Method, system and equipment for determining saturation of liquid in porous medium

Abstract

The invention discloses a method, a system and equipment for determining saturation of liquid in a porous medium. The method for determining the saturation degree of the liquid in the porous medium comprises the following steps: determining the type of the porous medium according to the pore size distribution condition of the porous medium; if the porous medium is a single-scale porous medium, respectively obtaining a first nuclear magnetic resonance relaxation spectrum and a second nuclear magnetic resonance relaxation spectrum of the liquid in the porous medium when the liquid in the porous medium is in a saturated state and an unsaturated state; and obtaining the saturation of the liquid in the porous medium according to the first nuclear magnetic resonance relaxation spectrum, the second nuclear magnetic resonance relaxation spectrum and the bulk phase transverse relaxation time of the liquid. By adopting the method and the device, the liquid saturation condition in the porous medium can be better determined, and the method and the device are further suitable for analyzing the occurrence and transportation process of porous multiphase system fluids with complex pore sizes and phase state distribution conditions.

Description

Technical Field

[0001] The present application relates to the technical field of heat and mass transport in porous media, and in particular to a method, system, and device for determining liquid saturation in a porous medium. Background Art

[0002] Fluid transport within porous media is a widespread phenomenon in numerous engineering fields, including aerospace, construction, and underground oil and gas extraction. The mechanisms of fluid transport within porous media are complex due to the influence of numerous factors, including the pore size and interfacial interactions of porous materials. Understanding the distribution and migration patterns of liquids within pores is crucial for a deeper understanding of fluid transport within porous media. The complex solid skeleton and pore network of porous materials make it difficult to directly observe fluid behavior within porous media using conventional experimental methods. For example, gravimetric methods can only measure changes in the total liquid content within the material, but cannot reveal microscopic information about the liquid within the complex pores of porous media. Low-field nuclear magnetic resonance (NMR) measurement is a powerful, nondestructive method for characterizing hydrogen-containing fluids within porous media. By measuring the hydrogen atomic relaxation process, it can reveal the interaction between moisture and pores, and thus can be applied to studying the structure of porous media and the transport of different types of liquids within them. However, existing NMR analysis methods, based on the assumption of saturated isolated pores, measure relaxation spectra to obtain the pore size distribution of the liquid, without directly linking the liquid morphology within complex pores to the NMR relaxation spectrum. Since there are a large number of liquid-unsaturated pores inside the porous system during the fluid transport process inside the actual porous materials, and the liquid relaxation in pores of different scales is mutually coupled, it is difficult to analyze the liquid properties in complex porous systems through nuclear magnetic resonance experimental measurements based on existing nuclear magnetic resonance relaxation spectrum analysis methods.

[0003] Obtaining the state of liquid inside the pores is crucial for a deeper understanding of the fluid migration laws within porous media materials. Existing methods for measuring liquid inside porous media mainly include weight measurement and microscopic observation. Among them, the weight method can only obtain the changes in the total liquid content inside the material, and cannot obtain the microscopic information of the liquid inside the complex pores of the porous medium, such as the distribution and morphological changes of the liquid between micro-nano pores; while optical microscopy measurement is only applicable to transparent samples. For porous structures with complex solid skeletons, it is difficult to directly observe the fluid behavior inside the pores of porous media. Nuclear magnetic resonance technology can non-destructively detect the moisture content and distribution in porous media, but existing nuclear magnetic resonance analysis methods obtain the pore size distribution of the liquid by measuring the relaxation spectrum based on the saturated isolated pore hypothesis. It does not directly link the liquid morphology in the complex pores with the nuclear magnetic relaxation spectrum, making it difficult to analyze the liquid properties in complex porous systems by measuring the nuclear magnetic relaxation spectrum. Summary of the Invention

[0004] Based on this, it is necessary to provide a method, system and equipment for determining the liquid saturation in porous media to address the above technical problems, which can better determine the liquid saturation in porous media, and thus be suitable for the analysis of fluid storage and transport processes in porous multiphase systems with complex pore sizes and phase distributions.

[0005] In a first aspect, the present application provides a method for determining liquid saturation in a porous medium, comprising:

[0006] Determining the type of the porous medium according to the pore size distribution of the porous medium;

[0007] If the porous medium is a single-scale pore medium, obtaining a first nuclear magnetic resonance relaxation spectrum and a second nuclear magnetic resonance relaxation spectrum of the liquid in the porous medium when the liquid in the porous medium is in a saturated state and an unsaturated state, respectively;

[0008] The liquid saturation in the porous medium is obtained according to the first nuclear magnetic resonance relaxation spectrum, the second nuclear magnetic resonance relaxation spectrum and the bulk transverse relaxation time of the liquid.

