A core displacement-reaction-sand production monitoring integrated experimental device and method

Abstract

The application discloses a core displacement-reaction-sand production monitoring integrated experimental device and method, which comprises a core holder, a reaction chamber located on one side of a cavity for accommodating a core, and a confining pressure cavity arranged around the periphery of the cavity and the reaction chamber. The core holder is provided with an inlet and an outlet pipeline at both ends, respectively. A false core is detachably arranged in the reaction chamber, and the false core is provided with a flow guide channel in the inside for guiding fluid from the reaction chamber to the outlet pipeline during displacement experiment or sand production experiment. A fluid injection system is in communication with the inlet of the core holder for injecting fluid into the core holder. A confining pressure and back pressure control system is in communication with the confining pressure cavity and the outlet pipeline, respectively, for applying confining pressure and back pressure to the core. The device can be switched between core reaction experiment mode, displacement experiment mode and sand production experiment mode by detaching or installing the false core.

Description

Technical Field

[0001] This application relates to the field of rock physics and seepage experimental technology, and in particular to an integrated experimental device and method for monitoring core displacement-reaction-sand production. Background Technology

[0002] In underground engineering projects such as aquifer gas storage, aquifer compressed air energy storage, and CO2 saline aquifer sealing, multiphase flow, rock-fluid reactions, and particle exfoliation and migration in the rock porous medium are all involved. These processes can lead to changes in reservoir-caprock permeability, injection-production efficiency, and increased sand production risk, directly affecting the efficiency and safety of the project operation.

[0003] Currently, most commonly used indoor experimental setups focus on a single function: conventional reaction vessels are mainly used for rock-fluid reaction studies; displacement and seepage devices are mainly used for core displacement and seepage parameter testing; and sand production-related experiments require additional collection and separation equipment. These devices are highly independent and difficult to adapt to a single experimental platform by simple module replacement or minor modifications, making them capable of simultaneously performing reaction, displacement, and sand production monitoring experiments.

[0004] Specifically, the existing technology has the following shortcomings: First, the functions are dispersed, making it difficult to study the coupled process. Rock reaction, displacement seepage, and sand production monitoring are conducted in different experimental devices, and there is a lack of unified experimental conditions (temperature, pressure, core condition, etc.) among the three. If the three experiments are carried out separately on different devices, not only will the experimental conditions not be consistent, but it will also be difficult to simulate the real process of the coupling between reaction, seepage, and sand production in engineering practice.

[0005] Secondly, the experimental process is fragmented and inefficient. Because each device operates independently, researchers need to transfer core samples between different devices, reload samples, and re-establish temperature and pressure conditions. This process is cumbersome, time-consuming, and the repeated disassembly and reassembly may damage the core samples.

[0006] Third, the modules have poor versatility and high modification costs. The existing devices' pipe interfaces, temperature and pressure control methods, and data acquisition systems are incompatible with each other. Even when conducting multiple types of experiments on the same core sample, it is difficult to achieve functional switching through simple component replacement.

[0007] Therefore, there is an urgent need in this field for an integrated experimental device that can simultaneously perform reaction, displacement, and sand production monitoring on the same experimental platform through simple module replacement, so as to improve the efficiency of coupled process research and the consistency of experimental conditions. Summary of the Invention

[0008] To address the technical need for integrated experimental devices and methods for monitoring rock reaction, displacement seepage, and sand production in existing reactors, core displacement devices, and sand production devices, which are functionally fragmented and difficult to implement on a single experimental platform through simple component replacement, this application provides an integrated experimental device and method for core displacement-reaction-sand production monitoring. The technical solution is as follows: This application provides an integrated experimental device for monitoring core displacement, reaction, and sand production, comprising: a core holder having an internal cavity for accommodating the core, a reaction chamber located on one side of the cavity, and a confining pressure chamber surrounding the cavity and the reaction chamber; inlet and outlet pipelines respectively provided at both ends of the core holder; a dummy core detachably disposed within the reaction chamber, the dummy core having an internal flow channel for guiding fluid from the reaction chamber to the outlet pipeline during displacement or sand production experiments; and a fluid injection system connected to the inlet of the core holder for injecting fluid into the core. Fluid is injected into the core holder; a confining pressure and back pressure control system, connected to the confining pressure chamber and the outlet pipeline respectively, is used to apply confining pressure and back pressure to the core; a temperature control system is used to control the temperature of the core holder; a separation and collection system, connected to the outlet pipeline of the core holder, is used to perform gas-liquid separation or solid-liquid separation of the outlet fluid and collect it; a data acquisition system is used to collect pressure, flow rate, temperature and acoustic signals in real time during the experiment; wherein, by disassembling or installing the dummy core, the device can switch between core reaction experiment mode, displacement experiment mode and sand production experiment mode. According to the above embodiment, by integrating the core cavity, reaction cavity and confining pressure chamber in the same core holder, and setting up a detachable dummy core and supporting fluid injection, confining pressure and back pressure control, temperature control, separation and collection and data acquisition system, the effect is: to construct an integrated experimental platform that can flexibly switch between three experimental modes by simply disassembling and installing the dummy core. This device enables rock reaction experiments, displacement seepage experiments, and sand production monitoring experiments to be completed in the same high-temperature and high-pressure clamping system. The three experiments share the confining pressure system, temperature control system, and data acquisition system, avoiding inconsistencies in experimental conditions (such as temperature, pressure, and core state) caused by using different devices. It fundamentally solves the shortcomings of traditional devices that have dispersed functions and are difficult to carry out coupled research on the same platform, and provides unified experimental conditions for the study of the coupled rock reaction-displacement-sand production process.

