Method and device for determining permeability during displacement seepage of porous rock media

Abstract

The present invention provides a method and device for determining the permeability of a porous medium displacement seepage process in a rock, the method comprising obtaining the core relaxation time before and after the porous medium displacement based on nuclear magnetic resonance technology. T 2 Distribution curve; based on the core relaxation time before and after the displacement T 2 Distribution curves are used to determine the porosity distribution, core pore fractal dimension, tortuosity fractal dimension and maximum pore diameter before and after displacement; based on the porosity distribution, core pore fractal dimension, tortuosity fractal dimension and maximum pore diameter before and after displacement, the permeability before and after displacement is determined; in this way, the dynamic changes of pore structure, tortuosity and permeability can be obtained without destroying the porous medium, so as to deeply study the distribution of rock pore size and its influence on fluid behavior.

Description

Technical Field

[0001] The present invention relates to the technical fields of oil and gas reservoir development engineering, geotechnical engineering, chemical engineering, and more particularly to a method and device for determining the permeability of a rock porous medium displacement seepage process. Background Art

[0002] In the process of oil and gas reservoir or marine gas hydrate exploitation, there is multiphase fluid displacement of oil, gas, water and sand. Due to changes in formation pressure, clay expansion, and migration of clay or fine silt particles, the reservoir permeability changes, which directly affect the efficiency of oil and gas reservoir or gas hydrate exploitation. Therefore, it is urgent to propose an effective method for quantitatively evaluating the permeability of reservoir porous media in the process of oil and gas reservoir exploitation displacement. Summary of the invention

[0003] The present disclosure provides a method and device for determining the permeability of a rock porous medium displacement seepage process, so as to at least solve the above technical problems existing in the prior art.

[0004] According to a first aspect of the present disclosure, a method for determining permeability in a rock porous medium displacement seepage process is provided, comprising:

[0005] Obtaining the first core relaxation time of each layer before porous media displacement based on nuclear magnetic resonance technology T 2 distribution curve, and the second core relaxation time of each layer after the porous medium displacement T 2Distribution curve;

[0006] Based on the first core relaxation time T 2 distribution curve to determine the porosity distribution of each layer before the porous medium displacement and the first core pore fractal dimension before the porous medium displacement; based on the porosity distribution of each layer before the porous medium displacement, determine the first tortuosity fractal dimension of each layer before the porous medium displacement;

[0007] Based on the second core relaxation time T 2 distribution curve to determine the porosity distribution of each layer after the porous medium displacement and the second core pore fractal dimension after the porous medium displacement; based on the porosity distribution of each layer after the porous medium displacement, determine the second tortuosity fractal dimension of each layer after the porous medium displacement;

[0008] Determining the first absolute permeability of each layer before the porous medium is displaced based on the first tortuosity, the first maximum pore diameter, the first core pore fractal dimension and the first tortuosity fractal dimension of each layer before the porous medium is displaced;

[0009] Based on the second tortuosity, the second maximum pore diameter, the second core pore fractal dimension and the second tortuosity fractal dimension of each layer after the porous medium is displaced, the second absolute permeability of each layer after the porous medium is displaced is determined.

[0010] In the above scheme, the first absolute permeability of each layer after the porous medium displacement is determined based on the first tortuosity, the first maximum pore diameter, the first core pore fractal dimension and the first tortuosity fractal dimension of each layer before the porous medium displacement, including:

[0011] The first absolute permeability of any layer before the porous medium is flooded is calculated based on the following formula:

[0012]

[0013] in, For the i The first absolute permeability before sheet flooding, is the first tortuosity, is the average thickness of each layer of the porous medium, is the fractal dimension of the first core pore, is the first tortuosity fractal dimension, is the maximum pore diameter of the porous medium before displacement.

[0014] In the above scheme, the second absolute permeability of each layer after the porous medium displacement is determined based on the second tortuosity, the second maximum pore diameter, the second core pore fractal dimension and the second tortuosity fractal dimension of each layer after the porous medium displacement, including:

[0015] The second absolute permeability of any layer after the porous medium is flooded is calculated based on the following formula:

[0016]

[0017] in, For the i The first absolute permeability after sheet flooding, is the second tortuosity, is the average thickness of each layer of the porous medium, is the fractal dimension of the second core pore, is the second tortuosity fractal dimension, is the maximum pore diameter of the porous medium after displacement.

[0018] In the above scheme, the method further includes:

[0019] Based on the average thickness of each layer of the porous medium, the first tortuosity of each layer before the porous medium is displaced, the second tortuosity of each layer after the multi-block medium is displaced, the pore diameter before the displacement, the pore diameter after the displacement, the first core pore fractal dimension, the second core pore fractal dimension, the first tortuosity fractal dimension and the second tortuosity fractal dimension, the ratio of the permeability before and after the porous medium is displaced is determined, including:

[0020] The ratio of the permeability before and after the porous medium displacement is determined based on the following formula:

[0021]

[0022] in, is the ratio of the permeability before and after porous media displacement, is the first tortuosity, is the second tortuosity, is the average thickness of each layer of the porous medium, is the first tortuosity fractal dimension, is the second tortuosity fractal dimension, is the fractal dimension of the first core pore, is the fractal dimension of the second core pore, is the maximum pore diameter of the porous medium before displacement, is the maximum pore diameter of the porous medium after displacement.

