Sandwiched rock core high-pressure brine erosion test device and erosion damage inversion method

Abstract

The application provides a sandwich core high-pressure brine erosion test device and an erosion damage inversion method, relates to the technical field of rock mechanics test, underground fluid erosion simulation and salt cavern engineering safety evaluation, and comprises a sealed pressure-bearing steel pipe test cavity; end sealing assemblies are arranged at the two ends of the sealed pressure-bearing steel pipe test cavity, and a self-centering directional core clamping assembly is arranged in the sealed pressure-bearing steel pipe test cavity; a liquid injection port is arranged on the side wall of the sealed pressure-bearing steel pipe test cavity; the liquid injection port is connected with a high-pressure precision pressure increasing assembly; a multi-point sensor array is arranged on the pipe wall of the sealed pressure-bearing steel pipe test cavity; the sealed pressure-bearing steel pipe test cavity is communicated with an online isolation type pressure reduction sampling assembly; and the multi-point sensor array and the high-pressure precision pressure increasing assembly are electrically connected with an external data acquisition and control assembly uniformly. The application accurately simulates the underground high-pressure brine environment and pressure disturbance working conditions, realizes multi-period online sampling without damaging the pressure state of the main test cavity, and improves the test repeatability and directional comparability.

Description

Technical Field

[0001] This invention relates to the fields of rock mechanics testing, underground fluid erosion simulation, and safety evaluation of salt cavern engineering. Specifically, it relates to a high-pressure brine erosion testing device for interlayer rock cores and a method for erosion damage inversion. Background Technology

[0002] Interlayered cores are widely found in salt rock strata, underground reservoirs, and deep rock masses. Under high-pressure brine environments, due to differences in mineral composition, structural heterogeneity, and bedding plane effects, interlayered areas are prone to dissolution, softening, fracture propagation, and the formation of local seepage channels, which in turn affect reservoir stability, salt cavern sealing, and the long-term safety of underground engineering.

[0003] Existing experimental devices mostly focus on conventional immersion, static pressure bearing, or single mechanical loading, and are insufficient in simulating the long-term erosion process of interlayer cores under high-pressure brine. In particular, there is a lack of specialized devices and methods for controllable interlayer orientation, continuous monitoring of the erosion process, online sampling under uninterrupted pressure holding conditions, and erosion damage evaluation based on multi-source signals.

[0004] Existing testing methods typically focus only on single pressure-bearing capacity or final failure results, making it difficult to reveal the gradual evolution of interlayer cores under long-term high-pressure brine erosion, from local dissolution, pore expansion, and fracture initiation to the formation of seepage channels. Especially in practical studies, interlayers are often the preferential areas for high-pressure brine erosion, and also the sites where damage occurs earliest and is most sensitive to evolution. Therefore, a testing technology system capable of simultaneously acquiring data on the directional arrangement of interlayers, monitoring local responses, and changes in the composition of the eroding fluid is needed. Summary of the Invention

[0005] The present invention aims to solve the problems of inaccurate core positioning, uncontrollable interlayer direction, rough pressure loading, difficulty in online sampling, single monitoring dimension, and difficulty in quantitative evaluation of erosion damage in existing devices.

[0006] To address the aforementioned problems, this invention provides a high-pressure brine erosion test device for interlayer rock cores, comprising a sealed pressure-bearing steel pipe test chamber; The sealed pressure-bearing steel pipe test chamber is equipped with end sealing assemblies at both ends, and the end sealing assemblies include an upper end cap and a lower end cap; The sealed pressure-bearing steel pipe test chamber is equipped with a self-centering directional core clamping assembly; The side wall of the sealed pressure-bearing steel pipe test chamber is equipped with a liquid injection port; The injection port is connected to the high-pressure precision booster assembly; A multi-point sensor array is installed on the wall of the sealed pressure-bearing steel pipe test chamber; The sealed pressure-bearing steel pipe test chamber is connected to the online isolated pressure-reducing sampling assembly; The multi-point sensor array and high-voltage precision booster are uniformly electrically connected to the external data acquisition and control components; A safety pressure relief assembly is installed at the top of the sealed pressure-bearing steel pipe test chamber; The top cover has an exhaust port.

