CN113514626B - Experimental device and experimental method for determining rock dilatation change rule - Google Patents
Experimental device and experimental method for determining rock dilatation change rule Download PDFInfo
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- 239000011435 rock Substances 0.000 title claims abstract description 172
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- 238000002347 injection Methods 0.000 claims abstract description 185
- 239000007924 injection Substances 0.000 claims abstract description 185
- 239000007788 liquid Substances 0.000 claims abstract description 159
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- 125000006850 spacer group Chemical group 0.000 description 6
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
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- 239000008367 deionised water Substances 0.000 description 1
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- 239000012153 distilled water Substances 0.000 description 1
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Abstract
The invention provides an experimental device and an experimental method for determining rock dilatation rules. The experimental device comprises an experimental box body, a rock sample with a liquid injection hole, a confining pressure loading assembly loaded on the periphery of the rock sample, a liquid injection assembly extending into the liquid injection hole, and a data acquisition assembly arranged on the confining pressure loading assembly and the liquid injection assembly. The experimental method comprises the following steps: alternately loading confining pressure and injecting liquid into the rock sample, and stopping confining pressure loading and injecting liquid when the target confining pressure is reached; continuously injecting liquid into the rock sample stably, and stopping when the injection liquid pressure obviously rises and reaches the core fracture pressure; when the injection pressure drops below the core fracture pressure, injecting liquid into the rock sample in a small displacement mode; stopping small-displacement liquid injection when the liquid injection pressure reaches the core fracture pressure and does not drop or the pressure drop is small; and obtaining the rock core volume expansion and volume expansion pressure change curve according to the pressure data recorded in the whole process. The invention has the advantages of being capable of monitoring the rock capacity expansion change process in the whole process, improving the capacity expansion transformation volume and effect, being high in experimental safety and the like.
Description
Technical Field
The invention relates to the field of oil and gas field development, in particular to an experimental device and an experimental method for determining rock dilatation change rule.
Background
In the development of volume modifications to sandstone reservoirs, the porosity of the reservoir rock is typically increased by using rock dilatation techniques to form complex, large volume microscopic Zhang Jianlie seam areas in near wellbore zones. However, in the existing rock capacity expansion technology, no experimental device and method for monitoring the capacity expansion change process of the rock in the whole process of fluid injection process exist, and in particular:
The Chinese patent CN201711043563 discloses a surrounding rock displacement early warning method based on a damage capacity expansion theory, which is mainly based on a traditional Fennar formula, obtains a surrounding rock pressure calculation formula through elastic mechanical solution, considers the capacity expansion effect of surrounding rock damage capacity expansion deformation along with the excavation process, and obtains a hole wall displacement formula considering the capacity expansion effect of a surrounding rock damage area, but cannot monitor the rock capacity expansion change process in the whole course and cannot provide a rock core capacity expansion volume calculation formula. Chinese patent CN201810450260 discloses a method for evaluating the compressibility of a tight reservoir based on a stress-strain curve, which determines a rock sample expansion point according to an axial strain-fracture volume strain relation curve, and obtains the strain energy by the envelope area of the stress-strain curve enclosed from the expansion point to the fracture point, but also cannot monitor the rock expansion change process in the whole injection process. The literature 'sandstone capacity expansion characteristics and shear expansion angle functions thereof under high stress unloading conditions' analyzes the influence effect of an unloading stress path on sandstone capacity expansion by developing triaxial pre-peak unloading confining pressure tests and conventional triaxial compression tests with different initial confining pressure levels, but cannot monitor the rock capacity expansion change rule in the fluid injection process; the literature on the modified rock expansion model and expansion limit research provides a modified incremental expansion model by researching the change rule of the rock test piece volume strain along with the bias stress, but the literature can not fully monitor the rock expansion change process under the action of hydraulic force and also can not provide a rock core expansion volume calculation formula.
Because the experimental device and the method for monitoring the capacity expansion change process of the rock under the action of the water power in the whole process are not provided in the prior art, the capacity expansion change rule of the rock under the condition of being lower than the core fracture pressure is not deeply known, the capacity expansion volumes of different rocks under different injection pressure cannot be accurately predicted, the capacity expansion process parameters cannot be optimized during on-site development and reservoir transformation, and the sandstone reservoir volume is difficult to fully transform and the capacity expansion process transformation effect is poor.