[0009] For example, in the integrated core displacement-reaction-sand production monitoring experimental device provided in one embodiment, the dummy core is a high-strength alloy block with a flow guide groove on one end face facing the core. The flow guide channel is located inside the dummy core and communicates with the flow guide groove. The aperture of the flow guide channel is selected from different sizes according to the experimental mode. In the reaction experimental mode, no dummy core is installed; in the displacement experimental mode, a dummy core with a first aperture flow guide channel is installed; and in the sand production experimental mode, a dummy core with a second aperture flow guide channel is installed, where the second aperture is larger than the first aperture. According to the above embodiment, by limiting the dummy core to a high-strength alloy block and setting the flow guide groove and flow guide channel, and by using the first aperture for the displacement experiment and the second aperture (the second aperture is larger than the first aperture) for the sand production experiment, the effect is that a precise match is achieved between the experimental mode switching and the fluid flow requirements. The guide channel and flow channel ensure that the fluid can flow smoothly from the reaction chamber to the outlet during displacement and sand discharge experiments, avoiding pressure distortion caused by dead zones or excessive flow resistance. More importantly, the pseudo-cores with different apertures specifically address the core requirements of different experiments: the displacement experiment requires the fluid to pass through the core uniformly and be carried out in the form of droplets, and the small aperture (first aperture) can ensure the stability of the gas-driven water flow; the sand discharge experiment requires the sand particles carried out by the gas to pass through the pseudo-core smoothly without clogging, and the large aperture (second aperture) provides a smooth transport channel for the sand particles, avoiding the accumulation and blockage of sand particles at the pseudo-core that would lead to experimental failure.

[0010] For example, in one embodiment of the integrated experimental device for core displacement-reaction-sand production monitoring, the fluid injection system includes a liquid piston container, a gas piston container, a double-bar constant-speed and constant-pressure pump, and multiple injection pipelines. The liquid piston container and the gas piston container are selectively connected to the inlet and outlet pipelines of the core holder through independent valves to achieve forward and reverse displacement. According to the above embodiment, by limiting the fluid injection system to include a liquid piston container and a gas piston container, and selectively connecting them to the inlet and outlet pipelines of the core holder through independent valves, the effect is that it enables free switching of the driving medium (gas / liquid) and the displacement direction (forward / reverse). In multiphase flow and rock-fluid reaction studies, the type and direction of the injected fluid both affect the phase distribution and seepage path within the core pores. This design allows operators to switch media and directions without disassembling pipelines, significantly improving experimental flexibility and avoiding the risk of decreased sealing and pressure leakage caused by repeated pipeline disassembly and reassembly.

[0011] For example, in one embodiment of the integrated experimental device for monitoring core displacement-reaction-sand production, the separation and collection system includes a gas-liquid separator and a solid separator. The gas-liquid separator has a baffle inside for gas-liquid separation of the outlet fluid. The solid separator has a filter inside, and its bottom is connected to a visual sand collection tank via a connecting valve for solid-liquid separation of the outlet fluid and collection of sand particles. According to the above embodiment, by setting up a gas-liquid separator (with baffle) and a solid separator (with filter and connecting valve), the effect is that the optimal separation and collection method is automatically matched according to the different forms of the experimental products. The outlet products of the reaction and displacement experiments are mainly gas-liquid mixtures, and the baffle-type gas-liquid separator utilizes the principle of gravity sedimentation to achieve efficient gas-liquid separation. The outlet product of the sand production experiment is a three-phase mixture of gas, liquid, and solid, and the solid separator uses a filter to trap sand particles and guide them to the visual collection tank. The combined configuration of the two ensures efficient separation and accurate collection of the outlet products under different experimental modes, providing a reliable sample basis for subsequent physicochemical composition analysis and quantitative analysis of sand production.

[0012] For example, in one embodiment of the integrated experimental device for monitoring core displacement-reaction-sand production, a high-speed camera is also included. This high-speed camera is positioned beside the visualized sand collection tank and is used to monitor the sand collection process in real time. According to the above embodiment, by continuously capturing images with a high-speed camera positioned beside the visualized sand collection tank, the effect is to achieve real-time visualized monitoring and dynamic recording of the sand production process. Traditional sand production experiments rely on weighing the total sand volume after the experiment, which cannot reveal the temporal evolution of sand production. The high-speed camera can capture the instantaneous state and accumulation process of sand particles entering the collection tank. Combined with sampling and weighing at fixed time intervals, it can provide time-series data on sand production and identify abnormal sand production events (such as sudden large-scale sand production) through image playback, providing dynamic visual evidence for plotting the "sand production volume - injection volume" change curve.

[0013] For example, in one embodiment of the integrated experimental device for monitoring core displacement-reaction-sand production, the data acquisition system includes a pulse generator and a digital display. The pulse generator is used to emit P-waves and S-waves to the core, and the digital display is used to receive and display the propagation time and amplitude changes of the P-waves and S-waves to characterize the evolution of the core's structural state during the reaction process. According to the above embodiment, by emitting P-waves and S-waves to the core through a pulse generator and recording the propagation time and amplitude changes, the effect is to achieve real-time, non-destructive monitoring of the internal structural state of the core during the reaction process. When the rock is immersed in the reaction solution, mineral dissolution, precipitation, or particle migration can lead to changes in porosity and elastic modulus. These changes directly affect the propagation speed and attenuation characteristics of the P-waves and S-waves. This design allows researchers to determine whether the core structure has undergone significant changes through the changing trends of acoustic parameters without stopping the reaction or damaging the core, providing an objective basis for determining a reasonable reaction time (t-value) and judging the reaction endpoint.

