A multi-working-condition coupled water-rock interaction full-automatic simulation test device and method

Abstract

The application provides a multi-working-condition coupled water-rock interaction full-automatic simulation test device and method, which comprises a liquid storage unit, a liquid supply unit, a sample reaction cabin, a detection unit and a central controller; the output end of the liquid supply unit is connected to the spray branch and the soaking branch of the sample reaction cabin through a mode selection valve group, and the mode selection valve group comprises a spray branch valve and a soaking branch valve; through the mode selection valve group, a liquid level sensor, an electric control drainage valve and the cooperation of the interlocking logic in the central controller, the spray working condition, the soaking working condition and the emptying transition process between working condition switching can be automatically completed, the spray branch and the soaking branch can be prohibited from being opened at the same time from the logic level, the reaction cabin liquid level is prevented from being out of control, the residual liquid in the cabin is forced to be emptied when the soaking is switched to spraying, and the interference of the residual liquid in the previous working condition on the subsequent test conditions is eliminated.

Description

Technical Field

[0001] This invention relates to the field of geological engineering technology, and in particular to a fully automated simulation test device and method for multi-condition coupled water-rock interaction. Background Technology

[0002] Water-rock interaction is influenced by temperature, solution flow rate, gas composition, solution chemical state, and alternating wet-dry processes. Natural rainfall infiltration typically manifests as unsaturated spraying or leaching, and a rise in groundwater level can create a soaking environment. Therefore, it is difficult to replicate the continuous environmental processes actually experienced on the same sample using only single flow or single static conditions.

[0003] Existing devices can separately achieve dynamic leaching, static soaking, temperature control, carbon dioxide supply, or online detection. However, simply juxtaposing these functions still presents the following problems: First, the spraying and soaking branches lack liquid level, drainage, and interlocking structures, requiring manual operation for switching between operating conditions. Second, the solutions before and after the reaction are typically measured by different sensors, and differences in sensor zero points and drift will affect the calculation results. Third, carbon dioxide-containing solutions may alter the gas-liquid balance during open degassing or detection processes, leading to distortion of parameters such as pH. Fourth, adjusting carbon dioxide supply solely based on a single post-reaction pH level makes it difficult to distinguish between changes caused by storage condition drift and rock reactions. Summary of the Invention

[0004] In view of this, the present invention aims to provide a fully automated simulation test device and method for multi-condition coupled water-rock interaction, so as to solve or alleviate the technical problems existing in the prior art, and at least provide a beneficial option.

[0005] To solve the above-mentioned technical problems, one technical solution adopted in this application is: to provide a fully automatic simulation test device for water-rock interaction under multiple operating conditions, including a liquid storage unit, a liquid supply unit, a sample reaction chamber, a detection unit, and a central controller. The output of the liquid supply unit is connected to the spray branch and the immersion branch of the sample reaction chamber through a mode selection valve group, which includes a spray branch valve and an immersion branch valve. The sample reaction chamber is equipped with a liquid level sensor and an electrically controlled drain valve located at the bottom outlet. The detection unit includes a flow path selection valve, a closed low dead volume flow detection cell, and a measurement outlet distribution unit. The two input ports of the flow path selection valve are respectively connected to a reference sampling branch and a post-reaction sampling branch. The reference sampling branch is taken from the upstream of the sample reaction chamber and is used to obtain the original solution that has not reacted with the rock before entering the reaction chamber. The post-reaction sampling branch is taken from the downstream of the sample reaction chamber and is used to collect the product solution after the rock sample undergoes water-rock interaction. The output port of the flow path selection valve is connected to the closed low dead volume flow detection cell, and the output end of the closed low dead volume flow detection cell is connected to the measurement outlet distribution unit. The measurement outlet distribution unit can selectively connect the displacement fluid discharge valve and the recovery distribution valve. The central controller is connected to the electrical signals of the mode selection valve group, the liquid level sensor, the electrically controlled drain valve, the flow path selection valve, the replacement liquid discharge valve, and the sensors inside the sealed low dead volume flow detection cell. The central controller is configured as follows: In the spraying mode, the spraying branch valve is opened and the soaking branch valve is closed, and the electrically controlled drain valve is in the draining working state to simulate the natural rain leaching and unsaturated infiltration environment. The sprayed liquid is continuously discharged from the bottom of the sample reaction chamber to the outside, and no soaking liquid will accumulate in the chamber. During the immersion process, the spray branch valve is closed and the immersion branch valve is opened. Based on the liquid level signal collected by the liquid level sensor, the immersion branch valve and the electrically controlled drain valve are adjusted to maintain the set liquid level inside the sample reaction chamber and simulate the static immersion environment in which the rock is completely submerged after the groundwater level rises. The control flow path selection valve alternately selects the reference sampling branch and the post-reaction sampling branch, enabling the reference solution and the post-reaction solution to share the same set of sensors for detection at different times, avoiding zero-point drift and system deviation caused by multiple sets of sensors. After each sampling branch switch is completed, the displacement fluid discharge valve is opened to discharge the preset displacement volume of fluid, replacing the residual test liquid from the previous operating condition inside the flow path and eliminating cross-contamination of liquid samples. When the detection parameters collected by the closed low dead volume flow detection cell meet the preset stability criteria, the corresponding reference measurement value or post-reaction measurement value is recorded. Based on the difference between the reference measurement value and the post-reaction measurement value, the parameter changes caused by the conditional drift of the storage liquid itself and the rock-water-rock reaction are distinguished, and the operating conditions of the experiment are adjusted accordingly.

