Rock sample physical property measurement system and measurement method with adjustable reservoir parameters

Abstract

The present invention provides a rock sample physical property measurement system and method with adjustable reservoir parameters, wherein the measurement system includes: a core holder, a temperature control mechanism, a pressure loading mechanism, a fluid saturation adjustment mechanism and a measuring device; the core holder includes a barrel and a sample tube; the barrel is hollow and filled with a liquid medium; the sample tube is used to load the rock sample and penetrates the barrel axially; the temperature control mechanism is used to regulate the temperature of the liquid medium inside the core holder; the pressure loading mechanism is used to regulate the pressure of the liquid medium inside the core holder; the fluid saturation adjustment mechanism is used to regulate the fluid saturation of the fluid medium injected into the sample tube; the measuring device connects the two ends of the sample tube and is used to measure and read the resistivity and elastic wave velocity of the rock sample. The present invention can accurately measure the reservoir parameters measured during fluid displacement, such as the changing relationship between temperature, pressure, fluid saturation and elastic wave velocity and resistivity.

Description

Technical Field

[0001] The invention relates to the field of engineering geology, and in particular to a rock sample physical property measurement system and a measurement method with adjustable reservoir parameters. Background Art

[0002] In CO2 geological storage, oil and gas reservoir transformation and exploitation projects, fluid displacement processes (water displacement of oil and gas, CO2 displacement of water, CO2 displacement of crude oil, etc.) are involved. However, the relationship between the physical properties of rock samples (including elastic wave velocity and resistivity) and reservoir parameters (including the temperature, pressure and fluid saturation of the rock samples) in this process has not been studied; even if there are a few studies, they only involve principle analysis, which is a qualitative study, but lacks quantitative research. Some existing rock sample detection devices are not suitable for quantitative research on the relationship between the physical properties of rock samples and reservoir parameters.

[0003] It should be noted that the above introduction to the technical background is only for the convenience of providing a clear and complete description of the technical solutions of the present application and for the convenience of understanding by those skilled in the art. It cannot be considered that the above technical solutions are well known to those skilled in the art simply because they are described in the background technology section of the present application. Summary of the invention

[0004] In view of the shortcomings of the prior art described above, the purpose of the present invention is to provide a rock sample physical property measurement system and measurement method with adjustable reservoir parameters, which is used to solve the problem that the prior art is unable to analyze and measure the qualitative and quantitative relationship between the physical properties of the rock sample (including elastic wave velocity and resistivity) and the reservoir parameters (including the temperature, pressure and fluid saturation of the rock sample).

[0005] To achieve the above-mentioned and other related purposes, the present invention provides a rock sample physical property measurement system with adjustable reservoir parameters, comprising:

[0006] Core holder, temperature control mechanism, pressure loading mechanism, fluid saturation adjustment mechanism and measuring device;

[0007] The core holder comprises a cylinder and a sample tube; the cylinder is hollow and filled with a liquid medium; the sample tube passes through the cylinder in the axial direction and is hollow inside for loading the rock sample; wherein the side wall in the middle of the sample tube is set as an elastic structure, so that the rock sample can receive the pressure of the liquid medium;

[0008] The temperature control mechanism is arranged outside the sample tube and is used to control the temperature of the liquid medium inside the core holder;

[0009] The pressure loading mechanism is arranged outside the cylinder and is used to regulate the pressure of the liquid medium inside the core holder;

[0010] The fluid saturation adjustment mechanism is arranged outside the cylinder and injects a fluid medium pressurized by a preset pressure and adjusted in fluid saturation into the sample tube to perform a fluid displacement process; wherein each fluid medium in the fluid displacement process is pressurized and transported separately;

[0011] The measuring device is connected to both ends of the sample tube and is used at least to measure and read out the resistivity and elastic wave velocity of the rock sample during the fluid displacement process.

[0012] Optionally, the sample tube further comprises acoustic-electric plungers disposed at both ends of the elastic structure, and the rock sample is fixed to the elastic structure via the two acoustic-electric plungers.

[0013] Optionally, the measuring device includes an oscilloscope and a digital bridge; the oscilloscope measures the elastic waves of the rock sample based on the signals emitted by the two acoustic-electric plungers; and the two test ends of the digital bridge are respectively connected to the two acoustic-electric plungers to measure the resistivity of the rock sample.

[0014] Optionally, the measuring device further comprises a fluid displacement monitor; the fluid displacement monitor is connected to the two acoustic-electric plungers and is used to monitor the start time and the end time of fluid displacement during the fluid displacement process.

[0015] Optionally, the temperature control mechanism includes a heating structure and a cooling structure; the heating structure includes a heating tube arranged in the cylinder; the heating tube includes a shell and a resistance wire arranged inside the shell, and the resistance wire is pressurized so that the heating tube generates temperature and heats the liquid medium; the cooling structure includes a cooling liquid inlet, a cooling liquid outlet and a cooling pipeline arranged on the cylinder, and the cooling pipeline connects the cooling liquid inlet and the cooling liquid outlet, and cools the liquid medium based on the inflow and outflow of cooling liquid.

[0016] Optionally, the pressure loading mechanism includes a confining pressure adjustment component and an axial pressure adjustment component;

[0017] The confining pressure regulating assembly comprises a first container loaded with a liquid medium, a confining pressure boosting pump and a confining pressure input port; the first container and the confining pressure boosting pump are arranged outside the core holder, the first end of the confining pressure boosting pump is connected to the first container, and the second end is connected to the confining pressure input port; the confining pressure input port is arranged on the side wall of the cylinder, so that the liquid medium pressurized by the confining pressure boosting pump is injected along the radial direction of the cylinder, so that the rock sample receives the radial pressure of the liquid medium;

[0018] The axial pressure regulating assembly comprises a second container loaded with a liquid medium, an axial pressure booster pump, an axial pressure input port and a first piston; the second container and the axial pressure booster pump are arranged outside the core clamp, the first end of the axial pressure booster pump is connected to the second container, and the second end is connected to the axial pressure input port; the axial pressure input port is arranged on the side wall of the first end of the cylinder, and the first piston is arranged at the first end of the sample tube, and the cross section of the first piston is located on the path of the axial pressure input port to inject the liquid medium; the liquid medium pressurized by the axial pressure booster pump is injected along the axial pressure input port in the axial direction of the cylinder and pressurized onto the first piston, so that the rock sample can receive the axial pressure of the liquid medium.