[0014] The second aspect of this application provides a method for an integrated core displacement-reaction-sand extraction experiment, comprising the following steps: Core preparation step: loading the core into a core holder, selectively installing or not installing a dummy core in the reaction chamber according to the experimental mode; Core saturation step: injecting saturated liquid into the core holder, applying confining pressure and back pressure, monitoring the inlet pressure, outlet pressure and flow rate in real time, and determining saturation completion after the inlet pressure and outlet pressure stabilize; Experimental mode selection and execution step: selecting at least one of the reaction experimental mode, displacement experimental mode or sand extraction experimental mode for the experiment according to experimental requirements; Data acquisition step: acquiring pressure, flow rate, temperature and acoustic signals in real time during the experiment, and collecting the outlet fluid or solid product for subsequent analysis. According to the above embodiment, by sequentially executing the steps of core preparation, core saturation, experimental mode selection and execution, and data acquisition, a unified starting point is established between different experimental modes. The core saturation step provides core samples with a consistent initial state (known water content m) for all experimental modes. w As a benchmark for recovery calculation, it ensures the comparability of the results of reaction experiments, displacement experiments and sand production experiments, and the three modes can be carried out sequentially on the same sample (such as reaction first, displacement then sand production), realizing a truly "integrated" coupled experiment.

[0015] For example, in one embodiment of the integrated core displacement-reaction-sand extraction experiment method, the reaction experiment mode includes: not installing a dummy core in the reaction chamber; injecting reaction liquid into the core holder, heating to a set temperature and maintaining the pressure in the reaction chamber, and maintaining the reaction time t to complete the rock-fluid reaction; during the reaction, the propagation time and amplitude changes of P-waves and S-waves are collected in real time using a pulse generator to characterize the evolution of the core structure state during the reaction; after the reaction, the back pressure is released, the liquid in the reaction chamber is collected into a beaker, and the reacted core is taken out for subsequent analysis. According to the above embodiment, by not installing a dummy core to allow the reaction liquid to fully contact the core end face, heating and pressurizing and maintaining the reaction time t, collecting P / S wave signals throughout the process, collecting the reaction liquid after the reaction, and taking out the core for subsequent analysis, the effect is that it provides a static reaction environment close to formation conditions for the study of rock-fluid chemical interactions. The reaction chamber is directly connected to the core end face, avoiding the limitation of the contact area between the reaction fluid and the core by the fake core; maintaining the reaction time t and keeping the temperature and pressure stable, it simulates the long-term fluid-rock contact conditions in underground reservoirs; comparative analysis of the mineral composition and pore structure of the core before and after the reaction (supplemented by real-time monitoring of P / S waves) can quantitatively reveal the spatiotemporal evolution characteristics of the water-rock reaction.

[0016] For example, in one embodiment of the integrated core displacement-reaction-sand extraction experiment method, the displacement experiment mode includes: installing a dummy core with a first-aperture flow channel in the reaction chamber; injecting displacement gas into the core holder; and monitoring the inlet pressure P in real time. in (t), inlet gas flow rate Q2(t), and outlet pressure P out (t); The instantaneous apparent permeability k(t) is calculated based on real-time monitoring data, and the calculation formula is as follows:

[0017] Among them, P std Q is the pressure under standard conditions. std (t) is the volumetric flow rate under standard conditions, μ is the gas dynamic viscosity, L is the core length, and A is the core cross-sectional area; Liquid is collected from the gas-liquid separator at fixed time intervals, and the recovery rate is calculated.

[0018] Where m2 is the cumulative mass of produced liquid, m w This represents the initial water content of the core. Using the cumulative injected gas volume as the abscissa, curves depicting the changes in instantaneous apparent permeability and recovery rate were plotted. According to the above embodiment, by installing a first-diameter dummy core, injecting gas, monitoring pressure and flow rate in real time, calculating the instantaneous apparent permeability k(t) and recovery rate ω(t), and plotting the curves, the effect is that dynamic and quantitative characterization of seepage capacity and recovery efficiency during gas-driven water treatment is achieved. Using the curves of instantaneous permeability and recovery rate with the cumulative injected gas volume, the advancement of the displacement front, the evolution of gas-liquid two-phase seepage resistance, and the final degree of recovery can be clearly presented. The real-time calculation of the Darcy formula eliminates the influence of gas compressibility on flow rate measurement, making the permeability calculation results more realistically reflect the actual response of the core pore structure to fluid flow.

[0019] For example, in one embodiment of the integrated core displacement-reaction-sand production experiment method, the sand production experiment mode includes: installing a fake core with a second-diameter flow channel in the reaction chamber; injecting gas into the core holder, and monitoring the inlet pressure, inlet gas flow rate, and outlet pressure in real time; the gas carrying sand and liquid into a solid separator, the sand entering a visual sand collection tank after gravity settling, and the gas and liquid being discharged after filtration; real-time monitoring of the visual sand collection tank using a high-speed camera; removing sand at fixed time intervals for drying to obtain a cumulative sand production mass (m3); and plotting a curve showing the change in cumulative sand production mass with the cumulative injected gas volume as the abscissa. According to the above embodiment, by installing a second-diameter fake core, injecting gas to carry sand, using a solid separator to collect sand, real-time monitoring with a high-speed camera, and periodically weighing and plotting a cumulative sand production mass curve, the effect is to provide a quantitative experimental evaluation method for the entire process of sand production initiation, development, and stabilization. Large-diameter fake cores ensure that the actual sand output is not affected by human blockage; the slope change of the cumulative sand output quality curve can clearly distinguish the three typical stages of sand output (slow increase in the initial stage, rapid growth in the main sand output stage, and gradual flattening in the stabilization stage). The shape of this curve can be further used to fit the sand output rate and predict the final total sand output, providing experimental basis for the classification of sand output risk and the design of sand control measures in engineering sites.