[0006] As a further preferred embodiment of this technical solution: the liquid storage unit includes a carbon dioxide gas source, an inert carrier gas source, a first gas mass flow controller, a second gas mass flow controller, a gas mixer, and a closed gas-liquid balance liquid storage unit. The carbon dioxide gas source and the inert carrier gas source are respectively connected to the gas mixer via a first gas mass flow controller and a second gas mass flow controller. The two gas sources are precisely proportioned by their respective mass flow controllers to achieve uniform mixing inside the gas mixer. The mixed gas output end of the gas mixer is connected to a closed gas-liquid balance storage unit through a microporous aeration head. The microporous aeration head disperses the mixed gas into tiny bubbles, allowing the gas phase and liquid phase to fully contact each other and achieve gas-liquid balance. The headspace of the sealed gas-liquid balance storage unit is equipped with a headspace pressure sensor and a back pressure valve. The headspace pressure sensor monitors the gas phase pressure inside the storage unit in real time, and the back pressure valve maintains a slightly positive pressure environment inside the storage unit, which ensures the gas-liquid balance effect and avoids the risk of overpressure inside the system.

[0007] As a further preferred embodiment of this technical solution: the liquid supply unit includes a constant flow pump and a pipeline heat exchange and temperature control device located downstream of the constant flow pump; the constant flow pump provides a stable fluid delivery flow rate for the entire test flow path, and the pipeline heat exchange and temperature control device exchanges heat on the delivered test solution to achieve precise control of the solution temperature; The sample reaction chamber is equipped with a reaction zone temperature sensor, which is used to directly collect the actual temperature of the reaction zone where the sample is located, rather than just collecting the pipeline temperature. The central controller receives feedback signals from the temperature sensor in the reaction zone and adjusts the output of the pipeline heat exchange temperature control device to form a closed-loop temperature control, ensuring that the temperature of the reaction environment where the rock sample is located meets the preset experimental conditions.

[0008] As a further preferred embodiment of this technical solution: the sample reaction chamber includes a sealed top cover, a dynamic spray assembly, a static immersion inlet, a porous sample tray, a multi-layer filter assembly, a conical shrink outlet, and an insulation layer; the sealed top cover ensures the overall airtightness of the reaction chamber, reducing the interference of ambient gases on the system inside; the insulation layer reduces the impact of external temperature fluctuations on the reaction system inside; the conical shrink outlet facilitates the complete drainage of liquid inside the chamber, preventing residual liquid accumulation; the multi-layer filter assembly intercepts mineral debris from rock fragments, preventing debris from entering the downstream sampling flow path and causing contamination of pipelines and sensors; the porous sample tray is used to hold rock samples while ensuring that liquid can flow downwards; The dynamic spraying assembly includes a drip head array and a flow equalization plate arranged below the drip head array; the drip head array outputs spray liquid, and the flow equalization plate disperses the liquid flow to make the liquid evenly distributed, thereby achieving uniform leaching of the rock sample surface. The sample reaction chamber is also equipped with a removable lateral sealing sleeve, which covers the outer periphery of the rock sample. When conducting an axial infiltration test on the rock, the sealing sleeve is installed to restrict the sprayed liquid from forming a bypass flow along the outer wall of the rock sample, forcing the liquid to only penetrate through the inside of the rock sample. When it is necessary to conduct a rock surface scouring test, the lateral sealing sleeve can be removed so that the liquid acts on the outer surface of the rock simultaneously.

[0009] As a further preferred embodiment of this technical solution: the central controller has a built-in mode interlock logic program; The mode interlock logic program is used to prevent the spray branch valve and the soaking branch valve from being open at the same time, so as to prevent the liquid level in the tank from getting out of control due to the simultaneous operation of the spray and soaking liquid inlets. When switching from immersion mode to spray mode, the central controller first closes the immersion branch valve to cut off the immersion liquid inlet, and opens the electrically controlled drain valve to completely drain the original immersion liquid in the chamber until the liquid level inside the sample reaction chamber drops to the preset drain level. After confirming that there is no accumulated liquid in the chamber, the spray branch valve is then opened to ensure the reliability of the mode switching logic and avoid residual immersion liquid from interfering with the spray filtration test conditions.

[0010] As a further preferred embodiment of this technical solution: the sealed low dead volume flow detection cell is a sealed flow cell that is not directly connected to the outside atmosphere, thus preventing the solution from directly contacting the atmosphere; The closed low dead volume flow detection cell is equipped with at least two of the following sensors: pH sensor, conductivity sensor, redox potential sensor, and dissolved carbon dioxide sensor. The detection parameters can be flexibly selected according to the needs of experimental research. The outlet of the closed low dead volume flow detection cell maintains a preset back pressure higher than the ambient atmospheric pressure. The back pressure suppresses the escape of carbon dioxide gas from the test solution, avoids the distortion of pH and dissolved carbon dioxide detection results caused by carbon dioxide degassing, and maintains the original gas-liquid balance of the test solution.