Disclosure of Invention
The invention aims to solve the technical problems of overcoming the defects of the prior art and providing the experimental device and the experimental method for measuring the rock dilatation change rule, which can monitor the rock dilatation change process in the whole process, improve the dilatation reconstruction volume and effect and have high experimental safety.
In order to solve the technical problems, the technical scheme provided by the invention is as follows:
An experimental device for determining rock capacity expansion rules comprises an experimental box body, a rock sample with a liquid injection hole, a confining pressure loading assembly for loading confining pressure to the rock sample so as to simulate a ground stress environment, a liquid injection assembly for injecting liquid into the rock sample to simulate rock capacity expansion, and a data acquisition assembly for acquiring liquid injection pressure, loading confining pressure and confining pressure after rock capacity expansion in real time, wherein the rock sample is arranged in the experimental box body, and the confining pressure loading assembly is loaded on the periphery of the rock sample; the injection end of the injection assembly extends into the injection hole of the rock sample; the data acquisition assembly is arranged on the confining pressure loading assembly and the liquid injection assembly.
As a further improvement of the above technical scheme:
the confining pressure loading assembly comprises an elastic clamping piece, a loading hydraulic cavity, a pressurizing pipeline and a loading control unit, wherein the elastic clamping piece is wrapped on the periphery of the rock sample, and the top end of the elastic clamping piece is higher than the top end of the rock sample; the loading hydraulic cavity is arranged between the elastic clamping piece and the experiment box body; and two ends of the pressurizing pipeline are respectively communicated with the loading hydraulic cavity and the loading control unit.
The data acquisition system comprises a data acquisition and control unit, a loading confining pressure detection part and a capacity expansion confining pressure detection part, wherein the data acquisition and control unit is respectively connected with the loading confining pressure detection part and the capacity expansion confining pressure detection part so as to receive and record detection values of the detection parts; the loading confining pressure detection part is arranged on the loading control unit, and the capacity expansion confining pressure detection part is arranged on the pressurizing pipeline.
The liquid injection assembly comprises a liquid injection pipe column, a liquid injection pipeline and a liquid injection control unit, one end of the liquid injection pipe column extends into a liquid injection hole of the rock sample, and the other end of the liquid injection pipe column is communicated with the liquid injection control unit through the liquid injection pipeline.
The data acquisition system comprises a data acquisition and control unit and an injection pressure detection part, wherein the data acquisition and control unit is connected with the injection pressure detection part to receive and record the detection value of the detection part; the injection pressure detection part is arranged on the liquid injection pipeline.
The experimental device further comprises an isolation sealing assembly for ensuring that liquid only enters the rock sample from the liquid injection assembly, the isolation sealing assembly comprises a separation sheet and a liquid injection hole sealing ring, the separation sheet covers the upper end face of the rock sample, and an avoidance hole corresponding to the liquid injection hole is formed in the separation sheet; the liquid injection hole sealing ring is arranged in the liquid injection hole in a sealing way, and the liquid injection hole sealing ring is provided with a through hole for the injection end of the liquid injection component to be inserted into the liquid injection hole.
The diameter d1 of the liquid injection hole and the diameter d2 of the rock sample meet d1= (1/5-1/4) d2; the height a of the liquid injection hole and the height b of the rock sample meet a= (1/2-4/5) b.
The experimental device further comprises a pressure relief assembly for relieving the internal pressure of the experimental box body after the experiment, the pressure relief assembly comprises a pressure relief valve and a pressure relief pipeline, the pressure relief pipeline is connected to the bottom of the experimental box body, and the pressure relief valve is arranged on the pressure relief pipeline.
The experimental method of the experimental device for determining rock dilatation law, comprising the following steps:
1) Alternately loading confining pressure and injecting liquid into the rock sample, and stopping loading and injecting liquid when the confining pressure is loaded to the target confining pressure;
2) Continuously injecting liquid into the rock sample stably, and stopping injecting liquid stably when the injection liquid pressure obviously rises and reaches the core fracture pressure; when the injection pressure drops below the core fracture pressure, injecting liquid into the rock sample in a small displacement mode; stopping small-displacement liquid injection when the liquid injection pressure reaches the core fracture pressure and does not drop or the pressure drop is small; in the whole process of liquid injection, the liquid injection pressure, the loading confining pressure and the confining pressure after rock expansion are recorded when the stable liquid injection and the small-displacement liquid injection are stopped;
3) And drawing a pressure change curve of rock capacity expansion according to the pressure data recorded in the whole process, and calculating to obtain the rock core capacity expansion volume.
