
The beneficial effects of adopting the further technical scheme are as follows: the sampling method can obtain a reasonable comparison result and prevent the mutual influence of sampling data, thereby improving the accuracy of the test.
Further, the crack extension calibration method comprises the following steps: a dye method, a physical model method, a radar monitoring method or a numerical simulation method.
The beneficial effects of adopting the further technical scheme are as follows: the crack expansion condition is monitored by adopting methods such as radar monitoring, the crack form is described by adopting methods such as dye calibration, rock splitting, three-dimensional modeling and the like after the crack is pressed, multipoint sampling is respectively carried out on a rock sample and a sleeve before and after the experiment, the influence of the shock wave fracturing on rock mechanical parameters and sleeve metal performance is compared and analyzed, the relation between the crack expansion rule and the shock wave operation times after the pressing is recognized, the technical safety of the pulse-type controllable shock wave reservoir transformation is verified, and data support is provided for the field test of the pulse-type controllable shock wave reservoir transformation technology.
Further, the method of the coloring agent comprises the following steps: adding a coloring agent into the fracturing fluid, calibrating crack expansion through the dyed fracturing fluid, and performing 3D modeling on the crack morphology on the basis of rock sample subdivision;
The physical model method is as follows: obtaining a fracture morphology physical model by injecting a solidifiable fluid into a wellbore;
the radar monitoring method comprises the following steps: scanning a rock sample by adopting a ground penetrating radar, determining the position and the form of a crack according to the time difference and the position difference of the electromagnetic wave propagating in the rock sample, and describing the crack form based on signal receiving data;
the numerical simulation method comprises the following steps: the simulation is carried out by adopting finite difference software or finite element program, a model is established according to actual engineering geological parameter setting, the model comprises four groups of drilling holes, casings, cement rings and rock strata, the numerical simulation is divided into three parts, firstly, the simulation is carried out on an indoor model test, then the field scale model simulation of the casings, the perforating holes and the cement rings is considered, finally, a similar test model is simulated, the similar model test is guided based on the numerical simulation result, and the numerical simulation is verified and perfected through the model test.
The beneficial effects of adopting the further technical scheme are as follows: and (3) adding a coloring agent into the fracturing fluid, and calibrating crack expansion through the dyed fracturing fluid. And calibrating crack propagation at different stages by adopting different colors of coloring agents, and performing 3D modeling on crack morphology on the basis of rock subdivision. A physical model of fracture morphology may be obtained by injecting a curable fluid, such as an epoxy, paraffin, low melting point metal, or the like, into the wellbore. And scanning the rock sample by adopting a ground penetrating radar, determining the position and the form of the crack according to the time difference and the position difference of the electromagnetic wave propagating in the rock sample, and describing the crack form based on the signal receiving data.
Further, step S1 includes: cutting edges and corners of the surface of the rock sample by a cutting machine to enable the edges and corners to be close to a cube structure;
and casting the rock sample by using a triaxial pulse type shock wave fracturing rock experimental system and a casting template to form the rock sample with a cube structure.
The beneficial effects of adopting the further technical scheme are as follows: the stress triaxial pulse type shock wave fracturing rock experimental system is utilized to pour cement to the rock sample to form a cube structure, the operation process is simple, more equipment is omitted, repeated carrying of the rock sample is not needed, and the trimming efficiency is improved.
Further, the length, width and height dimensions of the rock sample are all larger than 1m, the inner diameter of the shaft is 127mm, and the wall thickness of the shaft is 10mm.
The beneficial effects of adopting the further technical scheme are as follows: the method is suitable for large-volume rock, can simulate the shock wave fracturing reservoir process under real stratum environment (high temperature and high pressure) and well shaft conditions (casing, well cementation and perforation), is convenient for observing the pulse controllable shock wave fracturing rock crack extension rule, realizes the pulse controllable shock wave fracturing rock physical simulation experiment of a large-scale rock sample (2 m multiplied by 1 m) under the condition of approaching the true triaxial stress of the stratum, and realizes the organic unification of indoor experimental conditions and site construction parameters. The structure is reasonable in setting, easy to operate, high in safety, capable of greatly improving the efficiency of the experimental process and providing accurate experimental results.
Further, in step S3, the stress in the horizontal X-axis direction, the stress in the horizontal Y-axis direction and the stress in the vertical direction are pressurized at a speed of less than 1MPa/min, the stress in the horizontal X-axis direction and the stress in the horizontal Y-axis direction have a numerical range of 55-65MPa, and the stress in the vertical direction has a numerical range of 35-45MPa.
The beneficial effects of adopting the further technical scheme are as follows: the impact waves simulating the stratum environment break the rock, so that the stress is the same as or close to the actual environment of the rock, and the accuracy of experimental data is improved.
Further, the step of drilling and sampling a sample hole in a rock sample further comprises: taking 60 degrees as a rotation angle, taking 30cm as a sampling interval, and uniformly sampling at different positions away from a shaft; and drilling a plunger sample at each sampling position before and after the experiment, and injecting a consolidation material into the sampling hole for plugging after each sampling.
The beneficial effects of adopting the further technical scheme are as follows: injecting a concretionary material into the sampling hole for plugging after each sampling, avoiding interference to subsequent crack expansion, wherein the concretionary material can adopt epoxy resin.
Further, step S8 includes: s81, observing the morphology and distribution of each rock sample crack under the condition of different operation times, and comparing and analyzing the rock mechanical parameter change in the pulse shock wave fracturing process;
S82, respectively performing multipoint sampling on the wellbores before and after the experiment, sampling in a metal cutting mode, testing the compression resistance and the tensile strength of the wellbores, comparing the performance parameters of the wellbores before and after the experiment, and analyzing whether the wellbores are damaged by pulse shock wave fracturing.
The beneficial effects of adopting the further technical scheme are as follows: and (3) carrying out experimental analysis on the metal performances of the shaft before and after impact, sampling in a metal cutting mode, and respectively carrying out compressive strength test and tensile strength test. Therefore, the influence of the shock wave fracturing on the metal performance of the shaft is judged, whether the shaft is damaged or not is judged, and the basis is made for the selection of the subsequent shaft.
Further, step S8 includes: respectively performing multipoint sampling on rock samples before and after a fracturing experiment, preparing a rock column by adopting linear cutting, and comparing and analyzing the change condition of the pore-permeation parameters of the rock samples;
and respectively performing multipoint sampling on the rock samples before and after the fracturing experiment, performing rock column preparation by adopting linear cutting, performing compression resistance, tensile resistance and shear strength mechanical parameter test, and comparing and analyzing the rock mechanical parameter change condition of the rock samples.
The beneficial effects of adopting the further technical scheme are as follows: and (5) respectively performing multipoint sampling on the sleeve before and after the fracturing, and analyzing the tensile property change of the sleeve before and after the fracturing.
Additional aspects of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
Fig. 1 is a schematic structural diagram of a triaxial pulse type shock wave fracturing rock experiment system according to an embodiment of the present invention.
Fig. 2 is a second schematic structural diagram of a triaxial pulse type shock wave fracturing rock experimental system according to an embodiment of the present invention.
Fig. 3 is a third schematic structural diagram of a triaxial pulse type shock wave fracturing rock experiment system according to an embodiment of the present invention.
Fig. 4 is a schematic structural diagram of a triaxial pulse type shock wave fracturing rock experiment system according to an embodiment of the present invention.