[0009] In some examples, determining the type of the porous medium based on the pore size distribution of the porous medium includes:

[0010] Obtaining the pore volume of the porous medium;

[0011] The type of the porous medium is determined according to the distribution of the pore volume in the micron segment and the nanometer segment in the porous medium.

[0012] In some examples, obtaining the liquid saturation in the porous medium according to the first nuclear magnetic resonance relaxation spectrum, the second nuclear magnetic resonance relaxation spectrum, and the bulk transverse relaxation time of the liquid includes:

[0013] Obtaining a transverse relaxation time of the liquid in the porous medium under a liquid saturation state according to the first nuclear magnetic resonance relaxation spectrum;

[0014] Obtaining a transverse relaxation time of the liquid in the porous medium in a non-liquid saturated state according to the second nuclear magnetic resonance relaxation spectrum;

[0015] obtaining a bulk transverse relaxation time of the liquid;

[0016] The liquid saturation in the porous medium is obtained according to the transverse relaxation time of the liquid in the porous medium in a liquid-saturated state, the transverse relaxation time of the liquid in the porous medium in a non-liquid-saturated state, and the bulk transverse relaxation time of the liquid.

[0017] In some examples, this also includes:

[0018] If the porous medium is a micro-nano multi-porosity medium, then obtaining a coupling relationship between liquid relaxation in micropores and nanopores in the porous medium;

[0019] According to the coupling relationship, the liquid saturation in the porous medium is obtained using a corresponding strategy.

[0020] In some examples, obtaining the liquid saturation in the porous medium using a corresponding strategy according to the coupling relationship includes:

[0021] When the relaxation of the liquid in the micropores and the nanopores is fully coupled, when the liquid in the porous medium is in a saturated state and an unsaturated state, respectively obtaining a third nuclear magnetic resonance relaxation spectrum and a fourth nuclear magnetic resonance relaxation spectrum of the liquid in the porous medium;

[0022] The overall liquid saturation in the porous medium is obtained according to the third nuclear magnetic resonance relaxation spectrum, the fourth nuclear magnetic resonance relaxation spectrum, and the bulk transverse relaxation time of the liquid.

[0023] In some examples, obtaining the liquid saturation in the porous medium according to the coupling relationship using a corresponding strategy further includes:

[0024] When the relaxation of the liquid in the micropores is slower than that in the nanopores and the speed satisfies the predetermined requirement,

[0025] When the relaxation of the liquid in the micropores and the nanopores is fully coupled, when the liquid in the micropores of the porous medium is in a saturated state and an unsaturated state, respectively obtaining a fifth nuclear magnetic resonance relaxation spectrum and a sixth nuclear magnetic resonance relaxation spectrum of the liquid in the micropores;

[0026] The overall liquid saturation in the porous medium is obtained according to the fifth nuclear magnetic resonance relaxation spectrum, the sixth nuclear magnetic resonance relaxation spectrum, and the bulk transverse relaxation time of the liquid.

[0027] In some examples, obtaining the coupling relationship between liquid relaxation in micropores and nanopores in the porous medium includes:

[0028] placing the porous medium in a predetermined environment and allowing it to remain stationary for a predetermined time;

[0029] After the nanopores of the porous medium are filled with liquid, a seventh nuclear magnetic resonance relaxation spectrum of the liquid in the porous medium is obtained;

[0030] Obtaining a transverse relaxation time of the liquid in the nanopore according to the seventh nuclear magnetic resonance relaxation spectrum;

[0031] Obtaining a characteristic self-diffusion time of the liquid in the micropores according to the micropore size in the porous medium and the self-diffusion coefficient of the liquid;

[0032] The coupling relationship between the relaxation of the liquid in the micropore and the nanopore is determined based on the transverse relaxation time of the liquid in the nanopore and the characteristic self-diffusion time of the liquid in the micropore.

[0033] In a second aspect, a system for determining liquid saturation in a porous medium is provided, comprising:

[0034] A type determination module, configured to determine the type of the porous medium according to the pore size distribution of the porous medium;

[0035] an acquisition module, configured to obtain, when the porous medium is a single-scale pore medium and the liquid in the porous medium is in a saturated state and an unsaturated state, a first nuclear magnetic resonance relaxation spectrum and a second nuclear magnetic resonance relaxation spectrum of the liquid in the porous medium, respectively;

[0036] A determination module is configured to obtain the liquid saturation in the porous medium according to the first nuclear magnetic resonance relaxation spectrum, the second nuclear magnetic resonance relaxation spectrum, and the bulk transverse relaxation time of the liquid.