[0019] Optionally, the first container and the second container are realized by the same pressurized liquid container, and the confining pressure booster pump and the axial pressure booster pump are realized by the same pressure booster pump.

[0020] Optionally, the fluid saturation regulating mechanism comprises a third container loaded with a first fluid medium, a fourth container loaded with a second fluid medium, a fifth container loaded with a third fluid medium, a first control valve, a second control valve, a third control valve, a first boosting pump and a second boosting pump; the first fluid medium and the third fluid medium are set as different fluid media;

[0021] The first fluid medium loaded in the third container is pressurized by the first booster pump and then output, and is output to the first end of the sample tube through the first control valve and the third control valve; the second fluid medium output by the fourth container is pressurized by the second booster pump; a second piston is arranged inside the fifth container; the second piston isolates the second fluid medium and the third fluid medium, and pressurizes the third fluid medium based on the second fluid medium; the third fluid medium loaded in the fifth container is pressurized and then output, and is output to the first end of the sample tube through the second control valve and the third control valve;

[0022] The first control valve and the second control valve are controlled to be opened and closed to adjust the fluid saturation, and the third control valve is controlled to be opened so that the fluid medium flows through the rock sample and is output from the second end of the sample tube.

[0023] Optionally, the fluid saturation adjustment mechanism further includes a fluid pressure correction device; the fluid pressure correction device is arranged between the third control valve and the sample tube.

[0024] Optionally, the fluid saturation adjustment mechanism further includes a saturation measuring device; the saturation measuring device is connected to the second end of the sample tube to measure the saturation of the corresponding fluid medium flowing out of the sample tube.

[0025] To achieve the above-mentioned and other related purposes, the present invention provides a method for measuring physical properties of rock samples with adjustable reservoir parameters, comprising:

[0026] S1, placing the rock sample at the elastic structure of the sample tube, and regulating the temperature and pressure of the liquid medium so that the rock sample is at a preset temperature and a preset pressure; pressurizing the fluid medium and adjusting the fluid saturation to perform a fluid displacement process so that the rock sample is at a preset pressure and fluid saturation; wherein each fluid medium in the fluid displacement process is pressurized and transported separately;

[0027] S2. At least used to measure and read out the resistivity and elastic wave velocity of the rock sample during fluid displacement.

[0028] Optionally, when the fluid saturation regulating mechanism comprises a third container loaded with a first fluid medium, a fourth container loaded with a second fluid medium, a fifth container loaded with a third fluid medium, a first control valve, a second control valve, a third control valve, a first boosting pump and a second boosting pump,

[0029] The first control valve and the second control valve are controlled to be opened and closed to adjust the fluid saturation, and the third control valve is controlled to be opened so that the fluid medium flows through the rock sample and is output from the second end of the sample tube.

[0030] Optionally, after the third fluid medium is injected into the sample tube, the second control valve is closed and the first control valve is opened, so that the volume proportion of the first fluid medium increases while the volume proportion of the third fluid medium decreases, and the resistivity and elastic wave velocity of the rock sample under different fluid saturation conditions are read.

[0031] As described above, the rock sample physical property measurement system and measurement method with adjustable reservoir parameters of the present invention have the following beneficial effects:

[0032] The present invention provides a new rock sample physical property measurement system with adjustable reservoir parameters, which can accurately measure the reservoir parameters measured during fluid displacement, such as the changing relationship between temperature, pressure, fluid saturation and elastic wave velocity, resistivity and other rock sample physical properties. In addition, the rock sample physical property measurement system and measurement method with adjustable reservoir parameters of the present invention have a simple structure, a simple method, can effectively simulate the reservoir parameters of the rock sample, and can improve the accuracy of the measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Shown is a schematic structural diagram of a rock sample physical property measurement system with adjustable reservoir parameters according to the present invention.

[0034] Figure 2 Shown is a schematic structural diagram of the core holder of the present invention.

[0035] Figure 3 Display as Figure 2 Enlarged schematic diagram of part A.

[0036] Figure 4 It shows the longitudinal wave waveform diagram of the rock sample tested under specific temperature, pressure and fluid saturation conditions of the present invention.

[0037] Figure 5 It shows the shear wave waveform diagram of the rock sample tested under specific temperature, pressure and fluid saturation conditions of the present invention.

[0038] Component number description

[0039] 1- Rock sample physical property measurement system with adjustable reservoir parameters; 11- Core holder; 111- Sample tube; 1111- Elastic structure; 1112- Acoustic-electric plunger; 1113- Displacement fluid outlet valve; 112- Barrel; 12- Temperature control mechanism; 121- Resistance wire; 122- Cooling liquid inlet; 123- Cooling liquid outlet; 13- Pressure loading mechanism; 131 Confining pressure input port; 132- Axial pressure input port; 133- Pressurized liquid container; 134- Pressure boosting pump; 1341- Pressure pipeline; 1342- Booster pump switch; 14-fluid saturation adjustment mechanism; 141-third container; 142-fourth container; 143-fifth container; 144-first booster pump; 145-second booster pump; 146-first control valve; 147-second control valve; 148-third control valve; 149-saturation measuring device; 1491-measuring container; 1492-balance; 15-measuring device; 151-oscilloscope; 152-digital bridge; 1521-resistance test connector; 153-host computer; 16-control box. DETAILED DESCRIPTION

[0040] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0041] See also Figure 1~Figure 5It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner, and the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0042] Seismic wave velocity is a sensitive indicator that can reflect changes in lithology, porosity and saturation. Lithology, including intrinsic properties of rocks such as microscopic pore structure, permeability and fluid viscosity, plays a key role in controlling the fluid displacement process of immiscible fluid pairs such as carbon dioxide (CO2) and water. The displacement between such immiscible fluid pairs (CO2 displacing water) not only significantly affects the seismic wave velocity, but also reduces the amplitude of seismic waves through inelastic attenuation. Currently, the dispersive attenuation mechanism is believed to be dominated by scattering caused by small-scale heterogeneities such as cracks, and inertial friction caused by viscous flow. In the CO2 storage process, the mechanism of viscous fluid action may be the most important factor.