[0007] The present invention provides a high-pressure brine erosion test device and erosion damage inversion method for interlayer rock cores, which, compared with the prior art, has the following beneficial effects, but are not limited to: The sealed pressure-bearing steel pipe test chamber described in this invention ensures long-term sealing reliability under high-pressure brine environment, and the end sealing component ensures sealing effect.

[0008] The high-pressure precision pressurization component is used to inject and pressurize brine into the test chamber to create a preset high-pressure brine erosion environment. A multi-point sensor array is used to collect real-time local pressure timing responses at different locations on the outer side of the interlayer core. The online isolated depressurization sampling component enables online time-sharing sampling without disrupting the pressure environment of the main test chamber. The data acquisition and control component is used to achieve multi-channel pressure signal acquisition, time synchronization recording, pressure path control, sampling time recording, and data management throughout the entire test process.

[0009] Compared with the prior art, the present invention has the following beneficial effects: This invention achieves stable clamping, interlayer orientation, and annular flow channel formation of interlayered cores in a closed, high-pressure environment through a self-centering directional core clamping assembly, thereby improving experimental repeatability and directional comparability. This invention achieves closed-loop pressure control through a high-pressure precision booster component, which can accurately simulate the underground high-pressure brine environment and pressure disturbance conditions. This invention enables multi-stage online sampling without disrupting the pressure of the main test chamber by using an online isolated pressure-reducing sampling component; This invention achieves quantitative characterization of the degree of erosion and damage evolution of interlayer rock cores through joint analysis of multi-point sensor array and erosion fluid components; The device of this invention is highly adaptable and can be used for experimental research under brine conditions of different sizes, different interlayer development directions, and different mineralization degrees.

[0010] Furthermore, the self-centering directional core clamping assembly includes a radial floating support cage inside which multiple sets of interlayer cores are arranged, and the radial floating support cage is arranged inside a sealed pressure-bearing steel pipe test chamber. The radial floating support cage is equipped with axial limiting caps at both the upper and lower ends; A replaceable directional positioning sleeve is provided at the connection between the axial limiting cap and the radial floating support cage.

[0011] Furthermore, the replaceable directional positioning sleeve is provided with interlayer direction markings.

[0012] Furthermore, the high-pressure precision booster assembly includes a liquid storage tank, a pre-pressurization pump, a plunger-type high-pressure booster pump, a pressure stabilizing assembly, a reference pressure sensor, a proportional pressure regulating valve, and a controller; the pressure stabilizing assembly includes a pulsation damper and a pressure stabilizing buffer. The outlet of the storage tank is connected to the injection port of the sealed pressure-bearing steel pipe test chamber via a liquid delivery pipeline; The infusion pipeline is equipped with a pre-pressure pump, a plunger-type high-pressure booster pump, a pressure stabilizing component, and a proportional pressure regulating valve in sequence. A reference pressure sensor is embedded in the sealed pressure-bearing steel pipe test chamber; The reference pressure sensor is electrically connected to the controller; The controller's output is electrically connected to the control terminals of the plunger-type high-pressure booster pump and the proportional pressure regulating valve.

[0013] Furthermore, the sealed pressure-bearing steel pipe test chamber is equipped with axial measuring points and circumferential measuring points; The multi-point sensor array includes multiple pressure sensors mounted on axial measuring points and multiple pressure sensors on circumferential measuring points; the axial measuring points are arranged in layers along the axial direction of the sealed pressure-bearing steel pipe test chamber, and the circumferential measuring points are distributed along the circumferential direction. The multi-point sensor array covers at least the upper, middle, and lower regions of multiple sets of interlayer core samples.

[0014] Furthermore, the online isolated pressure-reducing sampling assembly includes a sampling branch, a first high-pressure isolation valve, a pressure-reducing sampling chamber, a second pressure regulating valve, a sample collection container, a pressure detection element, and a volume measuring instrument; The sampling branch is connected to the sealed pressure-bearing steel pipe test chamber; The sealed pressure-bearing steel pipe test chamber is equipped with a first high-pressure isolation valve, which is connected to the pressure-reducing sampling chamber. The outlet of the depressurized sampling chamber is connected to the sample collection container via a second pressure regulating valve.

[0015] Furthermore, the pressure-reducing sampling chamber is equipped with a pressure detection element, and the inner wall of the pressure-reducing sampling chamber is equipped with a volume measuring device.