Fig. 5 is a schematic diagram of a triaxial pulse type shock wave fracturing rock experimental system according to an embodiment of the present invention.
Fig. 6 is a schematic structural diagram of a triaxial pulse type shock wave fracturing rock experiment system according to an embodiment of the present invention.
Fig. 7 is a schematic diagram of a triaxial pulse type shock wave fracturing rock experimental system according to an embodiment of the present invention.
Fig. 8 is a schematic structural diagram of a triaxial pulse type shock wave fracturing rock experiment system according to an embodiment of the present invention.
Fig. 9 is a schematic diagram of a triaxial pulse type shock wave fracturing rock experimental system according to an embodiment of the present invention.
Fig. 10 is a schematic diagram of a triaxial pulse type shock wave fracturing rock experimental system according to an embodiment of the present invention.
Fig. 11 is a schematic diagram of an arrangement of sampling holes according to an embodiment of the present invention.
Fig. 12 is a schematic diagram of a bulk modulus experiment flow provided in an embodiment of the present invention.
FIG. 13 is a second schematic diagram of a large object model experiment according to an embodiment of the present invention.
Fig. 14 is a schematic flow chart of a shock wave rock breaking experimental method for simulating a formation environment according to an embodiment of the present invention.
Reference numerals illustrate: 1. a rock sample; 2. a base; 21. a chute; 22. rectangular grooves; 3. a circumferential loading mechanism; 31. an annular frame; 32. a first horizontal force application device; 33. a second horizontal force application device; 34. a horizontal force application plate; 35. loading space; 36. a carrier; 4. a vertical loading mechanism; 41. a moving frame; 411. a moving wheel; 412. a step hole; 42. a vertical force application device; 43. a vertical force application plate; 431. a through hole; 5. a rock displacement mechanism; 51. a support plate; 52. a frame lifting device; 53. hanging rings; 54. a supporting plate lifting device; 541. a ball; 55. a force bearing plate; 56. a telescoping device; 6. a shock wave generator; 61. a fixing ring; 62. a window; 7. a lifting mechanism; 8. a fixing rope; 9. a wellbore; 10. a sampling hole; 11. pouring a template; 12. casting space; 13. a pressure sensor; 14. an abutting plate; 15. a force transfer plate; 16. an electrical heating assembly; 17. and a heat insulation layer.
Detailed Description
The principles and features of the present invention are described below with reference to the drawings, the examples are illustrated for the purpose of illustrating the invention and are not to be construed as limiting the scope of the invention.
As shown in fig. 14, the embodiment of the invention provides a shock wave rock breaking experimental method for simulating a stratum environment, which comprises the following steps:
s1, preprocessing a rock sample to form a rock sample with a cube structure;
s2, drilling a reserved hole in the rock sample, and installing a shaft in the reserved hole;
s3, placing the rock sample into a triaxial pulse type shock wave fracturing rock experiment system, loading stress in the horizontal X-axis direction, stress in the horizontal Y-axis direction and stress in the vertical direction on the rock sample, and heating the rock sample;
s4, calibrating crack extension by a crack extension calibration method, and placing a shock wave generator into a shaft;
s5, performing shock wave operation fracturing on the rock sample through a shock wave generator;
s6, repeating the step S5 until the crack breaks through the boundary of the rock sample and no new crack is generated;
s7, recording the fracturing radius and the crack expansion form, and drilling a sampling hole on the rock sample and sampling;
s8, comparing and analyzing the sampling result to obtain the change condition of the pore-penetration parameter of the rock sample and the change condition of the mechanical parameter of the rock sample.
The technical scheme of the invention has the beneficial effects that: the method is suitable for large-volume rock, can simulate the shock wave fracturing reservoir process under real stratum environment (high temperature and high pressure) and well shaft conditions (casing, well cementation and perforation), is convenient for observing the pulse controllable shock wave fracturing rock crack extension rule, realizes the pulse controllable shock wave fracturing rock physical simulation experiment of a large-scale rock sample (2 m multiplied by 1 m) under the condition of approaching the true triaxial stress of the stratum, and realizes the organic unification of indoor experimental conditions and site construction parameters. The structure is reasonable in setting, easy to operate, high in safety, capable of greatly improving the efficiency of the experimental process and providing accurate experimental results. And (3) respectively carrying out multipoint sampling on the rock sample and the sleeve before and after the experiment, comparing and analyzing the influence of the shock wave fracturing on the rock mechanical parameters and the metal performance of the sleeve, recognizing the relation between the crack extension rule after the fracturing and the shock wave operation times, verifying the technical safety of the pulse controllable shock wave reservoir reconstruction, and providing data support for the field test of the pulse controllable shock wave reservoir reconstruction technology.
Specifically, a rock sample 1 is collected, a hole is drilled on the rock sample 1 for sampling, and then the rock sample 1 is preprocessed, so that the rock sample 1 forms a cube structure.
The natural outcrop rock sample 1 can be adopted, the lithology comprises conglomerate, sandstone, shale and the like, and the length, width and height dimensions of the rock sample 1 are all larger than 1m. The pretreated rock sample 1 forms a cubic structure, and the surface of the rock sample is flat.
A preformed hole is drilled in the rock sample 1 and the wellbore 9 is installed in the preformed hole. And then cementing is carried out, so that the stability and safety of the shaft 9 are ensured.
The shaft 9 is made of TP110H material, the inner diameter is 127mm, the wall thickness is 10mm, the perforation scheme adopts single-cluster spiral perforation, the perforation aperture is 10mm, the perforation depth is 30cm, the phase angle is 120 degrees, the perforation interval is 6cm, and the perforation is 3 holes in a single cluster. And a closed structure is arranged at the tail end of the sleeve, and the pressure resistance at the bottom of the well is required to reach 100MPa.
The rock sample 1 is placed in the centre of the support plate 51, the support plate 51 is located in the rectangular slot 22 in the upper surface of the base 2, and the support plate 51 is located in the loading space 35 in the centre of the annular frame 31, the loading space 35 being of a cuboid construction.
The control frame lifting means 52 lifts the ring frame 31 off the base 2, and then the control stay plate lifting means 54 lifts the stay plate 51 off the base 2 such that the upper surface of the stay plate 51 and the lower surface of the ring frame 31 are spaced apart.
The first horizontal force application device 32 and the second horizontal force application device 33 on two adjacent side walls of the annular frame 31 are controlled, so that the horizontal force application plates 34 at force application ends of the first horizontal force application device and the second horizontal force application device push the rock sample 1 and the support plate 51 to move towards the bearing bodies 36 of the other two side walls of the annular frame 31 together until the two side walls of the rock sample 1 are respectively abutted with the two bearing bodies 36.
The first 32 and second 33 horizontal force applying means act as both stress loading means and means for moving the rock sample 1.
The control stay plate lifting device 54 drops the support plate 51 to be in contact with the base 2, and the control frame lifting device 52 drops the ring frame 31 to be in contact with the base 2 and the support plate 51.
The moving frame 41 is controlled to move so that the vertical force applying device 42 on the upper part of the moving frame 41 is positioned right above the rock sample 1, and the vertical force applying plate 43 at the force applying end of the vertical force applying device 42 is controlled to move so that the vertical force applying plate 43 is abutted against the upper surface of the rock sample 1.
The first horizontal force applying device 32 and the second horizontal force applying device 33 are controlled so that the horizontal force applying plate 34 at the force applying end applies a horizontal stress to the rock sample 1 until the set main stress range is reached.