[0020] Compared with existing experimental devices with dispersed functions, the integrated core displacement-reaction-sand production monitoring experimental device provided in this application, by integrating the core cavity and reaction cavity in the same core holder and setting up a detachable dummy core and a matching separation and collection system, has the following significant advantages: (1) This application enables flexible switching between three experimental modes on the same platform, providing unified experimental conditions for the study of coupled processes: The core holder is equipped with both a core cavity and a reaction cavity. By disassembling or installing a dummy core, the experiment can be switched between core reaction experiments, displacement seepage experiments, and sand production monitoring experiments. The three modes share the same confining pressure system, temperature control system, and data acquisition system, ensuring the consistency of experimental conditions. Cores after the reaction experiment can be directly used for displacement experiments on the same device without transfer. Cores after displacement can also be used for sand production experiments in situ, thus realistically simulating the continuous process of rock reaction-seepage-sand production coupling in actual engineering. This provides a reliable experimental means to reveal the coupling mechanism of reservoir-caprock permeability evolution, injection-production efficiency changes, and sand production risk.

[0021] (2) The dual-aperture pseudo-core design precisely matches the flow requirements of different experimental modes: This application sets up pseudo-cores with first and second apertures respectively to meet the different requirements of displacement and sand production experiments for flow channel size. The displacement experiment requires gas to pass through the core uniformly and carry out droplets, requiring an appropriate aperture to maintain a stable gas-liquid two-phase flow; the sand production experiment requires sand particles carried out by the gas to pass through the pseudo-core smoothly without blockage, requiring a larger aperture to avoid sand accumulation. The dual-aperture pseudo-core design ensures that the accuracy of recovery and permeability measurements in the displacement experiment is not affected by flow channel resistance distortion, while ensuring that the actual sand production in the sand production experiment is not interfered with by artificial blockage, so that the measurement results of both experiments can truly reflect the physical response of the core itself.

[0022] (3) A dual-mode collection system for gas-liquid and solid-liquid separation was constructed to meet the collection needs of different experimental products: This application sets up a gas-liquid separator (with baffle) and a solid separator (with filter screen and visual sand collection tank) at the outlet. The outlet products of the reaction experiment and the displacement experiment are mainly gas-liquid mixtures. The baffle-type gas-liquid separator uses the principle of gravity sedimentation to achieve efficient separation. The outlet product of the sand discharge experiment is a three-phase mixture of gas, liquid and solid. The solid separator intercepts sand particles through the filter screen and guides them to the visual collection tank. The independent configuration and collaborative operation of the two separation methods ensure efficient separation and accurate quantitative collection of outlet products under different experimental modes, providing a reliable sample basis for subsequent physicochemical composition analysis, recovery rate calculation and sand discharge statistics.

[0023] (4) Realized dynamic real-time characterization of permeability and recovery rate during displacement: In the displacement experiment, this application uses Darcy's formula to calculate the instantaneous apparent permeability hourly based on real-time monitored inlet pressure, outlet pressure, and flow rate data, and simultaneously calculates the recovery rate. Compared with the traditional method that only measures steady-state permeability and final recovery rate, this application can plot the dynamic change curves of permeability and recovery rate with the cumulative injected gas volume, clearly presenting the entire process of displacement front advancement and gas-liquid two-phase flow resistance evolution, providing richer information for evaluating reservoir injection and production efficiency.

[0024] (5) Real-time visualization monitoring and quantitative characterization of the sand discharge process: This application uses a high-speed camera to continuously photograph the visualized sand collection tank and monitor the sand discharge process in real time. Traditional sand discharge experiments rely on weighing the total sand volume after the experiment, which cannot know the time evolution characteristics of sand discharge; this application can provide a dynamic change curve of sand discharge volume with cumulative injected gas volume, clearly dividing the three stages of sand discharge start-up, main sand discharge, and stabilization, providing experimental basis for sand discharge risk classification and sand control measure design in engineering sites.

[0025] (6) Non-destructive real-time monitoring of core structure during the reaction process was achieved through acoustic signals: In the reaction experiment, P-waves and S-waves were emitted to the core through a pulse generator, and the propagation time and amplitude changes were collected in real time. When the rock is soaked in the reaction solution, mineral dissolution, precipitation or particle migration will lead to changes in porosity and elastic modulus. The changing trend of acoustic parameters can reflect the evolution state of the internal structure of the core in real time. It is possible to determine whether the core structure has changed significantly without stopping the reaction, which provides an objective basis for determining the reasonable reaction time and judging the reaction endpoint. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this specification or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the core holder structure; Figure 2 This is a schematic diagram of the false core structure; Figure 3 This is a schematic diagram of a gas-liquid separator. Figure 4 This is a schematic diagram of an integrated experimental device system for core displacement-reaction-sand extraction. Figure 5 This is a schematic diagram showing the changes in recovery rate and permeability as a function of cumulative injected gas volume. Figure 6This is a schematic diagram showing the change in cumulative sand output mass as a function of cumulative injected gas volume. Detailed Implementation

[0028] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0029] Unless otherwise defined, the technical or scientific terms used in this disclosure shall have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms “first,” “second,” and similar terms used in this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as “comprising” or “including” mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as “connected” or “linked” are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as “upper,” “lower,” “left,” and “right” are used only to indicate relative positional relationships, and these relative positional relationships may change accordingly when the absolute position of the described objects changes.