[0016] Furthermore, the safety relief assembly includes one or more combinations of a safety relief valve, a rupture disc, and a manual relief valve.

[0017] A method for erosion damage inversion from high-pressure brine erosion tests on interbedded rock cores includes the following steps: Step S1: Load the interlayer core into the self-centering directional core clamping assembly and complete the interlayer orientation calibration by using the replaceable directional positioning sleeve; Step S2: Place the clamped interlayer core into the sealed pressure-bearing steel pipe test chamber and seal it using the end sealing assembly; Step S3: Inject brine into the sealed pressure-bearing steel pipe test chamber through the injection port, and exhaust the gas in the chamber through the exhaust port; Step S4: The high-pressure precision booster component performs constant-speed pressure increase, constant-pressure maintenance, or cyclic disturbance loading according to a preset pressure path; Step S5: Collect the pressure time-series response at different measuring points using a multi-point sensor array; Step S6: Collect erosion fluid samples using an online isolated depressurization sampling assembly at set time intervals; Step S7: Based on the multi-point pressure response characteristics and changes in the composition of the eroding fluid, establish parameters for characterizing the degree of erosion and damage evolution of the interlayer core.

[0018] Furthermore, the erosion degree and damage evolution characterization parameters in step S7 include at least one of the following indicators: local pressure decay rate, axial pressure non-uniformity coefficient, circumferential pressure non-uniformity coefficient, cyclic loading response hysteresis, erosion fluid ion concentration change rate, and coupling parameters of the indicators; wherein, the coupling parameters are used to comprehensively characterize the erosion degree and damage evolution state of the interlayer core under high-pressure brine environment. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the high-pressure brine erosion test device for interlayer rock cores according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the clamping structure of the interlayer rock core in the high-pressure brine erosion test apparatus of the interlayer rock core according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of a multi-point sensor array according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the circumferential measuring point structure of the multi-point sensor array according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the structure of the online isolated pressure reduction sampling component according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the high-voltage precision booster assembly according to an embodiment of the present invention.

[0020] Explanation of reference numerals in the attached figures: 1. Sealed pressure-bearing steel pipe test chamber; 2. Upper end cap; 3. Lower end cap; 4. Interlayer core; 5. Axial limiting cap; 6. Radial floating support cage; 7. Replaceable directional positioning sleeve; 8. Injection port; 9. Exhaust port; 10. High-pressure precision booster assembly; 11. Storage tank; 12. Pre-pressurization pump; 13. Plunger-type high-pressure booster pump; 14. Pressure stabilizing assembly; 15. Controller; 16. Reference pressure sensor; 17. Proportional pressure regulating valve; 18. Multi-point... Sensor array; 19. Axial measuring point; 20. Circumferential measuring point; 21. Online isolated pressure-reducing sampling assembly; 22. Sampling branch; 23. First high-pressure isolation valve; 24. Pressure-reducing sampling chamber; 25. Second pressure regulating valve; 26. Sample collection container; 27. Pressure detection element; 28. Volume meter; 29. ​​Data acquisition and control assembly; 30. Safety pressure relief assembly; 31. Safety pressure relief valve; 32. Rupture disc; 33. Manual pressure relief valve. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this application clearer, specific embodiments of this application are described clearly and completely below with reference to the accompanying drawings. It should be understood that the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments described in this application without creative effort will fall within the scope of protection of this application.

