A core holder and method of holding

Abstract

The application discloses a kind of core clamping device and clamping method, it is related to oil and gas development technical field, core clamping device includes: confining pressure assembly, sample containing component, first liquid supply component and pressure measurement component;Wherein, sample containing component is installed in confining pressure cavity, and connecting hole is opened on sample containing component, connecting hole is used to be set correspondingly with the pressure tapping on core, first liquid supply component is connected with sample containing component, and first liquid supply component is used to provide displaced fluid to sample containing component, the detection end of pressure measurement component is installed on connecting hole, and the detection end of pressure measurement component is used to be connected with the pressure tapping, can directly measure the pressure inside core, using this directly to the pressure detection mode of core inside, it is guaranteed that core has reached saturated state before experiment, to be able to truly reflect the state of core in formation, effectively improve the accuracy and reliability of experiment.

Description

Technical Field

[0001] This invention relates to the field of oil and gas development technology, and in particular to a core clamping device and clamping method. Background Technology

[0002] Deep oil and gas reservoirs are a key area for oil and gas resource exploration and development in my country. These reservoirs have complex rock mechanical properties, varied geological structures, and are generally located under harsh formation conditions of high temperature, high pressure, low porosity, and low permeability. Conducting core laboratory physical simulation experiments is a core technical means to reveal reservoir seepage characteristics, rock mechanical response laws, and oil and gas development mechanisms.

[0003] Core holders, as key devices for simulating formation environments, primarily apply confining and pore pressures to the core by introducing high-pressure fluid into the device's internal cavity. The high-pressure fluid is then injected into the core to achieve fluid saturation, thereby reproducing the true stress state and fluid conditions of the underground rock and providing reliable experimental data for reservoir evaluation and development plan design. In existing technologies, core saturation operations typically rely solely on external indirect indicators such as fluid flow rate and pressure stability at the outlet end to determine whether the core has reached saturation. This method cannot accurately characterize the uniformity and degree of fluid saturation within the core in real time, easily leading to problems such as localized unsaturation, residual gas phase retention, or uneven fluid distribution. Relying solely on external parameters cannot guarantee sufficient and uniform fluid saturation, ultimately resulting in significant deviations between the simulated formation environment and the actual state of the underground rock. This distorts experimental data in rock mechanics parameter testing and seepage law research, failing to accurately reflect the actual geological characteristics of deep oil and gas reservoirs and severely impacting the accuracy and reliability of deep oil and gas reservoir exploration and development research.

[0004] Therefore, there is an urgent need for a core clamping device that can improve the accuracy and reliability of experiments. Summary of the Invention

[0005] The purpose of this invention is to provide a core clamping device and clamping method to solve the problems existing in the prior art. By connecting the pressure measuring component to the pressure tap on the core, the pressure inside the core can be measured to ensure that all parts inside the core are saturated before the experiment, thereby improving the accuracy and reliability of the experiment.

[0006] To achieve the above objectives, the present invention provides the following solution: This invention provides a core clamping device, comprising: a confining pressure assembly, a sample receiving assembly, a first liquid supply assembly, and a pressure measuring assembly; wherein, the confining pressure assembly has a confining pressure cavity capable of providing a confining pressure environment, the sample receiving assembly is installed in the confining pressure cavity and is used to hold the core, the sample receiving assembly has a connection hole for corresponding to a pressure tap on the core, the first liquid supply assembly is connected to the sample receiving assembly and is used to supply displaced fluid to the sample receiving assembly, the detection end of the pressure measuring assembly is installed on the connection hole, the detection end of the pressure measuring assembly is used to connect to the pressure tap and is used to measure the pressure inside the core.

[0007] In one embodiment, multiple connection holes are provided, and the multiple connection holes are distributed at intervals along the axial direction of the sample receiving assembly. The pressure measuring assembly includes pressure lines and pressure sensors. Multiple pressure lines are connected to the pressure tapping port through the connection holes, and the sensor is connected to the other end of the pressure lines.

[0008] As one embodiment, a ferrule connector is installed on the connection hole, and a ferrule is installed on the pressure tapping end of the pressure line of the pressure measuring assembly, the ferrule being matched with the ferrule connector.

[0009] As one embodiment, it also includes a second liquid supply component and a saturation measuring component. The second liquid supply component is connected to the sample containing component and is used to supply displacement liquid into the sample containing component. The saturation measuring component is capable of measuring the displacement edge within the core.

