An experimental device and experimental method for simulating dynamic imbibition of shale oil reservoir in-situ environment

Abstract

The application discloses an experimental device and an experimental method for simulating dynamic imbibition of shale oil reservoirs in situ environment, and belongs to the technical field of reservoir exploration and development. The experimental device comprises a fluid supply system, an imbibition kettle body, an environment simulation system, an in-situ monitoring system and a control system. The fluid supply system comprises sequentially communicated liquid supply units, pumping units and multi-way valve units. The liquid supply units are used for storing initial displacement fluids. The pumping units are used for providing displacement power. The multi-way valve units can selectively communicate different intermediate containers to provide different experimental fluids. The imbibition kettle body is provided with a clamping mechanism for clamping and fixing shale cores. The environment simulation system is used for heating and pressurizing the inside of the imbibition kettle body. The in-situ monitoring system comprises an imbibition front monitoring unit and a mass change monitoring unit. The experimental method adopts the above experimental device to realize dynamic imbibition experiments in simulated real reservoir environment, and improves the reliability of experimental results.

Description

Technical Field

[0001] This invention relates to the field of oil reservoir exploration and development technology, and in particular to an experimental apparatus and method for simulating the dynamic seepage and absorption in situ environment of shale oil reservoirs. Background Technology

[0002] In the development of shale oil reservoirs, percolation and displacement refers to the process of replacing crude oil existing in fractures into matrix pores through capillary force, thereby effectively improving crude oil recovery.

[0003] In existing technologies, experimental setups for studying shale percolation and displacement behavior typically consist of containers holding shale samples, devices for injecting fluid, and components for collecting exudate. These setups aim to simulate the basic elements of the percolation and displacement process, providing fundamental conditions for research. However, existing percolation experimental setups can only conduct experiments under single temperature or pressure conditions, lacking the ability to simulate the actual high-temperature and high-pressure environment of shale reservoirs. Furthermore, most experimental equipment lacks the capability to dynamically monitor and capture the morphology of the percolation front.

[0004] However, shale oil reservoirs are located deep underground, with complex and variable temperature and pressure conditions, making it difficult for experimental results under single conditions to accurately reflect the actual situation. Furthermore, in actual reservoir environments, the dynamic changes at the adsorption front are crucial for understanding the crude oil replacement process and assessing oil production efficiency. Because existing equipment cannot accurately reflect the dynamic processes in the in-situ reservoir environment, the accuracy and reliability of related studies are significantly affected, making it difficult to meet the needs of shale oil reservoir development for a deeper understanding of adsorption mechanisms. Summary of the Invention

[0005] The purpose of this invention is to provide an experimental apparatus and method for simulating the dynamic in-situ permeation of shale oil reservoirs, in order to solve the technical problems in the prior art where experimental apparatus for studying shale permeation and displacement behavior cannot simulate the actual environment of shale oil reservoirs and cannot truly reflect the dynamic processes in the in-situ environment of the reservoir, resulting in poor experimental results.

[0006] To achieve this objective, the present invention adopts the following technical solution: On the one hand, the present invention provides an experimental apparatus for simulating the dynamic percolation of shale oil reservoirs in situ, comprising: A fluid supply system includes a liquid supply unit, a pumping unit, and a multi-way valve unit connected in sequence. The liquid supply unit is used to store the initial displacement fluid, the pumping unit is used to provide displacement power, and the multi-way valve unit can selectively connect to different intermediate containers to provide different experimental fluids. The infiltration vessel body is connected to the fluid supply system; a clamping mechanism is provided inside the infiltration vessel body, which is used to clamp and fix the shale core. An environmental simulation system is installed inside the percolation vessel to heat and pressurize the interior of the percolation vessel. An in-situ monitoring system is installed inside the seepage reactor. The in-situ monitoring system includes a seepage front monitoring unit and a mass change monitoring unit. The seepage front monitoring unit is configured to monitor the morphology and propagation parameters of the seepage front inside the shale core in real time during the seepage process. The mass change monitoring unit is configured to monitor the mass change of the shale core in real time during the seepage process. The control system is electrically connected to the fluid supply system, the environmental simulation system, and the in-situ monitoring system, respectively, and is used to control experimental conditions and collect monitoring data.

[0007] Preferably, the multi-way valve unit includes a first multi-way valve and a second multi-way valve; the inlet of the first multi-way valve is connected to the pumping unit, and the multiple outlets of the first multi-way valve are respectively connected to the bottom of the multiple intermediate containers; the multiple inlets of the second multi-way valve are respectively connected to the top of the multiple intermediate containers, and the outlet of the second multi-way valve is connected to the inlet of the percolation vessel.

[0008] Preferably, the experimental fluid includes simulated formation water, a surfactant solution, and crude oil. The intermediate container includes a first container for containing the simulated formation water, a second container for containing the surfactant solution, and a third container for containing the crude oil. The first and second multi-way valves are electrically operated switching valves and are electrically connected to the control system, enabling them to automatically switch flow paths under the command of the control system to pump different experimental fluids into the percolation vessel in a predetermined sequence.

[0009] Preferably, the clamping mechanism includes: a slide rail disposed within the infiltration vessel body; a rubber cylinder slidably mounted on the slide rail, the rubber cylinder being used to accommodate the shale core; and the rubber cylinder being deformable to wrap around and fix the shale core when confining pressure is applied within the infiltration vessel body.

[0010] Preferably, an annular flow space is formed between the inner wall of the infiltration vessel and the outer wall of the rubber cylinder; the experimental device for simulating the in-situ dynamic infiltration of shale oil reservoirs further includes a fluid circulation system, which includes a liquid circulation pipe connected to the flow space and a circulation pump connected to the liquid circulation pipe. The circulation pump is electrically connected to the control system. The circulation pump is used to pump fluid into the flow space to apply confining pressure, and / or the circulation pump is used to establish circulating flow in the flow space to simulate the dynamic fluid environment in shale fractures.

[0011] Preferably, the environmental simulation system includes: a heating unit, comprising a heating vessel sleeved outside the percolation vessel and heating tubes disposed inside the heating vessel, wherein a plurality of heating tubes are arranged at intervals along the inner peripheral wall of the heating vessel, and the heating tubes are used to heat the percolation vessel; a temperature sensor and a pressure sensor, disposed inside the percolation vessel, for real-time monitoring of the temperature and pressure inside the percolation vessel; wherein the heating unit, the temperature sensor, and the pressure sensor are all electrically connected to the control system, and the control system is configured to control the working state of the heating unit and the external pressure source according to the feedback signals of the temperature sensor and the pressure sensor, so as to maintain the temperature and pressure conditions inside the percolation vessel at a set value.