[0043] Understanding changes in rock physical parameters is essential for reliable monitoring of CO2 geological storage. Although seismic methods are able to detect the presence of gas, they are limited in providing quantitative information. In contrast, electromagnetic methods are more effective in predicting gas saturation. In addition, electrical conductivity has been shown to be a sensitive indicator of the replacement of conductive pore fluids by resistive gases or supercritical CO2 in porous media, making conductivity / resistivity measurements a powerful complement to seismic monitoring.

[0044] Conductivity measurement is an active geophysical method that reconstructs the conductivity / resistivity distribution of the subsurface by injecting low-frequency current into the ground and recording the resulting magnetic field. This method has been applied in the field to identify CO2 leaks (LeRoux et al., 2013; Zhou et al., 2012). Some studies have shown that conductivity monitoring can detect changes in porous media caused by CO2. For example, studies by Giese et al. (2009), Kiessling et al. (2010), Schmidt-Hattenberger (2011), Strazisar et al. (2009), Würdemann et al. (2010) and Zhou et al. (2012) have shown that the flow of CO2 in porous media can be detected by conductivity monitoring. Strazisar et al. (2009) showed that after CO2 injection, the conductivity in the vertical injection well increased significantly, which was caused by the dissolution of CO2 in the pore water. Lewicki et al. (2007) also pointed out that even if only a small amount of CO2 is dissolved in the pore water system during the release process, it will cause a slight increase in the pore water conductivity. This is due to the ionization of CO2 in the pore water, which increases the ionic strength of the solution.

[0045] However, in projects such as CO2 geological storage, oil and gas reservoir transformation and exploitation, fluid displacement is involved (water displacing oil and gas, CO2 displacing water, CO2 displacing crude oil, etc.). This process will cause significant changes in elastic wave velocity and resistivity. For example, when CO2 displaces brine in rocks, when the water saturation is high, the longitudinal wave velocity shows high sensitivity to changes in saturation, but when the CO2 saturation is high, the longitudinal wave velocity becomes less sensitive, while the resistance changes dramatically after CO2 breaks through the rock sample. However, in current research, there are few research results on the changes in elastic wave velocity and resistance with saturation, temperature, and pressure, and most of them are single elastic wave velocity measurements. However, a single parameter cannot effectively characterize the saturation of CO2 and brine.

[0046] Based on this, how to measure the changing relationship between reservoir parameters such as temperature, pressure and fluid saturation and rock sample physical properties such as elastic wave velocity and resistivity during fluid displacement has become an urgent problem to be solved.

[0047] like Figure 1 As shown, this embodiment provides a rock sample physical property measurement system 1 with adjustable reservoir parameters, comprising: a core holder 11 , a temperature control mechanism 12 , a pressure loading mechanism 13 , a fluid saturation adjustment mechanism 14 and a measurement device 15 .

[0048] like Figure 1As shown, the core holder 11 includes a barrel 112 and a sample tube 111; the barrel 112 is hollow inside and filled with a liquid medium for simulating a reservoir environment; the sample tube 111 penetrates along the axial direction of the barrel 112 and is hollow inside for loading a rock sample 10; wherein, the middle side wall of the sample tube 111 is set as an elastic structure 1111 (set as an elastic rubber sleeve in this embodiment, and can also be set as other elastic structures and is not limited to this embodiment), so that the rock sample can receive the pressure of the liquid medium. The rock sample 10 is located in the middle of the barrel 112 and is surrounded by the pressure of the liquid medium.

[0049] Specifically, Figure 2 As shown, the sample tube 111 further includes acoustic-electric plungers 1112 disposed at both ends of the elastic structure 1111 , and the rock sample 10 is fixed to the elastic structure 1111 via the two acoustic-electric plungers 1112 .

[0050] In the present embodiment, the cylinder 112 is configured as a high temperature and high pressure resistant stainless steel cavity, and the sample tube 111 includes two acoustic electric plungers 1112 and the two acoustic electric plungers 1112 are connected by an elastic structure 1111 of a high temperature and high pressure resistant rubber sleeve, so that the rock sample 10 can be in a reservoir environment of simulated pressure (including confining pressure and axial pressure). In the present embodiment, the acoustic electric plunger 1112 is detachable to ensure that the rock sample 10 is fixed by the acoustic electric plungers 1112 at both ends after being placed in the sample tube 111. Ultrasonic probes are built into the two acoustic electric plungers 1112, which facilitates the subsequent use of the piezoelectric effect of the chip to realize the conversion of electrical energy and acoustic energy for transmitting and receiving ultrasonic waves. It should be noted that the actual connection relationship or fixing method is not limited to this embodiment.

[0051] like Figure 1 As shown, the temperature control mechanism 12 is disposed outside the sample tube 111 and is used to control the temperature of the liquid medium inside the core holder 11 .

[0052] Specifically, the temperature control mechanism 12 includes a temperature increasing structure and a temperature decreasing structure.

[0053] As an example, the heating structure includes a heating tube disposed in the barrel 112; the heating tube includes a shell (not shown in the figure) and a resistance wire 121 disposed inside the shell, which is also filled with a heat transfer medium. The pressurized resistance wire heats up and heats the liquid medium outside the heating tube in the form of heat exchange through the heat transfer medium.

[0054] In this embodiment, the rock sample physical property measurement system 1 with adjustable reservoir parameters further includes a temperature sensor (not shown in the figure) and a control box 16. The temperature of the heating tube is regulated by an operation panel or supporting software of the control box 16, and the corresponding temperature is fed back by the temperature sensor. In this embodiment, the temperature sensor is arranged on the side wall of the cylinder 112, and the specific position is not limited to this embodiment.

[0055] In this embodiment, the cooling structure includes a cooling liquid inlet 122, a cooling liquid outlet 123 and a cooling pipeline (not shown in the figure) arranged on the cylinder 112, and the cooling pipeline is connected to the cooling liquid inlet 122 and the cooling liquid outlet 123, and the liquid medium is quickly cooled based on the inflow and outflow of the cooling liquid. When cooling, cooling water can be passed into the inner cavity of the clamp to accelerate cooling. In actual use, the core clamp 11 can also be cooled naturally, and the cooling method is not limited to this embodiment.