[0022] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the specification of this application is for the purpose of describing specific embodiments only and is not intended to limit this application; the terms "comprising," "including," "having," "containing," "comprise," etc., in the specification, claims, and accompanying drawings of this application are open-ended terms, indicating that a method comprises one or more steps, or an apparatus comprises one or more elements, but do not exclude the inclusion of other steps or elements. The terms "first," "second," etc., in the specification, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or primary / secondary relationship. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0023] In the description of this application, it should be understood that the terms "upper", "lower", "left", "right", "front", "rear", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0024] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0025] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0026] See Figures 1-6 An embodiment of the present invention provides a high-pressure brine erosion test device and erosion damage inversion method for interlayer rock cores, comprising a sealed pressure-bearing steel pipe test chamber 1; The sealed pressure-bearing steel pipe test chamber 1 is provided with end sealing assemblies at both ends, and the end sealing assemblies include an upper end cover 2 and a lower end cover 3; The sealed pressure-bearing steel pipe test chamber 1 is equipped with a self-centering directional core clamping assembly; The side wall of the sealed pressure-bearing steel pipe test chamber 1 is equipped with a liquid injection port 8; The injection port 8 is connected to the high-pressure precision booster assembly 10; A multi-point sensor array 18 is installed on the pipe wall of the sealed pressure-bearing steel pipe test chamber 1; The sealed pressure-bearing steel pipe test chamber 1 is connected to the online isolated pressure-reducing sampling assembly 21; The multi-point sensor array 18 and the high-voltage precision booster assembly 10 are uniformly electrically connected to the external data acquisition and control assembly 29. The top of the sealed pressure-bearing steel pipe test chamber 1 is equipped with a safety pressure relief component 30; The upper cover 2 is provided with an exhaust port 9.

[0027] The sealed pressure-bearing steel pipe test chamber 1 of this invention is preferably made of thick-walled corrosion-resistant alloy steel pipe, with detachable upper end cap 2 and lower end cap 3 at both ends. The upper end cap 2, lower end cap 3, and the steel pipe can form a composite sealing structure through a metal sealing ring and a corrosion-resistant elastic sealing ring to ensure long-term sealing reliability under high-pressure brine conditions. The axial length of the test chamber is preferably 1.3 to 2.0 times the length of the core, and the inner diameter is slightly larger than the outer diameter of the core to form an annular fluid channel and meet the clamping space requirements. The end sealing components ensure the sealing effect.

[0028] The high-pressure precision booster assembly 10 is used to inject and pressurize brine into the test chamber through the injection port 8 to form a preset high-pressure brine erosion environment. The high-pressure precision booster assembly 10 realizes closed-loop tracking control of preset pressure paths such as constant speed pressurization, constant pressure maintenance and cyclic disturbance loading. After the test, the brine is discharged through the drain port at the bottom.

[0029] The multi-point sensor array 18 is used to collect the local pressure time-series response at different locations on the outside of the interlayer core in real time.

[0030] The online isolated pressure reduction sampling component 21 enables online time-sharing sampling without damaging the pressure environment of the main test chamber.

[0031] The data acquisition and control component 29 is used to realize multi-channel pressure signal acquisition, time synchronization recording, pressure path control, sampling time recording, and data management throughout the entire test process. Preferably, the data acquisition and control component includes a data acquisition card, a signal conditioning module, a control terminal, and data analysis software.

[0032] Compared with the prior art, the present invention has the following beneficial effects: This invention achieves stable clamping, interlayer orientation, and annular flow channel formation of interlayered cores in a closed, high-pressure environment through a self-centering directional core clamping assembly, thereby improving experimental repeatability and directional comparability. This invention achieves closed-loop pressure control through a high-pressure precision booster component 10, which can accurately simulate the underground high-pressure brine environment and pressure disturbance conditions. This invention achieves multi-stage online sampling without disrupting the pressure of the main test chamber through an online isolated pressure-reducing sampling component 21; This invention achieves quantitative characterization of the degree of erosion and damage evolution of interlayer rock cores through joint analysis of multi-point sensor array 18 and erosion fluid components; The device of this invention is highly adaptable and can be used for experimental research under brine conditions of different sizes, different interlayer development directions, and different mineralization degrees.

[0033] Furthermore, the self-centering directional core clamping assembly includes a radial floating support cage 6, multiple sets of interlayer cores 4 are arranged inside the radial floating support cage 6, and the radial floating support cage 6 is arranged inside the sealed pressure-bearing steel pipe test chamber 1. The radial floating support cage 6 is provided with axial limiting caps 5 at both the upper and lower ends; A replaceable directional positioning sleeve 7 is provided at the connection between the axial limiting cap 5 and the radial floating support cage 6.

[0034] The axial limiting cap 5 of this invention is used to limit the axial displacement of the core under pressurization and fluid disturbance. A radial floating support cage 6 has multiple support ribs along the outer periphery of the core, keeping the core on the central axis of the test chamber and forming a continuous annular fluid channel around the core to ensure that the brine acts uniformly on the outer periphery of the core. A replaceable directional positioning sleeve 7 is used for calibrating and locking the interlayer direction.

