Microscopic visualization experiment equipment and method for physical property characteristics of rock under stratum condition

Abstract

The invention discloses microscopic visualization experiment equipment and a microscopic visualization experiment method for physical property characteristics of rocks under stratum conditions. The experimental equipment comprises a rock core clamping device, a heating box, a pressurizing device, a temperature sensor, a pressure sensor, a pressure release valve and an electron microscope, a heater is arranged in the heating box, and the core clamping device, the temperature sensor and the pressure sensor are also arranged in the heating box; a top cover of the heating box is a visual window, and the electron microscope is used for collecting microscopic images of a rock sample clamped by the rock core clamping unit in real time through the visual window. By means of the device, changes of physical parameters and pore throat structures in the rock compression and heating process under the simulated stratum condition can be obtained, and continuous dynamic microscopic visual observation can be conducted.

Description

Technical Field

[0001] The present invention relates to the technical field of petroleum exploration and development, and in particular to a microscopic visualization experimental device and method for rock physical property characteristics under formation conditions. Background Art

[0002] Measuring the pore structure and physical properties of reservoir rocks is key to studying oil and gas exploration. Unconventional reservoirs are highly heterogeneous, with narrow throats and a predominantly micro- and nano-scale pore throat system. They differ from sandstones with higher permeability in petrographic terms in the following ways: (1) primary pores are lost through diagenesis; (2) most pores appear in secondary pore (dissolution) spaces; and (3) slit-like pores exist between the secondary enlarged edges of adjacent quartz on sand grains, forming interconnected channels for fluid flow. In short, secondary dissolution pores constitute reservoir pores, and the width of the slit-like pores determines the effect of permeability on fluid flow. Therefore, clarifying the pore structure characteristics of tight reservoirs is key to improving oil recovery and achieving commercial development.

[0003] Currently, there are many experimental methods for measuring reservoir petrophysical properties, including gas logging, liquid logging, and nuclear magnetic resonance (NMR). Gas logging, also known as the gas expansion method, involves expanding gas into the sample's pores and recording the pressures before and after equilibrium to determine the rock's skeletal volume. This method can be used on both cylindrical core samples and granular samples. Its advantage is that it is unaffected by the properties of the applied fluid and provides a comprehensive picture of the entire spatial volume of the rock sample. This method is generally used to measure petrophysical properties at room temperature. Although a few methods have considered temperature fluctuations, subsequent studies of the rock's pore structure primarily involve removing the sample and manually observing and identifying it under a scanning electron microscope. The main challenges with these experiments are: first, most petrophysical property measurements fail to account for the effects of temperature; second, the heated sample must be removed during both the heating and observation steps. This reduces the temperature and pressure of the shale sample during SEM observation, potentially altering the rock's pore structure due to temperature fluctuations. Although some experiments have considered the effects of temperature, the latter issue also persists. Therefore, how to solve the problem of measuring the pore structure and physical properties of reservoir rocks under formation conditions, while also avoiding the impact of temperature and pressure changes on the results of subsequent scanning electron microscopy observations of the samples after the test, is one of the technologies that urgently need to be tackled in the current unconventional oil exploration and development. Summary of the Invention

[0004] In order to enrich product types, enrich process routes, and increase selection space, the embodiments of the present invention provide a microscopic visualization experimental device and method for rock physical property characteristics under formation conditions, which can actually obtain the changes in physical parameters and pore throat structure of rocks during the compression and heating of rocks under simulated formation conditions, and perform continuous dynamic microscopic visualization observations, thereby solving the problem that the temperature and pressure changes of samples taken out after the physical property measurement experiment in traditional methods affect the subsequent scanning electron microscope observation results, and improving the accuracy of experimental analysis results.

[0005] In a first aspect, an embodiment of the present invention provides a microscopic visualization experimental device for rock physical properties under formation conditions, comprising a core clamping device, a heating box, a pressurizing device, a temperature sensor, a pressure sensor, a pressure relief valve, and an electron microscope;

[0006] A heater is provided in the heating box, and the core clamping device, temperature sensor and pressure sensor are also provided in the heating box;

[0007] The top cover of the heating box is a visual window, and the electron microscope is used to collect a microscopic image of the rock sample clamped by the core clamp in real time through the visual window.

[0008] In some embodiments, the pressurizing device includes a high-pressure pump, a pressure regulating valve, and a pressure gauge connected in sequence through a pipeline, and the end of the pipeline away from the high-pressure pump extends into the heating box.