[0056] In the present embodiment, the cooling liquid and the liquid medium are both set to water. In the present embodiment, the cooling pipeline is arranged on the side wall of the cylinder, and the cooling pipeline is connected with the cooling liquid inlet 112 and the cooling liquid outlet 123. The cooling liquid can pass through the configured cooling pipe so that the cooling liquid reduces the temperature of the liquid medium through heat exchange. In order to further improve the efficiency of cooling, it is preferred to set the exchange area between the cooling liquid and the liquid medium to be the largest, and the cooling liquid inlet 122 and the cooling liquid outlet 123 are arranged relative to each other (that is, when the cooling liquid inlet 122 is arranged on one side of the cylinder 112, the cooling liquid outlet 123 is arranged on the side away from the side where the cooling liquid inlet 122 is located). At the same time, when the cooling liquid inlet 122 is arranged close to one end face of the cylinder 112, the cooling liquid outlet 123 is arranged close to the other end face of the cylinder 112.

[0057] In this embodiment, in order to improve the temperature control effect, the outer ring of the rock sample holder 11 has a heat-insulating layer to prevent temperature loss and prevent burns.

[0058] It should be noted that, in this embodiment, the cooling liquid flow direction of the cooling liquid inlet 122 and the cooling liquid outlet 123 is not limited to this embodiment, that is, the cooling liquid inlet 122 can be set as the outlet and the cooling liquid outlet 123 can be set as the inlet.

[0059] It should be further explained that the specific setting of the temperature control mechanism 12 is not limited to the present embodiment, and any setting that can adjust the temperature of the liquid medium, such as directly heating and cooling the outside of the cylinder 112 to heat exchange the temperature to the liquid medium inside the cylinder 112, is within the protection scope of the present embodiment.

[0060] like Figure 1 As shown, the pressure loading mechanism 13 is disposed outside the cylinder 112 and is used to regulate the pressure of the liquid medium inside the core holder 11 .

[0061] Specifically, the pressure loading mechanism 13 includes a confining pressure regulating assembly and an axial pressure regulating assembly.

[0062] As an example, the confining pressure regulating assembly includes a first container loaded with a liquid medium, a confining pressure booster pump and a confining pressure input port 131; the first container and the confining pressure booster pump are arranged outside the core holder 11; the first end of the confining pressure booster pump is connected to the first container, and the second end is connected to the confining pressure input port 131; the confining pressure input port 131 is arranged on the side wall of the cylinder 112, so that the liquid medium pressurized by the confining pressure booster pump is injected into the cylinder 112 along the radial direction of the cylinder 112. Among them, the rock sample 10 is subjected to the pressure along the radial direction of the cylinder 112 as the confining pressure, which facilitates the rock sample to receive the radial pressure of the liquid medium. In this embodiment, an elastic rubber sleeve is arranged at the position of the rock sample in the middle of the sample tube to load the external pressure on the rock sample 10.

[0063] As an example, the axial pressure regulating assembly includes a second container loaded with a liquid medium, an axial pressure booster pump, an axial pressure input port 132 and a first piston; the second container and the axial pressure booster pump are arranged on the outside of the core clamp; the first end of the axial pressure booster pump is connected to the second container, and the second end is connected to the axial pressure input port 132; the axial pressure input port 132 is arranged on the side wall of the first end of the cylinder 112, and the first piston is arranged at the first end of the sample tube 111; the cross-section of the first piston is located on the path of the axial pressure input port 132 for injecting the liquid medium; the liquid medium pressurized by the axial pressure booster pump is injected along the axial pressure input port 132 in the axial direction of the cylinder and pressurized onto the first piston, so that the rock sample 10 receives the axial pressure of the liquid medium.

[0064] In this embodiment, if Figure 2 and Figure 3 As shown, the first container and the second container are realized by the same boosting liquid container 133, the confining pressure boosting pump and the axial pressure boosting pump are realized by the same pressure boosting pump 134, and the liquid medium provided by the boosting liquid container 133 is input and output through the pressure boosting pump 134. In addition, when the pressure boosting pump 134 outputs to the confining pressure input port 131 and the axial pressure output port 132, it is divided into two paths based on the same pressure pipeline 1341 and through the boosting pump switch 1342 so that the confining pressure and the axial pressure are turned on at the same time. In other embodiments, the confining pressure regulating component and the axial pressure regulating component in the pressure loading mechanism 13 can set the pressure separately based on different boosting pumps and boosting pump switches.

[0065] In this embodiment, the confining pressure and the axial pressure are regulated by the control panel or the supporting software of the control box 16, and the corresponding pressure is fed back by the pressure sensor (not shown in the figure). In this embodiment, the pressure sensor is arranged on the side wall of the cylinder 112, and the specific arrangement position is not limited to this embodiment.

[0066] like Figure 1As shown, the fluid saturation regulating mechanism 14 is arranged outside the cylinder 112 and injects the fluid medium pressurized by a preset pressure and adjusted in fluid saturation into the sample tube 111 to perform a fluid displacement process; wherein each fluid medium in the fluid displacement process is pressurized and transported separately.

[0067] Specifically, as an example, the fluid saturation regulating mechanism 14 includes a third container 141 loaded with a first fluid medium, a fourth container 142 loaded with a second fluid medium, a fifth container 143 loaded with a third fluid medium, a first control valve 146, a second control valve 147, a third control valve 148, a first booster pump 144, and a second booster pump 145; the first fluid medium and the third fluid medium are set as different fluid media; in this embodiment, the fluid in the third container 141 is set to displace the fluid in the fifth container 143. In this embodiment, the fluid in the fifth container 143 is the original fluid in the rock sample 10, so as to better simulate the conditions of the rock sample 10.