As a further improvement of the above technical scheme:
In step 1), always keeping the loaded confining pressure higher than the injection pressure; in step 2), the injection pressure is always kept below the core fracture pressure.
Compared with the prior art, the invention has the advantages that:
The rock sample is arranged in the experimental box body, and the confining pressure loading assembly is loaded on the periphery of the rock sample so as to load the rock sample with confining pressure to simulate a ground stress environment; the injection end of the injection assembly extends into the injection hole of the rock sample so as to inject liquid into the rock sample to simulate the rock dilatation phenomenon; the data acquisition assembly is arranged on the confining pressure loading assembly and the liquid injection assembly to acquire the liquid injection pressure, the confining pressure after loading and rock capacity expansion in real time. The whole structure is simple and the layout is compact. Meanwhile, the invention realizes the simulation of the rock capacity expansion process through the combined form of the experimental box body, the confining pressure loading assembly, the liquid injection assembly and the data acquisition assembly, can detect the change condition of confining pressure and liquid injection pressure in the whole process, realizes the whole-process monitoring of the rock capacity expansion change process during the liquid injection, can effectively master the capacity expansion change rules of different rocks under the conditions of different confining pressures and different liquid injection pressures, and can accurately predict the capacity expansion volumes of different rocks under the conditions of different injection pressures through the acquired pressure values so as to provide guidance for the optimization design of the capacity expansion process parameters, effectively improve the capacity expansion transformation volume and maximally ensure the capacity expansion process transformation effect.
The experimental method of the invention has the advantages as well, and the experimental process has high safety, in particular: in the step 1), the rock sample is gradually increased to the target confining pressure in a small pressure difference range by alternately loading confining pressure and injecting liquid into the rock sample, so that the phenomenon that the rock sample is damaged when the confining pressure is injected once is avoided.
Drawings
The invention will be described in more detail hereinafter on the basis of embodiments and with reference to the accompanying drawings. Wherein:
Fig. 1 is a schematic structural diagram of an experimental device for measuring rock dilatation change rule according to the invention.
FIG. 2 is a schematic diagram of the positional relationship of the components within the experimental box of the present invention.
Fig. 3 is a schematic view of an exploded construction of the rock sample and isolation seal assembly of the present invention.
Fig. 4 is a flow chart of an experimental method for determining rock dilatation change law according to the present invention.
The reference numerals in the drawings denote:
1. an experiment box body; 2. a rock sample; 21. a liquid injection hole; 3. a confining pressure loading assembly; 31. an elastic clamping member; 32. loading a hydraulic cavity; 33. a pressurized line; 34. a load control unit; 4. a liquid injection assembly; 41. a liquid injection pipe column; 42. a liquid injection pipeline; 43. a liquid injection control unit; 5. a data acquisition component; 51. a data acquisition and control unit; 52. loading a confining pressure detection part; 53. a capacity-expansion confining pressure detection part; 54. an injection pressure detecting member; 6. isolating the seal assembly; 61. a spacer; 62. a liquid injection hole sealing ring; 7. a pressure relief assembly; 71. a pressure release valve; 72. a pressure relief line.
Detailed Description
The invention will now be described in further detail with reference to the drawings and the specific examples, which are not intended to limit the scope of the invention.
Fig. 1 shows an embodiment of an experimental device for determining rock dilatation rules, which is mainly used for dynamic monitoring of rock dilatation change rules in oil and gas field sites and indoor experiments and mainly aims at sandstone reservoirs, including loose sandstone, compact sandstone and the like. In this embodiment, experimental apparatus includes experiment box 1, rock specimen 2, confining pressure loading subassembly 3, annotate liquid subassembly 4 and data acquisition subassembly 5. Wherein, the rock sample 2 is arranged in the experiment box body 1, and the rock sample 2 is provided with a liquid injection hole 21; the confining pressure loading assembly 3 is loaded on the periphery of the rock sample 2 so as to load the rock sample 2 with confining pressure to simulate a ground stress environment; the injection end of the injection assembly 4 extends into the injection hole 21 of the rock sample 2 so as to inject liquid into the rock sample 2 to simulate the rock expansion phenomenon; the data acquisition component 5 is arranged on the confining pressure loading component 3 and the liquid injection component 4 to acquire confining pressure after filling liquid pressure, loading confining pressure and rock capacity expansion in real time. The whole structure is simple and the layout is compact.