[0009] In some embodiments, the outer wall of the heating box is provided with a temperature control switch for controlling the heating temperature of the heater;

[0010] The pressure relief valve is arranged on the outer wall of the heating box, and is used to reduce the pressure in the heating box by discharging the gas in the heating box.

[0011] In some embodiments, the core holding device includes a first fixing tube, a first fixing clamp, a second fixing tube, and a second fixing clamp;

[0012] The first fixing clamp and the second fixing clamp are used to fix the rock sample;

[0013] One end of the first fixed tube is fixed to the inner wall of the heating box, and the other end is connected to the first fixed clamp. One end of the second fixed tube is fixed to the inner wall of the heating box, and the other end is connected to the second fixed clamp.

[0014] In some embodiments, the visual window includes an upper transparent plate and a lower transparent plate, and the cavity between the upper transparent plate and the lower transparent plate is a vacuum cavity;

[0015] The four sides of the viewing window are sealed and connected to the inner wall of the heating box through a sealing ring.

[0016] In some embodiments, the distance between the upper transparent plate and the lower transparent plate is 8 to 12 cm.

[0017] In some embodiments, the device further includes a data acquisition board, and the temperature sensor and the pressure sensor are both electrically connected to the data acquisition board.

[0018] In some embodiments, the apparatus further comprises a physical property parameter calculation device;

[0019] The data acquisition board is used to send the collected temperature data and pressure data to the physical property parameter calculation device, so that the physical property calculation device determines the physical property parameters of the rock sample according to the received temperature data and pressure data.

[0020] In some embodiments, the apparatus further comprises a data acquisition device;

[0021] The data acquisition device is used to acquire the microscopic image taken by the electron microscope, or,

[0022] The data acquisition device is used to acquire the microscopic image taken by the electron microscope and the temperature data and pressure data acquired by the data acquisition board.

[0023] In a second aspect, an embodiment of the present invention provides a method for microscopic visualization of rock physical properties under formation conditions, comprising performing the following experimental steps using any of the above-mentioned microscopic visualization experimental devices for rock physical properties under formation conditions:

[0024] The rock sample is held by a core clamping device, and an inert gas is injected into the heating box by a pressurizing device to exhaust the air in the pipeline and the heating box;

[0025] Using a pressurizing device and / or a pressure relief valve to adjust the pressure in the cavity of the heating box to a set pressure, and using the heating box to adjust the temperature in the cavity to a set temperature;

[0026] The temperature data and pressure data in the heating box cavity are respectively obtained by a temperature sensor and a pressure sensor, and the microscopic image of the rock sample under corresponding temperature and pressure conditions is obtained by an electron microscope.

[0027] The beneficial effects of the above technical solutions provided by the embodiments of the present invention include at least:

[0028] The present invention provides a microscopic visualization experimental device for rock physical property characteristics under formation conditions, comprising a core clamping device, a heating box, a pressurizing device, a temperature sensor, a pressure sensor, a pressure relief valve, and an electron microscope. The heating box is provided with a heater, and the core clamping device, temperature sensor, and pressure sensor are also disposed within the heating box. The top cover of the heating box is a viewing window, through which the electron microscope is used to capture real-time microscopic images of the rock sample held by the core clamp. The heater and pressurizing device enable simulation of formation conditions. The electron microscope and viewing window enable continuous dynamic microscopic visualization of changes in physical parameters and pore throat structure during the process of rock being subjected to pressure and heating under simulated formation conditions, as well as image acquisition. This addresses the problem of traditional methods whereby temperature and pressure changes in samples removed after a physical property measurement experiment affect subsequent scanning electron microscopy observations, thereby improving the accuracy of experimental analysis results. The measurement data obtained from the temperature and pressure sensors can be used to determine the physical properties of the rock sample under the corresponding temperature and pressure conditions, providing a theoretical basis and technical support for fields such as reservoir research, oil thermal recovery, and geothermal reservoir reconstruction.

[0029] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present invention. The purposes and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description, claims, and drawings.

[0030] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0032] Figure 1 This is a schematic diagram of the structure of the experimental equipment for microscopic visualization of rock physical properties under formation conditions in Example 1 of the present invention;

[0033] Figure 2 Schematic diagram of the structure of the visual window in the first embodiment of the present invention;

[0034] Figure 3 This is a flow chart of the experimental method for microscopic visualization of rock physical property characteristics under formation conditions in Example 2 of the present invention. DETAILED DESCRIPTION

[0035] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0036] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any intermediate value within a stated value or stated range and any other stated value or intermediate value within the stated range is also encompassed by the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0037] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the invention belongs. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In the event of any conflict with any incorporated document, the content of this specification shall prevail.

