An integrated experimental device for CO2-water-rock reaction and rock seepage

Abstract

This invention relates to an integrated experimental apparatus for CO2-water-rock reaction and rock seepage, comprising a carbon dioxide supply mechanism connected to the inlets of a first and second reaction vessel. The first reaction vessel is connected to a refrigeration mechanism, and the second reaction vessel is connected to a first heating mechanism. The liquid inlets of both the first and second reaction vessels are connected to a liquid injection mechanism. The bottom drains of the first and second reaction vessels are connected to the inlet of the seepage channel of a rock seepage triaxial chamber via pipes and valves. The outlet of the seepage channel is connected to a collection container placed on a weighing element. The confining pressure chamber of the rock seepage triaxial chamber is connected to a liquid injection mechanism. The rock seepage triaxial chamber is also connected to a second heating mechanism. This experimental apparatus integrates reaction and seepage experiments, reducing investment in experimental equipment.

Description

Technical Field

[0001] This invention relates to the field of geotechnical engineering experimental technology, specifically to an integrated experimental device for CO2-water-rock reaction and rock seepage. Background Technology

[0002] The statements herein provide only background information in relation to this invention and do not necessarily constitute prior art.

[0003] One of the core scientific issues in engineering technologies such as CO2 geological storage, CO2 enhanced oil recovery (EOR), and shale gas development is the interaction mechanism between CO2 and rocks and formation water in the underground environment, and the impact of this interaction on rock mechanical properties and permeability evolution. CO2 exists in four phases—gas, liquid, solid, and supercritical—under different temperatures and pressures. The physicochemical properties of CO2 in different phases differ significantly (e.g., density, viscosity, solubility), leading to orders-of-magnitude differences in its reaction pathways (dissolution, mineral transformation, pore blockage, etc.) and reaction rates with rocks. Simultaneously, the change in rock permeability after the reaction directly affects the CO2 storage efficiency and engineering safety; therefore, it is necessary to conduct a full-process experimental study of "CO2 phase regulation-reaction-seepage characteristic testing."

[0004] The existing technology has the following key drawbacks: 1. Functional fragmentation and poor experimental consistency: Most devices can only perform a single function. For example, the CO2-water-rock reaction device cannot carry out seepage experiments. When the seepage medium in the rock seepage device contains carbon dioxide, it is necessary to provide additional carbon dioxide supply mechanisms and water supply mechanisms with different phases, which increases the cost of experimental equipment.

[0005] 2. Insufficient adaptability to multiphase states: Existing reaction devices mostly focus on supercritical CO2 (deep formation conditions) and lack the ability to adapt to liquid and solid CO2 (shallow low-temperature formations or special conditions), thus failing to cover the simulation needs of all operating conditions. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the purpose of this invention is to provide an integrated experimental device for CO2-water-rock reaction and rock seepage, which can cover four phases of CO2, realize integrated reaction and seepage experiments, and reduce equipment costs.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solution: An embodiment of the present invention provides an integrated experimental apparatus for CO2-water-rock reaction and rock seepage, including a carbon dioxide supply mechanism connected to the inlet of a first reaction vessel and a second reaction vessel. The first reaction vessel is connected to a refrigeration mechanism, and the second reaction vessel is connected to a first heating mechanism. The liquid inlets of both the first and second reaction vessels are connected to a liquid injection mechanism. The bottom drain outlets of the first and second reaction vessels are connected to the inlet of the seepage channel of the rock seepage triaxial chamber through pipes and valves. The outlet of the seepage channel is connected to a collection container, which is placed on a weighing element. The confining pressure chamber of the rock seepage triaxial chamber is connected to a liquid injection mechanism, and the rock seepage triaxial chamber is also connected to a second heating mechanism.

[0008] Optionally, the carbon dioxide supply mechanism includes a carbon dioxide cylinder, the outlet of which is connected to one end of a first supply pipe, the other end of which extends into a buffer tank, and one end of a second supply pipe extending into the buffer tank. The end of the second supply pipe is provided with a first branch and a second branch. The first branch is connected to the air inlet of the first reactor, and the second branch is connected to the air inlet of the second reactor. The second supply pipe is provided with a booster pump, and the buffer tank is placed in a constant temperature cooling water bath. Furthermore, the first supply pipe is equipped with a first valve and a first pressure gauge; Furthermore, the second supply pipe is equipped with a second valve and a pressure regulating valve. Along the flow direction of carbon dioxide, the pressure regulating valve is located downstream of the booster pump. The second supply pipe is also connected to an exhaust pipe, which is equipped with a third valve. Furthermore, the constant-temperature cooling water bath is connected to a temperature detection element.

[0009] Optionally, the first branch is equipped with a fourth valve and a second pressure gauge, and the second branch is equipped with a fifth valve and a third pressure gauge.

[0010] Optionally, the refrigeration mechanism includes a refrigeration unit and a cooling medium circulation pipeline. The first reaction vessel has a double-layer jacket structure, and the internal space of the vessel wall is used to accommodate the cooling medium and is connected to the refrigeration unit through the cooling medium circulation pipeline.

[0011] Optionally, the first heating mechanism includes an electric heating jacket wrapped around the outer periphery of the second reactor. The electric heating jacket is connected to a temperature control device, and the outer periphery of the electric heating jacket is wrapped with a heat insulation layer.

[0012] Optionally, the top of the first reactor is connected to a first back pressure pipeline, which is equipped with a first back pressure valve, a fourth pressure gauge and a first exhaust valve.

[0013] Optionally, the top of the second reactor is connected to a second back pressure pipeline, which is equipped with a second back pressure valve, a fifth pressure gauge, and a second exhaust valve.