The vertical force application device 42 is controlled to apply a vertical stress to the rock sample 1 until a set vertical stress range is reached.
Before pressurization, the horizontal force application plate 34 and the vertical force application plate 43 are guaranteed to be completely attached to the surface of the rock sample 1, sundries are not contained in the horizontal force application plate, before loading stress, safety inspection is carried out on the pressurization part and the rock sample 1, whether cracks exist on the surface of the rock sample 1 and whether the surface of a force application device is smooth or not is observed, the area near the pressurization part is cleaned, after each item is confirmed to be normal, the area with the radius of 50m around the pressurization part is set as a high-pressure operation area, a warning line is pulled up, and personnel are forbidden to enter in the pressurization process. In the process of applying stress, the pressurizing speed is strictly controlled below 1MPa/min, and the state of the rock sample 1 is monitored in real time through a fracturing monitoring device (which can be a stress strain gauge). The stress in the horizontal direction is 55-65 MPa, and the stress in the vertical direction is 35-45 MPa.
A fracturing fluid is injected into the wellbore 9 and the shock wave generator 6 is placed into the wellbore 9 with the window 62 of the shock wave generator 6 aligned with the shock wave operating point.
The following steps are repeated until the crack breaks through the boundary of the rock sample 1 and no new crack is generated: the rock sample 1 is subjected to a shock wave operation by a shock wave generator 6 to be fractured, and after a set number of times, the fracture radius and the fracture propagation form are recorded, and then the rock sample 1 is drilled and sampled.
Sampling principle: taking 60 degrees as a rotation angle, taking 30cm as a sampling interval, and uniformly sampling at different positions away from a shaft; sampling requirements: each sampling position is drilled with a plunger sample before and after the experiment.
And (3) comparing and analyzing the sampling result to obtain the change condition of the pore permeability parameter of the rock sample 1 and the change condition of the mechanical parameter of the rock sample 1, and finally comparing and analyzing the rock physical property and rock mechanical parameter change before and after the impact wave action.
The invention can also observe the crack form and distribution condition of each rock sample 1 under different operation times, and compare and analyze the rock mechanical parameter change in the pulse controllable shock wave fracturing process.
And (3) respectively performing multipoint sampling on the sleeve before and after the experiment, testing the compression strength and the tensile strength of the sleeve, comparing the performance parameters of the sleeve before and after the experiment, and analyzing whether the sleeve is damaged by pulse-type controllable shock wave fracturing.
The pore permeation parameter determination method comprises the following steps: and respectively performing multipoint sampling on the rock sample 1 before and after the fracturing experiment, performing rock column preparation by adopting linear cutting, and comparing and analyzing the change condition of the 1-hole permeability parameter of the rock sample, wherein the experimental operation rules refer to the GB/T29172-2012 core analysis method.
And (3) testing the mechanical properties of the rock: and respectively performing multipoint sampling on the rock sample 1 before and after the fracturing experiment, performing rock column preparation by adopting linear cutting, performing mechanical parameter tests such as compression resistance, tensile strength, shear strength and the like, comparing and analyzing the rock mechanical parameter change of the rock sample 1, and referring to the test procedure of the physical and mechanical properties of the rock of DZ/T0276.20-2015 by the experimental operation procedure.
And (3) performing experimental analysis on the metal performance of the sleeve before and after impact, sampling in a metal cutting mode, and respectively performing compressive strength test and tensile strength test. Therefore, the influence of the impact wave fracturing on the metal performance of the sleeve is judged, whether the sleeve is damaged or not is judged, and the basis is made for the selection of the subsequent sleeve.
The sleeve before and after pressing is sampled at multiple points respectively, the change of tensile properties of the sleeve before and after fracturing is analyzed, and the test process is referred to the section 1 of GB/T228.1-2021 tensile test of metallic materials: room temperature test method.
As shown in fig. 12, large rock sample preparation, small plunger processing, real wellbore construction, stress loading, impact fracturing experiments, post-impact sampling tests, and fracturing effect analysis.
As shown in fig. 13, 1, large object model experiment; 2. conglomerates, sandstones, and shale; 3. a confining pressure-free experiment and a confining pressure-adding experiment; 4. drilling a small column of a rock sample, testing physical properties and mechanical parameters of the rock, and testing the strength of a sleeve; 5. crack morphology and crack reconstruction; 6. analyzing the effect of the rock sample caused by the shock waves; 7. simulating and calculating the effective acting distance; 8. numerical simulation; 9. simulation software CDEM; 10. establishing a mathematical model; 11. a uniform intensity simulation and a random intensity simulation; 12. correcting simulation parameters; step 7 is entered.
Key links of large object model experiment and experimental scheme: preparing a large rock sample: processing and preparing a large-size (2 m multiplied by 1 m) conglomerate, sandstone and shale outcrop sample; and (3) shaft construction: the real sleeve (TP 125V, pressure resistance 125 MPa) is adopted, 3 holes are ejected in a single cluster spiral way, and the hole spacing is 6cm. Stress loading: the horizontal bi-directional stress is respectively loaded with 20MPa and 10MPa; impact experiment: a large-energy impact experiment is carried out, and the fracturing effect of the rock sample is recorded by pausing observation description every 3 times of action; and (3) monitoring in compression: 3 dyes (main monitoring) +pre-buried stress blocks and surface mount strain gauges (auxiliary monitoring). And (3) small plunger machining: small plungers with diameters of 2.5cm and heights of 5cm before and after the drilling impact test are uniformly distributed at different positions away from a shaft; and (3) crack characterization: and splitting the rock sample along the crack direction, measuring parameters such as crack size, density and the like, and performing digital modeling.
In this embodiment, after each sampling, a curable material is injected into the sampling hole 10 for plugging, so as to avoid interference to subsequent crack propagation, and the curable material can be epoxy resin.
As shown in fig. 11, in this embodiment, the sampling holes 10 for each sampling are all located on the same straight line, and the straight lines formed by the sampling are uniformly distributed in the circumferential direction of the reserved hole.
The distance between every two adjacent sampling holes 10 in the plurality of sampling holes 10 sampled each time is 25 cm-35 cm, and the distance between any sampling hole 10 and the reserved hole is larger than 25cm.
The sampling method can obtain a reasonable comparison result, so that the accuracy of the test is improved.
In this embodiment, a coloring agent is added to the fracturing fluid, and the crack propagation is calibrated by the dyed fracturing fluid.
According to the invention, the crack propagation at different stages can be calibrated by adopting the coloring agents with different colors, and the 3D modeling is performed on the crack morphology on the basis of rock subdivision.
The invention can also adopt a physical model method: by injecting a curable fluid, such as an epoxy, paraffin, low melting point metal, etc., into the wellbore 9, a physical model of the fracture morphology can be obtained.
The invention can also adopt a radar monitoring method: the rock sample 1 is scanned by adopting a ground penetrating radar, the position and the form of the crack are determined according to the time difference and the position difference of the electromagnetic wave propagating in the rock sample 1, and the crack form is described based on signal receiving data.
The invention also adopts a numerical simulation method: and simulating by adopting finite difference software or a finite element program, and establishing a model according to actual engineering geological parameter settings, wherein the model comprises four groups of drilling holes, casing pipes (containing perforation), cement rings and rock stratum. The numerical simulation is divided into three parts, namely, firstly, the simulation is carried out on an indoor model test, then the site scale model simulation of the casing, the perforation and the cement sheath is considered, and finally, a similar test model is simulated. And guiding a similar model test based on the numerical simulation result, and verifying and perfecting the numerical simulation through the model test.