[0035] Furthermore, the replaceable directional positioning sleeve 7 is provided with interlayer direction markings.

[0036] The interlayer orientation marker is used to calibrate the interlayer orientation, so that the interlayer position and the external multi-point sensor array form a predetermined spatial correspondence, thereby realizing the repeatability control of the interlayer orientation test and the comparative test.

[0037] Furthermore, the high-pressure precision booster assembly 10 includes a liquid storage tank 11, a pre-pressure pump 12, a plunger-type high-pressure booster pump 13, a pressure stabilizing assembly 14, a reference pressure sensor 16, a proportional pressure regulating valve 17, and a controller 15; the pressure stabilizing assembly 14 includes a pulsation damper and a pressure stabilizing buffer. The outlet end of the storage tank 11 is connected to the injection port of the sealed pressure-bearing steel pipe test chamber 1 through a liquid delivery pipeline; The infusion pipeline is equipped with a pre-pressure pump 12, a plunger-type high-pressure booster pump 13, a pressure stabilizing component 14, and a proportional pressure regulating valve 17 in sequence. A reference pressure sensor 16 is embedded in the sealed pressure-bearing steel pipe test chamber 1; The reference pressure sensor 16 is electrically connected to the controller 15; The output terminal of the controller 15 is electrically connected to the control terminal of the plunger-type high-pressure booster pump 13 and the control terminal of the proportional pressure regulating valve 17.

[0038] The present invention includes a storage tank 11 for storing pre-prepared brine; a pre-pressurization pump 12 for supplying liquid to a high-pressure booster pump; a plunger-type high-pressure booster pump 13 for pressurizing the brine and sending it into a sealed pressure-bearing steel pipe test chamber; a pressure stabilizing component 14 for reducing pressure pulsation during the pressurization process and improving loading stability; a reference pressure sensor 16 for monitoring the reference pressure signal of the test chamber or loading circuit; and a controller 15 for adjusting the output of the plunger-type high-pressure booster pump 13 according to the feedback signal from the reference pressure sensor 16, so as to achieve closed-loop tracking control of preset pressure paths such as constant speed pressurization, constant pressure maintenance, and cyclic disturbance loading.

[0039] Furthermore, the sealed pressure-bearing steel pipe test chamber 1 is equipped with axial measuring points 19 and circumferential measuring points 20; The multi-point sensor array 18 includes multiple pressure sensors mounted on axial measuring points 19 and multiple pressure sensors on circumferential measuring points 20; the axial measuring points 19 are arranged in layers along the axial direction of the sealed pressure-bearing steel pipe test chamber 1, and the circumferential measuring points 20 are distributed along the circumferential direction. The multi-point sensor array 18 covers at least the upper, middle and lower regions of multiple sets of interlayer cores 4.

[0040] This invention arranges high-density measuring points at corresponding positions along the interlayer direction to improve the ability to identify local erosion, seepage changes, and damage evolution of the interlayer. The sensor on the axial measuring point 19 is convenient for measuring the pressure of different interlayer cores 4, and the sensor on the circumferential measuring point 20 is convenient for measuring the pressure at different locations around the same interlayer core 4; the multi-point sensor array 18 preferably adopts a high-pressure resistant diaphragm pressure sensor or a membrane pressure sensor, and each sensor is connected to the data acquisition and control components to collect the local pressure time-series response at different locations on the outside of the interlayer core in real time.

[0041] Furthermore, the online isolated pressure-reducing sampling assembly 21 includes a sampling branch 22, a first high-pressure isolation valve 23, a pressure-reducing sampling chamber 24, a second pressure regulating valve 25, a sample liquid collection container 26, a pressure detection element 27, and a volume measuring device 28; Sampling branch 22 is connected to the sealed pressure-bearing steel pipe test chamber 1; The sealed pressure-bearing steel pipe test chamber 1 is equipped with a first high-pressure isolation valve 23, which is connected to the pressure-reducing sampling chamber 24. The outlet of the pressure-reducing sampling chamber 24 is connected to the sample collection container 26 via the second pressure regulating valve 25.