[0014] Optionally, the sidewall of the rock seepage triaxial chamber includes an inner wall and an outer wall, the second heating mechanism uses an electric heating wire wound around the outer periphery of the inner wall, and the space between the outer wall and the inner wall is filled with thermal insulation cotton.

[0015] Optionally, the outlet of the rock seepage triaxial chamber is connected to one end of the seepage liquid pipe, and the other end of the seepage pipe extends into the collection container. The seepage pipe is equipped with a third back pressure valve, a sixth pressure gauge, and a sixth valve.

[0016] Optionally, the first and second reaction vessels are placed on a movable support, and the bottom of the movable support is equipped with multiple casters.

[0017] The beneficial effects of this invention are as follows: The experimental apparatus of this invention comprises a first reaction vessel and a second reaction vessel, both capable of holding rock samples. The first reaction vessel is connected to a refrigeration mechanism, and the second reaction vessel is connected to a first heating mechanism. Both reaction vessels are connected to a liquid injection mechanism. The second reaction vessel enables experiments on the reaction of gaseous and supercritical carbon dioxide with water and rock, while the first reaction vessel enables experiments on the reaction of liquid and solid carbon dioxide with water and rock. This allows the entire experimental apparatus to cover formations from shallow low-temperature strata (<1000 m) to deep high-temperature strata (>5000 m). The full-condition simulation requirement of m) solves the technical bottleneck that the existing device can only adapt to a single phase, and improves the applicability of the entire experimental device. The bottom drain ports of the first and second reaction vessels are connected to the inlet of the seepage channel of the rock seepage triaxial chamber through pipelines and valves. Since the first and second reaction vessels are connected to the carbon dioxide supply mechanism, the first and second reaction vessels can provide carbon dioxide or liquid of different phases into the seepage channel of the seepage triaxial chamber for seepage experiments. There is no need to provide additional carbon dioxide supply mechanism and water supply mechanism. The carbon dioxide-water-rock reaction experiments of different phases and the seepage experiment can share a set of carbon dioxide supply mechanism and liquid injection mechanism, which reduces the cost of experimental equipment. Attached Figure Description

[0018] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0019] Figure 1 This is a schematic diagram of the overall structure of Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the internal structure of the triaxial chamber for rock seepage in Embodiment 1 of the present invention; The components include: 1. Carbon dioxide cylinder; 2. Flexible electric heating jacket; 3. Constant temperature cooling water bath; 4. Buffer tank; 5. Booster pump; 6. First reaction vessel; 7. Refrigeration unit; 8. Second reaction vessel; 9. First heating mechanism; 10. Liquid constant flow injection pump; 11. Rock seepage triaxial chamber; 12. Water injection pressure pump; 13. Collection bottle; 14. Pressure regulating valve; 15. First back pressure valve; 16. Second back pressure valve; 17. Third back pressure valve; 18. First thermometer; 19. Second thermometer; 20. Third thermometer; 21. Fourth thermometer; 22. First pressure gauge; 23. Second pressure gauge; 24. Third pressure gauge; 25. Fourth pressure gauge; 26. Fifth pressure gauge; 27. Eighth pressure gauge. 28. Ninth pressure gauge, 29. Sixth pressure gauge, 30. First valve, 31. Second valve, 32. Third valve, 33. Fourth valve, 34. Fifth valve, 35. First vent valve, 36. Second vent valve, 37. First drain valve, 38. Second drain valve, 39. Ninth valve, 40. Tenth valve, 41. Seventh valve, 42. Eighth valve, 43. Eleventh valve, 44. Third drain valve, 45. Sixth valve, 46. Electronic balance, 47. Rock sample, 48. Silicone heat shrink tubing, 49. Rock sample holder, 50. Inlet, 51. Outlet, 52. Seepage channel, 53. Confining pressure water outlet, 54. Confining pressure water inlet, 55. Confining pressure chamber, 56. Electric heating wire. Detailed Implementation

[0020] Example 1 This embodiment provides an integrated experimental device for CO2-water-rock reaction and rock seepage, such as... Figures 1-2 As shown, the system includes a carbon dioxide supply mechanism, a first reaction vessel 6, a second reaction vessel 8, a rock seepage triaxial chamber 11, and a liquid injection mechanism. The first reaction vessel 6 is connected to a refrigeration mechanism that cools the medium inside the first reaction vessel 6. The second reaction vessel 8 is connected to a first heating mechanism that heats the medium inside the second reaction vessel 8. The drain ports of the first reaction vessel 6 and the second reaction vessel 8 are connected to the inlet of the seepage channel of the rock seepage triaxial chamber 11. The outlet of the seepage channel is connected to one end of the seepage pipe, and the other end of the seepage pipe extends into the inside of a collection container, which is placed on a weighing element. The inlets of the first reaction vessel 6 and the second reaction vessel 8 are connected to the liquid injection mechanism, which injects water for the reaction into the first reaction vessel 6 and the second reaction vessel 8.

[0021] The carbon dioxide supply mechanism includes a carbon dioxide cylinder 1, which is used to fill carbon dioxide. The outlet of the carbon dioxide cylinder is connected to one end of a first supply pipe. The other end of the first supply pipe extends into a buffer tank 4. One end of a second supply pipe extends into the buffer tank 4. The end of the second supply pipe is provided with a first branch and a second branch. The first branch is connected to the air inlet of the first reactor 6, and the second branch is connected to the air inlet of the second reactor 8. The second supply pipe is equipped with a booster pump 5. The buffer tank 4 is placed in a constant temperature cooling water bath 3.