[0037] In a third aspect, a computer device is provided, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, the steps of the method for determining the liquid saturation in a porous medium according to the first aspect and any possible implementation of the first aspect are implemented.

[0038] In a fourth aspect, a computer-readable storage medium is provided, on which a computer program is stored. When the program is executed by a processor, the steps of the method for determining the liquid saturation in a porous medium of the above-mentioned first aspect and any possible implementation of the first aspect are implemented.

[0039] By using the embodiments of the present application, pore-scale microscopic information such as the liquid saturation inside the pores of porous materials can be obtained through online measurement and analysis. Compared with existing nuclear magnetic resonance measurement and analysis methods, the influence of complex liquid distribution and pore conditions such as liquid unsaturation and micro-nanoporosity on the transverse relaxation time is taken into account. Therefore, the liquid saturation in the porous medium can be better determined, and thus, it is suitable for the analysis of fluid storage and transport processes in porous multiphase systems with complex pore sizes and phase distributions. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Other features, objects and advantages of the present application will become more apparent upon reading the detailed description of non-limiting embodiments made with reference to the following drawings:

[0041] Figure 1 This is a flow chart of a method for determining liquid saturation in a porous medium provided in an embodiment of the present application;

[0042] Figure 2 Schematic diagram of the NMR transverse relaxation time spectrum of nanoporous materials in liquid water saturation and partial saturation states;

[0043] Figure 3 Schematic diagram of the NMR transverse relaxation time spectrum of micro-nano porous materials in liquid water saturation and partial saturation states;

[0044] Figure 4 This is a structural block diagram of a system for determining liquid saturation in a porous medium provided in an embodiment of the present application;

[0045] Figure 5 This is a structural block diagram of the computer device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0046] The present application will be further described in detail below with reference to the embodiments and accompanying drawings. It should be understood that the specific embodiments described herein are intended only to illustrate the relevant application and are not intended to limit the application. It should also be noted that, for ease of description, only the portions relevant to the application are shown in the accompanying drawings.

[0047] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0048] The following describes in detail the method, system, and apparatus for determining liquid saturation in a porous medium according to embodiments of the present application with reference to the accompanying drawings.

[0049] The method, system and equipment for determining the liquid saturation in porous media of the present application solve the technical problem of the lack of accurate characterization of the liquid state in the pores of porous media in existing porous measurement technologies, and realize accurate measurement of the liquid saturation in the pores of porous media such as micro-nano porous media.

[0050] This application, based on the fundamental theory of nuclear magnetic resonance relaxation, uses nuclear magnetic resonance measurements to obtain nuclear magnetic resonance relaxation spectra of porous media. This is combined with porous media pore characterization methods to determine the pore size distribution of the porous media. By establishing a quantitative relationship between liquid saturation and the nuclear magnetic resonance relaxation spectrum, the liquid saturation within the porous media is calculated and analyzed. The porous media, as referred to in this application, is also referred to as porous materials.

[0051] Figure 1 FIG. 1 is a flow chart of a method for determining liquid saturation in a porous medium according to an embodiment of the present application. Figure 1As shown, the method for determining the liquid saturation in a porous medium according to an embodiment of the present application includes the following steps:

[0052] S101: Determine the type of the porous medium according to the pore size distribution of the porous medium.

[0053] In one embodiment of the present application, determining the type of the porous medium based on the pore size distribution of the porous medium includes: obtaining the pore volume of the porous medium; and determining the type of the porous medium based on the distribution of the micron segment and the nano segment of the pore volume in the porous medium.

[0054] In specific applications, the micro- and nano-pore distribution of a porous material is first measured. Samples of the porous material under investigation are then taken and the relationship between the pore volume (V) and pore diameter (D) is measured using low-temperature nitrogen adsorption or mercury intrusion porosimetry. If the pore volume has a distinct distribution in both the micron and nanometer ranges, the porous material is considered a micro- and nano-porous material (i.e., a micro- and nano-multi-porous medium). If the pore volume has a unimodal distribution in either the micron or nanometer ranges, the porous material is considered a single-scale porous material (i.e., a single-scale porous medium).

[0055] S102: If the porous medium is a single-scale pore medium, obtaining a first nuclear magnetic resonance relaxation spectrum and a second nuclear magnetic resonance relaxation spectrum of the liquid in the porous medium when the liquid in the porous medium is in a saturated state and an unsaturated state, respectively.