[0030] I. Device Structure like Figures 1 to 4 As shown, the integrated experimental device for monitoring core displacement-reaction-sand production provided in this application mainly includes: a core holder 29, a fake core 8, a fluid injection system, a confining pressure and back pressure control system, a temperature control system, a separation and collection system, and a data acquisition system.

[0031] 1. Core holder like Figure 1 As shown, the core holder 29 has a cavity for accommodating the core 1, a reaction chamber 2 located on one side of the cavity, and a confining pressure chamber 6 surrounding the cavity and the reaction chamber. The core holder 29 has a fluid injection pipe 3 (inlet) and an outlet pipe 4 at both ends. The confining pressure fluid enters the confining pressure chamber 6 through the confining pressure fluid injection port 5, and the confining pressure fluid acts on the outside of the rubber sleeve 7 to apply confining pressure to the core 1.

[0032] 2. False core like Figure 2As shown, the fake core 8 is a high-strength alloy block with the same dimensions as the reaction chamber 2. One end of the fake core 8, facing the core 1, has a flow guide groove 9, and a flow guide channel 10 is located at its center. The aperture of the flow guide channel is selected from different sizes depending on the experimental mode: no fake core is installed in the reaction experiment mode; a fake core with a first aperture (e.g., 4 mm) flow guide channel is installed in the displacement experiment mode; and a fake core with a second aperture (e.g., 10 mm) flow guide channel is installed in the sand discharge experiment mode, where the second aperture is larger than the first aperture.

[0033] 3. Fluid Injection System The fluid injection system includes a liquid piston container 21, a gas piston container 20, a dual-bar constant-speed and constant-pressure pump 23, and multiple injection pipelines. The liquid piston container 21 and the gas piston container 20 are selectively connected to the inlet and outlet pipelines 4 of the core holder 29 through independent valves to achieve forward displacement and reverse displacement.

[0034] 4. Confining pressure and back pressure control system The confining pressure pump 31 injects confining pressure fluid into the confining pressure chamber 6 through the confining pressure fluid injection port 5 and gradually increases the pressure to form a confining pressure P in the confining pressure chamber 6. c The back pressure pump 46 slowly pressurizes the back pressure container 45, setting the back pressure P at the outlet of the core holder. b .

[0035] 5. Temperature control system The temperature control system includes temperature control system a22 and temperature control system b30. Temperature control system a22 is used to heat the gas in the gas piston container 20; temperature control system b30 is used to heat the core holder 29.

[0036] 6. Separation and collection system The separation and collection system includes a gas-liquid separator 47 and a solid separator 40. For example... Figure 3 As shown, the gas-liquid separator 47 has a baffle 13 inside for gas-liquid separation of the outlet fluid. The solid separator 40 has a filter screen 39 inside, and its bottom is connected to the visible sand collection tank 42 through a connecting valve 41 for solid-liquid separation of the outlet fluid and collection of sand particles.

[0037] 7. Data Acquisition System The data acquisition system includes a pulse generator 32, a digital display 33, and data acquisition software 34. The pulse generator 32 is used to transmit P-waves and S-waves to the core sample, and the digital display 33 is used to receive and display the propagation time and amplitude changes of the P-waves and S-waves.

[0038] Experimental methods (a) Core saturation A standard core with a diameter of 50 mm and a height of 100 mm was taken and subjected to low-temperature drying treatment. The mass of the dried core, m0, was measured. The dried core 1 was placed in a core holder, and a dummy core was placed in the reaction chamber 2. The core holder was constructed as follows. Figure 1 As shown. The fake core 8 is a high-strength alloy block, with the same dimensions as the reaction chamber: 45mm in diameter and 60mm in height. Its left end face has a guide groove 9, and a 4mm diameter guide channel 10 is located at its center. Figure 2 As shown.

[0039] After connecting the core holder to the equipment pipeline, open valves d27, f35, and h37 in sequence, and close valves c24, e28, g36, and i38. Slowly pressurize the backpressure container 45 using the backpressure pump 46 to set the backpressure Pb at the core holder outlet. Then, use the confining pressure pump 31 to inject confining pressure fluid into the confining pressure chamber 6 through the confining pressure fluid injection port 5 and gradually increase the pressure to create a confining pressure P within the confining pressure chamber 6. c The confining fluid acts on the outside of the rubber sleeve 7 to apply confining pressure to the core, and the confining pressure satisfies P. c >P b Start the dual-bar constant speed and constant pressure pump 23 and adjust it to constant flow mode. At a constant flow rate Q0, inject the saturated liquid (deionized water or simulated formation water) in the liquid piston container 21 into the core holder through the fluid injection pipe 3 via the valve d, so that the saturated liquid enters the core and is discharged from the outlet pipe 4.

[0040] During the saturation process, the inlet pressure P is monitored in real time. in Export pressure P out And the reading q0 of gas flow meter 52. A dryer 51 is installed upstream of gas flow meter 52, when the outlet pressure P out Reaching and matching back pressure P b Maintain consistency, inlet pressure P in When the reading q0 of the gas flow meter 52 decreases and tends to stabilize over a period of time, it is determined that the core saturation is complete.

[0041] Turn off the double-bar constant-speed constant-pressure pump 23, slowly release the back pressure to atmospheric pressure, and then remove the confining pressure. Open the core holder and remove the saturated core. After wiping away the free water from the core surface, weigh the saturated core (m1) and calculate the mass (m) of the water contained in the saturated core. w =m1-m0, which serves as the benchmark for calculating the recovery rate in subsequent displacement experiments.