[0022] In this embodiment, carbon dioxide cylinder 1 is a 40L high-pressure cylinder with a rated pressure of 15MPa, used to store liquid carbon dioxide. The outlet of carbon dioxide cylinder 1 is equipped with a pressure reducing valve with a built-in filter. The filter has a filtration accuracy of 5µm to prevent impurities from entering subsequent pipelines. Existing equipment can be used for the pressure reducing valve, and its specific structure will not be described in detail here.

[0023] The carbon dioxide cylinder 1 is surrounded by a heating element. In this embodiment, the heating element is an existing flexible electric heating sleeve 2, which is wrapped around the carbon dioxide cylinder 1. The heating power is adjustable from 0 to 2 kW, and the heating temperature range is 0 to 100°C. The carbon dioxide cylinder 1 is connected to a first thermometer 18, which monitors the heating temperature in real time to achieve a pre-pressure of 8-10 MPa inside the carbon dioxide cylinder 1. The core function of pre-pressure is to increase the inlet pressure of the booster pump 5, avoid cavitation in the booster pump 5, and improve the boosting efficiency (the boosting time is shortened by 30% after pre-pressure).

[0024] The flexible electric heating jacket 2 can be made using existing equipment, and its specific structure will not be described in detail here.

[0025] The booster pump 5 adopts an existing dual-plunger high-pressure pump with a displacement of 5 L / min, a maximum output pressure of 25 MPa, and a pressure regulation accuracy of ±0.1 MPa. The booster pump 5 has a built-in pressure sensor and PID controller. When the outlet pressure reaches the set value, it automatically switches to the pressure holding mode, with pressure fluctuation ≤ ±0.1 MPa. The booster pump 5 is equipped with a water-cooling system to ensure that there is no overheating phenomenon during continuous operation for more than 8 hours, and supports dual control by local buttons and remote computer.

[0026] The first supply pipe is equipped with a first valve 30 and a first pressure gauge 22. Along the flow direction of carbon dioxide, the first pressure gauge 22 is located downstream of the first valve 30.

[0027] The first valve 30 can be an existing on / off valve, used to control the opening and closing of the first supply pipe, and the first pressure gauge 22 is used to detect the pressure of carbon dioxide in the first supply pipe.

[0028] Along the flow direction of carbon dioxide, the second supply pipe is sequentially equipped with a second valve 31, a booster pump 5, and a pressure regulating valve 14.

[0029] The second valve 31 can be an existing on / off valve, used to control the opening and closing of the second supply pipe. The pressure regulating valve 14 is used to regulate the carbon dioxide injection pressure, with an adjustment range of 0-25 MPa and an accuracy of ±0.1 MPa.

[0030] The second supply pipe is also connected to an exhaust pipe, which is equipped with a third valve 32. The third valve 32 can be an existing on / off valve, used to control the opening and closing of the exhaust pipe.

[0031] The constant temperature cooling water bath 3 can use existing equipment, and its specific structure will not be described in detail here. In this embodiment, the constant temperature cooling water bath 3 adopts a dual mode of compressor cooling + electric heating, with a temperature control range of -10℃ to 100℃ and a temperature control accuracy of ±1℃. The bath volume is 15 L, and it has a built-in stirrer (speed adjustable from 0-500 rpm) to ensure uniform temperature in the bath. The bath is equipped with a liquid level sensor, which automatically alarms when the liquid level is low to prevent dry burning. At the same time, the bath is also equipped with a temperature detection element, which is a second thermometer 19, used to detect the temperature of the constant temperature cooling water bath 3.

[0032] The buffer tank 4 is made of Hastelloy-C material with an effective volume of 5 L, which enables sufficient temperature exchange of CO2. The top of the buffer tank 4 is equipped with a seventh pressure gauge (measuring range 0-30 MPa, accuracy ±0.25% FS) and a safety valve (starting pressure 28MPa) to ensure equipment safety. The bottom is equipped with a drain valve for easy periodic cleaning of impurities.

[0033] The seventh pressure gauge is used to detect the pressure of carbon dioxide in buffer tank 4.

[0034] The second supply pipe has two branches at its end, namely a first branch and a second branch. The end of the first branch is connected to the air inlet at the top of the first reactor 6, and the end of the second branch is connected to the air inlet at the top of the second reactor 8.

[0035] Along the flow direction of carbon dioxide, the first branch is provided with a fourth valve 33 and a second pressure gauge 23. The fourth valve 33 can be an existing on / off valve, used to control the opening and closing of the first branch, and the second pressure gauge 23 is used to detect the pressure of carbon dioxide in the first branch.

[0036] Along the flow direction of carbon dioxide, the second branch is provided with a fifth valve 34 and a third pressure gauge 24. The fifth valve 34 can be an existing on / off valve, used to control the opening and closing of the second branch. The third pressure gauge 24 is used to detect the pressure of carbon dioxide in the second branch.

[0037] Both the first reactor 6 and the second reactor 8 include a reactor body, with a lid on the top of the reactor body. The reactor body and lid are made of Hastelloy-C. The effective volume of the reactor body is 5L. The lid is equipped with an air inlet, a liquid inlet, and a safety valve interface. The bottom of the reactor body is equipped with a drain outlet and a sludge outlet. The lid and the top of the reactor body are connected by a flange, and the flanges are sealed with a metal spiral wound gasket with a sealing pressure ≥30 MPa. It is equipped with a sapphire observation window (transmittance ≥95%), which allows for real-time observation of the reaction process.

[0038] The first reactor 6 is a low-temperature high-pressure reactor with a design pressure of 30MPa, an operating pressure of 0-25MPa, an operating temperature of -100℃-20℃, and a temperature control accuracy of ±1℃. It is used to realize the reaction between liquid CO2 (temperature -56.6-31.1℃, pressure ≥5.18MPa) and solid CO2 (temperature ≤-56.6℃) and rock.