[0011] As a further preferred embodiment of this technical solution: the preset replacement volume is k times the total internal volume V of the flow path between the flow path selection valve and the outlet of the closed low dead volume flow detection pool, where k is 1.5 to 5, to ensure that the residual old liquid in the pipeline is fully replaced; The stability criterion is: the difference between the maximum and minimum values ​​of the same detection parameter obtained from n consecutive samplings is not greater than the corresponding parameter threshold, or the absolute value of the parameter change rate from n consecutive samplings is not greater than the corresponding parameter threshold, where n is not less than 3. The measurement results are only accepted when the parameter fluctuates continuously and meets the stability condition, thus avoiding misjudgment caused by transient fluctuations when the liquid sample is just switched. The central controller calculates at least one parameter difference between the reference measurement value and the post-reaction measurement value; the parameter difference includes pH difference, conductivity difference, redox potential difference, and dissolved carbon dioxide difference; the reference value characterizes the background conditions of the influent, and the difference characterizes the reaction contribution of the rock; The central controller, in conjunction with the parameter difference, reference measurement value, and preset adjustment priority, adjusts at least one of the components, namely the first gas mass flow controller, the second gas mass flow controller, the quantitative replenishment pump, the constant flow pump, and the pipeline heat exchange temperature control device, to achieve closed-loop maintenance of test conditions.

[0012] As a further preferred embodiment of this technical solution: the recovery distribution valve is connected to the circulation branch and the waste liquid branch respectively. The circulation branch is connected back to the closed gas-liquid balance storage unit to realize the recycling and reuse of the solution after the qualified reaction. The waste liquid branch is connected to the waste liquid collection container. When the reaction products accumulate too high and are not suitable for recycling, the waste liquid branch is switched to discharge directly. The liquid storage unit also includes a fresh solution tank, a metering pump, and a liquid level sensor; the fresh solution tank is used to store newly prepared base solutions, the metering pump can replenish fresh solutions to the closed gas-liquid balance liquid storage unit to compensate for solution consumption during the experiment; the liquid level sensor monitors the liquid level inside the liquid storage unit in real time. The central controller receives signals from the liquid level sensor. When the detected liquid level is below the lower limit, the central controller stops the constant flow pump and outputs an alarm signal to remind the operator to replenish the test solution and avoid running the pump dry and damaging the equipment.

[0013] As a further preferred embodiment of this technical solution: the central controller is configured with fault safety handling logic; When the system identifies abnormal conditions such as overpressure, overtemperature, low liquid level, or sensor malfunction, it immediately cuts off the gas supply, locks the mode selection valve group, stops supplying liquid to the reaction chamber, shuts down the constant flow pump, and simultaneously executes the safety discharge procedure to release system pressure and drain liquid from the chamber, thereby achieving safety protection under equipment failure conditions and avoiding the risk of damage to the test equipment and sample scrapping.

[0014] To solve the above-mentioned technical problems, another technical solution adopted in this application is: a fully automated simulation test method for water-rock interaction, implemented using the aforementioned multi-condition coupled fully automated simulation test device for water-rock interaction, comprising the following steps: S1. Prepare a test solution with preset gas components and preset temperature. Select to install or remove the lateral sealing sleeve around the rock sample according to the test type. Then place the rock sample inside the sample reaction chamber to complete the device sealing. S2. According to the preset test sequence, execute at least two of the following conditions: spraying, soaking, and draining transition conditions, to replicate the alternating wet and dry environment of rainfall and groundwater level fluctuations. In the spraying condition, open the spraying branch valve, close the soaking branch valve, and keep the electrically controlled drain valve in the draining state to continuously carry out unsaturated leaching. In the soaking condition, close the spraying branch valve, open the soaking branch valve, and use the upper and lower limits of the liquid level sensor to achieve hysteresis control of the soaking liquid level. When the liquid level reaches the upper limit, stop the liquid inlet; when the liquid level falls back to the lower limit, replenish the liquid to maintain the immersion conditions. When switching from the soaking condition to the spraying condition, execute the sequence of cutting off the soaking liquid inlet, draining the liquid in the chamber, and confirming that the liquid level meets the standard before starting the spraying to eliminate mutual interference between the conditions. S3. Within each measurement cycle, the control flow path selection valve selects the reference sampling branch, discharges the first preset displacement volume of fluid, and flushes the residual liquid in the pipeline; when the parameter to be detected meets the stability criterion, the reference measurement value is recorded; then the flow path selection valve is switched to select the post-reaction sampling branch, discharges the second preset displacement volume of fluid, and the sampling flow path replacement is completed; when the parameter to be detected meets the stability criterion, the post-reaction measurement value is recorded; the background solution and post-reaction solution are detected in time-division multiplexing within this cycle; S4. Calculate the parameter difference between the reference measurement value and the post-reaction measurement value. When the reference measurement value deviates from the preset allowable range, it indicates that the background conditions of the inlet liquid have drifted. Prioritize adjusting the gas mixing ratio or the liquid replenishment volume of the quantitative replenishment pump to correct the input solution conditions. When the reference measurement value is within the preset allowable range, and the parameter difference between the reference measurement value and the post-reaction measurement value exceeds the preset threshold, it indicates that the rock-water-rock reaction effect has changed. Adjust the liquid supply flow rate, the duration of the operating condition, or switch the circulation branch and the waste liquid branch to maintain the experimental conditions. Continuously monitor the equipment status throughout the experiment. Once abnormal conditions such as overpressure, overtemperature, low liquid level in the storage tank, or sensor failure are identified, immediately execute the fault safety handling logic to ensure the safety of the experiment and the equipment.