[0010] In one embodiment, the confining pressure assembly includes a confining pressure vessel body, a first plug, and a third liquid supply assembly. The two first plugs are respectively installed at both ends of the confining pressure vessel body. The third liquid supply assembly is connected to the confining pressure chamber. An exhaust port is provided at the upper end of the confining pressure chamber, and a switch is provided on the exhaust port.

[0011] As one embodiment, it also includes a temperature control system connected to the confining pressure chamber, the temperature control system being able to heat the liquid in the confining pressure chamber to a target temperature.

[0012] As one embodiment, the sample receiving assembly is further provided with a first discharge port, which is located at the upper end of the sample receiving assembly; the sample receiving assembly includes a rubber tube and a second plug, the second plug is installed at both ends of the rubber tube, and the first discharge port is opened on the second plug.

[0013] As one embodiment, it also includes a support frame, on which a balance shaft is provided. The balance shaft is rotatably connected to the support frame, and the axis of the balance shaft is perpendicular to the axis of the confining pressure assembly. The balance shaft is connected to the confining pressure assembly.

[0014] The present invention also provides a core clamping method, characterized by comprising the following steps: Step S1: Place the core into the sample receiving assembly; Step S2: Provide a first confining pressure to the sample receiving assembly through the confining pressure assembly; Step S3: After the first confining pressure stabilizes, the displaced liquid is supplied to the sample containing component through the first liquid supply component until the sample containing component is filled with the displaced liquid. Step S4: Continue to supply the displaced liquid into the sample containment assembly and increase the confining pressure provided by the confining pressure assembly so that the confining pressure provided by the confining pressure assembly is always greater than the pressure value in the sample containment assembly. Step S5: When the pressure in the sample holding assembly reaches the target pressure value, perform pressure holding observation; Step S6: Repeat steps S4 and S5 until the pressure value detected by the pressure measuring component no longer changes.

[0015] As one implementation, in step S4, the confining pressure value provided by the confining pressure assembly is always 3-5 MPa higher than the pressure value in the sample containing assembly.

[0016] The present invention achieves the following technical effects compared to the prior art: In the core clamping device disclosed in this invention, a confining pressure component provides a confining pressure environment for the core, and a first liquid supply component introduces a displaced liquid into the sample receiving component. Under high pressure, the displaced liquid can gradually penetrate into the core. The detection end of the pressure measuring component is connected to the pressure tap on the core through a connection hole, so that the pressure inside the core can be directly measured by the pressure measuring component. When the pressure inside the core no longer changes, it indicates that the core has reached a saturated state, so as to carry out subsequent experiments. That is, by adopting this method of directly measuring the pressure inside the core, it is ensured that the core has reached a saturated state before the experiment, so as to truly reflect the state of the core in the formation and effectively improve the accuracy and reliability of the experiment. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the core clamping device in an embodiment of the present invention; Figure 2 This is a schematic diagram of the installation of the pressure pipeline in an embodiment of the present invention; Figure 3 This is a schematic diagram of a core clamping device in another embodiment of the present invention.

[0019] The components are as follows: 1. Confining pressure chamber; 2. Connecting hole; 3. Pressure measuring component; 4. Pressure pipeline; 5. Pressure sensor; 6. Compression fitting; 7. Compression fitting; 8. Saturation measuring component; 9. Confining pressure vessel body; 10. First plug; 11. Exhaust port; 12. First discharge port; 13. Glue tube; 14. Second plug; 15. Support frame; 16. Balance shaft; 17. Liquid inlet; 18. Liquid outlet; 19. First feed inlet; 20. Second feed inlet; 21. Second discharge port; 22. Glue tube bracket; 23. Temperature control system chassis; 24. Display; 25. Outer shell. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] The purpose of this invention is to provide a core clamping device and clamping method to solve the problems existing in the prior art. By directly detecting the internal pressure of the core through a pressure measuring component, the accuracy and reliability of the experiment are improved.