[0039] The first reactor 6 is connected to the refrigeration mechanism. Specifically, the side wall of the first reactor 6 adopts a double-layer jacket mechanism, with an inner layer and an outer layer. A space for accommodating the cooling medium is provided between the inner and outer layers. This space is connected to the refrigeration unit 7 through a cooling medium circulation pipeline. The cooling medium circulation pipeline and the refrigeration unit 7 together constitute the refrigeration mechanism.

[0040] The cooling medium circulation pipeline can circulate within the refrigeration unit 7 and the internal space of the side wall of the reactor body, thereby cooling the interior of the first reactor 6.

[0041] The refrigeration unit 7 can use existing refrigeration equipment. In this embodiment, the refrigeration unit 7 adopts two-stage compression refrigeration technology, with a cooling capacity of 5 kW, a minimum cooling temperature of -100℃, and a temperature control accuracy of ±1℃. Existing equipment can be used, and its specific structure will not be described in detail here.

[0042] Preferably, the cooling medium is an aqueous solution of ethylene glycol, which is circulated to ensure uniform temperature inside the first reaction vessel.

[0043] The second reactor 8 is a high-temperature and high-pressure reactor with a design pressure of 30 MPa, an operating pressure of 0-25 MPa, an operating temperature range of 20℃~200℃, and a temperature control accuracy of ±1℃. It is used to realize the reaction of gaseous CO2 (temperature ≥31.1℃, pressure <7.38 MPa) and supercritical CO2 (temperature ≥31.1℃, pressure ≥7.38 MPa) with rocks.

[0044] The second reactor 8 is connected to the first heating mechanism 9, which can heat the medium inside the second reactor 8.

[0045] Specifically, the first heating mechanism 9 is an electric heating jacket wrapped around the outer periphery of the second reaction vessel 8. The electric heating jacket has a power of 5 kW and an adjustable heating rate of 0-10℃ / min. It is equipped with an overheat protection device (automatic power-off when the temperature exceeds 20℃). Existing equipment can be used for the electric heating jacket, which will not be described in detail here. The electric heating jacket is connected to a temperature control device, which can adjust the power of the electric heating jacket to control the heating temperature. Existing equipment can be used for the temperature controller, which supports PID regulation and temperature fluctuation ≤ ±1℃. Its specific structure will not be described in detail here.

[0046] The outer periphery of the electric heating jacket is wrapped with an insulation layer. Preferably, the insulation layer is made of ceramic fiber (with an insulation effect of not less than 80%) to reduce heat loss.

[0047] Furthermore, the first reactor 6 is equipped with a third thermometer 20 for displaying the internal temperature of the first reactor 6, and a fourth thermometer 21 is connected to the second reactor 8 for detecting the internal temperature of the second reactor 8.

[0048] The safety valve interface on the top of the lid of the first reactor 6 is connected to a first back pressure pipeline, and a first back pressure valve 15, a fourth pressure gauge 25 and a first exhaust valve 35 are sequentially installed on the first back pressure pipeline.

[0049] The first back pressure valve 15 is a needle valve used to stabilize the internal pressure of the first reaction vessel 6 and avoid pressure fluctuations from affecting the experimental results. The fourth pressure gauge 25 is used to detect the pressure in the first back pressure pipeline.

[0050] The safety valve interface of the lid of the second reactor 8 is connected to a second back pressure pipeline, which is equipped with a second back pressure valve 16, a fifth pressure gauge 26 and a second exhaust valve 36.

[0051] The second back pressure valve 16 is a needle valve used to stabilize the internal pressure of the second reaction vessel 8 and avoid pressure fluctuations from affecting the experimental results. The fifth pressure gauge 26 is used to detect the pressure in the second back pressure pipeline.

[0052] The liquid inlets of the lids of the first reactor 6 and the second reactor 8 are both connected to the liquid injection mechanism via pipelines. In this embodiment, the liquid injection mechanism adopts a constant flow injection pump 10. The constant flow injection pump 10 is a dual plunger constant flow pump with a flow rate adjustment range of 0.1-100 ml / min, a rated working pressure of 25 MPa, a flow accuracy of ≤±0.5% FS, and a repeatability error of ≤±0.2%. The liquid beam injection pump 10 can use existing equipment and is equipped with a touch screen, which can set parameters such as flow rate, injection volume, and injection time. It supports both continuous injection and intermittent injection modes. The pump head is made of Hastelloy-C, which has strong corrosion resistance and is suitable for various liquid working fluids such as acids and alkalis. Its further specific structure will not be described in detail here.

[0053] A ninth valve 39 is installed on the pipeline between the first reactor 6 and the liquid constant flow injection pump 10 to control the opening and closing of the pipeline, and a tenth valve 40 is installed on the pipeline between the second reactor 8 and the liquid constant flow injection pump 10 to control the opening and closing of the pipeline.

[0054] The bottom drain of the first reactor 6 is connected to the inlet 50 of the seepage channel 52 of the rock seepage triaxial chamber 11 through the first drain pipe, and the bottom drain of the second reactor 8 is connected to the inlet 50 of the seepage channel 52 of the rock seepage triaxial chamber 11 through the second drain pipe.

[0055] Specifically, the first and second drainage pipes converge and are connected to the inlet 50 of the seepage channel 52 of the rock seepage triaxial chamber 11.

[0056] The section of the pipeline where the first and second drainage pipelines converge is equipped with an eighth pressure gauge 27, used to detect seepage pressure.