[0042] (II) Reaction Experiment Load the saturated core into the core holder 29. Do not place a dummy core in the reaction chamber 2 during the reaction experiment. After connecting the core holder to the equipment pipeline, open valves c24, e28, h37, and j48, and close valves d27, f35, g36, and i38. Use the back pressure pump 46 and the confining pressure pump 31 to set the back pressure P respectively. b and confining pressure P c Start the temperature control system b30 to heat the core holder to the set temperature T1.

[0043] Start the dual-bar constant-speed and constant-pressure pump 23 and adjust it to constant-flow mode. At a constant flow rate Q1, inject the reaction liquid (deionized water or simulated formation water) from the liquid piston container 21 into the reaction chamber 2 of the core holder through the one-way valve and outlet pipeline 4. Observe the pressure P at the outlet. out At this time, the export pressure P out The pressure in the reaction chamber should be consistent with the pressure in the reaction chamber. Once liquid is collected in beaker 49 and the pressure in the reaction chamber reaches the preset value, the liquid injection should be stopped. The double-barrel constant-speed and constant-pressure pump 23 and valves C24 and E28 should be closed to maintain the pressure and temperature in the reaction chamber and maintain the reaction time t to complete the rock-fluid reaction experiment.

[0044] During the reaction, P and S wave signals are acquired in real time using a pulse generator 32, a digital display 33, and data acquisition software 34 to obtain the propagation time and amplitude changes of P and S waves, which are used to characterize the evolution of the core structure during the reaction. After the reaction, valve f35 is opened to slowly release the back pressure to atmospheric pressure while maintaining the confining pressure. Under the action of pressure difference, the liquid in the reaction chamber enters the gas-liquid separator 47 through the back pressure valve 44 from the gas-liquid separator inlet 11. Under the action of the baffle 13 inside the separator, the flow direction is changed and blocked, and the liquid is deposited at the bottom of the gas-liquid separator under the action of gravity; at the same time, the entrained gas is discharged along the upper outlet 12 of the separator. The separated liquid flows out from the bottom outlet of the gas-liquid separator and is collected in beaker 49. Then the confining pressure is released, the core holder is opened, the residual liquid in the reaction chamber is collected into the beaker, and the reacted core is taken out. Subsequently, depending on the experimental requirements, the physicochemical composition of the reaction solution collected in the beaker can be analyzed, and nuclear magnetic resonance scanning, XRD and other tests can be carried out on the rock after the reaction to analyze the changes in its mineral composition and pore structure before and after the reaction.

[0045] (III) Displacement Experiment The saturated core obtained in the core saturation step or the saturated core obtained after the reaction experiment is placed into the core holder 29, and a dummy core 8 (with a first-diameter flow channel) is placed in the reaction chamber. After connecting the core holder to the equipment pipeline, valve a16 is opened and valve b18 is closed. The gas in the gas cylinder 14 is initially pressurized by the gas booster pump 15 and then injected into the high-pressure gas storage tank 17. Subsequently, valves a16, c24, e28, g36, i38, and j48 are closed, and valves b18, d27, f35, and h37 are opened. The gas enters the gas piston container 20 from the high-pressure gas storage tank 17. The temperature control system a22 is started to heat the gas to the set temperature T2. The back pressure pump 46 and the confining pressure pump 31 are used to set the back pressure P respectively. b and confining pressure P c Then, the temperature control system b30 is activated to heat the core holder to the set temperature T3.

[0046] Start the dual-bar constant speed and constant pressure pump 23, adjust it to constant pressure mode, and set the core holder inlet injection pressure P. in Gas from the gas piston container 20 is injected into the core holder through valve d27. During the displacement process, the pressure P at the inlet of the core holder is monitored and recorded in real time. in (t), inlet gas flow rate Q2(t), and outlet pressure P out (t).

[0047] Since the flow state may be unsteady during the displacement process, the instantaneous apparent permeability k(t) is used to calculate the permeability in real time to achieve real-time characterization. Because Q2(t) is the volumetric flow rate measured by the flowmeter under operating conditions, to eliminate the influence of gas compressibility on the volumetric flow rate, Q2(t) is converted to the volumetric flow rate Q under standard conditions. std (t). Standard state takes P std =101.325kPa, T std =273.15K, the conversion relationship is:

[0048] in, The average pressure is given. Then, based on the Darcy relation for gas seepage, the instantaneous apparent permeability is calculated in real time:

[0049] Where μ is the gas dynamic viscosity, L is the core length, and A is the core cross-sectional area; P in (t) and P out (t) represents the absolute pressure at the inlet and outlet of the core holder.

[0050] Simultaneously, at fixed time intervals Δt, valve j48 is opened to collect the liquid from the gas-liquid separator. The collected liquid is placed in beaker 49, and the cumulative mass m2 of the produced liquid in the beaker is weighed using an electronic balance 50. The recovery rate at this point is calculated.

[0051] Where, m w This represents the initial water content of the core (obtained from the core saturation step). Simultaneously, the cumulative injected gas volume V is recorded in real-time by a dual-bar constant-speed, constant-pressure pump. g Plotting the cumulative injected gas volume on the x-axis and the instantaneous apparent permeability k(t) and recovery rate ω(t) on the y-axis respectively, yields curves showing the changes in permeability versus injected gas volume and the changes in recovery rate versus injected gas volume, as detailed below. Figure 5 As shown, this is used to characterize the evolution of seepage capacity and changes in harvesting efficiency during the displacement process.