[0022] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] Example 1 Please refer to Figures 1-3This embodiment provides a core clamping device, including: a confining pressure assembly, a sample receiving assembly, a first liquid supply assembly, and a pressure measuring assembly 3; wherein, the confining pressure assembly has a confining pressure cavity 1 capable of providing a confining pressure environment, the sample receiving assembly is installed in the confining pressure cavity 1, the sample receiving assembly is used to hold the core, the sample receiving assembly has a connection hole 2, the connection hole 2 is used to correspond to the pressure tapping port on the core, the first liquid supply assembly is connected to the sample receiving assembly, the first liquid supply assembly is used to provide the displaced liquid to the sample receiving assembly, the detection end of the pressure measuring assembly 3 is installed on the connection hole 2, the detection end of the pressure measuring assembly 3 is used to connect to the pressure tapping port, and is used to measure the pressure inside the core. Its working principle is as follows: the processed rock core is placed into the sample receiving assembly. The shape of the rock core matches the shape of the receiving space of the sample receiving assembly. A pressure tap is pre-drilled on the rock core. The operator can determine the location of the pressure tap according to the actual working conditions to ensure that the pressure tap and the connection hole 2 can accurately correspond after the rock core is placed into the sample receiving assembly. The confining pressure assembly provides confining pressure to the sample receiving assembly to simulate the stress on the rock core in the formation. The first liquid supply assembly can supply the displaced fluid into the sample receiving assembly. Under pressure, the displaced fluid can gradually seep into the interior of the rock core. The detection end of the pressure measuring assembly 3 is installed in the sample receiving assembly. On the connecting hole 2, under confining pressure, the outer wall of the container space of the sample container component is tightly fitted to the core. At this time, the connecting hole 2 will be tightly connected to the pressure tap. The pressure inside the pressure tap can be directly transmitted to the detection end of the pressure measuring component 3, thereby realizing the measurement of the internal pressure of the core. It can be understood that as the displaced fluid seeps into the core, the internal pressure of the core will change. When the pressure value measured by the pressure measuring component 3 remains stable, it means that the core is saturated, so as to carry out subsequent experiments. This can truly reflect the state of the core in the formation and effectively improve the accuracy and reliability of the experiment.

[0024] In one embodiment, multiple connection holes 2 are provided, and the multiple connection holes 2 are distributed at intervals along the axial direction of the sample receiving component. Correspondingly, the pressure measuring component 3 has multiple detection ends, and the multiple detection ends are respectively installed on a connection hole 2, so that pressure can be measured at multiple points along the axial direction of the sample receiving component. When the pressure at multiple points no longer changes, it can be determined that the core is saturated at each position along the axial direction.

[0025] It is understandable that the displaced fluid gradually permeates the core. Due to factors such as the heterogeneity of the core's internal texture and the location or method of supplying the displaced fluid, the degree of permeation at different locations in the core will vary. This phenomenon is particularly evident in long cores, i.e. cores with a large axial dimension. By adopting the above method, the error caused by single-point detection can be effectively avoided, thereby meeting the experimental requirements of long cores.

[0026] In one embodiment, the pressure measurement assembly 3 includes pressure lines 4 and pressure sensors 5. Multiple pressure lines 4 are connected to pressure taps via connection holes 2, and the sensors are connected to the other end of the pressure lines 4. The end of the pressure line 4 connected to the connection hole 2 serves as the detection end of the pressure measurement assembly 3, which can transmit pressure information from the pressure taps to the pressure sensor 5, so that operators can obtain pressure information within the core sample.

[0027] In one embodiment, a ferrule connector 6 is installed on the connection hole 2, and a ferrule 7 is installed on the pressure tapping end of the pressure line 4 of the pressure measuring assembly 3. The ferrule 7 matches the ferrule connector 6. The ferrule connector 6 is sealed to the connection hole 2, and the ferrule 7 is sealed to the pressure line 4. The ferrule connector 6 and the ferrule 7 enable a detachable connection between the pressure line 4 and the sample receiving assembly. It is understood that the ferrule 7 and the ferrule connector 6 are known structures in the prior art, and their specific usage and structure will not be described in detail here.

[0028] In one embodiment, the core clamping device further includes a second liquid supply component and a saturation measuring component 8. The second liquid supply component is connected to the sample receiving component and is used to supply displacement fluid into the sample receiving component. The saturation measuring component 8 can measure the displacement edge within the core. Its working principle is as follows: when the core in the sample receiving component reaches saturation, displacement fluid is introduced into the sample receiving component, and the displaced fluid is gradually discharged from the core. The saturation of the displacement fluid or the displaced fluid at the target location in the core can be measured by the saturation measuring component 8, thereby obtaining the position of the displacement edge within the core. It can be understood that the displacement edge refers to the boundary between the displacement fluid and the displaced fluid.