[0057] The first drain line is equipped with a seventh valve 41, and the second drain line is equipped with an eighth valve 42. Both the seventh valve 41 and the eighth valve 42 can be existing on / off valves, which will not be described in detail here.

[0058] Furthermore, the bottom drain port of the first reactor 6 is connected to a first drain pipe, and the first drain pipe is equipped with a first drain valve 37. The bottom drain port of the second reactor 8 is connected to a second drain pipe, and the second drain pipe is equipped with a second drain valve 38.

[0059] The rock seepage triaxial chamber 11 is made of Hastelloy-C, and the size of the rock sample chamber is adapted to standard rock samples of Φ50×100 mm (custom sizes such as Φ25×50 mm and Φ75×150 mm are supported). The rock seepage triaxial chamber 11 is equipped with a rock sample holder 49. The rock sample holder 49 can be made using existing equipment, and its specific structure will not be described in detail here.

[0060] The rock sample holder 49 is provided with a channel. After the rock sample holder clamps and fixes the rock sample 47, the channel inside it and the seepage gap inside the rock sample 47 together form a seepage channel. The channel of the top rock sample holder 47 is connected to the outlet end of the pipeline after the first drain pipe and the second drain pipe are combined, and the channel of the bottom rock sample holder 49 is connected to one end of the seepage pipeline.

[0061] Inside the rock seepage triaxial chamber 11, the space surrounding the rock sample area is used as a confining pressure chamber 55 to apply confining pressure to the rock sample 47.

[0062] The sidewall of the rock seepage triaxial chamber 11 also adopts a double-layer jacket structure, including an inner wall and an outer wall, with a space between the inner wall and the outer wall. The outer surface of the inner wall is provided with a second heating mechanism, which is used to heat the internal space of the rock seepage triaxial chamber 11.

[0063] In this embodiment, the second heating mechanism uses an electric heating wire 56 wound around the outer surface of the inner wall. The electric heating wire 56 is connected to a temperature control device, which controls its operation.

[0064] In this embodiment, the internal temperature of the rock seepage triaxial chamber 11 is controlled to be 20℃-200℃ by the electric heating wire 56. A fourth thermometer is connected to the confining pressure chamber to detect its internal temperature. The confining pressure control range of the confining pressure chamber 55 is 0-25 MPa, and the osmotic pressure control range of the seepage channel 52 is 0-25 MPa. The adjustment accuracy of both is ±0.1 MPa.

[0065] The bottom of the rock seepage triaxial chamber 11 is provided with a drain outlet, and a third drain pipe is provided at the drain outlet. The third drain pipe is provided with a third drain valve 44.

[0066] The confining pressure chamber 55 is connected to the liquid injection mechanism through the confining pressure water inlet 54, the confining pressure water outlet 53 and the circulation pipeline. The liquid injection mechanism adopts the water injection pressure pump 12, which is used to inject water into the confining pressure chamber 55 to provide confining pressure.

[0067] In this embodiment, the water injection pressure pump 12 adopts an existing manual water injection pressure pump. The manual water injection pressure pump has a maximum output pressure of 25 MPa and a volume of 20 L. It is used for confining pressure control and adjustment, with an adjustment accuracy of ±0.1 MPa. The manual water injection pressure pump is equipped with a pressure relief valve to ensure safe operation.

[0068] Furthermore, a ninth pressure gauge 28 and an eleventh valve 43 are sequentially installed on the pipeline between the water injection pressure pump 12 and the confining pressure chamber 55. The ninth pressure gauge 28 is used to detect the water injection pressure of the water injection pressure pump 12, and the eleventh valve 43 is used to control the connection and disconnection of the pipeline between the water injection pressure pump 12 and the confining pressure chamber 55.

[0069] The seepage pipe is equipped with a third back pressure valve 17, a sixth pressure gauge 29, and a sixth valve 45. By adjusting the third back pressure valve 17, the seepage pressure difference can be controlled, thereby calculating the permeability of the rock sample. The sixth pressure gauge 29 is used to detect the pressure of the seepage medium in the seepage pipe. The sixth valve 45 can be an existing on / off valve, used to control the opening and closing of the seepage pipe.

[0070] The inlet end of the seepage pipe is connected to the outlet 51 of the seepage channel 52, and the outlet end of the seepage pipe extends into the inside of the collection container. In this embodiment, the collection container is a collection bottle 13 with a volume of 1 L. The bottle mouth is equipped with a sealing cap to facilitate the composition analysis of the fluid after the reaction and the preservation of the sample.

[0071] The collection bottle is placed on a weighing element. In this embodiment, the weighing element is an electronic balance 46 (range 5 kg, accuracy ±0.01 g). The seepage flow rate is calculated in real time by the weight change of the collection bottle 13.

[0072] In this embodiment, all pressure gauges are strain gauge pressure sensors with a measurement range of 0-30 MPa, an accuracy of ±0.25% FS, and an output signal of 4-20 mA, supporting long-distance transmission.

[0073] All thermometers use PT100 platinum resistance sensors, with a measurement accuracy of ±0.1℃ and a response time of ≤1s, ensuring real-time temperature data.

[0074] Both the pressure gauge and thermometer are connected to an industrial-grade data acquisition card with an adjustable acquisition frequency of 1-10 Hz. It supports simultaneous acquisition of 8 pressure signals and 4 temperature signals. The data acquisition software is compatible with Windows systems and features real-time display, curve plotting, data storage, export, and alarm functions. Over-temperature (±5℃) and over-pressure (±1 MPa) alarm thresholds can be set, and the alarm method is audible and visual alarm.