[0012] Preferably, the infiltration front monitoring unit includes multiple electrode holes pre-drilled inside the shale core, electrode units respectively implanted in each of the electrode holes, and a resistor meter electrically connected to all the electrode units; the resistor meter is electrically connected to the control system, and the resistor meter is used to measure the resistivity change data between different locations inside the shale core, and transmit the resistivity change data to the control system.

[0013] Preferably, the plurality of electrode holes are arranged in a three-dimensional array inside the shale core; the electrode unit is an Ag / gCl electrode or a platinum electrode, and the electrode unit is led out of the shale core and connected to the resistance meter via a wire.

[0014] Preferably, the quality change monitoring unit includes: an upper electromagnet, fixedly mounted on the top of the infiltration vessel; and a lower electromagnet, connected to the top of the shale core within the clamping mechanism. The upper and lower electromagnets are arranged opposite to each other and work together. Both the upper and lower electromagnets are electrically connected to the control system. The control system is configured to monitor the change in electromagnetic force between the upper and lower electromagnets, and to calculate and record the quality change of the shale core during the infiltration process in real time.

[0015] On the other hand, the present invention also provides an experimental method for simulating the dynamic in-situ permeation of shale oil reservoirs. This experimental method employs the aforementioned experimental apparatus for simulating the dynamic in-situ permeation of shale oil reservoirs. Specifically, the experimental method includes: S1. Set multiple monitoring points inside the shale core, install the shale core in the clamping mechanism of the seepage reactor, and connect each monitoring point to the in-situ monitoring system; S2. Set the target temperature and target pressure values ​​through the control system and start the environmental simulation system to make the inside of the percolation vessel reach and maintain the set high temperature and high pressure in-situ environmental conditions. S3. The experimental fluid is supplied to the shale core inside the infiltration vessel through the fluid supply system to carry out the dynamic infiltration process; S4. The interior of the shale core is monitored in situ in real time by the infiltration front monitoring unit to obtain the morphology and propagation parameters of the infiltration front; The shale core is monitored in situ in real time by a mass change monitoring unit to obtain mass change data of the shale core. S5. The control system calculates and outputs key parameters reflecting the percolation process in real time based on the received morphology and propulsion parameters of the percolation front and the mass change data. The key parameters include at least one of percolation efficiency and percolation rate.

[0016] The beneficial effects of this invention are: The experimental apparatus for simulating the in-situ dynamic percolation environment of shale oil reservoirs proposed in this invention provides stable displacement power to the entire experimental apparatus through a pumping unit in the fluid supply system, and enables flexible switching and supply of different experimental fluids through a multi-way valve unit. This allows the apparatus to simulate the percolation process under various displacement fluid conditions, more closely resembling the complex fluid environment of actual oil reservoirs. The percolation vessel and its internal clamping mechanism ensure the stable installation and sealing of the shale core under high pressure, ensuring accurate core positioning during the experiment and providing a stable foundation for subsequent environmental simulation and monitoring. The environmental simulation system acts directly on the inside of the percolation vessel, precisely heating and pressurizing the enclosed space where the shale core is located. This realistically simulates the high-temperature and high-pressure in-situ environment deep underground in shale oil reservoirs in the laboratory, making the experimental conditions closer to reality and overcoming the limitation of existing technologies that can only conduct experiments under single temperature and pressure conditions. More importantly, the in-situ monitoring system installed inside the percolation reactor enables direct and dynamic sensing of the percolation process. The percolation front monitoring unit captures dynamic parameters such as the morphological evolution and propulsion velocity of the fluid front within the shale core in real time, reflecting the microscopic processes of percolation. Meanwhile, the mass change monitoring unit synchronously monitors the real-time changes in the shale core mass, calculating the amount of fluid displaced, thus avoiding errors caused by fluid emulsification, crossflow, or temperature variations in traditional external collection and metering methods. All these operations are uniformly coordinated and controlled by the control system, ensuring that the high-temperature, high-pressure environment, dynamic fluid displacement, and high-precision in-situ monitoring can be carried out synchronously and stably. The entire device realizes dynamic percolation experiments in a simulated real reservoir environment, and can perform in-situ, real-time, and quantitative characterization of the entire percolation process, improving the reliability and guiding value of the experimental results. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the experimental device for simulating the dynamic in-situ permeation of shale oil reservoirs provided in Embodiment 1 of the present invention; Figure 2 This is a cross-sectional view of the intermediate container provided in Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of the structure of the intermediate container provided in Embodiment 1 of the present invention; Figure 4 This is a schematic diagram of the structure of a shale core provided in Embodiment 1 of the present invention; Figure 5 This is a cross-sectional view of the percolation vessel provided in Embodiment 1 of the present invention; Figure 6 This is a schematic diagram of the structure of the percolation vessel provided in Embodiment 1 of the present invention; Figure 7 This is a flowchart of the experimental method for simulating the dynamic in-situ permeation of shale oil reservoirs, provided in Embodiment 2 of the present invention.

[0018] In the picture: 100. Shale core samples; 1. Fluid supply system; 11. Liquid supply unit; 12. Pumping unit; 13. Multi-way valve unit; 131. First multi-way valve; 132. Second multi-way valve; 14. Intermediate container; 14a. First container; 14b. Second container; 14c. Third container; 141. Cylindrical body; 142. Support; 143. Lower end cover; 144. Lower flow cover; 145. Piston mechanism; 146. Upper flow cover; 147. Upper end cover; 2. Absorption vessel body; 21. Clamping mechanism; 211. Slide rail; 212. Glue tube; 3. Environmental simulation system; 31. Heating unit; 311. Heating vessel; 312. Heating tube; 32. Temperature sensor; 33. Pressure sensor; 4. In-situ monitoring system; 41. Immersion front monitoring unit; 411. Electrode orifice; 412. Electrode unit; 413. Resistance meter; 42. Mass change monitoring unit; 421. Upper electromagnet; 422. Lower electromagnet; 5. Control system; 6. Fluid circulation system; 61. Liquid circulation pipe; 62. Circulation pump. Detailed Implementation

[0019] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar components or components having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0020] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection or a detachable connection; a mechanical connection or an electrical connection; a direct connection or an indirect connection through an intermediate medium; or the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0021] In the description of this invention, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0022] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0023] Example 1 See Figures 1 to 6 The experimental apparatus provided in this embodiment of the invention includes a fluid supply system 1, an absorption vessel 2, an environmental simulation system 3, an in-situ monitoring system 4, and a control system 5. The fluid supply system 1 includes a liquid supply unit 11, a pumping unit 12, and a multi-way valve unit 13 connected in sequence. The liquid supply unit 11 stores the initial displacement fluid, the pumping unit 12 provides displacement power, and the multi-way valve unit 13 can selectively connect to different intermediate containers 14 to provide different experimental fluids. The absorption vessel 2 is connected to the fluid supply system 1. A clamping mechanism 21 is provided inside the absorption vessel 2 to clamp and fix the shale core 100. The environmental simulation system 3 is located inside the absorption vessel 2 and is used to heat the interior of the absorption vessel 2. The system includes pressurization; the in-situ monitoring system 4 is installed inside the seepage vessel 2. The in-situ monitoring system 4 includes a seepage front monitoring unit 41 and a mass change monitoring unit 42. The seepage front monitoring unit 41 is configured to monitor the morphology and propulsion parameters of the seepage front inside the shale core 100 in real time during the seepage process. The mass change monitoring unit 42 is configured to monitor the mass change of the shale core 100 in real time during the seepage process. The control system 5 is electrically connected to the fluid supply system 1, the environmental simulation system 3 and the in-situ monitoring system 4 respectively, and is used to control the experimental conditions and collect monitoring data.