[0015] The embodiments of the present invention have the following advantages due to the adoption of the above technical solutions: First, this invention achieves fully automated interlocking switching between multiple operating conditions, including spraying, soaking, and draining, avoiding experimental errors caused by human operation. Through a mode selection valve group, a liquid level sensor, and an electrically controlled drain valve, combined with the central controller's built-in interlocking logic, this invention can automatically complete the transition process between spraying, soaking, and draining conditions. Logically, it can prevent the simultaneous opening of the spraying and soaking branches, avoiding uncontrolled liquid levels in the reaction chamber. When switching from soaking to spraying, it forces the draining of residual liquid in the chamber, eliminating interference from residual liquid from the previous condition on subsequent experimental conditions. The entire process requires no manual valve switching by operators, allowing for long-term unattended dry-wet alternation simulation experiments, reducing operational errors introduced by human intervention and improving experimental repeatability.

[0016] Second, this invention employs a time-division multiplexing approach, using the same set of sensors to detect both the reference solution and the post-reaction solution, thus eliminating the bias of multi-sensor systems. Existing solutions typically use two sets of independent sensors to detect the influent and effluent separately, and zero-point drift and individual differences between different sensors are directly factored into the reaction calculation results. This invention relies on a flow path selection valve to switch the sampling source. The reference sampling branch and the post-reaction sampling branch share the same set of sensors inside the closed flow cell to complete the measurement. Within the same cycle, the reference value and the post-reaction ratio are obtained from the same hardware, eliminating the system bias between different sensors at its source, making the calculation results of parameter differences caused by the water-rock reaction more accurate and reliable.

[0017] Third, a flow path replacement process and parameter stability criteria are set to suppress cross-contamination of liquid samples and transient fluctuation interference. After each switching of sampling branches, the old liquid remaining in the pipeline is flushed out with a preset replacement volume of fluid to avoid cross-contamination caused by the residue of the previous liquid sample; and the instantaneous measurement data after the switch is not read directly, but the data is recorded only after the detection parameters meet the stability criteria, effectively filtering the transient fluctuations in the liquid sample switching stage and ensuring the validity of each set of reference and post-reaction measurement data.

[0018] Fourth, the closed-loop backpressure detection flow path design effectively suppresses distortion caused by degassing of the carbon dioxide-containing test solution. The entire flow detection cell is a closed structure that is not connected to the atmosphere, and the outlet maintains a backpressure condition higher than the ambient pressure to prevent carbon dioxide in the test solution from escaping into the atmosphere, protecting the original gas-liquid equilibrium state of the solution, and avoiding deviations in key detection parameters such as pH and dissolved carbon dioxide due to degassing. This significantly improves the data accuracy of carbonate systems and carbon dioxide-water-rock related simulation experiments.

[0019] Fifth, based on the hierarchical closed-loop control logic of the reference-post-reaction difference, it can distinguish between the storage liquid background drift and the rock-water-rock reaction effect. Traditional devices rely solely on single-point measurements after the reaction for control, failing to differentiate whether parameter changes originate from storage liquid condition drift or the rock's own dissolution reaction. This invention prioritizes judging the reference measurement value. When the reference value deviates from the preset range, it prioritizes correcting the air-fuel ratio or replenishing the liquid to rectify the inlet background conditions. Under the premise that the inlet background is qualified, it then adjusts the flow rate, operating time, and waste liquid-circulation branch based on the parameter difference between the reference and the post-reaction parameters. The control logic is clearly hierarchical, suitable for conducting long-term water-rock interaction simulations lasting several weeks or even months, ensuring stable operating conditions during long-term experiments.

[0020] Sixth, the sample reaction chamber is adaptable to two test modes, with strong hardware reusability. By assembling and disassembling the detachable lateral sealing sleeve, it can perform axial infiltration leaching tests on rock samples, forcing the liquid to completely penetrate the interior of the rock; by removing the sealing sleeve, it can perform scouring leaching tests on the outer surface of the rock. The same hardware can be compatible with two typical water-rock interaction test scenarios without replacing the test chamber itself. At the same time, the internal insulation layer and multi-layer filter components reduce environmental temperature interference, intercept rock debris, protect downstream sensors and flow paths, and reduce equipment failure rate.

[0021] Seventh, it possesses a complete fault safety handling mechanism, enhancing the safety of equipment and samples in long-cycle experiments. The system monitors abnormal operating conditions such as overpressure, overtemperature, low liquid level, and sensor malfunction in real time. Once a fault signal is identified, it automatically cuts off the gas supply, locks the inlet valve group, shuts down the delivery pump, and executes a safe discharge procedure. No manual intervention is required, avoiding accidents such as overpressure leakage, empty pump damage, and sample scrapping. It is suitable for long-term unattended experimental scenarios in the field and laboratory.