[0075] In this embodiment, all pipelines are made of Hastelloy-C tubing with a pressure resistance ≥30 MPa. All valves, including exhaust valves and drain valves, are shut-off needle valves with Hastelloy-C stems and hardened sealing surfaces with a hardness ≥HRC55 and a service life ≥10,000 opening and closing cycles. The valve operating torque is ≤5 N·m, facilitating manual control. The sealing components are made of PTFE-reinforced composite material (with added carbon fiber), with a temperature range of -100-250℃, a pressure resistance ≥30 MPa, and good corrosion resistance, making them suitable for media such as CO2 and carbonic acid.

[0076] Furthermore, the first reactor 6 and the second reactor 8 are placed on a movable support for easy transfer. The movable support is an aluminum alloy support made of 6061-T6 aluminum alloy with a load-bearing capacity of ≥500 kg. The bottom of the movable support is equipped with four casters (with brake function) that can rotate 360°, facilitating equipment handling and laboratory layout adjustments.

[0077] The booster pump 5 and the refrigeration unit 7 are equipped with stainless steel protective housings. The stainless steel protective housings have ventilation openings and observation windows, which not only protect the equipment from collisions, but also facilitate the observation of the operating status.

[0078] Both the reactor and the rock seepage triaxial chamber 11 are equipped with drain ports and inspection ports to facilitate internal cleaning and maintenance. Deposited impurities and accumulated liquids are periodically discharged through the drain ports.

[0079] Safety measures include equipping the unit with a main power switch, emergency stop button, safety valve, and other safety facilities. All high-pressure components have undergone hydrostatic testing (test pressure 37.5 MPa, pressure held for 30 minutes without leakage), which meets the requirements of the "TSG 21-2016 Safety Technical Supervision Regulations for Fixed Pressure Vessels".

[0080] The method for conducting the supercritical carbon dioxide-water-rock reaction and seepage coupling experiment (simulating deep strata) using the experimental apparatus of this embodiment includes the following steps: Step 1: Experimental preparation.

[0081] Rock sample selection: Select rocks from deep strata, process them into standard rock samples of Φ50×100 mm, dry them to constant weight (105℃, 24 hours), and measure the initial porosity and permeability; Device inspection: Check whether all pipeline connections are secure, whether the seals are intact, and whether the data acquisition system is functioning properly; inject ethylene glycol aqueous solution into the constant temperature cooling water bath 3, and inject simulated formation water into the liquid constant flow injection pump 10; Rock sample installation: Place the dried rock sample 47 into the second reaction vessel 8, and connect the vessel body and the vessel cover using a flange; take another identical rock sample 47 and place it on the rock sample holder 49 of the rock flow triaxial chamber 11. Use silicone heat shrink tubing 48 to completely wrap the rock sample 47 and the rock sample holder 49 at both ends, and use a hot air gun to heat and shrink the silicone heat shrink tubing 48 until the silicone heat shrink tubing 48 completely wraps and surrounds the rock sample 47 and fixes it. Tighten the sealing cover of the rock flow triaxial chamber 11, and inject distilled water into the confining pressure chamber 55 through the water injection pressure pump 12 to pre-apply a confining pressure of 5 MPa.

[0082] Step 2: Device preheating and parameter setting Start the first heating mechanism 9, set the temperature of the second reactor 8 to 80℃ (supercritical CO2 critical temperature 31.1℃), start the second heating mechanism of the rock seepage triaxial chamber 11, set the temperature to 80℃, and keep the temperature constant for 30 minutes to ensure temperature stability; Set the data acquisition frequency to 5 Hz, the over-temperature alarm threshold to 85℃, and the over-pressure alarm threshold to 18 MPa. The target pressure of booster pump 5 is set to 15 MPa (the critical pressure of supercritical CO2 is 7.38 MPa), the flow rate of liquid constant flow injection pump 10 is 10 ml / min, and the injection volume is 1.5 L (30% of the reactor volume).

[0083] Step 3: Carbon dioxide supply and phase regulation Open the pressure reducing valve of carbon dioxide cylinder 1, start the flexible electric heating jacket 2, set the heating temperature to 60℃, and raise the pressure inside carbon dioxide cylinder 1 to 9 MPa. Open the first valve 30 and the second valve 31. After the CO2 is buffered by the buffer tank 4 (the constant temperature cooling water bath 3 is set at 25°C), it enters the booster pump 5. Start the booster pump 5 to pressurize CO2 to 15 MPa. After stabilizing the pressure through the pressure regulating valve 14, inject it into the second reactor 8. Open the second exhaust valve 36 of the second reactor 8 to replace the air in the reactor for 5 minutes, and then close the second exhaust valve to maintain the pressure in the reactor at 15 MPa and the temperature at 80℃, so that CO2 is in a supercritical state.

[0084] Step 4: CO2-water-rock reaction experiment Turn on the liquid constant flow injection pump 10 and the tenth valve 40 to inject simulated formation water into the second reactor 8. After the injection volume is 1.5 L, close the tenth valve 40 and stop the liquid constant flow injection pump 10. Maintain the temperature of the second reactor 8 at 80℃ and the pressure at 15 MPa for 72 hours. The data acquisition system records the changes in pressure and temperature inside the reactor in real time.

[0085] Step 5: Percolation Coupling Experiment After the reaction is completed, open the eighth valve 42 between the second reactor 8 and the rock seepage triaxial chamber 11, and adjust the confining pressure of the rock seepage triaxial chamber 11 to 10 MPa and the osmotic pressure to 8 MPa. Start the liquid constant flow injection pump 10, inject simulated formation water into the seepage channel 52 through the eighth valve 42, set the flow rate to 5 ml / min, record the weight change through the electronic balance 46 corresponding to the collection bottle 13, and calculate the seepage pressure difference and rock permeability. During the experiment, the seepage pressure, confining pressure and temperature of the rock seepage triaxial chamber 11 were monitored in real time, and the data were recorded continuously for 24 hours.