[0029] In one embodiment, the saturation measuring component 8 is a resistance measuring device. When no displacing fluid or displaced fluid is introduced into the core, the resistance of the core is very high and it can hardly conduct electricity. As the displacing fluid or displaced fluid gradually seeps into the core, its resistance will gradually decrease. Moreover, the displacing fluid and the displaced fluid have different trends in their influence on the resistance of the core. Therefore, by measuring the resistance of the core, the saturation of the displacing fluid or displaced fluid in the core can be directly reflected.

[0030] In one embodiment, the resistance measuring device includes a positive resistance wire, a negative resistance wire, an ammeter, and a power supply. In use, a detection hole is made in the core sample. The positive and negative resistance wires are installed alternately in the detection hole, and the opening of the detection hole is sealed with insulating resin. The voltage of the power supply is known, and the ammeter can display the current in real time. Using Ohm's law, the resistance at the saturation detection location on the core sample can be obtained in real time, thus determining whether the saturation detection location is a displacing fluid or a displaced fluid. When the resistance abruptly changes from a stable value to another value, it indicates that the displacement edge has crossed that location. Of course, other known methods of measuring resistance can also be used to measure the resistance at the target location.

[0031] In one embodiment, the core clamping device is provided with multiple saturation measuring points, which are spaced apart along the axial direction of the sample receiving component, and each saturation measuring point is equipped with a saturation detection component.

[0032] In one embodiment, the saturation measurement component 8 is a CT scanning device or an MRI device.

[0033] In one embodiment, the confining pressure assembly includes a confining pressure vessel body 9, a first plug 10, and a third liquid supply assembly. Two first plugs 10 are respectively installed at both ends of the confining pressure vessel body 9. The third liquid supply assembly is connected to the confining pressure chamber 1. An exhaust port 11 is provided at the upper end of the confining pressure chamber 1, and a switch is provided on the exhaust port 11. When the confining pressure assembly needs to provide confining pressure, the third liquid supply assembly is turned on, and the switch on the exhaust port 11 is opened. During the process of the confining pressure liquid entering the confining pressure vessel body 9, the air inside the confining pressure vessel body 9 is discharged through the exhaust port 11 until confining pressure liquid flows out of the exhaust port 11. Then, the switch on the exhaust port 11 is closed, and the confining pressure liquid continues to be supplied. As the confining pressure liquid continues to be supplied, the pressure inside the confining pressure vessel body 9 will gradually increase, thereby applying confining pressure to the sample containing assembly.

[0034] In one embodiment, a liquid inlet 17 is provided on the first plug 10 at the lower end of the confining pressure vessel body 9. The liquid inlet 17 is connected to the third liquid supply component. This bottom-up liquid supply method ensures that the gas in the upper part of the confining pressure vessel body 9 can be completely discharged.

[0035] In one embodiment, a liquid outlet 18 is provided on the first plug 10 at the lower end of the confining pressure vessel body 9, through which the confining pressure liquid inside the confining pressure vessel body 9 can be quickly and thoroughly discharged.

[0036] In one embodiment, the pressure sensor 5 is installed outside the confined pressure vessel body 9, and a through hole is provided on the side wall of the confined pressure vessel body 9 for the pressure pipeline 4 to pass through, and the through hole is sealed.

[0037] In one embodiment, the core clamping device further includes a temperature control system connected to the confining pressure chamber 1, which can heat the liquid in the confining pressure chamber 1 to a target temperature.

[0038] In one embodiment, the temperature control system includes a heating device installed inside the confining pressure vessel 9, which can directly heat the confining pressure liquid inside the confining pressure vessel 9.

[0039] In one embodiment, the process of introducing confining fluid into the confining pressure vessel 9 is divided into a filling process and a pressurizing process. The process from introducing confining fluid into the confining pressure vessel 9 until the confining fluid fills the confining pressure vessel 9 is the filling process. The process from filling the confining pressure vessel 9 until the pressure inside the confining pressure vessel 9 reaches a preset value is the pressurizing process. When the filling process is completed, the heating device is turned on to heat the confining fluid inside the confining pressure vessel 9 to the target temperature. After the confining fluid reaches the target temperature, the pressurizing process is then carried out.