[0052] When the pressure P at the inlet of the core holder in (t), flow rate Q2(t), and outlet pressure P out When (t) tends to stabilize and no new liquid is added in the gas-liquid separator 46, the displacement is considered complete.

[0053] If further reverse displacement experiments are required, close valves d27 and f35, and open valves c24 and e28. At this time, the gas in the gas piston container 20 enters the core holder 29 through the outlet pipeline 4 via valve c24. It is then discharged through the fluid injection pipe 3 and enters the back pressure valve through valves e28 and h37.

[0054] By switching the opening and closing states of each valve and selecting a gas piston container or a liquid piston container as the displacement medium supply unit according to experimental requirements, forward and reverse displacement of gas or liquid in the core can be realized, thereby improving the adaptability of the equipment to experimental conditions with different displacement media and different displacement directions.

[0055] After the displacement experiment, the double-bar constant-speed and constant-pressure pump 23 was turned off and gas injection was stopped. The back pressure was slowly released to atmospheric pressure while maintaining the confining pressure. Once the pore-side pressure was released, the confining pressure was slowly removed. The core holder was opened, and the displaced core was removed. The changes in the core's mass and appearance were recorded. Subsequent experiments, such as nuclear magnetic resonance (NMR) scanning, CT imaging, or permeability retesting, can be performed on the displaced core to compare the changes in pore structure and seepage properties before and after displacement.

[0056] (iv) Sand discharge test The saturated core obtained in the core saturation step or the saturated core obtained after the reaction experiment is loaded into the core holder 29, and a fake core 8 with a large-diameter (e.g., 10 mm) flow channel is placed in the reaction chamber.

[0057] After connecting the core holder to the equipment pipeline, open valve a16 and close valve b18. Using gas booster pump 15, the gas in gas cylinder 14 is initially pressurized and injected into high-pressure gas storage tank 17. Then, close valves a16, c24, e28, and h37, and open valves b18, d27, f35, g36, and i38, allowing gas to enter the gas piston container 20 from high-pressure gas storage tank 17. Start temperature control system a22 to heat the gas to the set temperature T4. Using back pressure pump 46 and confining pressure pump 31, set the back pressure P respectively. b and confining pressure P c Then, the temperature control system b30 is activated to heat the core holder to the set temperature T5.

[0058] Start the dual-bar constant speed and constant pressure pump 23, adjust it to constant pressure mode, and set the core holder inlet injection pressure P. in The gas in the gas piston container 20 is injected into the core holder through valve d27 to start the sand discharge experiment.

[0059] Real-time monitoring and recording of the pressure P at the inlet of the core holder in (t), inlet gas flow rate Q3(t), and outlet pressure P out (t), and calculate the instantaneous permeability k(t) according to the method described in the displacement experiment section.

[0060] During the sand extraction process, gas passes through the core, carrying liquid and sand particles out of the core and into the solid separator 40. The sand particles and some entrained liquid, under gravity, pass through the connecting valve 41 into the visual sand collection tank 42; the remaining gas and liquid are filtered through the filter screen 39 and discharged from the solid separator 40. In the sand extraction experiment, a high-speed camera 43 continuously photographs the visual sand collection tube to monitor the sand extraction from the core in real time. At fixed time intervals Δt, the connecting valve 41 is closed, the visual sand collection tank is removed, the sand collection tank is opened, and the sand particles are removed and dried to obtain the cumulative sand extraction mass m3. Simultaneously, a dual-bar constant-speed constant-pressure pump records the cumulative injected gas volume V in real time. g The cumulative injected gas volume V g Plot a curve showing the change in sand output volume versus injection volume, with the x-axis representing the total sand output mass (m3) and the y-axis representing the cumulative sand output mass (m3). Figure 6 As shown in the figure, it is used to characterize the sand initiation, growth and stabilization stages and their changing patterns.

[0061] When the pressure P at the inlet of the core holderin (t), flow rate Q3(t), and outlet pressure P out When the temperature (t) stabilizes and no new sand particles appear in the solid separator, sand extraction is considered complete. Then, the double-bar constant-speed, constant-pressure pump 23 is turned off and gas injection is stopped. While maintaining the confining pressure, the back pressure is slowly released to atmospheric pressure. After the pore-side pressure is released, the confining pressure is slowly removed. The core holder is opened to remove the core, and the changes in the core's mass and appearance after the sand extraction experiment are recorded.

[0062] In summary, this application systematically solves the technical problems of existing devices, such as dispersed functions, difficulty in conducting coupled experiments, and low efficiency due to process fragmentation, by integrating the reaction chamber and detachable pseudo-core in the same core holder, setting up dual-aperture flow channels, constructing a dual-mode separation and collection system, and providing supporting methods such as dynamic permeability characterization, real-time sand production monitoring, and acoustic structure monitoring. It provides a unified, efficient, and quantitatively characterizable integrated experimental platform for the study of rock reaction-displacement-sand production coupled processes.

[0063] Although the embodiments of this application have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for this application. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, this application is not limited to the specific details and the illustrations shown and described herein.