[0086] Step 6: Experiment ends.

[0087] Turn off the first heating mechanism 9 and the data acquisition system, and slowly open each back pressure valve and exhaust valve to depressurize to normal pressure. The fluid in the second reaction vessel 8 and the rock seepage triaxial chamber 11 was discharged, the rock sample was taken out, the porosity and permeability after the reaction were measured, and the effect of the supercritical CO2-water-rock reaction on the rock properties was analyzed.

[0088] Understandably, the rock sample 47 after reaction in the second reaction vessel 8 can also be installed in the rock seepage triaxial chamber 11 to conduct a seepage experiment after reaction.

[0089] After the reacted rock sample 47 is installed in the rock seepage triaxial chamber 11, liquid carbon dioxide can be introduced into the seepage channel using the first reaction vessel 6 to conduct a liquid carbon dioxide seepage experiment on the rock sample 47.

[0090] The specific steps for conducting the second solid CO2-water-rock reaction experiment (simulating shallow low-temperature formation conditions) using the experimental apparatus of this embodiment are as follows: Step a: Experimental preparation Rock samples from shallow strata were selected, processed into standard rock samples of Φ50×100 mm, dried to constant weight, and initial parameters were measured. Refrigerant is injected into refrigeration unit 7, and distilled water is injected into liquid constant flow injection pump 10; Rock sample 47 was placed into the first reaction vessel 6, and the vessel body and lid of the first reaction vessel 6 were sealed and connected.

[0091] Step b: Pre-cooling and parameter setting of the device Start the refrigeration unit 7, set the temperature of the first reactor 6 to -60℃ (below the sublimation temperature of solid CO2 -56.6℃), and maintain the temperature for 30 minutes; Set the target pressure of booster pump 5 to 5 MPa, the flow rate of liquid constant flow injection pump 10 to 5 ml / min, and the injection volume to 500 ml.

[0092] Step c: CO2 supply and phase regulation Open carbon dioxide cylinder 1 and fourth valve 33 to inject CO2 into first reactor 6, control the injection pressure to 5 MPa, and CO2 condenses into solid at -60℃; Close the fourth valve 33 and maintain the temperature inside the first reactor 6 at -60℃ and the pressure at 5 MPa for 1 hour.

[0093] Step d: CO2-water-rock reaction experiment Turn on the liquid constant flow injection pump 10 and the ninth valve 39, inject 500 ml of distilled water into the first reaction vessel 6, and then close the ninth valve 39; Maintain the reaction conditions (-60℃, 5 MPa) for 48 hours, and monitor pressure and temperature changes in real time.

[0094] Step e: End of experiment Slowly raise the temperature of refrigeration unit 7 to room temperature (20℃-30℃) to allow solid CO2 to sublimate, open the first exhaust valve 35, and slowly depressurize; Fluid is discharged through the drain port of the first reaction vessel 6, rock samples are taken out, and the reaction products (such as carbonate minerals) and changes in the microstructure of the rock are analyzed.

[0095] Using the experimental setup of this embodiment, comparative experiments on the effects of different phases of carbon dioxide on rock permeability can also be conducted. The specific steps are as follows: Reactions of gaseous CO2 (25℃, 5 MPa), liquid CO2 (0℃, 6 MPa), solid CO2 (-60℃, 5 MPa), and supercritical CO2 (80℃, 15 MPa) with the same batch of rock samples were conducted using Experiment 1 and Experiment 2, respectively. Subsequently, the reacted rock sample 47 was placed in the rock seepage triaxial chamber 11 for seepage testing. The changes in rock permeability after the reaction of different phases of CO2 were compared to provide data support for optimizing the working conditions of CO2 geological sequestration.

[0096] Using the experimental setup of this embodiment, comparative experiments can also be conducted on the effects of single-phase CO2 on rock permeability under different temperatures, seepage pressure gradients, and confining pressures. The specific steps are as follows: Using the experimental procedures of Examples 1 and 2, a reaction experiment was conducted between a certain phase of CO2 and the same batch of rock samples. Subsequently, rock seepage coupling tests were carried out under different temperatures, seepage pressure gradients, and confining pressures. The permeability variation of the rock after the reaction of a single phase of CO2 under different working conditions was compared, providing data support for optimizing the working conditions of CO2 geological storage.

[0097] Using the experimental setup of this embodiment, the second reactor 8 enables the reaction experiments of gaseous and supercritical carbon dioxide with water and rock, while the first reactor 6 enables the reaction experiments of liquid and solid carbon dioxide with water and rock. Through the synergistic design of low-temperature (-100-20℃) and high-temperature (20℃-200℃) reactors, combined with a pressure control range of 0-25 MPa, the entire experimental setup covers formations from shallow low-temperature strata (<1000 m) to deep high-temperature strata (>5000 m). The full-condition simulation requirement of m) solves the technical bottleneck that the existing device can only adapt to a single phase, and improves the applicability of the entire experimental device. The bottom drain ports of the first reactor 6 and the second reactor 8 are connected to the inlet of the seepage channel 52 of the rock seepage triaxial chamber 11 through pipelines and valves. Since the first reactor 6 and the second reactor 7 are connected to the carbon dioxide supply mechanism and the liquid injection mechanism, the first reactor 6 and the second reactor 8 can provide carbon dioxide or water of different phases into the seepage channel of the rock seepage triaxial chamber 11 for seepage experiments. There is no need to provide additional carbon dioxide supply mechanism and water supply mechanism. The carbon dioxide-water-rock reaction experiment and seepage experiment of different phases can share a set of carbon dioxide supply mechanism and liquid injection mechanism, which reduces the cost of experimental equipment.