[0040] In one embodiment, the confining pressure inside the confining pressure vessel 9 is 5MPa-10MPa.

[0041] In one embodiment, the temperature control system further includes a temperature detector installed inside the confining pressure vessel 9, which enables real-time monitoring of the temperature of the confining pressure liquid.

[0042] In one embodiment, the sample containing assembly is further provided with a first outlet 12, which is located at the upper end of the sample containing assembly. When the displaced liquid is supplied to the sample containing assembly through the first liquid supply assembly, the first outlet 12 is first opened until the displaced liquid flows out from the first outlet 12, then the first outlet 12 is closed, and then the displaced liquid continues to be supplied to the sample containing assembly until the target pressure is reached. When the displaced liquid is supplied to the sample containing assembly, the displaced liquid is also discharged from the first outlet 12.

[0043] In one embodiment, the sample receiving assembly includes a glue tube 13 and a second plug 14, the second plug 14 being installed at both ends of the glue tube 13.

[0044] In one embodiment, the first discharge port 12 is located on the second plug 14 at the upper end of the rubber cylinder 13.

[0045] In one embodiment, a first feed port 19 is also provided on the second plug 14 at the upper end of the glue tube 13, and the first liquid supply component is connected to the glue tube 13 through the first feed port 19.

[0046] In one embodiment, the rubber sleeve 13 is coaxially arranged with the pressure vessel body 9, and the first plug 10 at the end of the pressure vessel body 9 is provided with a through hole corresponding to the first feed port 19 and the first discharge port 12.

[0047] In one embodiment, a second feed port 20 is provided on the second plug 14 at the lower end of the glue tube 13, and the second liquid supply assembly is connected to the glue tube 13 through the second feed port 20.

[0048] In one embodiment, a second discharge port 21 is also provided on the second plug 14 at the lower end of the rubber tube 13. The corresponding first plug 10 at the lower end of the pressure vessel body 9 is provided with through holes corresponding to the second inlet 20 and the second discharge port 21.

[0049] In one embodiment, the connection hole 2 is formed on the side wall of the rubber tube 13.

[0050] In one embodiment, the core clamping device further includes a rubber sleeve support 22, which is installed inside the confining pressure vessel 9 and connected to the inner wall of the confining pressure vessel 9. The rubber sleeve 13 is installed on the rubber sleeve support 22.

[0051] In one embodiment, the rubber sleeve support 22 is made of metal and can withstand pressures of over 80 MPa and temperatures of over 150°C. It is also not easily deformed and can maintain the stability of the rubber sleeve 13 when the pressure vessel body 9 is rotated to an inclined angle.

[0052] In one embodiment, the core clamping device further includes a support frame 15, on which a balance shaft 16 is mounted. The balance shaft 16 is rotatably connected to the support frame 15, and its axis is perpendicular to the axis of the confining pressure assembly. The confining pressure assembly is connected to the support frame 15 via the balance shaft 16, thereby achieving the positioning of the confining pressure assembly. The rotatable connection between the balance shaft 16 and the support frame 15 enables the confining pressure assembly to be rotated. When a core needs to be inserted, the confining pressure assembly is rotated to an angle that facilitates operation, allowing the operator to insert the core into the rubber sleeve 13 inside the confining pressure vessel body 9 from top to bottom.

[0053] In one embodiment, the core clamping device further includes a housing 25, within which a confining pressure assembly is installed, and the housing 25 provides protection for the confining pressure assembly. It is understood that the housing 25 has a through hole through which the balance shaft 16 passes.

[0054] In one embodiment, the first liquid supply assembly, the second liquid supply assembly, and the third liquid supply assembly each include a receiving cavity for containing the target liquid, the outlet of the receiving cavity is connected to a delivery pipeline, and a drive pump is provided on the delivery pipeline.

[0055] In one embodiment, a pressure gauge for detecting pipeline pressure is installed on the delivery pipeline.

[0056] In one embodiment, a pressure gauge is provided on the liquid inlet 17 and / or the feed inlet.

[0057] In one embodiment, the displacing fluid and the displaced fluid are two immiscible fluids.