[0023] In the above scheme, the method further includes:

[0024] The second total average permeability after the porous medium is flooded is determined based on the thickness of each layer after the porous medium is flooded and the second absolute permeability.

[0025] In the above scheme, the second total average permeability after the porous medium is displaced is determined based on the thickness of each layer after the porous medium is displaced and the second absolute permeability, including:

[0026] The second overall average permeability of the porous medium is determined based on the following formula:

[0027]

[0028] in, is the second overall average permeability after displacement, For porous media i The thickness of the layer, m is the layer mark of the displacement inlet, n is the layer mark of the displacement outlet, For the i Second absolute permeability after sheet flooding.

[0029] In the above scheme, the method further includes:

[0030] Based on the thickness of each layer after the porous medium is flooded and the first absolute permeability, the first total average permeability before the porous medium is flooded is determined.

[0031] In the above scheme, the first total average permeability before the porous medium is displaced is determined based on the thickness of each layer after the porous medium is displaced and the first absolute permeability, including:

[0032] The first overall average permeability of the porous medium before displacement is determined based on the following formula:

[0033]

[0034] in, is the first total average permeability before displacement, For porous media i The thickness of the layer, m is the layer mark of the displacement inlet, n is the layer mark of the displacement outlet, For the i First absolute permeability before sheet flooding.

[0035] According to a second aspect of the present disclosure, a device for determining permeability during displacement seepage of a porous rock medium is provided, the device comprising:

[0036] NMR unit, used to obtain the first core relaxation time of each layer before porous media displacement T 2 distribution curve, and the second core relaxation time of each layer after the porous medium displacement T 2Distribution curve;

[0037] a first processing unit, for determining a first core relaxation time based on the first core relaxation time; T 2 distribution curve to determine the porosity distribution of each layer before the porous medium displacement and the first core pore fractal dimension before the porous medium displacement; based on the porosity distribution of each layer before the porous medium displacement, determine the first tortuosity fractal dimension of each layer before the porous medium displacement;

[0038] a second processing unit for processing a second core relaxation time based on the second core relaxation time T 2 distribution curve to determine the porosity distribution of each layer after the porous medium displacement and the second core pore fractal dimension after the porous medium displacement; based on the porosity distribution of each layer after the porous medium displacement, determine the second tortuosity fractal dimension of each layer after the porous medium displacement;

[0039] A first absolute permeability determination unit, for determining the first absolute permeability of each layer before the porous medium is displaced based on the first tortuosity of each layer before the porous medium is displaced, the first maximum pore diameter, the first core pore fractal dimension and the first tortuosity fractal dimension;

[0040] The second absolute permeability determination unit is used to determine the second absolute permeability of each layer after the porous medium is displaced based on the second tortuosity of each layer after the porous medium is displaced, the second maximum pore diameter, the second core pore fractal dimension and the second tortuosity fractal dimension.

[0041] The method for determining the permeability of the rock porous medium displacement seepage process disclosed in the present invention obtains the first core relaxation time of each layer before the porous medium displacement based on the nuclear magnetic resonance technology. T 2 distribution curve, and the second core relaxation time of each layer after the porous medium displacement T 2 distribution curve; based on the first core relaxation time T 2 distribution curve to determine the porosity distribution of each layer before the porous medium displacement and the first core pore fractal dimension before the porous medium displacement; based on the porosity distribution of each layer before the porous medium displacement, determine the first tortuosity fractal dimension of each layer before the porous medium displacement; based on the second core relaxation time T 2 distribution curve to determine the porosity distribution of each layer after the porous medium displacement and the second core pore fractal dimension after the porous medium displacement; based on the porosity distribution of each layer after the porous medium displacement, determine the second tortuosity fractal dimension of each layer after the porous medium displacement; based on the first tortuosity, the first maximum pore diameter, the first core pore fractal dimension and the first tortuosity fractal dimension of each layer before the porous medium displacement, determine the first absolute permeability of each layer before the porous medium displacement; based on the second tortuosity, the second maximum pore diameter, the second core pore fractal dimension and the second tortuosity fractal dimension of each layer after the porous medium displacement, determine the second absolute permeability of each layer after the porous medium displacement. In this way, the T2 distribution curve of the porous medium can be drawn by the nuclear magnetic resonance imaging method without destroying the core, so as to deeply study the distribution of rock pore size and its influence on fluid behavior.

[0042] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present disclosure, nor is it intended to limit the scope of the present disclosure. Other features of the present disclosure will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The above and other objects, features and advantages of the exemplary embodiments of the present disclosure will become readily understood by reading the detailed description below with reference to the accompanying drawings. In the accompanying drawings, several embodiments of the present disclosure are shown in an exemplary and non-limiting manner, in which:

[0044] In the drawings, the same or corresponding reference numerals represent the same or corresponding parts.