[0098] In this embodiment, the reactor and all pipelines are made of Hastelloy-C material, which is resistant to CO2 and carbonic acid corrosion and has a service life of ≥8 years. Switching between operating conditions only requires operating the corresponding valves, without the need for complex pipeline modifications. The design of movable supports, inspection ports, and drain ports facilitates equipment handling and maintenance, and the maintenance time for a single operation is ≤1 hour.

[0099] The experimental setup in this embodiment has strong data traceability: the liquid injection flow rate accuracy reaches 0.1 ml / min, the pressure control accuracy is ±0.1 MPa, and the temperature control accuracy is ±1℃, which is far higher than the parameter accuracy of existing devices; the data acquisition system supports high-frequency acquisition and full-process recording of 1-10 Hz, and the raw data can be exported for subsequent analysis, with an experimental result reproducibility rate of ≥95%.

[0100] The experimental apparatus in this embodiment is highly adaptable and applicable to a wide range of scenarios: it supports rock samples of various sizes, such as Φ50×100 mm, and is suitable for different types of rocks, such as sandstone, shale, and limestone; the liquid working medium can be simulated formation water, distilled water, chemical reagents, etc., and the gaseous working medium can be replaced with N2, CH4, etc., making it suitable for experimental research in multiple fields such as CO2 geological storage, EOR, shale gas development, and nuclear waste disposal.

[0101] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An integrated experimental apparatus for CO2-water-rock reaction and rock seepage, characterized in that, It includes a carbon dioxide supply mechanism, which is connected to the air inlets of the first and second reactors. The first reactor is connected to a refrigeration mechanism, and the second reactor is connected to a first heating mechanism. The liquid inlets of both the first and second reactors are connected to a liquid injection mechanism. The bottom drain outlets of the first and second reactors are connected to the inlet of the seepage channel of the rock seepage triaxial chamber through pipelines and valves. The outlet of the seepage channel is connected to a collection container, which is placed on a weighing element. The confining pressure chamber of the rock seepage triaxial chamber is connected to a liquid injection mechanism. The rock seepage triaxial chamber is also connected to a second heating mechanism.

2. The integrated experimental apparatus for CO2-water-rock reaction and rock seepage as described in claim 1, characterized in that, The carbon dioxide supply mechanism includes a carbon dioxide cylinder, the outlet of which is connected to one end of a first supply pipe, the other end of which extends into a buffer tank, and one end of a second supply pipe extending into the buffer tank. The end of the second supply pipe is provided with a first branch and a second branch. The first branch is connected to the air inlet of the first reactor, and the second branch is connected to the air inlet of the second reactor. The second supply pipe is equipped with a booster pump, and the buffer tank is placed in a constant temperature cooling water bath. Furthermore, the first supply pipe is equipped with a first valve and a first pressure gauge; Furthermore, the second supply pipe is equipped with a second valve and a pressure regulating valve. Along the flow direction of carbon dioxide gas, the pressure regulating valve is located downstream of the booster pump. The second supply pipe is also connected to an exhaust pipe, which is equipped with a third valve. Furthermore, the constant-temperature cooling water bath is connected to a temperature detection element.

3. The integrated experimental apparatus for CO2-water-rock reaction and rock seepage as described in claim 1, characterized in that, The first branch is equipped with a fourth valve and a second pressure gauge, and the second branch is equipped with a fifth valve and a third pressure gauge.

4. The integrated experimental apparatus for CO2-water-rock reaction and rock seepage as described in claim 1, characterized in that, The refrigeration mechanism includes a refrigeration unit and a cooling medium circulation pipeline. The first reaction vessel has a double-layer jacket structure, and the internal space of the vessel wall is used to contain the cooling medium and is connected to the refrigeration unit through the cooling medium circulation pipeline.

5. The integrated experimental apparatus for CO2-water-rock reaction and rock seepage as described in claim 1, characterized in that, The first heating mechanism includes an electric heating jacket wrapped around the outer periphery of the second reactor. The electric heating jacket is connected to a temperature control device, and the outer periphery of the electric heating jacket is wrapped with a heat insulation layer.

6. The integrated experimental apparatus for CO2-water-rock reaction and rock seepage as described in claim 1, characterized in that, The top of the first reactor is connected to a first back pressure pipeline, which is equipped with a first back pressure valve, a fourth pressure gauge and a first exhaust valve.

7. The integrated experimental apparatus for CO2-water-rock reaction and rock seepage as described in claim 1, characterized in that, The top of the second reactor is connected to a second back pressure pipeline, which is equipped with a second back pressure valve, a fifth pressure gauge, and a second exhaust valve.

8. The integrated experimental apparatus for CO2-water-rock reaction and rock seepage as described in claim 1, characterized in that, The sidewall of the rock seepage triaxial chamber includes an inner wall and an outer wall. The second heating mechanism uses an electric heating wire wound around the outer periphery of the inner wall. The space between the outer wall and the inner wall is filled with thermal insulation cotton.

9. The integrated experimental apparatus for CO2-water-rock reaction and rock seepage as described in claim 1, characterized in that, The outlet of the rock seepage triaxial chamber is connected to one end of the seepage liquid pipe, and the other end of the seepage pipe extends into the collection container. The seepage pipe is equipped with a third back pressure valve, a sixth pressure gauge, and a sixth valve.

10. The integrated experimental apparatus for CO2-water-rock reaction and rock seepage as described in claim 1, characterized in that, The first and second reaction vessels are placed on a movable support, and the bottom of the movable support is equipped with multiple casters.

Images