[0024] The experimental apparatus for simulating the dynamic in-situ percolation of shale oil reservoirs proposed in this invention provides stable displacement power to the entire experimental apparatus through the pumping unit 12 in the fluid supply system 1, and achieves flexible switching and supply of different experimental fluids with the help of the multi-way valve unit 13. This allows the apparatus to simulate the percolation process under various displacement fluid conditions, more closely resembling the complex fluid environment of actual oil reservoirs. The percolation vessel 2 and its internal clamping mechanism 21 ensure the stable installation and sealing of the shale core 100 under high pressure, ensuring accurate core positioning during the experiment and providing a stable foundation for subsequent environmental simulation and monitoring. The environmental simulation system 3 acts directly inside the percolation vessel 2, precisely heating and pressurizing the enclosed space where the shale core 100 is located, thereby realistically simulating the high-temperature and high-pressure in-situ environment deep underground in shale oil reservoirs in the laboratory. This makes the experimental conditions closer to reality and overcomes the limitation of existing technologies that can only conduct experiments under single temperature and pressure conditions. More importantly, the in-situ monitoring system 4, installed within the seepage vessel 2, enables direct and dynamic sensing of the seepage process. Specifically, the seepage front monitoring unit 41 captures dynamic parameters such as the morphological evolution and propulsion speed of the fluid front within the shale core 100 in real time, reflecting the microscopic processes of seepage. Meanwhile, the mass change monitoring unit 42 synchronously monitors the real-time changes in the mass of the shale core 100, thereby calculating the amount of fluid displaced, avoiding errors caused by fluid emulsification, crossflow, or temperature variations in traditional external collection and metering methods. All of the above operations are uniformly coordinated and controlled by the control system 5, ensuring that the high-temperature, high-pressure environment, dynamic fluid displacement, and high-precision in-situ monitoring can be carried out synchronously and stably. The entire device realizes dynamic seepage experiments under simulated real reservoir conditions and can perform in-situ, real-time, and quantitative characterization of the entire seepage process, improving the reliability and guiding value of the experimental results.

[0025] The working principle and specific structure of the experimental device are explained in detail below.

[0026] The fluid supply system 1 provides a controllable and switchable fluid source and displacement power for the entire experimental setup. Among them, the liquid supply unit 11 is used to store the initial displacement fluid required for the experiment.

[0027] Specifically, the liquid supply unit 11 can be a graduated cylinder or other type of liquid storage container with precise volume graduations, and the liquid supply unit 11 contains the initial displacement fluid. The liquid supply unit 11 is connected to the inlet of the pumping unit 12 through a pipeline, providing the pumping unit 12 with a stable and clean fluid source.

[0028] Understandably, before the experiment begins, the initial displacing fluid is used to thoroughly flush and displace the entire fluid pipeline and the interior of the percolation vessel 2 to remove air from the system and ensure the flow path is clean. During the experiment, the initial displacing fluid, as the medium directly operating in the pumping unit 12, is pumped into the lower chamber of the intermediate container 14 connected by the multi-way valve unit 13. Through hydraulic transmission, it pushes the experimental fluid stored in the intermediate container 14 into the percolation vessel 2 in an equal volume, thereby protecting the pumping unit 12 from the influence of complex experimental fluids while achieving precise control of the injection flow rate or pressure of the experimental fluid.

[0029] Optionally, the initial displacement fluid can be pure water, chemically stable deionized water, or a brine solution used to simulate the salinity of specific formation water, etc., without limitation.

[0030] The pumping unit 12 is connected to the output of the liquid supply unit 11, and is used to provide precise and stable displacement power. In this embodiment, the pumping unit 12 is a constant-speed, constant-pressure plunger pump. The constant-speed, constant-pressure plunger pump can operate in constant-speed mode or constant-pressure mode according to experimental requirements. In constant-speed mode, the pumping unit 12 injects fluid into the system at a set constant flow rate; in constant-pressure mode, it maintains a constant pressure at the injection end. The constant-speed, constant-pressure plunger pump can simulate different injection-production pressures or injection rates in shale oil reservoir development, providing a controllable driving force for the percolation process. The outlet of the pumping unit 12 is connected to the subsequent multi-way valve unit 13, which pumps the initial displacement fluid from the liquid supply unit 11 or the experimental fluid obtained after switching to the percolation vessel 2.

[0031] Preferably, the constant speed and constant pressure plunger pump can operate in a constant flow or constant pressure mode, providing an injection flow rate of 0.001 mL / min to 10 mL / min or an injection pressure of 0.01 MPa to 70 MPa for the experiment, to simulate different injection and production pressures in shale oil reservoirs.

[0032] The multi-way valve unit 13 is used to select and switch the fluid in the fluid supply system 1. Specifically, the multi-way valve unit 13 includes a first multi-way valve 131 and a second multi-way valve 132. The inlet of the first multi-way valve 131 is connected to the pumping unit 12 via a pipeline to receive the displacement fluid from the pumping unit 12; the multiple outlets of the first multi-way valve 131 are respectively connected to the bottom interfaces of multiple intermediate containers 14 via independent pipelines. The inlet of the second multi-way valve 132 is also connected to the top interfaces of multiple intermediate containers 14 via multiple pipelines, and the outlet of the second multi-way valve 132 is connected to the fluid inlet of the percolation vessel 2 via a pipeline. Through this connection architecture, the fluid from the pumping unit 12 can be selectively introduced into the bottom of any intermediate container 14 via the first multi-way valve 131, thereby pushing the experimental fluid in the intermediate container 14 to flow out from its top, and then guided by the second multi-way valve 132, finally enters the percolation vessel 2.