Meanwhile, the invention realizes the simulation of the rock capacity expansion process in a combined form of the experiment box body 1, the confining pressure loading assembly 3, the liquid injection assembly 4 and the data acquisition assembly 5, can detect the change conditions of confining pressure and liquid injection pressure in the whole process, realizes the whole-process monitoring of the rock capacity expansion change process in the liquid injection process, can effectively master the capacity expansion change rules of different rocks under the conditions of different confining pressures and different liquid injection pressures, and can accurately predict the capacity expansion volumes of different rocks under the conditions of different injection pressures through the acquired pressure values so as to provide guidance for the optimization design of the capacity expansion process parameters, effectively improve the capacity expansion transformation volume and maximally ensure the capacity expansion process transformation effect.
Further, the confining pressure loading assembly 3 includes an elastic clamping member 31, a loading hydraulic chamber 32, a pressurizing line 33, and a loading control unit 34. The elastic clamping piece 31 is wrapped on the periphery of the rock sample 2, so that the rock sample 2 is uniformly and reliably stressed, and the effective simulation of the ground stress environment is ensured; and the top of elastic clamping piece 31 is higher than the top of rock specimen 2 to avoid loading hydraulic pressure chamber 32's liquid inflow rock specimen 2 up end, make liquid only get into inside the rock specimen 2 from annotating liquid subassembly 4, guarantee the accuracy of experimental result.
Meanwhile, a loading hydraulic cavity 32 is arranged between the elastic clamping piece 31 and the experiment box body 1, and two ends of a pressurizing pipeline 33 are respectively communicated with the loading hydraulic cavity 32 and a loading control unit 34. When the confining pressure is loaded, the loading control unit 34 controls the liquid amount entering the loading hydraulic cavity 32 so as to realize gradual loading of the confining pressure, and different ground stress environments can be effectively simulated. The confining pressure loading assembly 3 has the advantages of good loading effect, convenience in operation, simple overall structure and low cost. In this embodiment, the elastic clamping member 31 is a rubber clamping member.
In this embodiment, the data acquisition system includes a data acquisition and control unit 51, a loading confining pressure detecting member 52, and a capacity expanding confining pressure detecting member 53. Wherein, the loading confining pressure detecting piece 52 is arranged on the loading control unit 34 to collect the loading confining pressure in real time; the capacity-expansion confining pressure detecting member 53 is disposed on the pressurizing pipeline 33 to collect the confining pressure of the rock after the capacity expansion in real time. Before the rock sample 2 is not expanded, the detection values of the loading confining pressure detection part 52 and the expansion confining pressure detection part 53 are the same; when the rock core expands, the volume of the rock sample 2 is expanded, and at the moment, the expansion acting force of the rock sample 2 reacts on the elastic clamping piece 31, so that the volume of the loading hydraulic cavity 32 is compressed, and the detection value of the expansion confining pressure detection piece 53 starts to rise. Namely, the point at which the detected value of the capacity-expansion confining pressure detecting member 53 rises is the capacity-expansion critical point; when the detection value of the loading confining pressure detection part 52 is obviously lower than the detection value of the dilatation confining pressure detection part 53, the dilatation phenomenon of the rock core is shown.
Meanwhile, the data acquisition and control unit 51 is respectively connected with the loading confining pressure detecting piece 52 and the capacity expansion confining pressure detecting piece 53 to receive and record the detection values of the loading confining pressure detecting piece 52 and the capacity expansion confining pressure detecting piece 53, and the data acquisition and control unit 51 can output a control signal according to the detection values to control the confining pressure loading assembly 3 to act so as to adjust confining pressure.
As shown in fig. 1, the priming assembly 4 includes a priming string 41, a priming line 42, and a priming control unit 43. One end of the injection pipe column 41 extends into the injection hole 21 of the rock sample 2, and the other end of the injection pipe column 41 is communicated with the injection control unit 43 through an injection pipeline 42. In the experiment, the injection control unit 43 controls the injection amount of the injection pipe column 41, and the injection pipe column 41 injects liquid into the rock sample 2, so that the rock expansion phenomenon can be effectively simulated, and the operation is convenient and the structure is simple.