In this embodiment, the pretreatment of the rock sample 1 comprises the following steps:
cutting the edges and corners of the surface of the rock sample 1 by a cutting machine to enable the edges and corners to approach to a cube structure. The surface of the material is smoothly transited as much as possible.
The rock sample 1 is placed on the support plate 51, the rock sample 1 and the support plate 51 are fixed by the fixing rope 8, and the rock sample 1 and the support plate 51 are lifted to the center of the ring frame 31 by the lifting mechanism 7, so that the support plate 51 is positioned in the rectangular groove 22.
The control frame lifting means 52 lifts the ring frame 31 off the base 2, and then the control stay plate lifting means 54 lifts the stay plate 51 off the base 2 such that the upper surface of the stay plate 51 and the lower surface of the ring frame 31 are spaced apart.
The casting templates 11 are mounted on the surfaces of the two supporting bodies 36, and the first horizontal force application device 32 and the second horizontal force application device 33 are controlled to push the rock sample 1 and the supporting plate 51 to move towards the supporting bodies 36 together until the two side walls of the rock sample 1 are respectively abutted with the two casting templates 11.
The control stay plate lifting device 54 drops the support plate 51 to be in contact with the base 2, and the control frame lifting device 52 drops the ring frame 31 to be in contact with the base 2 and the support plate 51.
The horizontal force application plates 34 at the force application ends of the first horizontal force application device 32 and the second horizontal force application device 33 are replaced with the pouring templates 11, and the first horizontal force application device 32 and the second horizontal force application device 33 are controlled to make the two pouring templates 11 abut against the other two side walls of the rock sample 1. At this time, the support plate 51 and the four casting templates 11 form a semi-closed structure, and a casting space 12 is formed between the semi-closed structure and the rock sample 1.
Cement is injected into the casting space 12, after the cement is solidified, the casting template 11 is disassembled, the surface of the rock sample 1 is polished to be smooth, the rock sample 1 forms a cube structure, and then the site is cleaned.
There is a conventional way of cutting the rock sample 1 directly to a cubic structure by means of a cutter, which is highly equipment demanding. The flatness is also improved by directly coating cement, but the rock sample 1 of the invention has large volume, low efficiency and poor effect in the conventional trimming mode, so that the cement is poured by using the stress loading system to form a cube structure, the operation process is simple, more equipment is omitted, and the rock sample 1 does not need to be repeatedly carried.
In this embodiment, the telescopic end of the supporting plate lifting device 54 is provided with a ball 541, the ball 541 is disposed in a spherical cavity at the end of the telescopic end, and when the supporting plate lifting device 54 lifts the supporting plate 51 away from the base 2, the ball 541 abuts against the lower surface of the supporting plate 51.
When the support plate 51 moves, the balls 541 roll against the support plate 51.
In this embodiment, when the rock sample 1 is moved from one side of the carrier 36 to the center of the ring frame 31, the ring frame 31 is lifted off the base 2 by the control frame lifting device 52, and then the support plate 51 is lifted off the base 2 by the control support plate lifting device 54, so that the upper surface of the support plate 51 and the lower surface of the ring frame 31 are spaced apart.
The telescopic means 56 on the carrier 36 are controlled so that they push the rock sample 1 until the rock sample 1 and the carrier 36 together move to the centre of the ring frame 31.
After the experiment, the rock sample 1 and the carrier 36 can be moved to the center of the ring frame 31 together in such an operation manner, and then the rock sample 1 and the carrier 36 are lifted off together by the lifting mechanism 7.
Further, the step of drilling and sampling a sample hole in a rock sample comprises: the sampling holes are all positioned on the same straight line, the straight lines formed by sampling for many times are uniformly distributed in the circumference of the reserved hole, the distance between every two adjacent sampling holes in the sampling holes is 25cm-35cm, and the distance between any sampling hole and the reserved hole is larger than 25cm.
The beneficial effects of adopting the further technical scheme are as follows: the sampling method can obtain a reasonable comparison result and prevent the mutual influence of sampling data, thereby improving the accuracy of the test.
Further, the crack extension calibration method comprises the following steps: a dye method, a physical model method, a radar monitoring method or a numerical simulation method.
The beneficial effects of adopting the further technical scheme are as follows: the crack expansion condition is monitored by adopting methods such as radar monitoring, the crack form is described by adopting methods such as dye calibration, rock splitting, three-dimensional modeling and the like after the crack is pressed, multipoint sampling is respectively carried out on a rock sample and a sleeve before and after the experiment, the influence of the shock wave fracturing on rock mechanical parameters and sleeve metal performance is compared and analyzed, the relation between the crack expansion rule and the shock wave operation times after the pressing is recognized, the technical safety of the pulse-type controllable shock wave reservoir transformation is verified, and data support is provided for the field test of the pulse-type controllable shock wave reservoir transformation technology.
Further, the method of the coloring agent comprises the following steps: adding a coloring agent into the fracturing fluid, calibrating crack expansion through the dyed fracturing fluid, and performing 3D modeling on the crack morphology on the basis of rock sample subdivision;
The physical model method is as follows: obtaining a fracture morphology physical model by injecting a solidifiable fluid into a wellbore;
the radar monitoring method comprises the following steps: scanning a rock sample by adopting a ground penetrating radar, determining the position and the form of a crack according to the time difference and the position difference of the electromagnetic wave propagating in the rock sample, and describing the crack form based on signal receiving data;
the numerical simulation method comprises the following steps: the simulation is carried out by adopting finite difference software or finite element program, a model is established according to actual engineering geological parameter setting, the model comprises four groups of drilling holes, casings, cement rings and rock strata, the numerical simulation is divided into three parts, firstly, the simulation is carried out on an indoor model test, then the field scale model simulation of the casings, the perforating holes and the cement rings is considered, finally, a similar test model is simulated, the similar model test is guided based on the numerical simulation result, and the numerical simulation is verified and perfected through the model test.
The beneficial effects of adopting the further technical scheme are as follows: and (3) adding a coloring agent into the fracturing fluid, and calibrating crack expansion through the dyed fracturing fluid. And calibrating crack propagation at different stages by adopting different colors of coloring agents, and performing 3D modeling on crack morphology on the basis of rock subdivision. A physical model of fracture morphology may be obtained by injecting a curable fluid, such as an epoxy, paraffin, low melting point metal, or the like, into the wellbore. And scanning the rock sample by adopting a ground penetrating radar, determining the position and the form of the crack according to the time difference and the position difference of the electromagnetic wave propagating in the rock sample, and describing the crack form based on the signal receiving data.
Further, step S1 includes:
cutting edges and corners of the surface of the rock sample by a cutting machine to enable the edges and corners to be close to a cube structure;
and casting the rock sample by using a triaxial pulse type shock wave fracturing rock experimental system and a casting template to form the rock sample with a cube structure.
The beneficial effects of adopting the further technical scheme are as follows: the stress triaxial pulse type shock wave fracturing rock experimental system is utilized to pour cement to the rock sample to form a cube structure, the operation process is simple, more equipment is omitted, repeated carrying of the rock sample is not needed, and the trimming efficiency is improved.
Further, the length, width and height dimensions of the rock sample are all larger than 1m, the inner diameter of the shaft is 127mm, and the wall thickness of the shaft is 10mm.