[0022] Eighth, the liquid storage unit achieves closed-loop gas-liquid equilibrium preparation of the test solution. A dual-channel mass flow controller precisely proportions two gas sources, and a microporous aeration head ensures full gas-liquid contact. Combined with a headspace pressure sensor and back pressure valve, a slight positive pressure is maintained in the liquid storage unit, stably maintaining the gas phase partial pressure of the solution and ensuring controllable gas-liquid equilibrium conditions of the test solution entering the reaction chamber.

[0023] The above overview is for illustrative purposes only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features of the invention will become readily apparent from the accompanying drawings and the following detailed description. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art 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.

[0025] Figure 1 This is a schematic diagram of the overall structure of the device of the present invention.

[0026] Figure 2 This is a schematic cross-sectional view of the sample reaction chamber of the present invention.

[0027] Figure 3 This is a schematic diagram of the time-division reference detection flow path of the present invention.

[0028] Figure 4This is a schematic diagram of the input, output, and control logic of the central controller of the present invention.

[0029] Figure Descriptions: 101. Carbon dioxide gas source; 102. Inert carrier gas source; 103. First gas mass flow controller; 104. Second gas mass flow controller; 105. Gas mixer; 106. Closed gas-liquid balance storage unit; 107. Microporous aerator head; 108. Headspace pressure sensor; 109. Back pressure valve; 110. Fresh solution storage tank; 111. Quantitative replenishment pump; 112. Storage liquid level sensor; 201. Constant flow pump; 202. Pipeline heat exchange temperature control device; 203. Mode selection valve group; 203a. Spray branch valve; 203b. Immersion branch valve; 301. Sample reaction chamber; 302. Sealed top cover; 303. Dynamic spray assembly; 303a. Drip head array; 303b. Flow equalization plate; 304. Static immersion inlet; 305. Porous sample tray; 306. Multi-layer filter assembly; 307. Conical contraction outlet; 308. Reaction zone temperature sensor; 309. Insulation layer; 310. Liquid level sensor; 311. Electrically controlled drain valve; 312. Removable side sealing sleeve; 401. Flow path selection valve; 402. Reference sampling branch; 403. Post-reaction sampling branch; 404. Sealed low dead volume flow detection cell; 405. 406. pH sensor; 407. Conductivity sensor; 408. Oxidation-reduction potential sensor; 410. Dissolved carbon dioxide sensor; 411. Displacement fluid discharge valve; 412. Measurement outlet distribution unit; 503. Recovery distribution valve; 504. Circulation branch; 505. Waste liquid branch; 506. Waste liquid collection container; 607. Central controller. Detailed Implementation

[0030] The embodiments of this disclosure will now be described in detail with reference to the accompanying drawings.

[0031] It should be understood that the following specific examples illustrate the implementation of this disclosure, and those skilled in the art can easily understand other advantages and effects of this disclosure from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. This disclosure can also be implemented or applied through other different specific implementation methods, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this disclosure. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0032] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this disclosure, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0033] Example 1: Device Structure like Figure 1 As shown, carbon dioxide source 101 and inert carrier gas source 102 are respectively connected to first gas mass flow controller 103 and second gas mass flow controller 104. The inert carrier gas can be nitrogen or air. The central controller 601 sets the two flow rates according to the target gas phase carbon dioxide volume fraction. The mixed gas enters the closed gas-liquid balance storage unit 106 through microporous aeration head 107 after passing through gas mixer 105. Headspace pressure sensor 108 detects the headspace pressure of the storage unit, and back pressure valve 109 is used to maintain the preset pressure and prevent system overpressure.

[0034] A liquid level sensor 112 is installed inside the closed gas-liquid balance storage unit 106, and its liquid outlet is sequentially connected to a constant flow pump 201, a pipeline heat exchange and temperature control device 202, and a mode selection valve group 203. A fresh solution storage tank 110 is connected to the closed gas-liquid balance storage unit 106 via a quantitative replenishment pump 111. The central controller 601 can control the quantitative replenishment pump 111 based on the liquid level, reference pH, reference conductivity, or a preset replenishment program, but does not estimate the total ion concentration solely based on pH or conductivity.

[0035] The mode selection valve group 203 preferably consists of two normally closed solenoid valves or a multi-position valve with two output ports. The spray branch valve 203a is connected to the dynamic spray assembly 303, and the soaking branch valve 203b is connected to the static soaking inlet 304. The central controller 601 uses software and relay hardware interlocking to prevent the two valves from opening simultaneously.

[0036] like Figure 2As shown, the sample reaction chamber 301 can be made of corrosion-resistant transparent material or a metal lining structure. Its top is sealed by a top cover 302, and an insulation layer 309 is provided on the outer periphery. The bottom forms a conical contraction outlet 307 connected to an electrically controlled drain valve 311. The dynamic spray assembly 303 includes a drip head array 303a and a flow equalization plate 303b. The rock sample is placed on a porous sample tray 305, with a multi-layer filter assembly 306 arranged below. A removable lateral sealing sleeve 312 covers the outer periphery of the rock sample, restricting the liquid from bypassing the outer wall of the sample when axial infiltration needs to be studied; the sealing sleeve can be removed when studying surface scouring.