Further, the data acquisition system further includes an injection pressure detecting member 54, where the injection pressure detecting member 54 is disposed on the injection line 42 to acquire the injection pressure in real time. The data collection and control unit 51 is connected with the injection pressure detecting member 54 to receive and record the detected value of the injection pressure detecting member 54, and the data collection and control unit 51 can output a control signal according to the detected value to control the action of the injection assembly 4 so as to adjust the injection pressure. In this embodiment, the detection value of the injection pressure detecting element 54 corresponding to the time point when the detection value of the expansion confining pressure detecting element 53 rises is the core expansion critical pressure.
As shown in fig. 2 and 3, the experimental device for determining the rock dilatation law further comprises an isolation sealing assembly 6, wherein the isolation sealing assembly 6 comprises a spacer 61 and a liquid injection hole sealing ring 62. Wherein the spacer 61 covers the upper end face of the rock sample 2 to prevent the confining pressure liquid from penetrating into the rock sample 2 from the upper end face of the rock sample 2 at the time of confining pressure loading. Simultaneously, the liquid injection hole sealing ring 62 is arranged in the liquid injection hole 21 in a sealing way so as to seal the liquid injection hole 21, and ensure that liquid only enters the liquid injection hole 21 of the rock sample 2 from the liquid injection assembly 4. The invention adopts the combination of the spacer 61 and the liquid injection hole sealing ring 62 to ensure that liquid can only enter the rock sample 2 from the liquid injection component 4, thereby effectively ensuring the accuracy of experimental results.
Meanwhile, the spacer 61 is provided with an avoiding hole corresponding to the liquid injection hole 21, so that the sealing ring 62 of the liquid injection hole is conveniently placed in the liquid injection hole 21. The liquid injection hole sealing ring 62 is provided with a through hole, the aperture of which is the same as the pipe diameter of the liquid injection pipe column 41, so that the liquid injection pipe column 41 can be inserted into the liquid injection hole 21, and no liquid leakage gap exists. In this embodiment, the spacer 61 is an impermeable film, and the liquid injection hole seal 62 is a rubber seal.
Further, the diameter d1 of the liquid injection hole 21 and the diameter d2 of the rock sample 2 meet d 1＝(1/5～1/4)d2, so that liquid is effectively injected into the rock sample 2, and meanwhile, the phenomena of long experimental time, difficult data measurement and the like caused by too small diameter of the liquid injection hole 21 are avoided. The height a of the liquid injection hole 21 and the height b of the rock sample 2 meet the requirement of a= (1/2-4/5) b, so that the problems that the lower part of the rock sample 2 cannot be detected and the experimental error is large while the phenomenon that liquid is pressed through from the bottom of the rock sample due to the overlarge height of the liquid injection hole 21 is avoided.
In the embodiment, the rock sample 2 is a cylindrical rock sample with flat two ends, the height of the rock sample 2 is 15cm, and the diameter of the rock sample 2 is 5cm; the height of the liquid injection hole 21 was 10cm, and the diameter of the liquid injection hole 21 was 1.2cm. In other embodiments, the specific values of the heights and diameters of the rock sample 2 and the injection hole 21 can be adjusted according to actual requirements.
As shown in fig. 1, the experimental device for determining the rock dilatation law further comprises a pressure relief assembly 7, and the pressure relief assembly 7 comprises a pressure relief valve 71 and a pressure relief pipeline 72. The pressure release pipeline 72 is connected to the bottom of the experiment box 1, and the pressure release valve 71 is disposed on the pressure release pipeline 72. During the experiment, the pressure relief valve 71 was kept closed; after the completion of the experiment, the pressure release valve 71 was opened to release the internal pressure of the experiment case 1.
As shown in fig. 4, the experimental method of the experimental device for determining rock dilatation law according to the embodiment includes the following steps:
1) Alternately loading confining pressure and injecting liquid into the rock sample 2, and stopping loading and injecting liquid when the confining pressure is loaded to the target confining pressure;
2) Continuously injecting liquid into the rock sample 2 stably, and stopping injecting liquid stably when the injection liquid pressure obviously rises and reaches the core fracture pressure; when the injection pressure drops below the core fracture pressure, injecting liquid into the rock sample at 2 small displacement; stopping small-displacement liquid injection when the liquid injection pressure reaches the core fracture pressure and does not drop or the pressure drop is small; in the whole process of liquid injection, the liquid injection pressure, the loading confining pressure and the confining pressure after rock expansion are recorded when the stable liquid injection and the small-displacement liquid injection are stopped;
3) And (3) drawing a pressure change curve of rock capacity expansion according to the pressure data recorded in the step (2), and calculating to obtain the rock core capacity expansion volume.