[0033] In this embodiment, both the first multi-way valve 131 and the second multi-way valve 132 are six-way valves. The six-way valve can switch and control multiple fluid channels, meeting the fluid distribution requirements of this embodiment. In other embodiments, the first multi-way valve 131 and the second multi-way valve 132 can also be other types of multi-way valves such as three-way valves, four-way valves, or multi-way directional valves. The specific choice depends on the number of fluid channels, control logic, and functional requirements of the actual application scenario, and is not specifically limited here.

[0034] More specifically, the experimental fluid can be configured according to the research purpose. In this embodiment, the experimental fluid includes simulated formation water, different types of surfactant solutions, and crude oil. Accordingly, multiple intermediate containers 14 can be configured, specifically including a first container 14a for containing simulated formation water, a second container 14b for containing surfactant solutions, and a third container 14c for containing crude oil.

[0035] Preferably, each intermediate container 14 is designed as a high-pressure-resistant plunger-type container. The intermediate container 14 includes a cylindrical body 141, a support 142, a lower end cover 143, a lower flow cover 144, a piston mechanism 145, an upper flow cover 146, and an upper end cover 147. The cylindrical body 141 is the main body of the intermediate container 14 and is vertically mounted on the support 142. The bottom end of the cylindrical body 141 is sealed with the lower end cover 143. A fluid channel is opened on the lower end cover 143 and connected to the lower flow cover 144. The lower flow cover 144 is connected to the corresponding outlet of the first multi-way valve 131 through a pipeline for introducing the initial displacement fluid from the pumping unit 12. The top of the cylindrical body 141 is sealed with an upper end cap 147. The upper end cap 147 also has a fluid channel and is connected to an upper flow cover 146. The upper flow cover 146 is connected to the corresponding inlet of the second multi-way valve 132 via a pipeline, used to discharge the experimental fluid from the container. A piston mechanism 145 is slidably disposed within the internal cavity of the cylindrical body 141, dividing the internal cavity into an upper chamber and a lower chamber that are not interconnected. The lower chamber is connected to the displacement fluid pipeline via a lower flow cover 144 and is used to contain the initial displacement fluid; the upper chamber is connected to the experimental fluid pipeline via an upper flow cover 146 and is used to contain specific experimental fluids, such as simulated formation water, surfactant solutions, or crude oil. When the pumping unit 12 pumps the initial displacement fluid into the lower chamber, the piston mechanism 145 moves upward under pressure, thereby squeezing out the experimental fluid in the upper chamber in an equal volume and without contamination, achieving hydraulic isolation and precise transmission of the displacement power and the experimental fluid.

[0036] To achieve automation and precise control of the experimental process, the first multi-way valve 131 and the second multi-way valve 132 are preferably electrically operated switching valves, both of which are electrically connected to the control system 5. The control system 5 can issue commands to the electrically operated switching valves to coordinate the valve position states of the first multi-way valve 131 and the second multi-way valve 132, thereby automatically switching the flow paths in a predetermined sequence during the experiment.

[0037] For example, the control system 5 can first switch the flow path to connect the pumping unit 12 to the third container 14c, saturating the shale core 100 with crude oil; then it can switch back to connect with the first container 14a to conduct a simulated formation water displacement and infiltration experiment. This design ensures strict isolation and sequential control of different experimental fluids during the injection process, improving the repeatability and reliability of the experiment.

[0038] The percolation vessel 2 is a high-pressure sealed container that carries the shale core 100 and enables interaction between the shale core 100 and various systems. Specifically, the percolation vessel 2 includes a simple vessel body and a vessel cover that is detachably and sealingly connected to the vessel body. The vessel body and the vessel cover together form a sealed chamber capable of withstanding high temperature and high pressure. Experimental fluid from the fluid supply system 1 is transported to the sealed chamber of the percolation vessel 2 through a pipeline passing through an interface on the vessel cover.

[0039] Furthermore, the percolation vessel 2 is equipped with a clamping mechanism 21 for holding and fixing the shale core 100. Specifically, the clamping mechanism 21 includes a slide rail 211 disposed within the inner cavity of the percolation vessel 2, and a rubber sleeve 212 slidably mounted on the slide rail 211. The shale core 100 is placed within the internal cavity of the rubber sleeve 212. The rubber sleeve 212 is made of a material with good elasticity and temperature and corrosion resistance.

[0040] When external confining pressure is applied to the inside of the infiltration vessel 2, the rubber sleeve 212 can undergo radial deformation under pressure, thereby tightly wrapping and fixing the shale core 100 placed inside the rubber sleeve 212. This design allows the clamping mechanism 21 to adaptively clamp and fix core samples of different diameters, lengths, and even slightly irregular shapes, ensuring the stability of the core position and the reliability of the seal under high pressure.

[0041] Furthermore, after the rubber sleeve 212 is installed inside the percolation vessel 2, an annular flow space is formed between the outer wall of the rubber sleeve 212 and the inner wall of the percolation vessel 2. Specifically, the experimental apparatus also includes a fluid circulation system 6, which includes a liquid circulation pipe 61 connected to the flow space and a circulation pump 62 connected to the liquid circulation pipe 61. The circulation pump 62 is electrically connected to the control system 5 and is controlled by the control system 5. The circulation pump 62 has two main functions: first, to pump fluid into the flow space, thereby establishing and maintaining the required external confining pressure within the flow space. The external confining pressure acts on the outer wall of the rubber sleeve 212 to deform the rubber sleeve 212 and clamp the shale core 100. Secondly, by controlling the flow rate of the circulating pump 62, the dynamic flow environment of fluid in the fracturing fracture of the shale reservoir can be simulated in the annular flow space, so that the shale core 100 encased in the rubber sleeve 212 is in a dynamic fluid contact state, rather than static soaking, thus more realistically reproducing the fluid exchange process between the fracture and the matrix in the actual oil reservoir.

[0042] Specifically, two liquid circulation pipes 61 are provided and distributed on both sides of the percolation vessel 2. One end of each liquid circulation pipe 61 extends into the interior of the percolation vessel 2 through a fluid interface and is directly connected to the flow space formed between the outer wall of the rubber sleeve 212 and the inner wall of the percolation vessel 2. The other ends of the two liquid circulation pipes 61 extend to the outside of the percolation vessel 2 and are connected to the circulation pump 62, thus forming a complete fluid circuit. The circulation pump 62 pumps fluid into the flow space through the liquid circulation pipes 61.

[0043] The environmental simulation system 3 is integrated into the seepage vessel 2 and is used for in-situ underground temperature and pressure conditions in shale oil reservoirs. The environmental simulation system 3 includes a heating unit 31, a temperature sensor 32, and a pressure sensor 33.

[0044] Specifically, the heating unit 31 adopts an external heating method. The heating unit 31 includes a heating vessel 311 sleeved outside the percolation vessel body 2, and multiple sets of heating tubes 312 disposed inside the heating vessel 311. The multiple heating tubes 312 are evenly spaced along the inner peripheral wall of the heating vessel 311 to ensure that heat can be evenly transferred to the entire outer peripheral surface of the percolation vessel body 2, thereby achieving uniform and stable heating of the space inside the vessel.