[0058] In one embodiment, the displacing fluid is water, and the fluid being displaced is oil.

[0059] In one embodiment, the core clamping device further includes a back pressure pump connected to the first discharge port 12 for controlling the back pressure value.

[0060] In one embodiment, the device is capable of simultaneously loading multiple rock cores of the same diameter into the rubber sleeve 13.

[0061] In one embodiment, a gas flow meter is provided on the exhaust port 11.

[0062] In one embodiment, a computer is also included, which is connected to the pressure measuring component 3, the temperature detector, and the gas flow meter. The computer can collect relevant information.

[0063] In one embodiment, the first plug 10 is detachably connected to the pressure vessel body 9 via a bolt assembly, and the second plug 14 is detachably installed at both ends of the rubber tube 13 via a bolt assembly.

[0064] In one embodiment, the end of the first plug 10 near the rubber tube 13 is connected to the end of the second plug 14 away from the rubber tube 13 through a slot structure and a protrusion structure.

[0065] In one embodiment, eight pressure measuring points are arranged along the axial direction of the rubber sleeve 13, and each pressure measuring point is connected to the detection end of a pressure measuring component 3.

[0066] In one embodiment, each pressure line 4 transmits pressure through a pressure orifice with a diameter of 8 mm.

[0067] In one embodiment, nine saturation measuring points are provided along the axial direction of the rubber sleeve 13.

[0068] In one embodiment, the spacing between each saturation measurement point is 100 mm.

[0069] In one embodiment, the rubber sleeve 13 can detect cores with a maximum diameter of 1000 mm.

[0070] In one embodiment, the radial dimension of the glue sleeve 13 is 70mm-80mm. Optionally, the radial dimension of the glue sleeve 13 is 78mm.

[0071] In one embodiment, the temperature control system includes a temperature control system chassis 23, on which a display 24 is provided.

[0072] Example 2 This embodiment provides a core clamping method, including the following steps: Step S1: Place the core into a sample receiving assembly; Step S2: Provide a first confining pressure to the sample receiving assembly through a confining pressure assembly; Step S3: After the first confining pressure stabilizes, supply the displaced fluid into the sample receiving assembly through a first liquid supply assembly until the displaced fluid fills the sample receiving assembly; Step S4: Continue to supply the displaced fluid into the sample receiving assembly and increase the confining pressure provided by the confining pressure assembly so that the confining pressure value provided by the confining pressure assembly is always greater than the pressure value in the sample receiving assembly; Step S5: When the pressure in the sample receiving assembly reaches the target pressure value, perform pressure holding observation; Step S6: Repeat steps S4 and S5 until the pressure value detected by the pressure measuring assembly 3 no longer changes. This method can accelerate the rate at which the displaced fluid penetrates into the core, shorten the waiting time for core saturation, and also ensure a tight connection between the connecting hole 2 and the pressure tapping port.

[0073] In one embodiment, when installing the core, the first plug 10 at the upper end of the confining pressure vessel 9 and the second plug 14 at the upper end of the rubber tube 13 are first opened, the angle of the confining pressure vessel 9 is adjusted, the core is loaded into the rubber tube 13, and then the first plug 10 and the second plug 14 are put back onto the confining pressure vessel 9 and the rubber tube 13.

[0074] In one embodiment, there are two ways to ensure that the confining pressure provided by the confining pressure assembly is always greater than the pressure value in the sample containing assembly in step S4. The first way is to increase the confining pressure provided by the confining pressure assembly while continuing to supply the displaced liquid to the sample containing assembly; the second way is to alternate between the supply of the displaced liquid and the increase of the confining pressure, that is, first continue to supply a certain amount of displaced liquid, and then increase the confining pressure value to a certain value, and so on.

[0075] In one embodiment, in step S4, the confining pressure value provided by the confining pressure assembly is always 1 MPa-5 MPa higher than the pressure value in the sample containing assembly.

[0076] In one embodiment, the confining pressure provided by the confining pressure assembly is always 2 MPa higher than the pressure in the sample containment assembly.

[0077] In one embodiment, a back pressure pump is connected to the first discharge port 12, and the pressure drop during the experiment is controlled by the back pressure pump. The back pressure is set according to the design scheme, and the formation conditions, including experimental temperature and experimental pressure, are simulated according to the design scheme to conduct core experiments.