[0042] During the experiment of this invention, when sampling is required, the first high-pressure isolation valve 23 is opened first, allowing a small amount of high-pressure erosion liquid in the main test chamber to enter the depressurization sampling chamber 24; then the first high-pressure isolation valve 23 is closed, isolating the depressurization sampling chamber 24 from the sealed pressure-bearing steel pipe test chamber 1; then the pressure of the depressurization sampling chamber 24 is reduced in stages through the second pressure regulating valve 25, and finally the sample liquid is introduced into the sample liquid collection container 26, thereby realizing online time-sharing sampling without damaging the pressure environment of the main test chamber.

[0043] Furthermore, the pressure-reducing sampling chamber 24 is equipped with a pressure detection element 27, and the inner wall of the pressure-reducing sampling chamber 24 is equipped with a volume measuring device 28.

[0044] The pressure detection element 27 and volume meter 28 of the present invention are used to monitor the pressure status in the sampling chamber and the volume of each sample taken.

[0045] Furthermore, the safety relief assembly 30 includes one or more combinations of a safety relief valve 31, a rupture disc 32, and a manual relief valve 33.

[0046] The safety pressure relief component 30 of this invention is used to relieve pressure in a timely manner under overpressure or abnormal operating conditions, ensuring the safety of the device and operation.

[0047] A method for erosion damage inversion from high-pressure brine erosion tests on interbedded rock cores includes the following steps: Step S1: Load the interlayer core 4 into the self-centering directional core clamping assembly, and complete the interlayer direction calibration by using the interlayer direction mark on the replaceable directional positioning sleeve 7; ensure the vertical position of the radial floating support cage 6 in the self-centering directional core clamping assembly, so that the radial floating support cage 6 can be installed in accordance with the vertical direction marked by the interlayer direction mark in the subsequent installation. Step S2: Place the clamped interlayer core 4 into the sealed pressure-bearing steel pipe test chamber 1 and seal it through the end sealing assembly; Step S3: Inject brine into the sealed pressure-bearing steel pipe test chamber 1 through the injection port 8, and exhaust the gas in the chamber through the exhaust port 9. Step S4: The high-pressure precision booster assembly 10 performs constant-speed pressure increase, constant-pressure maintenance, or cyclic disturbance loading according to a preset pressure path; Step S5: Collect the pressure time-series response at different measuring points using the multi-point sensor array 18; Step S6: Collect erosion fluid samples using the online isolated depressurization sampling assembly 21 at set time intervals; Step S7: Based on the multi-point pressure response characteristics and changes in the composition of the eroding fluid, establish parameters to characterize the degree of erosion and damage evolution of the interlayer core.

[0048] This invention proposes a principle for inverting erosion damage in interlayer cores based on multi-point pressure response and changes in erosion fluid composition.

[0049] Under the long-term action of high-pressure brine, interlayered cores undergo a gradual evolution process in the interlayered areas and surrounding regions, including mineral dissolution, pore expansion, microfracture initiation, seepage channel formation, and local structural softening. These internal structural changes alter the local pressure transmission path, pressure dissipation patterns, and dynamic disturbance response characteristics of the fluid surrounding the core, resulting in differential pressure responses at different measuring points on the core wall. Simultaneously, mineral dissolution and fine particle migration within the core also lead to changes in component parameters such as ion concentration, suspended particle content, and conductivity in the corrosive fluid.

[0050] Therefore, this invention achieves erosion damage inversion by simultaneously acquiring the following two types of information: 1. Multi-point pressure response information: including local pressure values ​​at different axial and circumferential measuring points, pressure change curves over time, pressure fluctuation amplitude, local pressure decay rate, and response phase characteristics under cyclic loading; 2. Information on changes in the composition of the erosion solution: including the rate of change in ion concentration, the change in suspended particle content, the change in conductivity, or other component parameters that reflect the degree of dissolution obtained from time-series sampling.

[0051] In the initial stage of the experiment, the multi-point pressure distribution and the initial composition of the erosion fluid when the core is in a relatively intact state are used as the baseline state. In the subsequent loading and erosion process, if the local pressure response of the measuring point corresponding to the interlayer direction shows a continuous decrease, increased fluctuation, and increased unevenness of circumferential or axial pressure distribution relative to the non-interlayer area, and at the same time the ion concentration or particle content in the erosion fluid composition shows a continuous change, it can be determined that the interlayer area is undergoing intensified erosion and damage evolution.