[0045] To accurately sense the internal environment of the percolation vessel 2, temperature sensor 32 and pressure sensor 33 are directly installed in the internal cavity of the percolation vessel 2. The detection ends of temperature sensor 32 and pressure sensor 33 directly contact the fluid medium inside the cavity of the percolation vessel 2, so as to monitor the real temperature and pressure inside the percolation vessel 2 in real time and in situ.

[0046] The heating unit 31, temperature sensor 32, and pressure sensor 33 are all electrically connected to the control system 5 via cables.

[0047] During the experiment, the control system 5 was configured to precisely control the heating amount by adjusting the power of the heating tube 312 in the heating unit 31 using a PID control algorithm based on the real-time temperature signal fed back by the temperature sensor 32. This stabilized the internal temperature of the percolation vessel 2 at a set target value, such as any value within the range of room temperature to 200°C, and kept temperature fluctuations within a very small range. Simultaneously, based on the pressure signal fed back by the pressure sensor 33, the control system 5 dynamically controlled the confining pressure applied to the flow space by adjusting the injection pressure or flow rate of the circulation pump 62 in the fluid circulation system 6, which serves as an external pressure source. This maintained the pore pressure or confining pressure conditions acting on the core at a set value.

[0048] The in-situ monitoring unit 41, as part of the in-situ monitoring system 4, is configured to monitor the morphology and propagation parameters of the in-situ in-situ in real time the in-situ in-situ in the shale core 100 during the infiltration process.

[0049] The morphology of the adsorption front within shale core 100 refers to the geometric shape and distribution characteristics of the macroscopic interface between the displacing fluid and the displaced fluid within shale core 100 in three-dimensional space during the adsorption experiment. This morphology is not a simple plane, but rather an irregular, finger-like, or diffuse spatial curved surface or transition zone influenced by the heterogeneity of the pore structure of shale core 100, the displacement dynamics, and the fluid properties. Its characterization parameters include the geometric contour of the front surface, its distribution area, its projection shape on the cross-section of shale core 100, and its uniformity or fingering degree along different directions.

[0050] The propulsion parameters refer to the physical quantities that quantify the dynamic evolution of the aforementioned adsorption front. The propulsion parameters include the average and instantaneous propulsion velocity of the adsorption front along the main displacement direction or a specified path, the maximum or average propulsion distance from the inlet end face, and the expansion rate of the front in different spatial dimensions. These parameters are used together to objectively and quantitatively describe the speed and ripple efficiency of the adsorption process.

[0051] Specifically, the infiltration front monitoring unit 41 includes multiple electrode holes 411 pre-drilled inside the shale core 100, electrode units 412 respectively implanted in each electrode hole 411, and a resistor 413 electrically connected to all electrode units 412.

[0052] During the experimental preparation phase, multiple electrode holes 411 need to be drilled inside the shale core 100 to be tested. The preferred arrangement of the electrode holes 411 inside the core is a three-dimensional array, meaning measurement points are regularly set along the axial, radial, and circumferential directions of the core to construct a three-dimensional sensing network covering the main space of the core. An electrode unit 412 is implanted within each electrode hole 411. The electrode unit 412 can be a chemically stable Ag / AgCl electrode or an inert platinum electrode to adapt to high temperature, high pressure, and complex fluid environments. Each electrode unit 412 is led out of the shale core 100 via a wire, and all wires are ultimately connected to an external resistance meter 413. The resistance meter 413 is electrically connected to the control system 5.

[0053] Its working principle is as follows: Different fluid phases within the shale core 100, such as conductive formation water and non-conductive or weakly conductive crude oil, exhibit significant differences in resistivity. When the adsorption process occurs, the displacing fluid enters the core pores and replaces the original fluid, causing changes in the resistivity of local areas within the shale core 100. The resistivity meter 413, through a network of electrode units 412, continuously and synchronously measures the resistivity changes between various points within the shale core 100 and transmits this resistivity change data stream to the control system 5. The control system 5 integrates corresponding data processing algorithms and is configured to receive and process this resistivity change data. By comparing the resistivity distribution at different times and spatial locations, the control system 5 can identify the location of the displacement front. Furthermore, through three-dimensional interpolation and imaging technology, it dynamically reconstructs the spatial morphology, distribution range, and evolution of the adsorption front within the shale core 100 over time in the software. Meanwhile, the control system 5 can automatically calculate propulsion parameters such as the average propulsion speed, instantaneous propulsion speed, and propulsion distance in a specific direction of the infiltration front based on the change of the leading edge position over time.

[0054] As another key part of the in-situ monitoring system 4, the mass change monitoring unit 42 is configured to perform in-situ, continuous, and high-precision real-time monitoring of the mass change of the shale core 100 itself during the seepage process, thereby directly and accurately quantifying the mass of fluid displaced by seepage.

[0055] Specifically, the quality change monitoring unit 42 includes an upper electromagnet 421 and a lower electromagnet 422. The upper electromagnet 421 is fixedly installed on the top inner wall of the percolation vessel 2 or fixedly connected to the top cover of the percolation vessel 2, and its position remains constant. The lower electromagnet 422 is directly or indirectly connected to the top of the shale core 100 housed in the rubber sleeve 212 of the clamping mechanism 21, so that the lower electromagnet 422 can move synchronously with the shale core 100 as a whole. The upper electromagnet 421 and the lower electromagnet 422 are coaxially opposite each other in the vertical direction and work together to form a non-contact precision electromagnetic force measurement system. Both the upper electromagnet 421 and the lower electromagnet 422 are electrically connected to the control system 5 via cables.

[0056] Its working principle is as follows: When the seepage process occurs, the displacement of fluid inside the shale core 100 causes a slight change in the overall mass of the shale core 100. This change disrupts the balance between the gravity acting on the lower electromagnet 422 and the electromagnetic attraction generated by the upper electromagnet 421, thus causing a slight change in the air gap distance between the upper and lower electromagnets 421. The control system 5 is configured to monitor the balance between the upper and lower electromagnets 421 and 422 in real time. Through a high-precision closed-loop control circuit, the control system 5 rapidly adjusts the current supplied to the upper electromagnet 421 so that the electromagnetic attraction generated by the upper electromagnet 421 always accurately tracks and balances the change in gravity acting on the lower electromagnet 422 caused by the change in the mass of the shale core 100, thereby maintaining the distance between the upper and lower electromagnets 421 at the set initial value. Control system 5 monitors and records in real time the change in current required to maintain this force balance. Combined with the known electromagnetic constant, it can calculate and continuously record the instantaneous and cumulative mass changes of shale core 100 during the seepage process. This method achieves high-resolution, in-situ, and dynamic measurement of the shale core 100's mass, avoiding operational interference, time lag, and errors caused by removing the shale core 100 for weighing or relying on external fluid collection and measurement. It also provides direct and reliable core data for accurately evaluating seepage replacement efficiency.