The beneficial effects of adopting the further technical scheme are as follows: the method is suitable for large-volume rock, can simulate the shock wave fracturing reservoir process under real stratum environment (high temperature and high pressure) and well shaft conditions (casing, well cementation and perforation), is convenient for observing the pulse controllable shock wave fracturing rock crack extension rule, realizes the pulse controllable shock wave fracturing rock physical simulation experiment of a large-scale rock sample (2 m multiplied by 1 m) under the condition of approaching the true triaxial stress of the stratum, and realizes the organic unification of indoor experimental conditions and site construction parameters. The structure is reasonable in setting, easy to operate, high in safety, capable of greatly improving the efficiency of the experimental process and providing accurate experimental results.
Further, in step S3, the stress in the horizontal X-axis direction, the stress in the horizontal Y-axis direction and the stress in the vertical direction are pressurized at a speed of less than 1MPa/min, the stress in the horizontal X-axis direction and the stress in the horizontal Y-axis direction have a numerical range of 55-65MPa, and the stress in the vertical direction has a numerical range of 35-45MPa.
The beneficial effects of adopting the further technical scheme are as follows: the impact waves simulating the stratum environment break the rock, so that the stress is the same as or close to the actual environment of the rock, and the accuracy of experimental data is improved.
Further, the step of drilling and sampling a sample hole in a rock sample further comprises: taking 60 degrees as a rotation angle, taking 30cm as a sampling interval, and uniformly sampling at different positions away from a shaft; and drilling a plunger sample at each sampling position before and after the experiment, and injecting a consolidation material into the sampling hole for plugging after each sampling.
The beneficial effects of adopting the further technical scheme are as follows: injecting a concretionary material into the sampling hole for plugging after each sampling, avoiding interference to subsequent crack expansion, wherein the concretionary material can adopt epoxy resin.
Further, step S8 includes:
s81, observing the morphology and distribution of each rock sample crack under the condition of different operation times, and comparing and analyzing the rock mechanical parameter change in the pulse shock wave fracturing process;
S82, respectively performing multipoint sampling on the wellbores before and after the experiment, sampling in a metal cutting mode, testing the compression resistance and the tensile strength of the wellbores, comparing the performance parameters of the wellbores before and after the experiment, and analyzing whether the wellbores are damaged by pulse shock wave fracturing.
The beneficial effects of adopting the further technical scheme are as follows: and (3) carrying out experimental analysis on the metal performances of the shaft before and after impact, sampling in a metal cutting mode, and respectively carrying out compressive strength test and tensile strength test. Therefore, the influence of the shock wave fracturing on the metal performance of the shaft is judged, whether the shaft is damaged or not is judged, and the basis is made for the selection of the subsequent shaft.
Further, step S8 includes: respectively performing multipoint sampling on rock samples before and after a fracturing experiment, preparing a rock column by adopting linear cutting, and comparing and analyzing the change condition of the pore-permeation parameters of the rock samples;
and respectively performing multipoint sampling on the rock samples before and after the fracturing experiment, performing rock column preparation by adopting linear cutting, performing compression resistance, tensile resistance and shear strength mechanical parameter test, and comparing and analyzing the rock mechanical parameter change condition of the rock samples.
The beneficial effects of adopting the further technical scheme are as follows: and (5) respectively performing multipoint sampling on the sleeve before and after the fracturing, and analyzing the tensile property change of the sleeve before and after the fracturing.
The triaxial pulse type shock wave fracturing rock experiment system may be a triaxial pulse type shock wave fracturing rock experiment system including: the rock sample 1, base 2, cyclic loading mechanism 3, vertical loading mechanism 4, rock displacement mechanism 5, shock wave generator 6, pit shaft 9, pressure sensor 13, electrical heating assembly 16, rock sample 1 is installed on the rock displacement mechanism 5, cyclic loading mechanism 3 liftable install the top of base 2, vertical loading mechanism 4 and rock displacement mechanism 5 all slidable mounting are in the top of base 2, cyclic loading mechanism 3 encircles the week side of rock sample 1, vertical loading mechanism 4 is located the top of rock sample 1, install at the top of shock wave generator 6 on vertical loading mechanism 4, the bottom of shock wave generator 6 and pit shaft 9 all install in rock sample 1, pit shaft 9 is located the below of shock wave generator 6, cyclic loading mechanism 3 with the output of vertical loading mechanism 4 all install pressure sensor 13 and electrical heating assembly 16.
The technical scheme of the invention has the beneficial effects that: the stress in the horizontal direction can be loaded on the rock sample by arranging the annular loading mechanism, and the stress in the vertical direction can be loaded on the rock sample by arranging the vertical loading mechanism, so that a true triaxial ground stress environment is realized. The vertical loading mechanism can move, so that the rock sample can be placed and taken out conveniently. The rock shifting mechanism can assist workers in transferring rock samples and can move the rock samples to set positions so as to smoothly load stress. The method is suitable for large-volume rock, can simulate the shock wave fracturing reservoir process under real stratum environment (high temperature and high pressure) and well shaft conditions (casing, well cementation and perforation), is convenient for observing the pulse controllable shock wave fracturing rock crack extension rule, realizes the pulse controllable shock wave fracturing rock physical simulation experiment of a large-scale rock sample (2 m multiplied by 1 m) under the condition of approaching the true triaxial stress of the stratum, and realizes the organic unification of indoor experimental conditions and site construction parameters. The structure is reasonable in setting, easy to operate, high in safety, capable of greatly improving the efficiency of the experimental process and providing accurate experimental results.
Fig. 1 shows a state of hoisting a rock sample into a loading space, fig. 2 shows a state when an annular frame is lifted before an experiment, fig. 3 shows a state when the rock sample is pushed to be abutted against a carrier, fig. 4 shows a state after a casting template is installed, fig. 5 shows a state of controllable shock wave broken rock experiment simulating a stratum environment, fig. 6 shows a state when the annular frame is lifted after the experiment, fig. 7 shows a state when a telescopic device pushes the rock sample to the center of the loading space, fig. 8 shows a structure of a base and an annular loading mechanism, fig. 9 shows a mounting structure of a vertical loading mechanism, and fig. 10 shows structures of a pressure sensor, an abutment plate and a force transfer plate.
The triaxial pulse type shock wave fracturing rock experiment system provided by the embodiment of the invention can be a large-size true triaxial pulse type controllable shock wave fracturing rock experiment system, and comprises a base 2, a circumferential loading mechanism 3, a vertical loading mechanism 4, a shock wave fracturing mechanism and a rock shifting mechanism 5.
The vertical loading mechanism 4 includes a moving frame 41, a vertical force application device 42, and a vertical force application plate 43. The section of the movable frame 41 is of an n-shaped structure, the lower end of the movable frame 41 is clamped in the sliding groove 21 on the base 2, the movable frame 41 is in sliding connection with the base 2, an installation space is formed between the movable frame 41 and the base 2, and the base 2 is fixedly installed. The left and right sides of base 2 all are provided with spout 21, and the cross-section of spout 21 is L type structure, and the cross-section of the lower extreme of moving frame 41 is L type structure, and moving frame 41's lower extreme is provided with and moves round 411, moves round 411 and the bottom surface of spout 21 cooperatees. The sliding groove 21 and the lower end of the moving frame 41 are structurally arranged, so that the moving function of the moving frame 41 can be realized, the vertical stress can be smoothly loaded on the rock sample 1, and when the vertical stress is loaded, the upper surface of the lower end of the moving frame 41 is abutted against the top wall of the sliding groove 21. The moving wheel 411 at the lower end of the moving frame 41 can facilitate the movement of the moving frame 41.