[0052] This invention proposes an erosion damage inversion principle based on multi-point pressure response and changes in the composition of the eroding liquid, enabling the device to not only complete high-pressure brine erosion tests, but also to further develop erosion process diagnosis and damage evolution evaluation functions. Furthermore, the erosion degree and damage evolution characterization parameters in step S7 include at least one of the following indicators: local pressure decay rate, axial pressure non-uniformity coefficient, circumferential pressure non-uniformity coefficient, cyclic loading response hysteresis, erosion fluid ion concentration change rate, and coupling parameters of the indicators; wherein, the coupling parameters are used to comprehensively characterize the erosion degree and damage evolution state of the interlayer core under high-pressure brine environment.

[0053] To facilitate quantitative characterization, the present invention defines the following characteristic parameters: Local pressure decay rate: used to characterize the decay trend of local pressure at a certain measuring point over time, reflecting the evolution of fluid pressure transmission capacity and local seepage state in that area; Axial pressure non-uniformity coefficient: used to characterize the degree of pressure distribution difference between different measuring points along the core axis, reflecting the uneven erosion development in different parts of the interlayer (upper, middle, and lower); Circumferential pressure non-uniformity coefficient: used to characterize the degree of pressure distribution difference between different measuring points along the circumference of the core, reflecting the spatial difference of erosion and damage between the interlayer direction and the non-interlayer direction; Cyclic loading response hysteresis: used to characterize the amplitude attenuation and phase hysteresis characteristics of the pressure response at each measuring point relative to the loading signal under cyclic perturbation loading conditions, reflecting the degree of local damage accumulation and weakening of transmission performance; Erosion fluid ion concentration change rate: used to characterize the trend of change in characteristic ion concentration per unit time, reflecting the degree of mineral dissolution and material migration; Coupling parameters: Based on at least two of the aforementioned characteristic parameters, a comprehensive evaluation index is constructed to characterize the degree of erosion and damage evolution of interlayer cores within a specific time period.

[0054] This invention does not limit the specific mathematical form of the coupling parameters. As long as they are constructed based on multi-point pressure response characteristics and information on changes in the composition of the erosion fluid, and can achieve a comprehensive characterization of the degree of erosion and the state of damage evolution of the interlayer core, they are all within the scope of protection of this invention.

[0055] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A high-pressure brine erosion test device for interlayer rock cores, characterized in that, Including a closed pressure-bearing steel pipe test chamber (1); The sealed pressure-bearing steel pipe test chamber (1) is provided with end sealing assemblies at both ends, and the end sealing assemblies include an upper end cap (2) and a lower end cap (3). The sealed pressure-bearing steel pipe test chamber (1) is equipped with a self-centering directional core clamping assembly; The side wall of the sealed pressure-bearing steel pipe test chamber (1) is provided with a liquid injection port (8); The injection port (8) is connected to the high-pressure precision booster assembly (10); A multi-point sensor array (18) is provided on the pipe wall of the sealed pressure-bearing steel pipe test chamber (1). The sealed pressure-bearing steel pipe test chamber (1) is connected to the online isolated pressure-reducing sampling assembly (21); The multi-point sensor array (18) and the high-voltage precision booster assembly (10) are both electrically connected to the external data acquisition and control assembly (29); The top of the sealed pressure-bearing steel pipe test chamber (1) is equipped with a safety pressure relief component (30); The upper end cap (2) is provided with an exhaust port (9); The self-centering directional core clamping assembly includes a radial floating support cage (6), multiple sets of interlayer cores (4) are set inside the radial floating support cage (6), and the radial floating support cage (6) is set inside the sealed pressure-bearing steel pipe test chamber (1). The radial floating support cage (6) is provided with axial limiting caps (5) at both the upper and lower ends; A replaceable directional positioning sleeve (7) is provided at the connection between the axial limiting cap (5) and the radial floating support cage (6); The replaceable directional positioning sleeve (7) is provided with interlayer direction markings; The high-pressure precision booster assembly (10) includes a liquid storage tank (11), a pre-pressurization pump (12), a plunger-type high-pressure booster pump (13), a pressure stabilizing assembly (14), a reference pressure sensor (16), a proportional pressure regulating valve (17), and a controller (15); the pressure stabilizing assembly (14) includes a pulsation damper and a pressure stabilizing buffer; The outlet of the storage tank (11) is connected to the injection port of the sealed pressure-bearing steel pipe test chamber (1) through a liquid delivery pipeline; The infusion pipeline is sequentially equipped with a pre-pressure pump (12), a plunger-type high-pressure booster pump (13), a pressure stabilizing component (14), and a proportional pressure regulating valve (17). A reference pressure sensor (16) is embedded in the sealed pressure-bearing steel pipe test chamber (1). The reference pressure sensor (16) is electrically connected to the controller (15); The output terminal of the controller (15) is electrically connected to the control terminal of the plunger-type high-pressure booster pump (13) and the control terminal of the proportional pressure regulating valve (17); The online isolated pressure-reducing sampling assembly (21) includes a sampling branch (22), a first high-pressure isolation valve (23), a pressure-reducing sampling chamber (24), a second pressure regulating valve (25), a sample collection container (26), a pressure detection element (27), and a volume meter (28). The sampling branch (22) is connected to the sealed pressure-bearing steel pipe test chamber (1); The sealed pressure-bearing steel pipe test chamber (1) is equipped with a first high-pressure isolation valve (23), which is connected to the pressure-reducing sampling chamber (24); The outlet of the pressure-reducing sampling chamber (24) is connected to the sample collection container (26) via a second pressure regulating valve (25).