[0068] In this embodiment, the first fluid medium outputted from the third container 141 is pressurized by the first booster pump 144 and then outputted, and outputted to the first end of the sample tube 111 through the first control valve 146 and the third control valve 148; the second fluid medium outputted from the fourth container 142 is pressurized by the second booster pump; a second piston is arranged inside the fifth container 143; the second piston isolates the second fluid medium and the third fluid medium, and pressurizes the third fluid medium based on the second fluid medium; the third fluid medium loaded in the fifth container 143 is pressurized and then outputted, and outputted to the first end of the sample tube 111 through the second control valve 147 and the third control valve 148. The opening and closing of the first control valve 146 and the second control valve 147 are controlled to adjust the fluid saturation, and the third control valve 148 is adjusted so that the fluid medium flows through the rock sample 10 and is outputted from the second end of the sample tube 111 (in this embodiment, a displacement fluid outlet valve 1113 is also arranged at the second end of the sample tube to facilitate the output of the fluid medium). In this embodiment, the volume ratio between the first fluid medium and the third fluid medium and the rock pores is used as the saturation of the two fluids, and the volume of the fluid medium injected into the sample tube is set to 1, which is the sum of the first fluid medium and the third fluid medium. In this embodiment, the volume proportion of the first fluid medium in the fluid medium in the sample tube increases, and the volume proportion of the third fluid medium in the sample tube decreases. At the same time, in this embodiment, each fluid medium in the fluid displacement process is pressurized and transported separately to improve the accuracy of fluid medium detection in the fluid displacement process.

[0069] In this embodiment, the first control valve and the second control valve are controlled to open and close to adjust the fluid saturation, and the third control valve 147 is controlled to open so that the fluid medium flows through the rock sample 10 and is output from the second end of the sample tube 111. The ratio of the fluid input into the sample tube 111 is regulated by adjusting the opening and closing of the first control valve 146 and the second control valve 147. In this embodiment, the first fluid medium is CO2, and the second fluid medium is deionized water to ensure that the booster pump device is not easily damaged. The fifth container 143 is set to a salt water with a mineralization of 13g / L, which is displaced by the CO2 in the third container 142. The first control valve 146 controls the conduction or closing of the branch where CO2 is located; the second control valve 147 controls the conduction or closing of the branch where the salt water is located. The third control valve 148 controls the configured fluid medium to be input into the sample tube 111.

[0070] In this embodiment, the fluid saturation regulating mechanism also includes a fluid pressure correction device; the fluid pressure correction device is arranged between the third control valve 148 and the sample tube 111, and the pressure loss value in the pipeline is obtained by detecting the pressure of the fluid medium input by the third control valve 148 and comparing it with the previously preset boost pressure. Based on the pressure loss value, the first boost pump 144 and the second boost pump 145 are secondary-pressurized, and the secondary boost value is the loss pressure value, so as to adjust the pressure of the fluid medium input into the sample tube 111 accurately, and finally ensure the measurement accuracy in the dynamic fluid displacement process.

[0071] In this embodiment, it is preferred to set the apertures of the pipeline where the third control valve in the fluid saturation adjustment device is located and the acoustic-electric plunger in the sample tube to be equal to avoid input errors of the fluid medium and ensure the accuracy of the final experiment.

[0072] In this embodiment, the fluid saturation adjustment mechanism 14 also includes a saturation measurement device 149; the saturation measurement device 149 is connected to the second end of the sample tube 111 to measure the saturation of the fluid medium flowing out of the sample tube 111. In this embodiment, the saturation measurement device includes a measuring container 1491 and a high-precision balance 1492. Since this embodiment is based on CO2 displacement of brine, the brine displaced from the sample tube 111 is collected; in this embodiment, a displacement fluid outlet valve 1111 is provided at the second end of the sample tube 111. Anhydrous CaCl2 is placed in the measuring container 1491 to absorb the brine, and the brine is accurately weighed with a high-precision balance 1492 to monitor the change in fluid mass and estimate the saturation of the corresponding fluid in the rock sample.

[0073] It should be noted that the specific configuration of the fluid saturation adjustment mechanism 14 is not limited to this embodiment. In another embodiment, only the fifth container 143 and the third container 141 may be configured to inject the fluid medium into the sample tube 111 by air pressurization through corresponding control valves. In this embodiment, in order to further ensure the accuracy of the measurement, it is preferred that the fluid saturation adjustment mechanism 14 also includes a fourth container 142, and the pressurization of the third fluid medium is completed by the fourth container 142 to ensure that the saturation and pressure of the fluid medium input into the sample tube 111 by the fifth container 143 maintain the preset value, thereby ensuring the accuracy of the measurement.

[0074] It should be further explained that, in actual use, based on different actual measurement purposes, the first fluid medium, the second fluid medium and the third fluid medium can be set based on needs, and the first fluid medium and the third fluid medium can be set as different fluid media to complete the displacement of the fluid. In this embodiment, the solubility of the first fluid medium in the third fluid medium is set to be small, and it is preferred to set the first fluid medium and the third fluid medium to be mutually insoluble. In actual use, based on different actual measurement purposes, the first fluid medium, the second fluid medium and the third fluid medium can be set based on needs, such as setting the first fluid medium to water, the second fluid medium to deionized water, and the third fluid medium to oil and gas in another embodiment, measuring the physical properties of the rock sample 10 during the process of water displacing oil and gas, or setting the first fluid medium to CO2, the second fluid medium to white oil, and the third fluid medium to crude oil. In this embodiment, it is preferred to set the second fluid medium to a fluid medium that is not easy to leak and not easy to damage the instrument. In fact, as long as the first fluid medium and the third fluid medium are different fluid media, the second fluid medium provides a certain pressure, which is not limited to this embodiment.

[0075] In addition, in this embodiment, the saturation measurement device 149 can be adaptively adjusted based on the set first fluid medium and second fluid medium to measure the saturation of the fluid medium accordingly, which is not limited to this embodiment.

[0076] The working process of the fluid saturation adjustment mechanism 14 is described below:

[0077] The second control valve 147 is opened, and the third fluid medium in the fifth container 143 is pressurized through the fourth container 142 and the second booster pump 145, and the third fluid medium (brine) is loaded to a specific pressure; the third control valve 148 is opened to inject the third fluid medium (brine) into the rock sample 10 at a specific pressure and ensure water saturation. Then the second control valve 147 is closed, the first control valve 146 is opened, and the first fluid medium in the third container 141 is pressurized through the first booster pump 144, and the first fluid medium (CO2) is loaded to a specific pressure and injected into the rock sample 10 through the opened third control valve 148 to achieve a preset saturation. After the system is stabilized, the resistivity and elastic wave velocity of the rock sample 10 under the fluid saturation condition can be obtained. When CO2 is used to displace water, when the water saturation is large, the longitudinal wave velocity shows a high sensitivity to the change of saturation, but when the CO2 saturation is large, the longitudinal wave velocity becomes less sensitive, while the resistance changes dramatically after CO2 breaks through the rock sample.