The vertical force application device 42 is mounted on the upper portion of the moving frame 41, and a vertical force application plate 43 is mounted on the force application end of the vertical force application device 42. The n-shaped moving frame 41 can accommodate the annular loading mechanism 3, and the moving frame 41 capable of moving facilitates the placement and the taking out of the rock sample 1. The lower end of the moving frame 41 is engaged with the base 2, so that the vertical force application device 42 can apply a vertical stress to the rock sample 1 on the base 2 through the vertical force application plate 43.
The hoop load mechanism 3 includes an annular frame 31, a first horizontal force application device 32, a second horizontal force application device 33, and a horizontal force application plate 34. The annular frame 31 is installed on the upper surface of the base 2 and is located in the installation space, a loading space 35 is arranged in the center of the annular frame 31, the loading space 35 penetrates through the upper end and the lower end of the annular frame 31, and the loading space 35 is of a cube structure. The first horizontal force application device 32 and the second horizontal force application device 33 are respectively arranged on two adjacent side walls of the annular frame 31, the force application ends of the first horizontal force application device 32 and the second horizontal force application device 33 are respectively provided with a horizontal force application plate 34, and the other two side walls of the annular frame 31 are bearing bodies 36. By providing the first and second horizontal force applying devices 32, 33 and the two carriers 36, horizontal stress can be applied to the rock sample 1 on the base 2, avoiding the problem of complex structure due to the need of providing four force applying devices. The ring frame 31 is placed on the base 2, and the ring frame 31 and the moving frame 41 can be temporarily fixed by a fixing mechanism when stress is applied in order to ensure the stability of the ring frame 31. The first horizontal force application device 32, the second horizontal force application device 33, and the vertical force application device 42 each include more than one hydraulic pressurization assembly.
The horizontal force application plate 34 and the vertical force application plate 43 comprise a pressure sensor 13, and an abutting plate 14 and a force transmission plate 15 which are arranged at intervals, wherein the pressure sensor 13 is arranged between the abutting plate 14 and the force transmission plate 15, and the abutting plate 14 is close to one side of the true triaxial stress simulation space. The pressure sensor 13 is used to monitor the magnitude of the stress in real time. The two sides of the inside of the abutting plate 14 are respectively provided with an electric heating component 16 and a heat insulation layer 17, and the heat insulation layer 17 is close to one side of the pressure sensor 13. The electrical heating assembly 16 is capable of heating the rock sample 1 to simulate the temperature environment of a deep formation. The bearing plate 55 and the supporting plate 51 can be internally provided with the electric heating component 16, so that the rock sample 1 is uniformly heated, and the heating effect is improved.
The rock displacement mechanism 5 comprises a support plate 51, a frame lifting device 52, a stay plate lifting device 54, a suspension ring 53, a force bearing plate 55, a telescopic device 56 and a stay plate lifting device 54. The support plate 51 is disposed in the rectangular groove 22 on the upper surface of the base 2, and the upper surface of the support plate 51 is flush with the upper surface of the base 2. A plurality of mounting grooves are formed in the circumferential direction of the upper surface of the support plate 51, and hanging rings 53 are arranged in the mounting grooves. The rectangular grooves 22 are provided to facilitate the movement of the support plate 51, and the upper surface of the support plate 51 is flush with the upper surface of the base 2 after the movement, so that the loading of stress is not affected. The suspension ring 53 is arranged in the mounting groove, so that the suspension ring 53 does not influence the placement of the rock sample 1 and does not interfere with the ring frame 31.
The circumferential direction of the rectangular groove 22 extends below the annular frame 31. Specifically, the perimeter of the rectangular slot 22 extends below the carrier 36, while the other side of the ring frame 31 does not extend. The area of backup pad 51 is greater than the bottom area of rock specimen 1 during the in-service use, is convenient for the fixed and handling of rock specimen 1 like this, and the part that backup pad 51 is more can hold in the rectangular channel 22 of ring frame 31 below, can make rock specimen 1 and carrier 36 butt like this, is convenient for load horizontal direction's stress.
The frame lifting device 52 is mounted on the circumference of the base 2, and the telescopic end of the frame lifting device 52 is connected to the lower surface of the ring frame 31. The frame lifting means 52 serves to lift the ring frame 31 so as to facilitate the insertion of the support plate 51 into the lower portion of the ring frame 31 after the movement. The frame lifting device 52 employs a hydraulic lifting assembly.
The telescopic devices 56 are arranged on the two bearing bodies 36, the bearing plates 55 are arranged on the telescopic ends of the telescopic devices 56, one sides of the bearing plates 55 are used for being abutted against the bearing bodies 36, and the other sides of the bearing plates 55 are close to the true triaxial stress simulation space. The telescopic device 56 adopts a hydraulic telescopic component, and the telescopic device 56 can push the rock sample 1 to move through the bearing plate 55, so that the purpose of uniformly applying force is realized.
The supporting plate lifting device 54 is installed in the center of the upper surface of the base 2, the telescopic end of the supporting plate lifting device 54 is provided with a ball 541, the ball 541 is arranged in a spherical cavity at the end part of the telescopic end, and the ball 541 is used for being matched with the lower surface of the supporting plate 51. The supporting plate lifting device 54 adopts a hydraulic telescopic assembly, the balls 541 adopt steel balls, the balls 541 can realize the function of universal movement of the supporting plate 51, and the strength is high. The supporting plate lifting device 54 can lift the rock sample 1 and the supporting plate 51 together, so that the supporting plate 51 moves on the balls 541, friction force during movement of the supporting plate 51 is reduced, and the problem that the rock sample 1 is too large to carry is avoided.
The shock wave fracturing mechanism comprises a shock wave generator 6 and a controller which are electrically connected, wherein the shock wave generator 6 is detachably arranged on the movable frame 41. The construction of the shock wave generator 6 and the controller and the control method are not described again for the present embodiment of the prior art.
A fixing ring 61 is mounted on the upper end of the shock wave generator 6 in the circumferential direction.
The upper portion of the moving frame 41 is provided with a step hole 412, the center of the vertical force application plate 43 is provided with a through hole 431, the through hole 431 and the step hole 412 are coaxially arranged, the lower end of the shock wave generator 6 sequentially passes through the step hole 412 and the through hole 431, and the fixing ring 61 is clamped at the step of the step hole 412. The stepped hole 412 and the through hole 431 allow the shock wave generator 6 to pass therethrough, thereby facilitating the replacement of the wire or the energy rod of the shock wave generator 6 by a worker. The shock wave generator 6 can be mounted by the handling mechanism 7 and temporarily fixed by the fixing ring 61 and the moving frame 41.
A true triaxial stress simulation space with a cube structure is formed among the vertical force application plate 43, the two horizontal force application plates 34, the two bearing bodies 36 and the supporting plate 51, a window 62 for the passage of shock waves is arranged at the lower end of the shock wave generator 6, and the window 62 is positioned in the true triaxial stress simulation space. The true triaxial stress simulation space is used for placing the rock sample 1, and the lower end of the shock wave generator 6 extends into the shaft 9 of the rock sample 1. According to the invention, 35-65 MPa stress is required to be loaded on the rock sample 1, so that each bearing component adopts a steel plate and a steel structure frame to ensure the structural stability in the experimental process.