[0056] For example, for a single-scale porous material, evacuate it and saturate it with the liquid of interest. Then, place the liquid-saturated single-scale porous material in a low-field nuclear magnetic resonance device and use the Carr-Purcell-Meiboom-Gill (CPMG) sequence to measure the first nuclear magnetic resonance relaxation spectrum of the liquid in the material (i.e., the transverse relaxation time T2 spectrum). The top of the first nuclear magnetic resonance relaxation spectrum is T2, which is the transverse relaxation time T of the single-scale porous material when it is saturated with liquid. 2,sat The CPMG sequence measurement is also performed on the single-scale porous material under the condition of liquid unsaturation to obtain the corresponding transverse relaxation time T 2,tes .

[0057] S103: Obtaining the liquid saturation in the porous medium according to the first nuclear magnetic resonance relaxation spectrum, the second nuclear magnetic resonance relaxation spectrum, and the bulk transverse relaxation time of the liquid.

[0058] In one embodiment of the present application, the liquid saturation in the porous medium is obtained according to the first nuclear magnetic resonance relaxation spectrum, the second nuclear magnetic resonance relaxation spectrum and the bulk transverse relaxation time of the liquid, including: obtaining the transverse relaxation time of the liquid in the porous medium in a liquid-saturated state according to the first nuclear magnetic resonance relaxation spectrum; obtaining the transverse relaxation time of the liquid in the porous medium in a non-liquid-saturated state according to the second nuclear magnetic resonance relaxation spectrum; obtaining the bulk transverse relaxation time of the liquid; obtaining the liquid saturation in the porous medium according to the transverse relaxation time of the liquid in the liquid-saturated state of the porous medium, the transverse relaxation time of the liquid in the non-liquid-saturated state of the porous medium and the bulk transverse relaxation time of the liquid.

[0059] For example, the liquid saturation in the pores of the single-scale porous material can be calculated by the transverse relaxation time as shown in Formula 1, which is:

[0060]

[0061] Where s is the liquid saturation in the pores of the porous material; T 2,test is the characteristic transverse relaxation time measured by NMR in the unsaturated state of the liquid; T 2,sat is the characteristic transverse relaxation time measured by NMR in the liquid saturated state; T 2,b ——The bulk transverse relaxation time of the liquid under study.

[0062] For example, the change in liquid saturation in the pores of a nanoporous material during the process of CO2 displacing liquid water is analyzed as follows: the nanoporous material is sampled and the pore size distribution is tested by mercury intrusion porosimetry. The pore size of the material shows a unimodal distribution, and the peak pore size corresponds to 8nm.

[0063] The changes in liquid saturation in the pores of the material during the process of CO2 displacing liquid water were analyzed. First, the pores of the material were saturated with liquid water by vacuum method. The saturated material was loaded into a sample holder and placed in a low-field nuclear magnetic resonance device. The transverse relaxation time T2 spectrum was measured using a CPMG sequence. Figure 1 As shown by the solid line, the peak of the saturated water nuclear magnetic signal corresponds to the vertex T 2,sat The transverse relaxation time T2 spectrum of the sample was tested online using the CPMG sequence. Figure 1 As shown by the dotted line, the peak of the nuclear magnetic signal in this state corresponds to the vertex T 2,test is 8.53ms. Due to the bulk relaxation time T of liquid water 2,b =3s, the liquid water saturation s inside the pores of the nanoporous material can be calculated as:

[0064]

[0065] By conducting nuclear magnetic resonance experiments to measure the T2 spectrum, the liquid saturation in the pores of the nanoporous material under partially saturated conditions was obtained through analysis and calculation.

[0066] In one embodiment of the present application, the method for determining the liquid saturation in a porous medium further includes: if the porous medium is a micro-nano multi-porosity medium, obtaining the coupling relationship between the liquid relaxation in the micropores and nanopores in the porous medium; and obtaining the liquid saturation in the porous medium with a corresponding strategy based on the coupling relationship.

[0067] In this example, the liquid saturation in the porous medium is obtained according to the coupling relationship using a corresponding strategy, including: when the liquid relaxation in the micropores and nanopores is fully coupled, and when the liquid in the porous medium is in a saturated state and an unsaturated state, respectively obtaining a third nuclear magnetic resonance relaxation spectrum and a fourth nuclear magnetic resonance relaxation spectrum of the liquid in the porous medium; and obtaining the overall liquid saturation in the porous medium based on the third nuclear magnetic resonance relaxation spectrum, the fourth nuclear magnetic resonance relaxation spectrum and the bulk transverse relaxation time of the liquid.