[0057] The control system 5, as the central hub of the entire experimental setup, is electrically connected to the fluid supply system 1, the environmental simulation system 3, and the in-situ monitoring system 4. The control system 5 primarily receives real-time monitoring signals from various sensor units such as the temperature sensor 32, pressure sensor 33, resistor 413, and electromagnetic force measurement unit. Based on the preset experimental procedures and parameter settings, it sends control commands to various execution units such as the pumping unit 12, the multi-way valve unit 13, the heating unit 31, and the circulating pump 62, thereby coordinating the automatic and precise operation of the entire setup and simultaneously collecting, storing, and processing all experimental data.

[0058] Specifically, the control system 5 can use industrial control computers, programmable logic controllers (PLCs), or distributed controllers (DCS) commonly used in the field as the core controller, and is configured with corresponding data acquisition cards, signal conditioning modules, and human-machine interfaces. The working principle and specific internal circuit structure of the control system 5 are conventional applications of existing automation control technology and are not the inventive point of this application, and will not be described in detail here.

[0059] Embodiment 2 of the present invention also provides an experimental method for simulating the dynamic permeation in situ environment of shale oil reservoirs. This experimental method uses the experimental apparatus provided in Embodiment 1. The experimental method specifically includes the following steps: S1. Set up multiple monitoring points inside the shale core 100, install the shale core 100 in the clamping mechanism 21 of the seepage vessel body 2, and connect each monitoring point to the in-situ monitoring system 4. Specifically, firstly, a shale core 100 to be tested is selected, and multiple electrode holes 411 are drilled inside the shale core 100 using precision drilling equipment. These electrode holes 411 are arranged in a three-dimensional array, with each electrode hole 411 serving as a monitoring point. Next, Ag / AgCl electrodes or platinum electrodes are implanted into each electrode hole 411 to form electrode units 412. Each electrode unit 412 is led out of the shale core 100 via a wire. Then, the shale core 100 is placed inside the cavity of the rubber sleeve 212 of the clamping mechanism 21, and the rubber sleeve 212 is pushed along the slide rail 211 into the set position of the percolation vessel body 2. During installation, it is necessary to ensure a reliable connection between the connecting component at the top of the shale core 100 and the lower electromagnet 422 of the mass change monitoring unit 42. Finally, all wires leading from the electrode units 412 are connected to the resistance meter 413 of the percolation front monitoring unit 41 to complete the electrical connection of the monitoring points.

[0060] S2. Set the target temperature and target pressure values ​​through the control system 5, and start the environmental simulation system 3 to make the inside of the percolation vessel 2 reach and maintain the set high temperature and high pressure in-situ environmental conditions.

[0061] Specifically, the target temperature and pressure values ​​required for the experiment are set through the control system 5. The heating unit 31 of the environmental simulation system 3 is activated. Based on the feedback signal from the temperature sensor 32, the control system 5 adjusts the power of the heating tube 312 using a PID algorithm, gradually increasing the internal temperature of the percolation vessel 2 and stabilizing it at the target temperature value, with temperature fluctuations controlled within a minimal range. Simultaneously, the circulation pump 62 of the fluid circulation system 6 is activated, pumping fluid into the flow space between the rubber sleeve 212 and the inner wall of the percolation vessel 2. Based on the feedback signal from the pressure sensor 33, the control system 5 adjusts the discharge pressure or flow rate of the circulation pump 62, thereby establishing and maintaining the set target pressure value within the flow space. The pressure within the flow space creates confining pressure, causing the rubber sleeve 212 to deform, wrapping around and fixing the shale core 100.

[0062] S3. Experimental fluid is supplied to the shale core 100 inside the infiltration vessel 2 through the fluid supply system 1 to carry out the dynamic infiltration process.

[0063] S311, 100% saturated crude oil was extracted from shale core samples.

[0064] The purpose of this stage is to fully fill the pore space of the shale core 100 with experimental crude oil to simulate the original oil-bearing state of the reservoir. Specifically, the control system 5 first sends a command to the multi-way valve unit 13 to control the synchronous switching of the valve core positions of the first multi-way valve 131 and the second multi-way valve 132. Through the combination of the passages of the first multi-way valve 131 and the second multi-way valve 132, a complete fluid path is constructed from the pumping unit 12 through the lower chamber of the third container 14c to its upper chamber, and then to the percolation vessel 2, thereby connecting the pumping unit 12 with the crude oil stored in the third container 14c. Subsequently, the control system 5 starts the pumping unit 12 and makes the pumping unit 12 operate in a constant pressure mode. In this mode, the pumping unit 12 pumps the initial displacement fluid, which serves as the driving medium, into the lower chamber of the third container 14c at a preset constant injection pressure, such as 20 MPa. The increased pressure in the lower chamber pushes the piston mechanism 145 inside the third container 14c upwards, thereby squeezing out an equal volume of crude oil stored in the upper chamber of the third container 14c without cross-contamination. The discharged crude oil, driven by a constant pressure provided by the pumping unit 12, is injected through pipelines and flows through the shale core 100 within the infiltration vessel 2. This constant pressure is typically set higher than the capillary resistance of the shale core 100 to ensure that the crude oil can overcome the resistance of the pore throats and enter the depths of the shale core 100. The injection process continues until a continuous flow of bubble-free crude oil is observed from the outlet end of the shale core 100. At this point, the accessible pore space of the shale core 100 can be considered fully saturated with crude oil, establishing an initial oil saturation distribution similar to the original reservoir.

[0065] S312, Conduct dynamic permeation and displacement of 100 shale core samples.

[0066] This stage aims to simulate the percolation process during water injection development, where, under the dynamic flow of fracture fluid, the aqueous phase spontaneously replaces crude oil in the matrix core through capillary force. After the crude oil saturation step is completed, the control system 5 issues another command to operate the multi-way valve unit 13 to switch the flow path. At this time, the valve positions of the first multi-way valve 131 and the second multi-way valve 132 are adjusted to construct a new flow path from the pumping unit 12 through the first container 14a (which contains simulated formation water) to the percolation vessel 2. The control system 5 switches the operating mode of the pumping unit 12 to a constant flow mode and injects the initial displacement fluid into the system at a set, low constant flow rate, for example, 0.005 mL / min. The initial displacement fluid pushes the piston mechanism 145 of the first container 14a, thereby injecting simulated formation water into the shale core 100 at the same low flow rate. The purpose of selecting a low flow rate injection is to minimize the influence of the applied pressure gradient on the percolation process, making capillary force the main driving force for fluid replacement, thus realistically simulating the replacement mechanism dominated by percolation.