A lifting mechanism 7 is arranged above the base 2, the lower end of a lifting rope of the lifting mechanism 7 is used for being matched with the hanging ring 53, and two ends of the fixing rope 8 are used for being matched with the hanging ring 53. The lifting mechanism 7 is used for lifting in and lifting out the rock sample 1, and the lifting mechanism 7 can be in the form of a crown block or a crane. The fixing line 8 can fix the rock sample 1 and the support plate 51.
As shown in fig. 1 to 10, further, the vertical loading mechanism 4 includes: the vertical force application device 42 and the vertical force application plate 43 are installed on the vertical force application device 42, the vertical force application plate 43 is located above the rock sample 1, the pressure sensor 13 and the electric heating assembly 16 are installed on the vertical force application plate 43.
The beneficial effects of adopting the further technical scheme are as follows: the moving frame of the n-shaped structure can accommodate the annular loading mechanism, and the moving frame of the vertical loading mechanism can move, so that the rock sample can be placed and taken out conveniently. The installation space is formed between the movable frame and the base, the sliding groove and the structure of the lower end of the movable frame are arranged to realize the movable function of the movable frame, the vertical stress can be smoothly loaded on the rock sample, and when the vertical stress is loaded, the upper surface of the lower end of the movable frame is abutted to the top wall of the sliding groove.
As shown in fig. 1 to 10, further, the bottom of the moving frame 41 has an L-shaped structure, the chute 21 is an L-shaped chute, and a moving wheel 411 is disposed at the bottom end of the moving frame 41.
The beneficial effects of adopting the further technical scheme are as follows: the structure setting of spout and movable frame lower extreme not only can realize the function that the movable frame removed, can also load the stress of vertical direction to the rock specimen smoothly, and when loading the stress of vertical direction, the roof butt of upper surface and spout of movable frame lower extreme. The moving wheel 1 at the lower end of the moving frame can facilitate the moving of the moving frame.
As shown in fig. 1 to 10, further, the hoop load mechanism 3 includes: the annular frame 31, the first horizontal force application device 32, the second horizontal force application device 33 and the horizontal force application plate 34, wherein the annular frame 31 is installed at the top end of the base 2 in a lifting manner, the annular frame 31 is located in the vertical loading mechanism 4, the annular frame 31 is of a structure with opening at two ends of a loading space 35 with a cube structure, the first horizontal force application device 32 and the second horizontal force application device 33 are installed on two adjacent first inner side walls of the annular frame 31 in a one-to-one correspondence manner, the horizontal force application plate 34 is installed at the output ends of the first horizontal force application device 32 and the second horizontal force application device 33, the pressure sensor 13 and the electric heating assembly 16 are installed on the horizontal force application plate 34, and two adjacent second inner side walls of the annular frame 31 are the carrier 36.
The beneficial effects of adopting the further technical scheme are as follows: by arranging the first horizontal force application device, the second horizontal force application device and the two supporting bodies, horizontal stress can be loaded on the rock sample on the base, and the problem that four force application devices are complex in structure is avoided.
As shown in fig. 1 to 10, further, the horizontal force application plate 34 includes: the pressure sensor comprises an abutting plate 14, a force transfer plate 15 and a heat insulation layer 17, wherein the force transfer plate 15 is arranged at the output ends of the first horizontal force application device 32 and the second horizontal force application device 33, the pressure sensor 13 is arranged on the force transfer plate 15, the abutting plate 14 is arranged on the pressure sensor 13, the electric heating assembly 16 and the heat insulation layer 17 are arranged in the abutting plate 14, the heat insulation layer 17 is adjacent to the pressure sensor 13, and the casting template 11 is detachably arranged on the supporting body 36.
The beneficial effects of adopting the further technical scheme are as follows: the pressure sensor is arranged between the abutting plate and the force transmission plate, and the abutting plate is close to one side of the true triaxial stress simulation space. The pressure sensor is used for monitoring the stress in real time. The two sides of the abutting plate are respectively provided with an electric heating component and a heat insulation layer, and the heat insulation layer is close to one side of the pressure sensor. The electrical heating assembly is capable of heating the rock sample to simulate the temperature environment of the deep formation. The bearing plate and the supporting plate can be internally provided with an electric heating component, so that the rock sample is uniformly heated, and the heating effect is improved.
As shown in fig. 1 to 10, further, the rock displacement mechanism 5 includes: the device comprises a supporting plate 51, a frame lifting device 52, a hanging ring 53, a supporting plate lifting device 54, a bearing plate 55 and a telescopic device 56, wherein a rectangular groove 22 is formed in the top of a base 2, the rectangular groove 22 extends to the lower side of a circular loading mechanism 3, a rock sample 1 is installed on the supporting plate 51, the supporting plate 51 is slidably installed in the rectangular groove 22, the top end of the supporting plate 51 is flush with the top end of the base 2, an installation groove is formed in the top end of the supporting plate 51, the hanging ring 53 is installed in the installation groove, the frame lifting device 52 is installed at the top of the base 2, the output end of the frame lifting device 52 is connected with the circular loading mechanism 3, the telescopic device 56 is installed on two adjacent second inner side walls of the circular loading mechanism 3, the bearing plate 55 is installed at the output end of the telescopic device 56, the supporting plate lifting device 54 is installed in the middle of the top end of the base 2, and the output end of the supporting plate lifting device 54 is in butt joint with the supporting plate 51.
The beneficial effects of adopting the further technical scheme are as follows: the rock shifting mechanism can assist workers in transferring rock samples and can move the rock samples to set positions so as to smoothly load stress. The setting of rectangular channel can be convenient for backup pad remove to the upper surface of backup pad and the upper surface parallel and level of base after removing, thereby do not influence the loading of stress. The link sets up in the mounting groove, therefore the link can not influence the placing of rock specimen, also can not appear interfering with ring frame. The circumference of the rectangular groove extends to the lower part of the supporting body, and the other side of the annular frame does not extend. The area of backup pad is greater than the bottom area of rock specimen during in-service use, is convenient for the fixed and handling of rock specimen like this, and the part that the backup pad is more can hold in the rectangular channel of annular frame below, can make rock specimen and supporting body butt like this, the stress of loading horizontal direction of being convenient for. The frame lifting device is used for lifting the annular frame so as to facilitate the support plate to be inserted into the lower part of the annular frame after moving. The telescopic device can push the rock sample to move through the bearing plate, so that the purpose of uniformly applying force is achieved.
As shown in fig. 1 to 10, further, the output end of the supporting plate lifting device 54 is provided with a spherical cavity, a ball 541 is provided in the spherical cavity, and the ball 541 abuts against the supporting plate 51.
The beneficial effects of adopting the further technical scheme are as follows: the ball can realize the function of the universal movement of the support plate and has high strength. The supporting plate lifting device can lift the rock sample and the supporting plate together, so that the supporting plate moves on the balls, friction force when the supporting plate moves is reduced, and the problem that the rock sample is too large to carry is avoided.
As shown in fig. 1 to 10, further, a fixing ring 61 is installed at the top of the shock wave generator 6, a stepped hole 412 is provided at the top of the vertical loading mechanism 4, the fixing ring 61 is installed in the stepped hole 412, a window 62 for passing shock waves is provided at the bottom of the shock wave generator 6, and the window 62 is located in the rock sample 1.