[0078] like Figure 1 As shown, the measuring device 15 is connected to both ends of the sample tube 111 and is used to measure and read out the resistivity and elastic wave velocity of the rock sample 10 .

[0079] Specifically, an oscilloscope 151 and a digital bridge 152; each acoustic-electric plunger 1112 is respectively arranged at the two ends of the sample tube 111 and connected to the two ends of the rock sample 10; the oscilloscope 151 measures the elastic wave of the rock sample based on the signal emitted by the two acoustic-electric plungers 1112; the two test ends of the digital bridge 152 are respectively connected to the two acoustic-electric plungers 1112 to measure the resistivity of the rock sample 10.

[0080] In this embodiment, the measuring device 15 also includes two resistance test connectors 1521 and a data transmission line. The data transmission line is connected to the oscilloscope 151, and the longitudinal wave and transverse wave signals of the experimental point are collected and recorded using software; the resistance is mainly measured by the digital bridge 152. After adjusting the measurement method and range as needed, the two resistance test connectors 1521 of the digital bridge 152 are used to clamp the two ends of the two acoustic electric plungers of the clamp 11, and the matching software is used to continuously measure and record the resistance.

[0081] In this embodiment, the measuring device also includes a fluid displacement monitor (not shown in the figure); the fluid displacement monitor is connected to two acoustic electric plungers to monitor the start time of fluid displacement and the end time of fluid displacement during the fluid displacement process. In the present application, the fluid displacement monitor is implemented based on the digital bridge 152, and the digital bridge collects the small fluctuations of the resistivity of the rock sample 10 at the start and end time of fluid displacement to monitor the start time of fluid displacement and the end time of fluid displacement during the electric fluid displacement process, which is relative to the method of predicting whether displacement occurs by injecting the volume of fluid medium. On the one hand, it avoids the problem of inaccurate fluid saturation caused by the presence of unemptied fluid medium in the pipeline when the fluid medium is transported in the pipeline of the fluid saturation adjustment structure 14 during the fluid displacement process; on the other hand, it can more accurately obtain the fluid saturation in the sample tube 111 at a certain time, thereby improving the accuracy of displacement.

[0082] In this embodiment, the rock sample physical property measurement system 1 with adjustable reservoir parameters of this embodiment further includes a host computer 153 for processing the measured data.

[0083] It should be noted that, in this embodiment, the elastic wave velocity of the rock sample 10 is first measured by the oscilloscope 151, and then the resistivity of the rock sample 10 is tested by the digital bridge 152. In actual use, the two measurement data can also be read out at the same time to ensure that the resistivity and elastic wave velocity of the rock sample 10 are read out at the same temperature, pressure and fluid saturation to the greatest extent, and the readout order and the readout measurement method are not limited to this embodiment.

[0084] like Figure 1 As shown, this embodiment provides a method for measuring physical properties of rock samples with adjustable reservoir parameters, which is implemented based on the above-mentioned rock sample physical properties measuring system 1 with adjustable reservoir parameters, and includes:

[0085] S1. Place the rock sample 10 in the sample tube 111, and regulate the temperature and pressure of the liquid medium so that the rock sample 10 is under preset temperature and preset pressure conditions; pressurize the fluid medium and adjust the fluid saturation to perform a fluid displacement process so that the rock sample is under preset pressure and fluid saturation, wherein each fluid medium in the fluid displacement process is pressurized and transported separately.

[0086] S2, at least used to measure and read out the resistivity and elastic wave velocity of the rock sample 10 during the fluid displacement process.

[0087] Specifically, the fluid saturation regulating mechanism 14 includes a third container 141 loaded with a first fluid medium, a fourth container 142 loaded with a second fluid medium, a fifth container 143 loaded with a third fluid medium, a first control valve 146, a second control valve 147, a third control valve 148, a first booster pump 144, and a second booster pump 145. The first control valve 146 and the second control valve 147 are controlled to be opened and closed to adjust the fluid saturation, and the third control valve 148 is adjusted to make the fluid medium flow through the rock sample and output from the second end of the sample tube 111. The specific working principle has been described in the previous text and will not be repeated here.

[0088] As an example, after the third fluid medium is injected into the sample tube 111, the second control valve 147 is closed and the first control valve 146 is opened, so that the volume proportion of the first fluid medium (CO2) increases while the volume proportion of the third fluid medium (brine) decreases, and the resistivity and elastic wave velocity of the rock sample 10 under different proportions of fluid saturation conditions are read. In this embodiment, the liquid saturation in the fifth container 143 is first set to the maximum (if the second fluid medium is brine, it is set to the brine saturation in the rock sample in this embodiment), and the resistivity and elastic wave velocity of the rock sample 10 are measured and read, and then the saturated brine is displaced by CO2 to change the fluid saturation, and then the measurement is performed.

[0089] Combine the following Figure 1 The rock sample physical property measurement method of the adjustable reservoir parameter of this embodiment is described as follows:

[0090] First, the rock sample 10 to be tested (in this embodiment, the rock sample is placed under brine saturation conditions for the accuracy of the experiment) is placed in the core clamp 11 and then clamped and tightened at both ends by two acoustic-electric plungers 1112. Then, the temperature control mechanism 12 (in this embodiment, it is set to open the heating structure for heating) and the pressure loading mechanism 13 (in this embodiment, the confining pressure and axial pressure are adjusted based on the confining pressure adjustment component and the axial pressure adjustment component) are turned on to load the rock sample 10 to the temperature and pressure conditions required for the experiment.

[0091] Then open the second control valve 147, load the brine in the fifth container 143 to a specific pressure through the fourth container 142 and the second booster pump 145, open the third control valve 148, pressurize the brine into the rock sample 10 at a specific pressure to ensure water saturation, then close the second control valve 147, open the first control valve 141, and pressurize CO2 into the rock sample 10 at a specific pressure through the first booster pump 141 to reach the saturation required for the experiment. After the experimental conditions are loaded stably, connect the ultrasonic probes in the two acoustic and electrical plugs 11 to the oscilloscope to obtain the waveform of the elastic wave velocity (including longitudinal and transverse waves).