[0067] Meanwhile, to simulate the fluid flow environment in the fracture network after shale reservoir fracturing, the fluid circulation system 6 operates continuously. Under the command of the control system 5, the circulation pump 62 drives the confining fluid to continuously circulate within the flow space formed by the liquid circulation pipe 61, the circulation pump 62, and the outer wall of the rubber sleeve 212 and the inner wall of the seepage vessel 2. This circulation flow establishes dynamic fluid boundary conditions within the flow space adjacent to the outer surface of the shale core 100. It simulates the state in actual production where the fluid within the fractures continuously flows and renews, and continuously exchanges mass with the surface of the shale core 100. This dynamic boundary condition overcomes the limitations of static immersion experiments, allowing the fluid concentration or chemical potential on the outer surface of the shale core 100 to remain relatively constant or change as needed, thus more realistically reproducing the seepage and displacement process experienced by the shale core 100 in the dynamic fracture fluid environment under in-situ subsurface conditions.

[0068] S313, Perform chemical agent enhancement, permeation, and displacement.

[0069] Control system 5 re-operates multi-way valve unit 13, switching the flow path to connect with the second container 14b (which contains a surfactant solution of a specific concentration). Pumping unit 12 continues to inject the surfactant solution into shale core 100 at the same constant low flow rate. Simultaneously, fluid circulation system 6 maintains the dynamic flow environment of the annular space. During this process, the in-situ monitoring system continues to operate, acquiring and recording in real-time advance parameters of the adsorption front and mass change data of the shale core 100.

[0070] S4. The shale core 100 is monitored in situ in real time by the infiltration front monitoring unit 41 to obtain the morphology and propagation parameters of the infiltration front of the shale core 100; the shale core 100 is monitored in situ in real time by the mass change monitoring unit 42 to obtain the mass change data of the shale core 100.

[0071] Specifically, after the infiltration process begins, the infiltration front monitoring unit 41 and the mass change monitoring unit 42 start working synchronously. The resistivity meter 413 of the infiltration front monitoring unit 41 continuously measures the resistivity between each electrode unit 412 and transmits the resistivity change data to the control system 5 in real time. The electromagnetic force measurement system composed of the upper electromagnet 421 and the lower electromagnet 422 of the mass change monitoring unit 42 continues to work. The control system 5 calculates the mass change data of the shale core 100 in real time by monitoring the current change required to maintain a constant distance between the upper electromagnet 421 and the lower electromagnet 422.

[0072] S5. Based on the received morphology and propulsion parameters of the infiltration front and mass change data, the control system 5 calculates and outputs key parameters reflecting the infiltration process in real time. The key parameters include at least one of infiltration efficiency and infiltration rate.

[0073] The calculation principle of the seepage rate is as follows: The control system 5 processes and analyzes the resistivity change data collected by the seepage front monitoring unit 41 in real time. The principle is that as the seepage process proceeds, the conductive fluid gradually displaces the non-conductive or weakly conductive pre-phase fluid, causing a step or trend change in resistivity at a specific spatial location within the shale core 100. The control system 5 identifies the moment when significant fluid replacement occurs at each measurement point or measurement area using a preset resistivity threshold criterion or dynamic change rate analysis algorithm, thereby determining the precise arrival time of the seepage front at that point. Combined with the known three-dimensional spatial coordinates of the electrodes, the control system 5 can track the position of the seepage front in space in real time. The seepage rate is calculated based on the time derivative of this spatial position information.

[0074] Furthermore, the control system 5 can calculate the average adsorption velocity along the main seepage direction 100 along the shale core. The average adsorption velocity is the ratio of the distance the adsorption front advances along this direction within a specific time period to the duration of that time period. Simultaneously, through higher-frequency data acquisition and instantaneous position differential analysis, the control system 5 can also calculate the instantaneous adsorption velocity to reflect the details of the dynamic changes in the adsorption process. In addition, based on advancement data in multiple directions within three-dimensional space, the system can also calculate the lateral or radial expansion rate of the adsorption front.

[0075] The calculation principle of percolation efficiency is as follows: Percolation efficiency is a core indicator for evaluating the percolation replacement effect. The calculation of percolation efficiency integrates mass change data directly measured by the mass change monitoring unit 42. The mass change data of shale core 100 recorded in real time by the control system 5 directly corresponds to the mass of crude oil displaced from shale core 100 due to percolation. To calculate percolation efficiency, the mass of crude oil displaced from shale core 100 needs to be compared with the theoretically replaceable total amount. The control system 5 calculates percolation efficiency through one or a combination of the following two methods: Firstly, after the shale core 100 is fully saturated with crude oil in the initial stage of the experiment, the control system 5 can determine the initial oil content of the shale core 100 by recording the initial mass of the shale core 100 after saturation through the mass change monitoring unit 42. During the percolation process, the ratio of the cumulative produced oil mass to the initial oil content, which is recorded in real time, is calculated in real time and output as the cumulative percolation efficiency.

[0076] Secondly, the control system 5 can also combine the morphology and location of the seepage front reconstructed by the seepage front monitoring unit 41 to estimate the pore volume of the rock currently affected by the water phase, and then multiply it by the average oil saturation of that part of the rock to calculate the theoretical recoverable oil volume in the affected area. By comparing the cumulative oil production quality obtained in real time with the theoretical recoverable oil volume in the current affected area, the local seepage efficiency reflecting the displacement effect within the current affected area can be calculated.

[0077] The control system 5 will simultaneously display the calculated key parameters such as the infiltration rate and infiltration efficiency, along with the morphological image of the infiltration front and the mass change curve, on the human-computer interaction interface and store them in the storage medium, forming a complete, time-series related dynamic dataset of the infiltration process, thereby achieving accurate and quantitative evaluation of the infiltration mechanism and effect.