[0068] In one embodiment of the present application, according to the coupling relationship, the liquid saturation in the porous medium is obtained with a corresponding strategy, which also includes: when the relaxation of the liquid in the micropores is slower than the relaxation of the liquid in the nanopores and slower than the speed meets the predetermined requirements, and the relaxation of the liquid in the micropores and nanopores is fully coupled, when the liquid in the micropores of the porous medium is in a saturated state and an unsaturated state, obtaining a fifth nuclear magnetic resonance relaxation spectrum and a sixth nuclear magnetic resonance relaxation spectrum of the liquid in the micropores, respectively; according to the fifth nuclear magnetic resonance relaxation spectrum, the sixth nuclear magnetic resonance relaxation spectrum and the bulk transverse relaxation time of the liquid, the overall liquid saturation in the porous medium is obtained.

[0069] In the above example, obtaining the coupling relationship between the relaxation of liquid in the micropores and nanopores in the porous medium includes: placing the porous medium in a predetermined environment and keeping it stationary for a predetermined time; after liquid filling occurs in the nanopores of the porous medium, obtaining the seventh nuclear magnetic resonance relaxation spectrum of the liquid in the porous medium at this time; obtaining the transverse relaxation time of the liquid in the nanopores based on the seventh nuclear magnetic resonance relaxation spectrum; obtaining the self-diffusion characteristic time of the liquid in the micropores based on the micropore size in the porous medium and the self-diffusion coefficient of the liquid; and determining the coupling relationship between the relaxation of liquid in the micropores and nanopores based on the transverse relaxation time of the liquid in the nanopores and the self-diffusion characteristic time of the liquid in the micropores.

[0070] Specifically, for micro-nano dual-porous materials, the coupling relationship between the relaxation of liquids in micropores and nanopores is first determined. The porous material to be studied is placed in a humid environment with a relative humidity close to 100% and left to stand for a period of time. At this time, liquid capillary condensation can occur in the nanopores of the material to fill the pores, so that the nanopores are in a liquid saturated state. The porous material in the above state is taken out and placed in a low-field nuclear magnetic resonance device. The CPMG sequence is used to measure the transverse relaxation time T2 spectrum of the liquid in the material. The top of the relaxation spectrum corresponds to T2, which is the characteristic relaxation time T of the liquid in the nanopores. 2,n Calculate the characteristic time t of liquid molecules self-diffusion in micron pores sdm As shown in Formula 2, Formula 2 is:

[0071]

[0072] Wherein, L is the characteristic size of micropores in the micro-nano porous material; D is the self-diffusion coefficient of liquid molecules.

[0073] If t sd,m With T 2,n At the same order of magnitude, the liquid relaxation in the micro-nano double pores is fully coupled. At this time, the micro-nano double pore material is saturated with liquid using the vacuum method, and its nuclear magnetic resonance relaxation spectrum is measured. The relaxation spectrum will show a single-peak distribution, corresponding to the saturation transverse relaxation time T 2,sat For porous materials in an unsaturated liquid state, the transverse relaxation spectrum is measured in a nuclear magnetic device using a CPMG sequence and the transverse relaxation time T corresponding to the single relaxation peak is obtained. 2,test , the overall liquid saturation of the micro-nano double-pore system can be calculated as shown in Formula 3, which is:

[0074]

[0075] Among them, s total is the overall liquid saturation in the micro-nano bi-porous material; T 2,test is the characteristic transverse relaxation time measured by NMR in the unsaturated state of the liquid; T 2,sat is the characteristic transverse relaxation time measured by NMR in the liquid saturated state; T 2,b is the bulk transverse relaxation time of the liquid under study.

[0076] If t sd,m Much larger than T 2,n , the relaxation of the liquid in the micropore is significantly slower than that in the nanopore. At this time, the micro-nano double-pore material is saturated with liquid and its nuclear magnetic resonance relaxation spectrum is measured. The relaxation spectrum will be shown as T 2,n and T 2,mThe bimodal distribution of the two characteristic times corresponds to the liquid in the nanopores and micropores respectively. At this time, the porous material in the liquid unsaturated state is placed in the nuclear magnetic device and the transverse relaxation spectrum is measured by the CPMG sequence to obtain the maximum transverse relaxation time T corresponding to the liquid in the micropores. 2,m,test , the overall liquid saturation of the micro-nano double-pore system can be calculated as shown in Formula 4, which is:

[0077]

[0078] Among them, s total is the overall liquid saturation in the micro-nano bi-porous material; T 2,m,test T is the larger characteristic transverse relaxation time in the double-peak spectrum measured by NMR in the unsaturated state of liquid; 2,m,sat T is the larger characteristic transverse relaxation time in the double-peak spectrum measured by NMR under liquid saturation conditions; 2,b is the bulk transverse relaxation time of the liquid under study.