[0092] Afterwards, the two acoustic and electrical plugs 11 are connected to the digital bridge through the test fixture (not shown in the figure), and the parameters on the digital bridge are adjusted. In this embodiment, the measurement parameter combination is adjusted to "RQ", that is, the main parameter R is the resistance, and the secondary parameter Q is the quality factor. When the resistance of the rock sample 10 is high, the equivalent mode is set to "PAR" (parallel), the range is set to "automatic", the measurement speed is set to "FAST", and the test signal frequency is set to 100HZ, and then the resistance value of the rock sample is measured.

[0093] Finally, the fluid saturation regulating mechanism 14 is controlled to simulate the CO2 saline layer storage process, and CO2 is continuously injected to increase the CO2 saturation. During the process, the resistivity and elastic wave velocity of the rock sample 10 are continuously measured.

[0094] Combine the following Figure 4 and Figure 5 The calculation of the elastic wave velocity of rock sample 10 is described below:

[0095] Figure 4 and Figure 5 The figure shows the longitudinal wave waveform and the transverse wave waveform of a sandstone sample 10 under specific temperature, pressure and fluid saturation conditions. The first arrival of the longitudinal wave and the transverse wave is picked up, where the first arrival time tp of the longitudinal wave is 21.4μs and the first arrival time t S is 37.3μs, the length of the rock sample L is 41.34mm, the propagation time of the longitudinal wave is 7.13μs, and the propagation time of the shear wave is 13.15μs. Calculation shows that the longitudinal wave velocity Vp satisfies:

[0096] (1);

[0097] t0 is the sound wave propagation time measured by the acoustic electric plunger 1112 when the rock sample 10 is not placed.

[0098] The shear wave velocity Vs satisfies:

[0099] (2).

[0100] The calculation of the resistivity of rock sample 10 is described below:

[0101] Similarly, the length of the rock sample L is set to 41.34mm, and the resistance value R1 of the rock sample under the conditions of temperature 80℃, confining pressure 20MPa, axial pressure 10MPa, pressure and fluid saturation of CO2 saturation of 30.29% is 722.8Ω, and the radius of the rock sample is 12.5mm. The resistivity ρ1 of the rock sample satisfies the following formula and the calculated resistivity ρ1 is 8.578 (ohm·meter / Ω*m):

[0102] (3).

[0103] Under the condition of constant temperature and pressure, CO2 is continuously injected to displace the brine. When the CO2 saturation reaches 55.36%, the rock sample reaches the maximum residual saturation. At this time, the measured resistance value R2 of the rock sample is 1492.2Ω, and the resistivity ρ2 of the rock sample is 17.116 (ohm·meter / Ω*m):

[0104] (4).

[0105] It should be noted that the rock sample physical property measurement system and measurement method with adjustable reservoir parameters of the present embodiment provide a new test system, which can not only simulate and adjust the reservoir parameters of temperature and pressure, but also simulate and adjust the reservoir parameters of fluid saturation, thereby realizing qualitative and quantitative measurements of resistivity, elastic wave velocity, etc. in the physical properties of rock samples. At the same time, compared with some comparative examples that can only perform static measurements of a few points on common parameters such as temperature or pressure of rock samples, that is, only measurements of rock samples in a certain static environment can be obtained; the present embodiment is not only applicable to measurements when rock samples are in a static environment, but also to measurements when rock samples are in a dynamic environment (including when the external environment of rock sample 10 is in a fluid displacement process and continues to change). Therefore, the rock sample physical property measurement system and measurement method with adjustable reservoir parameters of the present embodiment can more accurately simulate the fluid displacement process environment, and then accurately measure the changes in the physical properties of the rock samples.

[0106] In summary, the present invention provides a rock sample physical property measurement system and method with adjustable reservoir parameters, wherein the measurement system includes: a core holder, a temperature control mechanism, a pressure loading mechanism, a fluid saturation adjustment mechanism and a measuring device; the core holder includes a barrel and a sample tube; the barrel is hollow and filled with a liquid medium; the sample tube is used to load the rock sample and penetrates along the axial direction of the barrel; the temperature control mechanism is used to regulate the temperature of the liquid medium inside the core holder; the pressure loading mechanism is used to regulate the pressure of the liquid medium inside the core holder; the fluid saturation adjustment mechanism is used to regulate the fluid saturation of the fluid medium injected into the sample tube; the measuring device connects the two ends of the sample tube to measure the resistivity and elastic wave velocity of the rock sample. The present invention can accurately measure the reservoir parameters measured during fluid displacement, such as the changing relationship between temperature, pressure, fluid saturation and elastic wave velocity and resistivity. Therefore, the present invention effectively overcomes the various shortcomings of the prior art and has a high industrial utilization value.

[0107] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A rock sample physical property measurement system with adjustable reservoir parameters, characterized in that: The rock sample physical property measurement system with adjustable reservoir parameters at least comprises: a core holder, a temperature control mechanism, a pressure loading mechanism, a fluid saturation adjustment mechanism and a measuring device; The core holder comprises a cylinder and a sample tube; the cylinder is hollow and filled with a liquid medium; the sample tube passes through the cylinder in the axial direction and is hollow inside for loading the rock sample; wherein the side wall in the middle of the sample tube is set as an elastic structure, so that the rock sample can receive the pressure of the liquid medium; The temperature control mechanism is arranged outside the sample tube and is used to control the temperature of the liquid medium inside the core holder; The pressure loading mechanism is arranged outside the cylinder and is used to regulate the pressure of the liquid medium inside the core holder; The fluid saturation adjustment mechanism is arranged outside the cylinder and injects a fluid medium pressurized by a preset pressure and adjusted in fluid saturation into the sample tube to perform a fluid displacement process; wherein each fluid medium in the fluid displacement process is pressurized and transported separately; The measuring device is connected to both ends of the sample tube and is used at least to measure and read out the resistivity and elastic wave velocity of the rock sample during the fluid displacement process; Among them, the sample tube also includes acoustic-electric plungers arranged at both ends of the elastic structure, and the rock sample is fixed to the elastic structure through the two acoustic-electric plungers; the measuring device also includes a fluid displacement monitor; the fluid displacement monitor is connected to the two acoustic-electric plungers, and is used to monitor the start time and end time of fluid displacement during the fluid displacement process; the fluid saturation adjustment mechanism also includes a fluid pressure correction device.