The experimental method disclosed by the invention also has the advantages of the experimental device for measuring the rock dilatation rule, and the safety of the experimental process is high. Specifically, the method comprises the following steps: in the step 1), the rock sample 2 is gradually increased to the target confining pressure in a small pressure difference range by alternately loading confining pressure and injecting liquid into the rock sample 2, so that the phenomenon that the rock sample 2 is damaged when the confining pressure is injected once is avoided.
As a further improvement of the above technical scheme:
In the step 1), the loaded confining pressure is always kept higher than the injection pressure, so that the phenomena of ejection of the rock sample 2, punching out of the confining pressure loading assembly 3 and the like caused by the overhigh injection pressure can be effectively avoided. In this embodiment, the applied confining pressure is always 2-5 MPa higher than the injection pressure, and in other embodiments, the pressure difference between the confining pressure and the injection pressure can be adjusted according to the actual experimental conditions, so long as the experimental device can be prevented from being damaged during the experiment.
When the confining pressure in the step 1) reaches the target confining pressure, recording the fluid injection amount loaded by the confining pressure so as to conveniently grasp the volume change rule of the rock during capacity expansion.
Further, deionized water or distilled water is adopted as the confining pressure loading medium, so that impurities are reduced, stable confining pressure loading is ensured, and the service life of the experimental device is prolonged.
In step 2), the injection pressure is always kept below the core fracture pressure to prevent the rock sample 2 from fracture during the experiment. In this embodiment, the injection pressure is kept at least 5MPa below the core fracture pressure, and in other embodiments, the pressure difference between the injection pressure and the core fracture pressure can be adjusted according to the actual experimental conditions, so long as the rock sample 2 can be prevented from being broken during the experiment.
In step 2), the core fracture pressure is predicted based on the core properties. And restarting to inject liquid into the rock sample 2 after the pressure is reduced to 2-3 MPa lower than the breaking pressure of the rock core. And stopping injecting the liquid when the injection pressure reaches the core fracture pressure and is not reduced or the pressure is reduced to 0.1MPa/30 min. The pressure data recorded in the whole course is collected by the data collecting component 5.
In step 3), the calculation expression of the core dilatation volume is:
Wherein P 1f is the confining pressure after rock expansion when small-displacement liquid injection is stopped, P 2f is the loading confining pressure when small-displacement liquid injection is stopped, C is the compression coefficient of a fluid medium, and e is a constant.
The experimental method can detect the change conditions of confining pressure and injection pressure in the whole process, realize the whole process monitoring of the expansion change process of the rock during the injection of the fluid, effectively grasp the expansion change rule of different rocks under the conditions of different confining pressures and different injection pressures, accurately predict the expansion volume of different rocks under the conditions of different injection pressures through the acquired pressure values, provide guidance for the optimization design of expansion process parameters, effectively improve the expansion transformation volume and furthest ensure the expansion process transformation effect.
While the invention has been described with reference to a preferred embodiment, various modifications may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In particular, the technical features mentioned in the respective embodiments may be combined in any manner as long as there is no structural conflict. The present invention is not limited to the specific embodiments disclosed herein, but encompasses all technical solutions falling within the scope of the claims.
Claims (9)
1. The experimental device for determining the rock capacity expansion rule is characterized by comprising an experimental box body, a rock sample with a liquid injection hole, a confining pressure loading assembly for loading confining pressure on the rock sample to simulate a ground stress environment, a liquid injection assembly for injecting liquid into the rock sample to simulate rock capacity expansion, and a data acquisition system for acquiring the liquid injection pressure, the loading confining pressure and the confining pressure after rock capacity expansion in real time, wherein the rock sample is arranged in the experimental box body, and the confining pressure loading assembly is loaded on the periphery of the rock sample; the injection end of the injection assembly extends into the injection hole of the rock sample; the data acquisition system is arranged on the confining pressure loading assembly and the liquid injection assembly and comprises a data acquisition and control unit, a loading confining pressure detection part and an expanding confining pressure detection part, and the data acquisition and control unit is respectively connected with the loading confining pressure detection part and the expanding confining pressure detection part so as to receive and record the detection value of the detection part; the loading confining pressure detection part is arranged on the confining pressure loading assembly to collect loading confining pressure in real time, the capacity expansion confining pressure detection part is arranged on the pressurizing pipeline to collect confining pressure of rock after capacity expansion in real time, and the capacity expansion critical point and whether capacity expansion phenomenon occurs or not are judged by comparing the detection values of the loading confining pressure detection part and the capacity expansion confining pressure detection part, so that whole-course monitoring is realized, and when the detection value of the loading confining pressure detection part is lower than the detection value of the capacity expansion confining pressure detection part, the capacity expansion phenomenon of the rock core is judged.