Claims

1. An integrated experimental device for monitoring core displacement, reaction, and sand production, characterized in that, include: The core holder has an internal cavity for accommodating the core, a reaction chamber located on one side of the cavity, and a confining pressure chamber surrounding the cavity and the reaction chamber. The core holder has inlet and outlet pipelines at both ends. A fake core is detachably installed inside the reaction chamber. The fake core has a flow channel inside, which is used to guide the fluid from the reaction chamber to the outlet pipeline during displacement experiments or sand discharge experiments. A fluid injection system, connected to the inlet of the core holder, is used to inject fluid into the core holder; A confining pressure and back pressure control system is connected to the confining pressure chamber and the outlet pipeline, respectively, and is used to apply confining pressure and back pressure to the core. Temperature control system, used to control the temperature of the core holder; A separation and collection system is connected to the outlet pipeline of the core holder and is used to perform gas-liquid separation or solid-liquid separation and collection of the outlet fluid; The data acquisition system is used to collect pressure, flow rate, temperature, and sound wave signals in real time during the experiment. The device can switch between core reaction test mode, displacement test mode and sand production test mode by disassembling or installing the fake core.

2. The integrated experimental device for core displacement-reaction-sand production monitoring according to claim 1, characterized in that, The dummy rock core is a high-strength alloy block, with a flow guide groove on one end face facing the rock core. The flow guide channel is located inside the dummy rock core and communicates with the flow guide groove. The aperture of the flow guide channel is selected from different sizes according to the experimental mode. In the reaction experimental mode, no dummy rock core is installed. In the displacement experimental mode, a dummy rock core with a flow guide channel of the first aperture is installed. In the sand discharge experimental mode, a dummy rock core with a flow guide channel of the second aperture is installed. The second aperture is larger than the first aperture.

3. The integrated experimental device for core displacement-reaction-sand production monitoring according to claim 1, characterized in that, The fluid injection system includes a liquid piston container, a gas piston container, a dual-bar constant speed and constant pressure pump, and multiple injection pipelines; the liquid piston container and the gas piston container are selectively connected to the inlet and outlet pipelines of the core holder through independent valves to achieve forward displacement and reverse displacement.

4. The integrated experimental device for core displacement-reaction-sand production monitoring according to claim 1, characterized in that, The separation and collection system includes a gas-liquid separator and a solid separator; the gas-liquid separator is equipped with a baffle for gas-liquid separation of the outlet fluid; the solid separator is equipped with a filter screen, and its bottom is connected to a visible sand collection tank through a connecting valve for solid-liquid separation of the outlet fluid and collection of sand particles.

5. The integrated experimental device for core displacement-reaction-sand production monitoring according to claim 4, characterized in that, It also includes a high-speed camera, which is set next to the visualization sand collection tank and is used to monitor the sand collection in real time during the sand discharge experiment.

6. The integrated experimental device for core displacement-reaction-sand production monitoring according to claim 1, characterized in that, The data acquisition system includes a pulse generator and a digital display. The pulse generator is used to transmit P-waves and S-waves to the core, and the digital display is used to receive and display the propagation time and amplitude changes of the P-waves and S-waves to characterize the evolution of the core structure state during the reaction process.

7. A method for conducting an integrated core displacement-reaction-sand extraction experiment using the apparatus described in any one of claims 1 to 6, characterized in that, Includes the following steps: Core preparation steps: Load the core into the core holder, and selectively install or not install a dummy core in the reaction chamber according to the experimental mode; Core saturation step: Inject saturation liquid into the core holder, apply confining pressure and back pressure, monitor inlet pressure, outlet pressure and flow rate in real time, and determine that saturation is complete after the inlet pressure and outlet pressure stabilize. Experimental mode selection and execution steps: Select at least one of the following experimental modes, namely reaction experimental mode, displacement experimental mode or sand discharge experimental mode, according to the experimental requirements; Data acquisition steps: During the experiment, pressure, flow rate, temperature and acoustic signals are collected in real time, and the outlet fluid or solid product is collected for subsequent analysis.

8. The method according to claim 7, characterized in that, The reaction experimental modes include: No fake core is installed inside the reaction chamber; Inject reaction liquid into the core holder, heat to the set temperature and maintain the pressure in the reaction chamber, and maintain the reaction time t to complete the rock-fluid reaction; During the reaction, the propagation time and amplitude changes of P-waves and S-waves were collected in real time using a pulse generator to characterize the evolution of the core structure during the reaction. After the reaction is complete, the back pressure is released, the liquid in the reaction chamber is collected into a beaker, and the core sample after the reaction is taken out for further analysis.

9. The method according to claim 7, characterized in that, The displacement experimental mode includes: A fake rock core with the first aperture flow channel is installed inside the reaction chamber; Displacement gas is injected into the core holder, and the inlet pressure P is monitored in real time. in (t), inlet gas flow rate Q2(t), and outlet pressure P out (t); The instantaneous apparent permeability k(t) is calculated based on real-time monitoring data, using the following formula: Among them, P std Q is the pressure under standard conditions. std (t) is the volumetric flow rate under standard conditions, μ is the gas dynamic viscosity, L is the core length, and A is the core cross-sectional area; Liquid is collected from the gas-liquid separator at fixed time intervals, and the recovery rate is calculated. Where m2 is the cumulative mass of produced liquid, m w This represents the initial water content of the core. Plot the curves of instantaneous apparent permeability and recovery rate with the cumulative injected gas volume as the x-axis.

10. The method according to claim 7, characterized in that, The sand output test modes include: A fake core with a flow channel of the second aperture is installed inside the reaction chamber; Gas is injected into the core holder, and the inlet pressure, inlet gas flow rate, and outlet pressure are monitored in real time. Gas carrying sand and liquid enters the solid separator. After gravity settling, the sand enters the visible sand collection tank. Gas and liquid are filtered through a filter screen and then discharged. Real-time monitoring of the visualized sand collection tank is achieved through high-speed camera imaging. Sand particles were taken out and dried at fixed time intervals to obtain the cumulative sand output mass m3; Plot the cumulative sand output quality curve with the cumulative injected gas volume as the horizontal axis.

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