2. The rock sample physical property measurement system with adjustable reservoir parameters according to claim 1, characterized in that: The measuring device includes an oscilloscope and a digital bridge; the oscilloscope measures the elastic waves of the rock sample based on the signals emitted by the two acoustic-electric plungers; the two test ends of the digital bridge are respectively connected to the two acoustic-electric plungers to measure the resistivity of the rock sample to measure.

3. The rock sample physical property measurement system with adjustable reservoir parameters according to claim 1, characterized in that: The temperature control mechanism includes a temperature increasing structure and a temperature decreasing structure; The heating structure comprises a heating tube arranged in the cylinder; the heating tube comprises a shell and a resistance wire arranged inside the shell, and the resistance wire is pressurized so that the heating tube generates temperature and heats the liquid medium; The cooling structure includes a cooling liquid inlet, a cooling liquid outlet and a cooling pipeline which are arranged on the cylinder. The cooling pipeline connects the cooling liquid inlet and the cooling liquid outlet, and cools the liquid medium based on the inflow and outflow of the cooling liquid.

4. The rock sample physical property measurement system with adjustable reservoir parameters according to claim 1, characterized in that: The pressure loading mechanism includes a confining pressure adjustment component and an axial pressure adjustment component; The confining pressure regulating assembly comprises a first container loaded with a liquid medium, a confining pressure boosting pump and a confining pressure input port; the first container and the confining pressure boosting pump are arranged outside the core holder, the first end of the confining pressure boosting pump is connected to the first container, and the second end is connected to the confining pressure input port; the confining pressure input port is arranged on the side wall of the cylinder, so that the liquid medium pressurized by the confining pressure boosting pump is injected along the radial direction of the cylinder, so that the rock sample receives the radial pressure of the liquid medium; The axial pressure regulating assembly comprises a second container loaded with a liquid medium, an axial pressure booster pump, an axial pressure input port and a first piston; the second container and the axial pressure booster pump are arranged outside the core clamp, the first end of the axial pressure booster pump is connected to the second container, and the second end is connected to the axial pressure input port; the axial pressure input port is arranged on the side wall of the first end of the cylinder, and the first piston is arranged at the first end of the sample tube, and the cross section of the first piston is located on the path of the axial pressure input port to inject the liquid medium; the liquid medium pressurized by the axial pressure booster pump is injected along the axial pressure input port in the axial direction of the cylinder and pressurized onto the first piston, so that the rock sample can receive the axial pressure of the liquid medium.

5. The rock sample physical property measurement system with adjustable reservoir parameters according to claim 4, characterized in that: The first container and the second container are realized by the same pressurized liquid container, and the confining pressure boosting pump and the axial pressure boosting pump are realized by the same pressure boosting pump.

6. The rock sample physical property measurement system with adjustable reservoir parameters according to claim 1, characterized in that: The fluid saturation regulating mechanism comprises a third container loaded with a first fluid medium, a fourth container loaded with a second fluid medium, a fifth container loaded with a third fluid medium, a first control valve, a second control valve, a third control valve, a first boosting pump and a second boosting pump; the first fluid medium and the third fluid medium are set as different fluid media; The first fluid medium loaded in the third container is pressurized by the first booster pump and then output to the first end of the sample tube through the first control valve and the third control valve; The second fluid medium outputted from the fourth container after being pressurized by the second booster pump; A second piston is disposed inside the fifth container; the second piston isolates the second fluid medium and the third fluid medium, and pressurizes the third fluid medium based on the second fluid medium; the third fluid medium loaded in the fifth container is pressurized and output, and is output to the first end of the sample tube through the second control valve and the third control valve; The first control valve and the second control valve are controlled to be opened and closed to adjust the fluid saturation, and the third control valve is controlled to be opened so that the fluid medium flows through the rock sample and is output from the second end of the sample tube.

7. The rock sample physical property measurement system with adjustable reservoir parameters according to claim 6, characterized in that: The fluid pressure correction device is arranged between the third control valve and the sample tube.

8. The rock sample physical property measurement system with adjustable reservoir parameters according to claim 6, characterized in that: The fluid saturation adjustment mechanism also includes a saturation measurement device; The saturation measuring device is connected to the second end of the sample tube to measure the saturation of the corresponding fluid medium flowing out of the sample tube.

9. A method for measuring physical properties of rock samples with adjustable reservoir parameters, implemented based on the system for measuring physical properties of rock samples with adjustable reservoir parameters as claimed in any one of claims 1 to 8, characterized in that: S1, placing the rock sample at the elastic structure of the sample tube, and regulating the temperature and pressure of the liquid medium so that the rock sample is under preset temperature and preset pressure conditions; The fluid medium is pressurized and the fluid saturation is adjusted to perform a fluid displacement process, so that the rock sample is at a preset pressure and fluid saturation; wherein each fluid medium in the fluid displacement process is pressurized and transported separately; S2. At least used to measure and read out the resistivity and elastic wave velocity of the rock sample during fluid displacement.

10. The method for measuring rock sample physical properties with adjustable reservoir parameters according to claim 9, characterized in that: When the fluid saturation adjustment mechanism comprises a third container loaded with a first fluid medium, a fourth container loaded with a second fluid medium, a fifth container loaded with a third fluid medium, a first control valve, a second control valve, a third control valve, a first boosting pump and a second boosting pump, The first control valve and the second control valve are controlled to be opened and closed to adjust the fluid saturation, and the third control valve is controlled to be opened so that the fluid medium flows through the rock sample and is output from the second end of the sample tube.

11. The method for measuring physical properties of rock samples with adjustable reservoir parameters according to claim 10, characterized in that: After the third fluid medium is injected into the sample tube, the second control valve is closed and the first control valve is opened, so that the volume proportion of the first fluid medium increases while the volume proportion of the third fluid medium decreases, and the resistivity and elastic wave velocity of the rock sample under different fluid saturation conditions are read.

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