2. The experimental device for determining rock dilatation law according to claim 1, wherein the confining pressure loading assembly comprises an elastic clamping piece, a loading hydraulic cavity, a pressurizing pipeline and a loading control unit, the elastic clamping piece is wrapped on the periphery of the rock sample, and the top end of the elastic clamping piece is higher than the top end of the rock sample; the loading hydraulic cavity is arranged between the elastic clamping piece and the experiment box body; and two ends of the pressurizing pipeline are respectively communicated with the loading hydraulic cavity and the loading control unit.
3. The experimental device for determining rock dilatation law according to claim 1 or 2, wherein the liquid injection assembly comprises a liquid injection pipe column, a liquid injection pipeline and a liquid injection control unit, one end of the liquid injection pipe column extends into a liquid injection hole of the rock sample, and the other end of the liquid injection pipe column is communicated with the liquid injection control unit through the liquid injection pipeline.
4. An experimental device for determining rock dilatation law according to claim 3, wherein said data acquisition system comprises a data acquisition and control unit and an injection pressure detection member, said data acquisition and control unit being connected to said injection pressure detection member for receiving and recording the detection value of the detection member; the injection pressure detection part is arranged on the liquid injection pipeline.
5. The experimental device for determining rock dilatation law according to claim 1 or 2, further comprising an isolation sealing assembly for ensuring that liquid only enters the rock sample from the liquid injection assembly, wherein the isolation sealing assembly comprises an isolation sheet and a liquid injection hole sealing ring, the isolation sheet covers the upper end face of the rock sample, and an avoidance hole corresponding to the liquid injection hole is formed in the isolation sheet; the liquid injection hole sealing ring is arranged in the liquid injection hole in a sealing way, and the liquid injection hole sealing ring is provided with a through hole for the injection end of the liquid injection component to be inserted into the liquid injection hole.
6. The experimental device for determining rock dilatation law according to claim 1 or 2, wherein the diameter d 1 of the injection hole and the diameter d 2 of the rock sample satisfy d 1＝(1/5～1/4)d2; the height a of the liquid injection hole and the height b of the rock sample meet a= (1/2-4/5) b.
7. The experimental device for determining rock dilatation law according to claim 1 or 2, further comprising a pressure relief assembly for venting the internal pressure of the experimental box after the experiment, wherein the pressure relief assembly comprises a pressure relief valve and a pressure relief pipeline, the pressure relief pipeline is connected to the bottom of the experimental box, and the pressure relief valve is arranged on the pressure relief pipeline.
8. An experimental method of an experimental device for determining rock dilatation law according to any one of claims 1 to 7, comprising the steps of:
1) Alternately loading confining pressure and injecting liquid into the rock sample, and stopping loading and injecting liquid when the confining pressure is loaded to the target confining pressure;
2) Continuously injecting liquid into the rock sample stably, and stopping injecting liquid stably when the injection liquid pressure obviously rises and reaches the core fracture pressure; when the injection pressure drops below the core fracture pressure, injecting liquid into the rock sample in a small displacement mode; stopping small-displacement liquid injection when the liquid injection pressure reaches the core fracture pressure and does not drop or the pressure drop is small; in the whole process of liquid injection, the liquid injection pressure, the loading confining pressure and the confining pressure after rock expansion are recorded when the stable liquid injection and the small-displacement liquid injection are stopped;
3) And drawing a pressure change curve of rock capacity expansion according to the pressure data recorded in the whole process, and calculating to obtain the rock core capacity expansion volume.
9. The method according to claim 8, wherein in step 1), the applied confining pressure is always kept higher than the injection pressure; in step 2), the injection pressure is always kept below the core fracture pressure.
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| CN108590601A (en) * | 2018-04-08 | 2018-09-28 | 西南石油大学 | A kind of water filling dilatation expansion preferred experimental method of construction parameter |
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