[0037] The liquid level sensor 310 can be a float, pressure, ultrasonic, or capacitive liquid level sensor. During immersion, the central controller 601 performs hysteresis control by setting upper and lower limits for the liquid level: when the liquid level is below the lower limit, the immersion branch valve 203b is opened and the electrically controlled drain valve 311 is closed; when the liquid level reaches the upper limit, the immersion branch valve 203b is closed. When continuous liquid replacement immersion is required, the immersion branch valve 203b and the electrically controlled drain valve 311 can be opened alternately in a small flow pulse manner.

[0038] Example 2: Time-division reference detection like Figure 3 As shown, the reference sampling branch 402 is led out from a predetermined position upstream or downstream of the pipeline heat exchanger temperature control device 202, and the post-reaction sampling branch 403 is connected to the bottom outlet of the sample reaction chamber 301. The two branches are respectively connected to the two inlets of the flow path selection valve 401. In order to make the reference measurement value correspond to the actual temperature entering the reaction chamber, it is preferable to take samples downstream of the pipeline heat exchanger temperature control device 202 and upstream of the mode selection valve group 203.

[0039] The sealed, low dead volume flow-through detection cell 404 can sequentially house a pH sensor 405, a conductivity sensor 406, a redox potential sensor 407, and a dissolved carbon dioxide sensor 408. The detection cell and connecting piping are airtight, and a small back pressure regulator can be installed at its outlet to ensure the pressure during measurement is higher than the ambient pressure. This flow path does not include a gas-liquid separator connected to the atmosphere; if free air bubbles need to be removed, a bubble collection chamber not connected to the outside environment can be used, and the collection chamber should be kept under the same back pressure.

[0040] Let V be the total internal volume between the flow path selection valve 401 and the measurement outlet distribution unit 411. After the central controller 601 switches the sampling branch, it first opens the displacement fluid discharge valve 410, discharging a cumulative volume of liquid kV according to the pump flow rate, where k can be set to 1.5 to 5. After the displacement is completed, sampling continues. When the range of n consecutive pH measurements is not greater than εpH, and the range of n consecutive conductivity measurements is not greater than εEC, the measurement is considered stable and recorded; n can be 3 to 20. For other sensors, corresponding stability thresholds can be set.

[0041] A complete measurement cycle includes, in sequence, reference branch replacement, reference stability determination, reference recording, post-reaction branch replacement, post-reaction stability determination, and post-reaction recording. Since the two liquid samples are measured using the same set of sensors, the post-reaction value within the same cycle can be subtracted from the reference value to obtain the parameter difference characterizing the contribution of the rock reaction.

[0042] Example 3: Control Method like Figure 4 As shown, the central controller 601 receives signals from the headspace pressure sensor 108, the liquid level sensor 112, the reaction zone temperature sensor 308, the liquid level sensor 310, and the sealed low dead volume flow detection tank 404, and outputs them to the two-way gas mass flow controller, the quantitative replenishment pump 111, the constant flow pump 201, the pipeline heat exchange temperature control device 202, the mode selection valve group 203, the electrically controlled drain valve 311, the flow path selection valve 401, the displacement liquid discharge valve 410, and the recovery distribution valve 501.

[0043] When the spraying operation begins, the central controller 601 confirms that the electrically controlled drain valve 311 is open and the liquid level is below the drain threshold, and then opens the spray branch valve 203a. When the soaking operation begins, the spray branch valve 203a is closed first, then the electrically controlled drain valve 311 is closed and the soaking branch valve 203b is opened until the set liquid level is reached. After soaking is completed, the soaking branch valve 203b is closed first, then the electrically controlled drain valve 311 is opened, and the next spraying operation is allowed only after the liquid level drops to the drain threshold.

[0044] The controller stores the reference pH value (pHr), the post-reaction pH value (pHo), and the difference ΔpH = pHo - pHr. If pHr deviates from the storage liquid setting range, the proportional gain of the two gas mass flow controllers or the quantitative replenishment pump 111 is adjusted first. If pHr is within the setting range but ΔpH exceeds the threshold, the flow rate of the constant flow pump 201, the spraying or soaking duration are adjusted according to the experimental purpose, or the recovery distribution valve 501 is switched to the waste liquid branch 503 to avoid the accumulation of reaction products. Temperature control uses feedback from the reaction zone temperature sensor 308 independently to reduce mutual interference between different control variables.

[0045] In one exemplary cycle, the device repeats the cycle in the following order: spraying for 30 minutes, draining for 10 minutes, soaking for 120 minutes, and draining for 10 minutes. These times are optional parameters and can be modified according to lithology, sample size, and research objectives. The controller can perform a time-division reference measurement cycle every 10 to 60 minutes.

[0046] When the headspace pressure exceeds the upper limit, the liquid level in the storage tank is lower than the lower limit, the reaction temperature exceeds the safe range, the liquid level sensor signal is abnormal, or the valve status is inconsistent with the control command, the central controller 601 enters a fault state, shuts off the gas supply and mode selection valve group 203, stops the constant flow pump 201, and opens the back pressure valve 109 or the electrically controlled drain valve 311 to perform safety procedures according to the fault type.

[0047] Example 4: Experimental Procedure S1: After processing, cleaning and drying the rock sample, place it on the porous sample tray 305, install or remove the removable lateral sealing sleeve 312 according to the research purpose, and seal the sample reaction chamber 301.