[0078] In one embodiment, after the experiment, the corresponding drive pump and back pressure pump are turned off first. When the temperature drops to a safe temperature, the pressure in the rubber cylinder 13 is unloaded through the first discharge port 12, and the confining pressure is unloaded through the liquid outlet 18. After unloading, the first plugs 10 at both ends of the confining pressure vessel body 9 and the second plugs 14 at both ends of the rubber cylinder 13 are opened, the test core is taken out, and the device is cleaned.

[0079] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A core clamping device, characterized in that, include: A confining pressure assembly having a confining pressure chamber (1) capable of providing a confining pressure environment. A sample holding assembly is installed inside the confining pressure chamber (1). The sample holding assembly is used to hold the rock core. A connecting hole (2) is provided on the sample holding assembly. The connecting hole (2) is used to correspond to the pressure tapping port on the rock core. A first liquid supply component is connected to the sample containing component and is used to supply the displaced liquid to the sample containing component. And a pressure measuring component (3), the detection end of which is installed on the connection hole (2), the detection end of which is used to connect to the pressure tap and to measure the pressure inside the core.

2. The core clamping device according to claim 1, characterized in that, The connection hole (2) is provided in multiple ways. The multiple connection holes (2) are distributed at intervals along the axial direction of the sample receiving component. The pressure measuring component (3) includes a pressure line (4) and a pressure sensor (5). The multiple pressure lines (4) are connected to the pressure tap through the connection hole (2). The sensor is connected to the other end of the pressure line (4).

3. The core clamping device according to claim 2, characterized in that, A ferrule connector (6) is installed on the connection hole (2), and a ferrule (7) is installed on the pressure tapping end of the pressure line (4) of the pressure measuring assembly. The ferrule (7) is matched with the ferrule connector (6).

4. The core clamping device according to claim 1, characterized in that, It also includes a second liquid supply component and a saturation measurement component (8). The second liquid supply component is connected to the sample container component and is used to supply displacement liquid into the sample container component. The saturation measurement component (8) is capable of measuring the displacement edge in the core.

5. The core clamping device according to claim 1, characterized in that, The confining pressure assembly includes a confining pressure vessel body (9), a first plug (10), and a third liquid supply assembly. Two first plugs (10) are respectively installed at both ends of the confining pressure vessel body (9). The third liquid supply assembly is connected to the confining pressure chamber (1). An exhaust port (11) is provided at the upper end of the confining pressure chamber (1). A switch is provided on the exhaust port (11).

6. The core clamping device according to claim 5, characterized in that, It also includes a temperature control system, which is connected to the confining pressure chamber (1) and can heat the liquid in the confining pressure chamber (1) to the target temperature.

7. The core clamping device according to claim 1, characterized in that, The sample containing assembly is also provided with a first discharge port (12), which is located at the upper end of the sample containing assembly. The sample containing assembly includes a rubber tube (13) and a second plug (14). The second plug (14) is installed at both ends of the rubber tube (13), and the first discharge port (12) is opened on the second plug (14).

8. The core clamping device according to claim 1, characterized in that, It also includes a support frame (15), on which a balance shaft (16) is provided. The balance shaft (16) is rotatably connected to the support frame (15). The axis of the balance shaft (16) is perpendicular to the axis of the confining pressure assembly. The balance shaft (16) is connected to the confining pressure assembly.

9. A method for holding a rock core, characterized in that, Includes the following steps: Step S1: Place the core into the sample receiving assembly; Step S2: Provide a first confining pressure to the sample receiving assembly through the confining pressure assembly; Step S3: After the first confining pressure stabilizes, the displaced liquid is supplied to the sample containing component through the first liquid supply component until the sample containing component is filled with the displaced liquid. Step S4: Continue to supply the displaced liquid into the sample containment assembly and increase the confining pressure provided by the confining pressure assembly so that the confining pressure provided by the confining pressure assembly is always greater than the pressure value in the sample containment assembly. Step S5: When the pressure in the sample holding assembly reaches the target pressure value, perform pressure holding observation; Step S6: Repeat steps S4 and S5 until the pressure value detected by the pressure measuring component (3) no longer changes.

10. The core clamping method according to claim 9, characterized in that, In step S4, the confining pressure provided by the confining pressure assembly is always 3-5 MPa higher than the pressure in the sample containing assembly.

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