[0078] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. An experimental apparatus for simulating the dynamic percolation of shale oil reservoirs in situ, characterized in that, include: The fluid supply system (1) includes a liquid supply unit (11), a pumping unit (12) and a multi-way valve unit (13) connected in sequence. The liquid supply unit (11) is used to store the initial displacement fluid, the pumping unit (12) is used to provide displacement power, and the multi-way valve unit (13) can selectively connect different intermediate containers (14) to provide different experimental fluids. The infiltration vessel body (2) is connected to the fluid supply system (1); a clamping mechanism (21) is provided inside the infiltration vessel body (2), which is used to clamp and fix the shale core (100). An environmental simulation system (3) is installed inside the percolation vessel (2) to heat and pressurize the interior of the percolation vessel (2); An in-situ monitoring system (4) is installed inside the seepage vessel (2). The in-situ monitoring system (4) includes a seepage front monitoring unit (41) and a mass change monitoring unit (42). The seepage front monitoring unit (41) is configured to monitor the morphology and propulsion parameters of the seepage front inside the shale core (100) in real time during the seepage process. The mass change monitoring unit (42) is configured to monitor the mass change of the shale core (100) in real time during the seepage process. The quality change monitoring unit (42) includes: The upper electromagnet (421) is fixedly installed on the top of the infiltration vessel body (2); The lower electromagnet (422) is connected to the top of the shale core (100) inside the clamping mechanism (21); The control system (5) is electrically connected to the fluid supply system (1), the environmental simulation system (3) and the in-situ monitoring system (4) respectively, and is used to control experimental conditions and collect monitoring data; The upper electromagnet (421) and the lower electromagnet (422) are arranged opposite to each other and work together. Both the upper electromagnet (421) and the lower electromagnet (422) are electrically connected to the control system (5). The control system (5) is configured to calculate and record the mass change of the shale core (100) during the seepage process in real time by monitoring the change of the electromagnetic force between the upper electromagnet (421) and the lower electromagnet (422).

2. The experimental apparatus for simulating the dynamic permeation of shale oil reservoirs in situ according to claim 1, characterized in that, The multi-way valve unit (13) includes a first multi-way valve (131) and a second multi-way valve (132); The inlet of the first multi-way valve (131) is connected to the pumping unit (12), and the multiple outlets of the first multi-way valve (131) are respectively connected to the bottom of the multiple intermediate containers (14); The multiple inlets of the second multi-way valve (132) are respectively connected to the top of the multiple intermediate containers (14), and the outlet of the second multi-way valve (132) is connected to the inlet of the percolation vessel body (2).

3. The experimental apparatus for simulating the dynamic percolation of shale oil reservoirs in situ according to claim 2, characterized in that, The experimental fluids include simulated formation water, surfactant solution and crude oil, and the intermediate container (14) includes a first container (14a) for containing the simulated formation water, a second container (14b) for containing the surfactant solution and a third container (14c) for containing the crude oil. The first multi-way valve (131) and the second multi-way valve (132) are electrically switched valves and are electrically connected to the control system (5). They can automatically switch flow paths under the command of the control system (5) to pump different experimental fluids into the percolation vessel (2) in a predetermined order.

4. The experimental apparatus for simulating the dynamic permeation of shale oil reservoirs in situ according to claim 1, characterized in that, The clamping mechanism (21) includes: The slide rail (211) is installed inside the infiltration vessel body (2); A rubber cylinder (212) is slidably mounted on the slide rail (211) for holding the shale core (100). When confining pressure is applied inside the infiltration vessel (2), the rubber sleeve (212) can deform to wrap around and fix the shale core (100).

5. The experimental apparatus for simulating the dynamic percolation of shale oil reservoirs in situ according to claim 4, characterized in that, An annular flow space is formed between the inner wall of the percolation vessel (2) and the outer wall of the rubber cylinder (212); The experimental apparatus for simulating the in-situ dynamic seepage of shale oil reservoirs also includes a fluid circulation system (6), which includes a liquid circulation pipe (61) connected to the flow space and a circulation pump (62) connected to the liquid circulation pipe (61). The circulation pump (62) is electrically connected to the control system (5). The circulation pump (62) is used to pump fluid into the flow space to apply confining pressure, and / or, the circulation pump (62) is used to establish a circulating flow in the flow space to simulate the dynamic fluid environment in shale fractures.

6. The experimental apparatus for simulating the dynamic percolation of shale oil reservoirs in situ according to claim 1, characterized in that, The environmental simulation system (3) includes: The heating unit (31) includes a heating vessel (311) sleeved outside the percolation vessel body (2) and heating tubes (312) disposed inside the heating vessel (311). A plurality of heating tubes (312) are arranged at intervals along the inner peripheral wall of the heating vessel (311), and the heating tubes (312) are used to heat the percolation vessel body (2). Temperature sensor (32) and pressure sensor (33) are installed inside the percolation vessel (2) to monitor the temperature and pressure inside the percolation vessel (2) in real time; The heating unit (31), the temperature sensor (32) and the pressure sensor (33) are all electrically connected to the control system (5). The control system (5) is configured to control the working state of the heating unit (31) and the external pressure source according to the feedback signals of the temperature sensor (32) and the pressure sensor (33) so as to maintain the temperature and pressure conditions inside the percolation vessel (2) at a set value.

7. The experimental apparatus for simulating the dynamic permeation of shale oil reservoirs in situ according to claim 1, characterized in that, The infiltration front monitoring unit (41) includes multiple electrode holes (411) pre-drilled inside the shale core (100), electrode units (412) respectively implanted in each of the electrode holes (411), and a resistance meter (413) electrically connected to all the electrode units (412). The resistivity meter (413) is electrically connected to the control system (5). The resistivity meter (413) is used to measure the resistivity change data between different locations inside the shale core (100) and transmit the resistivity change data to the control system (5).

8. The experimental apparatus for simulating the dynamic permeation of shale oil reservoirs in situ according to claim 7, characterized in that, Multiple electrode holes (411) are arranged in a three-dimensional array inside the shale core (100); the electrode unit (412) is an Ag / AgCl electrode or a platinum electrode, and the electrode unit (412) is led out of the shale core (100) and connected to the resistance meter (413) through a wire.

9. An experimental method for simulating the dynamic permeation in situ environment of shale oil reservoirs, characterized in that, The experimental apparatus for simulating the in-situ dynamic permeation of shale oil reservoirs as described in any one of claims 1-8 includes: S1. Multiple monitoring points are set inside the shale core (100), the shale core (100) is installed in the clamping mechanism (21) of the seepage vessel body (2), and each monitoring point is connected to the in-situ monitoring system (4). S2. Set the target temperature and target pressure values ​​through the control system (5) and start the environmental simulation system (3) to make the inside of the percolation vessel (2) reach and maintain the set high temperature and high pressure in-situ environmental conditions. S3. The experimental fluid is supplied to the shale core (100) in the infiltration vessel (2) through the fluid supply system (1) to carry out the dynamic infiltration process; S4. The shale core (100) is monitored in situ in real time by the infiltration front monitoring unit (41) to obtain the morphology and propulsion parameters of the infiltration front; The shale core (100) is monitored in situ in real time by the mass change monitoring unit (42) to obtain the mass change data of the shale core (100); S5. The control system (5) calculates and outputs key parameters reflecting the percolation process in real time based on the received morphology and propulsion parameters of the percolation front and the mass change data. The key parameters include at least one of percolation efficiency and percolation rate.

Images