[0048] S2: Add the base solution to the sealed gas-liquid balance storage unit 106, set the flow ratio of carbon dioxide to inert carrier gas, headspace pressure and target temperature, so that the solution reaches the preset initial state.

[0049] S3: Start the constant flow pump 201 and the pipeline heat exchange temperature control device 202. After the measured value of the reaction zone temperature sensor 308 enters the set range, perform a reference measurement and save the initial value.

[0050] S4: Perform spraying, soaking and evacuation operations according to the preset time sequence; perform reference and post-reaction time-minute measurements according to the set cycle in each operation.

[0051] S5: Perform gas mixing, liquid replenishment, flow rate, temperature and circulation / waste discharge control based on reference value, post-reaction value and difference, and record all control commands and sensor data.

[0052] S6: Stop the test after the preset time, cumulative dissolution amount or parameter stability conditions are reached, drain and clean the flow path, and take out the rock sample for quality, pore structure, mineral composition or mechanical property analysis.

[0053] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of this disclosure to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations therein.

Claims

1. A fully automated simulation test device for multi-condition coupled water-rock interaction, comprising a liquid storage unit, a liquid supply unit, a sample reaction chamber (301), a detection unit, and a central controller (601), characterized in that: The output end of the liquid supply unit is connected to the spray branch and the soaking branch of the sample reaction chamber (301) through the mode selection valve group (203), respectively. The mode selection valve group (203) includes a spray branch valve (203a) and a soaking branch valve (203b). The sample reaction chamber (301) is equipped with a liquid level sensor (310) and an electrically controlled drain valve (311) located at the bottom outlet. The detection unit includes a flow path selection valve (401), a closed low dead volume flow detection cell (404), and a measurement outlet distribution unit (411). The two input ports of the flow path selection valve (401) are respectively connected to the reference sampling branch (402) and the post-reaction sampling branch (403). The reference sampling branch (402) is taken from the upstream of the sample reaction chamber (301), and the post-reaction sampling branch (403) is taken from the downstream of the sample reaction chamber (301). The output port of the flow path selection valve (401) is connected to the closed low dead volume flow detection cell (404), and the output end of the closed low dead volume flow detection cell (404) is connected to the measurement outlet distribution unit (411). The measurement outlet distribution unit (411) can selectively connect the displacement liquid discharge valve (410) and the recovery distribution valve (501). The central controller (601) is connected to the sensor electrical signals inside the mode selection valve group (203), the liquid level sensor (310), the electrically controlled drain valve (311), the flow path selection valve (401), the replacement liquid discharge valve (410), and the sealed low dead volume flow detection cell (404). The central controller (601) is configured to: In the spraying operation, the spraying branch valve (203a) is opened, the soaking branch valve (203b) is closed, and the electrically controlled drain valve (311) is put into the draining operation state. During the immersion process, the spray branch valve (203a) is closed and the immersion branch valve (203b) is opened. Based on the liquid level signal collected by the liquid level sensor (310), the immersion branch valve (203b) and the electrically controlled drain valve (311) are adjusted to maintain the set liquid level inside the sample reaction chamber (301). The control flow path selection valve (401) alternately selects the reference sampling branch (402) and the post-reaction sampling branch (403); after each sampling branch switch is completed, the displacement fluid discharge valve (410) is opened to discharge the fluid of the preset displacement volume; when the detection parameters collected by the closed low dead volume flow detection cell (404) meet the preset stability criteria, the corresponding reference measurement value or post-reaction measurement value is recorded; the operating conditions of the test are adjusted according to the difference between the reference measurement value and the post-reaction measurement value.

2. The fully automated simulation test device for multi-condition coupled water-rock interaction according to claim 1, characterized in that, The liquid storage unit includes a carbon dioxide gas source (101), an inert carrier gas source (102), a first gas mass flow controller (103), a second gas mass flow controller (104), a gas mixer (105), and a closed gas-liquid balance liquid storage unit (106). The carbon dioxide gas source (101) and the inert carrier gas source (102) are connected to the gas mixer (105) via the first gas mass flow controller (103) and the second gas mass flow controller (104), respectively. The mixed gas output end of the gas mixer (105) is connected to the closed gas-liquid balance storage unit (106) via the microporous aeration head (107). The headspace of the sealed gas-liquid balance storage unit (106) is equipped with a headspace pressure sensor (108) and a back pressure valve (109).

3. The fully automated simulation test device for multi-condition coupled water-rock interaction according to claim 1 or 2, characterized in that, The liquid supply unit includes a constant flow pump (201) and a pipeline heat exchange and temperature control device (202) located downstream of the constant flow pump (201). The sample reaction chamber (301) is equipped with a reaction zone temperature sensor (308). The central controller (601) receives feedback signals from the reaction zone temperature sensor (308) and adjusts the output of the pipeline heat exchange temperature control device (202).

4. The fully automated simulation test device for multi-condition coupled water-rock interaction according to claim 1, characterized in that, The sample reaction chamber (301) includes a sealed top cover (302), a dynamic spray assembly (303), a static immersion inlet (304), a porous sample tray (305), a multi-layer filter assembly (306), a conical shrink outlet (307), and a thermal insulation layer (309). The dynamic spray assembly (303) includes a drip head array (303a) and a flow equalization plate (303b) arranged below the drip head array (303a). The sample reaction chamber (301) is also equipped with a removable lateral sealing sleeve (312), which covers the outer periphery of the rock sample and is used to restrict the sprayed liquid from forming a bypass flow along the outer wall of the rock sample.