The beneficial effects of adopting the further technical scheme are as follows: the wire or the energy rod of the shock wave generator is convenient for the staff to replace. The shock wave generator can be installed through a lifting mechanism and is temporarily fixed through a fixed ring and a movable frame. The lower end of the shock wave generator is provided with a window for the shock wave to pass through, and the window is positioned in the true triaxial stress simulation space.
As shown in fig. 1 to 10, further, a lifting mechanism 7 is arranged above the base 2, a lifting rope of the lifting mechanism 7 is connected with the rock displacement mechanism 5, and the rock sample 1 is mounted on the rock displacement mechanism 5 through a fixing rope 8.
The beneficial effects of adopting the further technical scheme are as follows: the rock shifting mechanism and the lifting mechanism can assist workers in transferring rock samples, and the rock samples can be moved to a set position so as to smoothly load stress. The lower end of the lifting rope of the lifting mechanism is used for being matched with the hanging ring, and the two ends of the fixed rope are used for being matched with the hanging ring. The lifting mechanism is used for lifting in and lifting out the rock sample, and can be in the form of a crown block or a crane. The fixing rope can fix the rock sample and the supporting plate.
As shown in fig. 1 to 10, further, the rock sample 1 has a cubic structure, the inner diameter of the well bore 9 is 127mm, and the wall thickness of the well bore 9 is 10mm.
The beneficial effects of adopting the further technical scheme are as follows: and the accuracy of experimental data is improved.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention.
Claims (10)
1. A shock wave broken rock experimental method for simulating stratum environment, comprising:
s1, preprocessing a rock sample to form a rock sample with a cube structure;
s2, drilling a reserved hole in the rock sample, and installing a shaft in the reserved hole;
s3, placing the rock sample into a triaxial pulse type shock wave fracturing rock experiment system, loading stress in the horizontal X-axis direction, stress in the horizontal Y-axis direction and stress in the vertical direction on the rock sample, and heating the rock sample;
s4, calibrating crack extension by a crack extension calibration method, and placing a shock wave generator into a shaft;
s5, performing shock wave operation fracturing on the rock sample through a shock wave generator;
s6, repeating the step S5 until the crack breaks through the boundary of the rock sample and no new crack is generated;
s7, recording the fracturing radius and the crack expansion form, and drilling a sampling hole on the rock sample and sampling;
s8, comparing and analyzing the sampling result to obtain the change condition of the pore-penetration parameter of the rock sample and the change condition of the mechanical parameter of the rock sample.
2. A method of shock wave broken rock testing according to claim 1, wherein the step of drilling and sampling a sample hole in the rock sample comprises: the sampling holes are all positioned on the same straight line, the straight lines formed by sampling for many times are uniformly distributed in the circumference of the reserved hole, the distance between every two adjacent sampling holes in the sampling holes is 25cm-35cm, and the distance between any sampling hole and the reserved hole is larger than 25cm.
3. The method for simulating the shock wave rock breaking experiment of the stratum environment according to claim 1, wherein the crack extension calibration method comprises the following steps: a dye method, a physical model method, a radar monitoring method or a numerical simulation method.
4. A method of simulating the impact wave breaking rock test in a subterranean environment according to claim 3, wherein the method of coloring agent is: adding a coloring agent into the fracturing fluid, calibrating crack expansion through the dyed fracturing fluid, and performing 3D modeling on the crack morphology on the basis of rock sample subdivision;
the physical model method is as follows: obtaining a fracture morphology physical model by injecting a solidifiable fluid into a wellbore;
the radar monitoring method comprises the following steps: scanning a rock sample by adopting a ground penetrating radar, determining the position and the form of a crack according to the time difference and the position difference of the electromagnetic wave propagating in the rock sample, and describing the crack form based on signal receiving data;
the numerical simulation method comprises the following steps: the simulation is carried out by adopting finite difference software or finite element program, a model is established according to actual engineering geological parameter setting, the model comprises four groups of drilling holes, casings, cement rings and rock strata, the numerical simulation is divided into three parts, firstly, the simulation is carried out on an indoor model test, then the field scale model simulation of the casings, the perforating holes and the cement rings is considered, finally, a similar test model is simulated, the similar model test is guided based on the numerical simulation result, and the numerical simulation is verified and perfected through the model test.
5. The method of claim 1, wherein step S1 comprises:
cutting edges and corners of the surface of the rock sample by a cutting machine to enable the edges and corners to be close to a cube structure;
and casting the rock sample by using a triaxial pulse type shock wave fracturing rock experimental system and a casting template to form the rock sample with a cube structure.
6. The method for simulating the rock breaking test of the stratum environment according to claim 1, wherein the length, width and height dimensions of the rock sample are all larger than 1m, the inner diameter of the shaft is 127mm, and the wall thickness of the shaft is 10mm.
7. The method according to claim 1, wherein in the step S3, the stress in the horizontal X-axis direction, the stress in the horizontal Y-axis direction, and the stress in the vertical direction are applied at a pressure rate of less than 1MPa/min, the stress in the horizontal X-axis direction and the stress in the horizontal Y-axis direction have a value range of 55 MPa to 65MPa, and the stress in the vertical direction has a value range of 35 MPa to 45MPa.
8. The method of claim 1, wherein the step of drilling and sampling a sample hole in the rock sample further comprises:
Taking 60 degrees as a rotation angle, taking 30cm as a sampling interval, and uniformly sampling at different positions away from a shaft; and drilling a plunger sample at each sampling position before and after the experiment, and injecting a consolidation material into the sampling hole for plugging after each sampling.
9. The method of claim 1, wherein step S8 is followed by:
s81, observing the morphology and distribution of each rock sample crack under the condition of different operation times, and comparing and analyzing the rock mechanical parameter change in the pulse shock wave fracturing process;
s82, respectively performing multipoint sampling on the wellbores before and after the experiment, sampling in a metal cutting mode, testing the compression resistance and the tensile strength of the wellbores, comparing the performance parameters of the wellbores before and after the experiment, and analyzing whether the wellbores are damaged by pulse shock wave fracturing.
10. The method of claim 9, wherein step S8 comprises: respectively performing multipoint sampling on rock samples before and after a fracturing experiment, preparing a rock column by adopting linear cutting, and comparing and analyzing the change condition of the pore-permeation parameters of the rock samples;
And respectively performing multipoint sampling on the rock samples before and after the fracturing experiment, performing rock column preparation by adopting linear cutting, performing compression resistance, tensile resistance and shear strength mechanical parameter test, and comparing and analyzing the rock mechanical parameter change condition of the rock samples.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117147321A (en) * | 2023-10-30 | 2023-12-01 | 新疆泰齐石油科技有限公司 | Method and device for representing crack morphology of experimental rock sample |
| CN117250068A (en) * | 2023-11-20 | 2023-12-19 | 华侨大学 | Soft rock sample preparation equipment and sample preparation method thereof |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117147321A (en) * | 2023-10-30 | 2023-12-01 | 新疆泰齐石油科技有限公司 | Method and device for representing crack morphology of experimental rock sample |
| 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 |
| CN117250068A (en) * | 2023-11-20 | 2023-12-19 | 华侨大学 | Soft rock sample preparation equipment and sample preparation method thereof |
| CN117250068B (en) * | 2023-11-20 | 2024-01-30 | 华侨大学 | Soft rock sample preparation equipment and sample preparation method thereof |
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