[0079] For example, the change in liquid saturation during moisture migration in a micro-nano porous material is analyzed as follows: the micro-nano porous material is sampled and the mercury intrusion method is used to test its pore size distribution. The pore size distribution of the material is found to be a bimodal distribution, with the peak pore sizes corresponding to 8 nm and 4 μm.

[0080] The changes in liquid saturation in the pores during moisture migration in the material were analyzed. First, the material was placed in a humid environment with a humidity of 98%, causing water vapor capillary condensation in the nanopores of the material and filling them with liquid water. The material was then placed in a low-field nuclear magnetic resonance device and the nuclear magnetic relaxation spectrum was measured using a CPMG sequence. The results showed a single-peak T2 spectrum, with the peak being the characteristic relaxation time T of the nanopores. 2,n = 3ms. According to the micropore size L = 4μm and the water molecule self-diffusion coefficient D = 2.3×10 -9 m 2 / s, the self-diffusion characteristic time t of water molecules in the micron pores of the material can be calculated sdm for:

[0081]

[0082] Obviously, the characteristic time t of water self-diffusion in the micropores of this material is sd,m and the nanopore characteristic relaxation time T 2n At the same order of magnitude, the liquid relaxation in the micro-nano double pores can be fully coupled. At this time, the micro-nano porous material is saturated with liquid water using the vacuum method and placed in a low-field nuclear magnetic resonance device to measure its nuclear magnetic resonance relaxation spectrum. The spectrum shows a single peak distribution as shown in Figure 3 The solid line shows the peak point T 2,satFor the moisture migration process inside the material, the moisture in the pores is in an unsaturated state. The CPMG sequence is used to test the transverse relaxation time T2 spectrum of the material at a certain moment in the moisture migration process. Figure 2 As shown by the dotted line, the nuclear magnetic signal peak in this state is still a single peak distribution, corresponding to the vertex T 2,test The liquid water saturation s inside the micro-nano porous material can be calculated as total for:

[0083]

[0084] By conducting nuclear magnetic resonance experiments to measure the T2 spectrum, the overall liquid saturation of the micro-nano porous material under the partially saturated state was obtained through analysis and calculation.

[0085] The embodiments of the present application directly correspond and establish a connection between the liquid morphology in the pores and the nuclear magnetic relaxation spectrum, which can realize non-destructive online measurement of the liquid saturation inside the pores in micro-nano porous materials and accurately interpret the nuclear magnetic measurement results corresponding to complex porous fluid systems. This is of great significance for guiding the analysis of nuclear magnetic measurement results of porous multiphase systems and obtaining the internal fluid storage state and migration laws.

[0086] According to the method for determining the liquid saturation in a porous medium according to an embodiment of the present application, pore-scale microscopic information such as the liquid saturation inside the pores of the porous material can be obtained by online measurement and analysis. Compared with the existing nuclear magnetic resonance measurement and analysis method, the influence of complex liquid distribution and pore conditions such as liquid unsaturation and micro-nanoporosity on the transverse relaxation time is taken into account. Therefore, the liquid saturation in the porous medium can be better determined, and further, it is suitable for the analysis of fluid storage and transport processes in porous multiphase systems with complex pore sizes and phase distributions.

[0087] Figure 4 FIG. 1 is a block diagram of a system for determining liquid saturation in a porous medium according to an embodiment of the present application. Figure 4 As shown, the system for determining liquid saturation in a porous medium according to an embodiment of the present application includes: a type judgment module 410, an acquisition module 420, and a determination module 430, wherein:

[0088] A type determination module 410 is configured to determine the type of the porous medium according to the pore size distribution of the porous medium;

[0089] an acquisition module 420 for respectively acquiring a first nuclear magnetic resonance relaxation spectrum and a second nuclear magnetic resonance relaxation spectrum of the liquid in the porous medium when the porous medium is a single-scale pore medium and the liquid in the porous medium is in a saturated state and an unsaturated state;

[0090] The determination module 430 is configured to obtain the liquid saturation in the porous medium according to the first nuclear magnetic resonance relaxation spectrum, the second nuclear magnetic resonance relaxation spectrum, and the bulk transverse relaxation time of the liquid.

[0091] According to the system for determining the liquid saturation in porous media according to the embodiment of the present application, pore-scale microscopic information such as the liquid saturation inside the pores of the porous material can be obtained by online measurement and analysis. Compared with the existing nuclear magnetic resonance measurement and analysis methods, the system takes into account the influence of complex liquid distribution and pore conditions such as liquid unsaturation and micro-nanoporosity on the transverse relaxation time. Therefore, the liquid saturation in the porous medium can be better determined, and further, the system is suitable for the analysis of fluid storage and transport processes in porous multiphase systems with complex pore sizes and phase distributions.