2. The high-pressure brine erosion test device for interlayer rock cores according to claim 1, characterized in that, The sealed pressure-bearing steel pipe test chamber (1) is equipped with axial measuring points (19) and circumferential measuring points (20). The multi-point sensor array (18) includes multiple pressure sensors installed on axial measuring points (19) and multiple pressure sensors on circumferential measuring points (20); the axial measuring points (19) are arranged in layers along the axial direction of the sealed pressure-bearing steel pipe test chamber (1), and the circumferential measuring points (20) are distributed along the circumferential direction. The multi-point sensor array (18) covers at least the upper, middle and lower regions of multiple sets of interlayer cores (4).

3. The high-pressure brine erosion test device for interlayer rock cores according to claim 2, characterized in that, The pressure-reducing sampling chamber (24) is equipped with a pressure detection element (27) and a volume measuring device (28) is provided on the inner wall of the pressure-reducing sampling chamber (24).

4. The high-pressure brine erosion test apparatus for interlayer rock cores according to claim 3, characterized in that, The safety relief assembly (30) includes one or more combinations of a safety relief valve (31), a rupture disc (32), and a manual relief valve (33).

5. The damage inversion method for the erosion test apparatus of the interlayer rock core high-pressure brine erosion test according to any one of claims 1-4, characterized in that, Includes the following steps: Step S1: Load the interlayer core (4) into the self-centering directional core clamping assembly and complete the interlayer direction calibration by using the interlayer direction mark on the replaceable directional positioning sleeve (7); Step S2: Place the clamped interlayer core (4) into the sealed pressure-bearing steel pipe test chamber (1) and seal it through the end sealing assembly; Step S3: Inject brine into the sealed pressure-bearing steel pipe test chamber (1) through the injection port (8) and exhaust the gas in the chamber through the exhaust port (9); Step S4: The high-pressure precision booster assembly (10) performs constant-speed pressure increase, constant-pressure maintenance, or cyclic disturbance loading according to the preset pressure path; Step S5: Collect the pressure time-series response at different measuring points using a multi-point sensor array (18); Step S6: Collect erosion fluid samples using the online isolated depressurization sampling assembly (21) at set time intervals; Step S7: Based on the multi-point pressure response characteristics and changes in the composition of the eroding fluid, establish parameters for characterizing the degree of erosion and damage evolution of the interlayer core.

6. The damage inversion method for the erosion test apparatus of the interlayer core high-pressure brine erosion test according to claim 5, characterized in that, The erosion degree and damage evolution characterization parameters in step S7 include at least one of the following indicators: local pressure decay rate, axial pressure non-uniformity coefficient, circumferential pressure non-uniformity coefficient, cyclic loading response hysteresis, erosion fluid ion concentration change rate, and coupling parameters of the indicators; wherein, the coupling parameters are used to comprehensively characterize the erosion degree and damage evolution state of the interlayer core under high-pressure brine environment.

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