[0038] In the description of the present invention, it should be noted that the terms “include”, “including”, “have”, “contain”, etc. are all open terms, which mean including but not limited to.

[0039] Example 1

[0040] The first embodiment of the present invention provides a microscopic visualization experimental device for rock physical properties under formation conditions, see Figure 1 As shown, it includes a core clamping device 1, a heating box 2, a pressurizing device 3, a temperature sensor 4, a pressure sensor 5, a pressure relief valve 6 and an electron microscope 7.

[0041] The heating box 2 is a heat-resistant and pressure-resistant heating box, and a heater 8 is provided in the heating box 2 .

[0042] Furthermore, the heating box 2 may be a rectangular parallelepiped; there may be two heaters 8 provided therein, which are respectively provided on two opposite wall panels to make the heating more uniform.

[0043] The wall panels of the heating box 2 can be heat-resistant and pressure-resistant steel plates.

[0044] The core clamping device 1 , the temperature sensor 4 and the pressure sensor 5 are also arranged in the heating box 2 .

[0045] The top of the heating box 2 is open, and its top cover is set as a viewing window 9. The electron microscope 7 is used to collect a microscopic image of the rock sample A clamped by the core clamp 1 in real time through the viewing window 9.

[0046] Optional, see Figure 2 As shown, the visual window 9 includes an upper transparent plate 9-1 and a lower transparent plate 9-2, and the cavity 9-3 between the upper transparent plate 9-1 and the lower transparent plate 9-2 is a vacuum cavity; the four sides of the visual window 9 are sealed and connected to the inner wall of the heating box 2 through a sealing ring 9-4.

[0047] The upper and lower transparent plates are heat-resistant and pressure-resistant glass plates. Furthermore, the heat resistance and pressure resistance of the upper transparent plate 9-1 may be inferior to those of the lower transparent plate 9-2.

[0048] The cavity 9 - 3 between the upper transparent plate 9 - 1 and the lower transparent plate 9 - 2 is a vacuum cavity, so that the viewing window 9 has a heat insulation effect.

[0049] Furthermore, the distance between the upper transparent plate 9-1 and the lower transparent plate 9-2 is 8 to 12 cm. If the distance between the two is too large, the visual effect will be affected; if the distance between the two is too small, the heat insulation effect will be poor.

[0050] The electron microscope 7 is a high-definition, heat-resistant and pressure-resistant scanning electron microscope, which is arranged above the heating box 2, with the lower objective lens facing the viewing window 9. The electron microscope 7 can monitor and record the rock sample A in the field of view, and automatically save each frame of the video as a separate continuous image according to the time parameter.

[0051] Optionally, the pressurizing device 3 may include a high-pressure pump 3-1, a pressure regulating valve 3-2 and a pressure gauge 3-3 connected in sequence through a pipeline, and an end of the pipeline away from the high-pressure pump 3-1 extends into the heating box 2.

[0052] The high-pressure pump 3 - 1 is used to input inert gas (such as nitrogen, helium, etc.) into the heating box 2 to increase the pressure in the cavity of the heating box 2 .

[0053] A temperature control switch 10 is provided on the outer wall of the heating box 2 for controlling the heating temperature of the heater 8 .

[0054] The pressure relief valve 6 is provided on the outer wall of the heating box 2 and is used to reduce the pressure in the heating box by discharging the gas in the heating box 2 .

[0055] The core clamping device 1 includes a first fixing tube 1-1, a first fixing clamp 1-2, a second fixing clamp 1-3, and a second fixing tube 1-4. The first fixing clamp 1-2 and the second fixing clamp 1-3 are used to fix the rock sample A. One end of the first fixing tube 1-1 is fixed to the inner wall of the heating box 2, and the other end is connected to the first fixing clamp 1-2. One end of the second fixing tube 1-4 is fixed to the inner wall of the heating box 2, and the other end is connected to the second fixing clamp 1-3.

[0056] Furthermore, the first fixing tube 1 - 1 , the first fixing clamp 1 - 2 , the second fixing clamp 1 - 3 and the second fixing tube 1 - 4 are arranged on the same horizontal line.

[0057] The above experimental equipment further includes a data acquisition board 11, and the temperature sensor 4 and the pressure sensor 5 are both electrically connected to the data acquisition board 11. The data acquisition board 11 is used to collect temperature data measured by the temperature sensor 4 and pressure data measured by the pressure sensor 5.

[0058] Optionally, the above-mentioned experimental equipment also includes a physical property parameter calculation device 12; the data acquisition board 11 is used to send the collected temperature data and pressure data to the physical property parameter calculation device 12, so that the physical property calculation device 12 determines the physical property parameters of the rock sample using the gas state equation formula based on the received temperature data and pressure data.