[0092] The specific definitions of the system for determining liquid saturation in a porous medium can be found in the definitions of the method for determining liquid saturation in a porous medium described above and will not be repeated here. The various modules of the system for determining liquid saturation in a porous medium described above can be implemented in whole or in part via software, hardware, or a combination thereof. Each of the modules can be embedded in or independent of a processor in a computer device in the form of hardware, or can be stored in the memory of the computer device in the form of software, so that the processor can call and execute the corresponding operations of each of the modules.

[0093] In one embodiment, a computer device is provided. Figure 5 This is a block diagram of the computer device provided in an embodiment of the present application. The computer device includes a memory and a processor. The memory stores a computer program. When the processor executes the computer program, it implements the aforementioned method for determining liquid saturation in a porous medium. For example, the method performs: determining the type of the porous medium based on the pore size distribution of the porous medium;

[0094] If the porous medium is a single-scale pore medium, obtaining a first nuclear magnetic resonance relaxation spectrum and a second nuclear magnetic resonance relaxation spectrum of the liquid in the porous medium when the liquid in the porous medium is in a saturated state and an unsaturated state, respectively;

[0095] The liquid saturation in the porous medium is obtained according to the first nuclear magnetic resonance relaxation spectrum, the second nuclear magnetic resonance relaxation spectrum and the bulk transverse relaxation time of the liquid.

[0096] The present application also provides a computer-readable storage medium storing a computer program. When a processor executes the computer program, the method for determining the liquid saturation in a porous medium is implemented. For example, the method may include: determining the type of the porous medium based on the pore size distribution of the porous medium;

[0097] If the porous medium is a single-scale pore medium, obtaining a first nuclear magnetic resonance relaxation spectrum and a second nuclear magnetic resonance relaxation spectrum of the liquid in the porous medium when the liquid in the porous medium is in a saturated state and an unsaturated state, respectively;

[0098] The liquid saturation in the porous medium is obtained according to the first nuclear magnetic resonance relaxation spectrum, the second nuclear magnetic resonance relaxation spectrum and the bulk transverse relaxation time of the liquid.

[0099] The present application embodiment provides a computer program product, which includes instructions. When the instructions are executed, the method described in the embodiment of the present application is executed. For example, you can execute Figure 1 The steps of the method for determining the liquid saturation in a porous medium shown, for example, are performed as follows: determining the type of the porous medium according to the pore size distribution of the porous medium;

[0100] If the porous medium is a single-scale pore medium, obtaining a first nuclear magnetic resonance relaxation spectrum and a second nuclear magnetic resonance relaxation spectrum of the liquid in the porous medium when the liquid in the porous medium is in a saturated state and an unsaturated state, respectively;

[0101] The liquid saturation in the porous medium is obtained according to the first nuclear magnetic resonance relaxation spectrum, the second nuclear magnetic resonance relaxation spectrum and the bulk transverse relaxation time of the liquid.

[0102] Those skilled in the art will appreciate that all or part of the processes in the methods for implementing the above embodiments can be accomplished by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include processes of the embodiments of the above methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in this application may include at least one of non-volatile and volatile memory. Non-volatile memory may include read-only memory (ROM), magnetic tape, floppy disk, flash memory or optical memory, etc. Volatile memory may include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).

[0103] The technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0104] The above embodiments merely illustrate several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A method for determining liquid saturation in a porous medium, characterized in that: include: Determining the type of the porous medium according to the pore size distribution of the porous medium; If the porous medium is a single-scale pore medium, obtaining a first nuclear magnetic resonance relaxation spectrum and a second nuclear magnetic resonance relaxation spectrum of the liquid in the porous medium when the liquid in the porous medium is in a saturated state and an unsaturated state, respectively; The liquid saturation in the porous medium is obtained according to the first nuclear magnetic resonance relaxation spectrum, the second nuclear magnetic resonance relaxation spectrum and the bulk transverse relaxation time of the liquid.

2. The method for determining liquid saturation in a porous medium according to claim 1, wherein: Determining the type of the porous medium according to the pore size distribution of the porous medium includes: Obtaining the pore volume of the porous medium; The type of the porous medium is determined according to the distribution of the pore volume in the micron segment and the nanometer segment in the porous medium.