5. The fully automated simulation test device for multi-condition coupled water-rock interaction according to claim 1, characterized in that, The central controller (601) has a built-in mode interlock logic program; The mode interlock logic program is used to prevent the spray branch valve (203a) and the soaking branch valve (203b) from being in the open state at the same time; When switching from immersion mode to spray mode, the central controller (601) first closes the immersion branch valve (203b), opens the electrically controlled drain valve (311), and continues until the liquid level inside the sample reaction chamber (301) drops to the preset drain level, and then opens the spray branch valve (203a).

6. The fully automated simulation test device for multi-condition coupled water-rock interaction according to claim 1, characterized in that, The sealed low dead volume flow detection cell (404) is a sealed flow cell that is not directly connected to the outside atmosphere. The closed low dead volume flow detection cell (404) is equipped with at least two of the following sensors: pH sensor (405), conductivity sensor (406), redox potential sensor (407), and dissolved carbon dioxide sensor (408). The outlet of the closed low dead volume flow detection cell (404) is maintained at a preset back pressure higher than the ambient atmospheric pressure to suppress the escape of carbon dioxide gas from the test solution.

7. The fully automated simulation test device for multi-condition coupled water-rock interaction according to claim 1, characterized in that, The preset replacement volume is k times the total internal volume V of the flow path between the flow path selection valve (401) and the outlet of the closed low dead volume flow detection pool (404), where 1.5≤k≤5; The stability criterion is: for the same detection parameter obtained from n consecutive samplings, the difference between its maximum and minimum values ​​is not greater than the corresponding parameter threshold, or the absolute value of the parameter change rate from n consecutive samplings is not greater than the corresponding parameter threshold, where n≥3; The central controller (601) calculates at least one parameter difference between the reference measurement value and the post-reaction measurement value; The parameter differences include pH difference, conductivity difference, redox potential difference, and dissolved carbon dioxide difference; The central controller (601) adjusts at least one of the following components in combination with the parameter difference, reference measurement value, and preset adjustment priority: the first gas mass flow controller (103), the second gas mass flow controller (104), the quantitative replenishment pump (111), the constant flow pump (201), and the pipeline heat exchange temperature control device (202).

8. The fully automated simulation test device for multi-condition coupled water-rock interaction according to claim 2, characterized in that, The recovery distribution valve (501) is connected to the circulation branch (502) and the waste liquid branch (503) respectively. The circulation branch (502) is connected back to the closed gas-liquid balance storage unit (106), and the waste liquid branch (503) leads to the waste liquid collection container (504). The liquid storage unit also includes a fresh solution storage tank (110), a quantitative replenishment pump (111), and a liquid level sensor (112). The central controller (601) receives the signal from the liquid level sensor (112); when the detected liquid level is lower than the lower limit, the central controller (601) controls the constant flow pump (201) to stop and outputs an alarm signal.

9. The fully automated simulation test device for multi-condition coupled water-rock interaction according to claim 8, characterized in that, The central controller (601) is configured with fault-safe handling logic; When the system identifies abnormal conditions such as overpressure, overtemperature, low liquid level, or sensor malfunction, it cuts off the gas supply, locks the mode selection valve group (203), shuts down the constant flow pump (201), and executes the safety discharge procedure.

10. A fully automated simulation test method for water-rock interaction, characterized in that, The experiment is conducted using the fully automated simulation test device for multi-condition coupled water-rock interaction as described in any one of claims 1-9, and includes the following steps: S1. Prepare a test solution with preset gas components and preset temperature, and place the rock sample inside the sample reaction chamber (301); S2. According to the preset test sequence, execute at least two of the following conditions: spraying, soaking, and emptying transition conditions. In the spraying condition, open the spraying branch valve (203a), close the soaking branch valve (203b), and keep the electrically controlled drain valve (311) in the draining state. In the soaking condition, close the spraying branch valve (203a), open the soaking branch valve (203b), and use the upper and lower limits of the liquid level sensor (310) to achieve hysteresis control of the soaking liquid level. When switching from the soaking condition to the spraying condition, execute the sequence operation of first cutting off the soaking liquid inlet, emptying the liquid in the chamber, and then opening the spraying. S3. During each measurement cycle, the control flow path selection valve (401) selects the reference sampling branch (402) to discharge the first preset displacement volume of fluid. If the parameters to be tested meet the stability criteria, the reference measurement value is recorded; then the flow path selection valve (401) is switched to select the sampling branch (403) after the reaction, and the second preset displacement volume of fluid is discharged. Once the parameter to be tested meets the stability criterion, record the measured value after the reaction. S4. Calculate the parameter difference between the reference measurement and the post-reaction measurement; When the reference measurement value deviates from the preset allowable range, the gas mixing ratio or the liquid replenishment volume of the quantitative replenishment pump (111) should be adjusted first. When the reference measurement value is within the preset allowable range, and the parameter difference between the reference measurement value and the post-reaction measurement value exceeds the preset threshold, the liquid supply flow rate and the duration of the operating condition are adjusted, or the circulation branch (502) and the waste liquid branch (503) are switched to maintain the test operating condition.

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