[0059] Optionally, the physical property parameter calculation device 12 may also be directly electrically connected to the temperature sensor 4 and the pressure sensor 5 , so as to directly collect temperature data and pressure data.

[0060] Optionally, the above experimental equipment further includes a data acquisition device 13 .

[0061] The user can adjust the parameters of the electron microscope 7 according to needs through the data acquisition device 13 to obtain a satisfactory field of view.

[0062] The data acquisition device 13 is used to acquire the microscopic image taken by the electron microscope 7 , or the data acquisition device 13 is used to acquire the microscopic image taken by the electron microscope 7 and the temperature data and pressure data acquired by the data acquisition board 11 .

[0063] The physical property parameter calculation device 12 and the data acquisition device 13 can be set on one terminal or on different terminals. Figure 1 In the example, the physical property parameter calculation device and the data acquisition device are respectively set at different terminals.

[0064] The first embodiment of the present invention provides a microscopic visualization experimental device for rock physical property characteristics under formation conditions, comprising a core clamping device, a heating box, a pressurizing device, a temperature sensor, a pressure sensor, a pressure relief valve, and an electron microscope. The heating box is provided with a heater, and the core clamping device, temperature sensor, and pressure sensor are also provided within the heating box. The top cover of the heating box is a viewing window, through which the electron microscope is used to capture real-time microscopic images of the rock sample clamped by the core clamp. The heater and pressurizing device enable simulation of formation conditions. The electron microscope and viewing window enable continuous dynamic microscopic visualization of changes in physical parameters and pore throat structure of the rock under pressure and heating under simulated formation conditions, as well as image acquisition. This solves the problem of traditional methods in which temperature and pressure changes in samples removed after physical property measurement experiments affect subsequent scanning electron microscopy observations, thereby improving the accuracy of experimental analysis results. The measurement data obtained from the temperature sensor and pressure sensor can be used to determine the physical properties of the rock sample under the corresponding temperature and pressure conditions, providing a theoretical basis and technical support for reservoir research, oil thermal recovery, geothermal reservoir reconstruction, and other fields.

[0065] Example 2

[0066] The second embodiment of the present invention provides a microscopic visualization experimental method of rock physical properties under formation conditions, see Figure 3 As shown, the following experimental steps are performed using the microscopic visualization experimental equipment for rock physical property characteristics under formation conditions in Example 1:

[0067] Step S31: The rock sample is held by a core clamping device, and an inert gas is injected into the heating box by a pressurizing device to exhaust the air in the pipeline and the heating box.

[0068] Take a core sample, cut it linearly, and make it into a cylindrical rock sample with a diameter of 3 to 5 cm and a height of 5 to 10 cm (the specific height value is flexibly set according to the clamping length of the first fixing clamp and the second fixing clamp). The left and right ends are fixed with the first fixing clamp and the second fixing clamp.

[0069] Step S32: using a pressurizing device and / or a pressure relief valve to adjust the pressure in the heating box cavity to a set pressure, and using the heating box to adjust the temperature in its cavity to a set temperature.

[0070] Connect the experimental equipment and use a high-pressure pump to input nitrogen (or other inert gases, such as helium) into the heating box to remove the air from the pipelines and the heating box.

[0071] Use a high-pressure pump to directly add the pressure required for the experiment; turn on the temperature control switch on the outer wall of the heating box to directly raise it to the required experimental temperature.

[0072] Step S33: obtaining temperature data and pressure data in the heating box cavity through a temperature sensor and a pressure sensor respectively, and obtaining a microscopic image of the rock sample under corresponding temperature and pressure conditions through an electron microscope.

[0073] Well enough:

[0074] (1) Maintaining a constant experimental temperature, using a high-pressure pump to displace at a constant pressure or speed, simulates and observes the changes in the state of rock heating under different pressure conditions;

[0075] (2) Constant experimental pressure, changing the experimental temperature by the temperature control switch on the outer wall of the heating box, with a temperature gradient of △T, simulates and observes the changes in the state of rock pressure under different temperature conditions.

[0076] When the experiment is over, shut down and organize the experimental equipment to ensure it can be used normally in the next experiment.

[0077] The above method may also include, during the above experimental process, determining the physical property parameters of the rock sample by using the temperature data and pressure data obtained in real time by the physical property calculation device; and collecting the microscopic image taken by the electron microscope and the temperature data and pressure data collected by the data acquisition board in real time by the data acquisition device.