3. The method for determining liquid saturation in a porous medium according to claim 1 or 2, characterized in that: Obtaining the liquid saturation in the porous medium according to the first nuclear magnetic resonance relaxation spectrum, the second nuclear magnetic resonance relaxation spectrum, and the bulk transverse relaxation time of the liquid includes: Obtaining a transverse relaxation time of the liquid in the porous medium under a liquid saturation state according to the first nuclear magnetic resonance relaxation spectrum; Obtaining a transverse relaxation time of the liquid in the porous medium in a non-liquid saturated state according to the second nuclear magnetic resonance relaxation spectrum; obtaining a bulk transverse relaxation time of the liquid; The liquid saturation in the porous medium is obtained according to the transverse relaxation time of the liquid in the porous medium in a liquid-saturated state, the transverse relaxation time of the liquid in the porous medium in a non-liquid-saturated state, and the bulk transverse relaxation time of the liquid.

4. The method for determining liquid saturation in a porous medium according to claim 1 or 2, characterized in that: Also includes: If the porous medium is a micro-nano multi-porosity medium, then obtaining a coupling relationship between liquid relaxation in micropores and nanopores in the porous medium; According to the coupling relationship, the liquid saturation in the porous medium is obtained using a corresponding strategy.

5. The method for determining liquid saturation in a porous medium according to claim 4, characterized in that: The method of obtaining the liquid saturation in the porous medium according to the coupling relationship and using a corresponding strategy includes: When the relaxation of the liquid in the micropores and the nanopores is fully coupled, when the liquid in the porous medium is in a saturated state and an unsaturated state, respectively obtaining a third nuclear magnetic resonance relaxation spectrum and a fourth nuclear magnetic resonance relaxation spectrum of the liquid in the porous medium; The overall liquid saturation in the porous medium is obtained according to the third nuclear magnetic resonance relaxation spectrum, the fourth nuclear magnetic resonance relaxation spectrum, and the bulk transverse relaxation time of the liquid.

6. The method for determining liquid saturation in a porous medium according to claim 4, wherein: The step of obtaining the liquid saturation in the porous medium using a corresponding strategy according to the coupling relationship further includes: When the relaxation of the liquid in the micropores is slower than that in the nanopores and the speed satisfies the predetermined requirement, When the relaxation of the liquid in the micropores and the nanopores is fully coupled, when the liquid in the micropores of the porous medium is in a saturated state and an unsaturated state, respectively obtaining a fifth nuclear magnetic resonance relaxation spectrum and a sixth nuclear magnetic resonance relaxation spectrum of the liquid in the micropores; The overall liquid saturation in the porous medium is obtained according to the fifth nuclear magnetic resonance relaxation spectrum, the sixth nuclear magnetic resonance relaxation spectrum, and the bulk transverse relaxation time of the liquid.

7. The method for determining liquid saturation in a porous medium according to claim 4, characterized in that: The obtaining of the coupling relationship between liquid relaxation in the micropores and nanopores in the porous medium includes: placing the porous medium in a predetermined environment and allowing it to remain stationary for a predetermined time; After the nanopores of the porous medium are filled with liquid, a seventh nuclear magnetic resonance relaxation spectrum of the liquid in the porous medium is obtained; Obtaining a transverse relaxation time of the liquid in the nanopore according to the seventh nuclear magnetic resonance relaxation spectrum; Obtaining a characteristic self-diffusion time of the liquid in the micropores according to the micropore size in the porous medium and the self-diffusion coefficient of the liquid; The coupling relationship between the relaxation of the liquid in the micropore and the nanopore is determined based on the transverse relaxation time of the liquid in the nanopore and the characteristic self-diffusion time of the liquid in the micropore.

8. A system for determining liquid saturation in a porous medium, characterized in that: include: A type determination module, configured to determine the type of the porous medium according to the pore size distribution of the porous medium; an acquisition module, configured to obtain, when the porous medium is a single-scale pore medium and the liquid in the porous medium is in a saturated state and an unsaturated state, a first nuclear magnetic resonance relaxation spectrum and a second nuclear magnetic resonance relaxation spectrum of the liquid in the porous medium, respectively; A determination module is configured to obtain the liquid saturation in the porous medium according to the first nuclear magnetic resonance relaxation spectrum, the second nuclear magnetic resonance relaxation spectrum, and the bulk transverse relaxation time of the liquid.

9. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the program, the method for determining the liquid saturation in the porous medium according to any one of claims 1 to 7 is implemented.

10. A computer-readable storage medium comprising a memory and a computer program stored in the memory and executable on a processor, characterized in that: When the program is executed by a processor, the method for determining the liquid saturation in a porous medium according to any one of claims 1 to 7 is implemented.

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