[0078] It should be understood that the specific order or hierarchy of steps in the disclosed processes is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the process can be rearranged without departing from the scope of the present disclosure. The accompanying method claims present elements of the various steps in an exemplary order and are not intended to be limited to the specific order or hierarchy described.

[0079] In the foregoing detailed description, various features are grouped together in a single embodiment to simplify the disclosure. This method of disclosure should not be interpreted as reflecting an intention that embodiments of the claimed subject matter require more features than are expressly recited in each claim. On the contrary, as reflected in the appended claims, the invention comprises less than all the features of any individual disclosed embodiment. The appended claims are therefore hereby expressly incorporated into the detailed description, with each claim standing on its own as a separate preferred embodiment of the invention.

[0080] The above description includes examples of one or more embodiments. Of course, it is impossible to describe all possible combinations of components or methods for the purpose of describing the above embodiments, but it will be appreciated by those skilled in the art that the various embodiments may be further combined and arranged. Therefore, the embodiments described herein are intended to encompass all such changes, modifications and variations that fall within the scope of protection of the appended claims. In addition, with respect to the term "comprising" used in the specification or claims, the word is encompassed in a manner similar to the term "including," as explained in terms of "including," used as a transitional word in the claims. In addition, any term "or" used in the specification of the claims is intended to mean "non-exclusive or." The terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance.

Claims

1. A microscopic visualization experimental device for rock physical properties under formation conditions, characterized by: The equipment includes a core holding device, a heating box, a pressurizing device, a temperature sensor, a pressure sensor, a pressure relief valve and an electron microscope; A heater is provided in the heating box, and the core clamping device, temperature sensor and pressure sensor are also provided in the heating box; The top cover of the heating box is a visual window, and the electron microscope is used to collect a microscopic image of the rock sample clamped by the core clamp in real time through the visual window.

2. The device according to claim 1, wherein The pressurizing device includes a high-pressure pump, a pressure regulating valve and a pressure gauge which are sequentially connected through a pipeline, and one end of the pipeline away from the high-pressure pump extends into the heating box.

3. The device according to claim 1, wherein The outer wall of the heating box is provided with a temperature control switch for controlling the heating temperature of the heater; The pressure relief valve is arranged on the outer wall of the heating box, and is used to reduce the pressure in the heating box by discharging the gas in the heating box.

4. The device according to claim 1, wherein The core clamping device includes a first fixing tube, a first fixing clamp, a second fixing tube and a second fixing clamp; The first fixing clamp and the second fixing clamp are used to fix the rock sample; One end of the first fixed tube is fixed to the inner wall of the heating box, and the other end is connected to the first fixed clamp. One end of the second fixed tube is fixed to the inner wall of the heating box, and the other end is connected to the second fixed clamp.

5. The device according to claim 1, wherein The visual window comprises an upper transparent plate and a lower transparent plate, and the cavity between the upper transparent plate and the lower transparent plate is a vacuum cavity; The four sides of the viewing window are sealed and connected to the inner wall of the heating box through a sealing ring.

6. The device according to claim 5, characterized in that The distance between the upper transparent plate and the lower transparent plate is 8 to 12 cm.

7. The device according to claim 1, wherein The device further comprises a data acquisition board, and the temperature sensor and the pressure sensor are both electrically connected to the data acquisition board.

8. The device according to claim 7, characterized in that The device also includes a physical property parameter calculation device; The data acquisition board is used to send the collected temperature data and pressure data to the physical property parameter calculation device, so that the physical property calculation device determines the physical property parameters of the rock sample according to the received temperature data and pressure data.

9. The device according to any one of claims 1 to 8, characterized in that: The device also includes a data acquisition device; The data acquisition device is used to acquire the microscopic image taken by the electron microscope, or, The data acquisition device is used to acquire the microscopic image taken by the electron microscope and the temperature data and pressure data acquired by the data acquisition board.

10. A microscopic visualization experimental method for rock physical properties under formation conditions, characterized by: The method comprises using the microscopic visualization experimental device for rock physical property characteristics under formation conditions according to any one of claims 1 to 9 to perform the following experimental steps: The rock sample is held by a core clamping device, and an inert gas is injected into the heating box by a pressurizing device to exhaust the air in the pipeline and the heating box; Using a pressurizing device and / or a pressure relief valve to adjust the pressure in the cavity of the heating box to a set pressure, and using the heating box to adjust the temperature in the cavity to a set temperature; The temperature data and pressure data in the heating box cavity are respectively obtained by a temperature sensor and a pressure sensor, and the microscopic image of the rock sample under corresponding temperature and pressure conditions is obtained by an electron microscope.

Images