[0045] Figure 1 A first optional flow chart of a method for determining permeability in a rock porous medium displacement seepage process provided by an embodiment of the present disclosure is shown;

[0046] Figure 2 A second optional flow chart of the method for determining the permeability of a rock porous medium displacement seepage process provided by an embodiment of the present disclosure is shown;

[0047] Figure 3 A porous media permeability calculation flow chart provided by an embodiment of the present disclosure is shown;

[0048] Figure 4 An optional flow chart of calculating the fractal dimension of core pores before and after porous media displacement provided by an embodiment of the present disclosure is shown;

[0049] Figure 5 A third optional flow chart of the method for determining the permeability of a rock porous medium displacement seepage process provided by an embodiment of the present disclosure is shown;

[0050] Figure 6 Shows core displacement schematic and core relaxation time T 2Distribution curve;

[0051] Figure 7 Shows the core relaxation time before and after the first sheet of porous media is displaced. T 2Distribution curve;

[0052] Figure 8 The schematic diagram of the porosity change of each layer before and after displacement is shown;

[0053] Fig. 9 A schematic diagram showing the comparison of the average pore diameter changes of each layer before and after displacement is shown;

[0054] Fig.10 A schematic diagram showing the comparison of the maximum pore diameter changes of each layer before and after displacement is shown;

[0055] Fig.11 A schematic diagram showing the comparison of the tortuosity changes of each layer before and after displacement is shown;

[0056] Fig.12 A schematic diagram showing the comparison of absolute permeability changes of each layer before and after displacement is shown;

[0057] Fig.13 A schematic diagram of the permeability ratio of each layer before and after displacement is shown;

[0058] Fig.14 An optional structural schematic diagram of a device for determining permeability during displacement seepage of a porous rock medium provided by an embodiment of the present disclosure is shown;

[0059] Fig.15 A schematic diagram of the structure of an electronic device according to an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0060] In order to make the purpose, features, and advantages of the present disclosure more obvious and easy to understand, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present disclosure.

[0061] In the following description, reference is made to “some embodiments”, which describe a subset of all possible embodiments, but it can be understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0062] In the following description, the terms "first\second" involved are merely used to distinguish similar objects and do not represent a specific ordering of the objects. It can be understood that "first\second" can be interchanged with a specific order or sequence where permitted, so that the embodiments of the present disclosure described herein can be implemented in an order other than that illustrated or described herein.

[0063] Unless otherwise defined, all technical and scientific terms used in this disclosure have the same meaning as those commonly understood by those skilled in the art to which this disclosure belongs. The terms used in this disclosure are only for the purpose of describing the embodiments of this disclosure and are not intended to limit this disclosure.

[0064] It should be understood that in the various embodiments of the present disclosure, the size of the serial number of each implementation process does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present disclosure.

[0065] Among the related technologies, porosity and permeability measurements mainly rely on mercury intrusion porosimeter and gas permeability tester. Although these methods are also accurate, they will damage the interior of the rock and cannot provide information on the distribution of fluids in the pores. Magnetic Resonance Imaging (MRI) technology can measure the relaxation time of fluids in rock pores, and obtain key parameters such as pore size distribution, tortuosity, and relative permeability through calculation and inference, which is crucial to the rock displacement process.

[0066] Although existing technologies have made significant progress in rock pore structure analysis and fluid behavior research, there are still some problems and challenges. Traditional relative permeability and porosity measurement methods often require strict experimental conditions and high requirements for experimental equipment. The experimental process is complicated and has certain destructiveness to the core. It is impossible to achieve multiple measurements in situ, which limits the monitoring of dynamic changes. At the same time, these methods are difficult to obtain the microscopic distribution information of fluids in pores. Nuclear Magnetic Resonance (NMR) technology provides rich data, but how to use it to analyze the microscopic distribution of fluids in pores is still a long way to go. T 2 Converting data into data needed for in-depth research remains a challenge.

[0067] The present disclosure can map the T2 distribution in porous media (such as porous rocks) through the nuclear magnetic resonance imaging method, so as to deeply study the distribution of rock pore size and its influence on fluid behavior. Fluid flow in porous media has complex behavioral characteristics, especially the fluid behavior in the displacement (or seepage) process. The pore size changes greatly at the displacement inlet and outlet, and the rock tortuosity also changes accordingly.

[0068] In the embodiment of the present disclosure, the core relaxation time is first obtained by nuclear magnetic resonance technology for a fully saturated core. T 2 distribution, and then combined with the porous media fractal theory to obtain the core pore fractal dimension D f and the fractal dimension of the core tortuosity D T , as well as the number of core pores N, the maximum pore diameter and the average pore diameter of the core, the core tortuosity is calculated, and finally the absolute permeability of each core layer and the relative permeability ratio before and after the core displacement are calculated by the absolute permeability formula. The total average permeability of the core is calculated for each series layer before and after the displacement.

[0069] Figure 1 A first optional flow chart of a method for determining the permeability of a rock porous medium displacement seepage process provided by an embodiment of the present disclosure is shown, and will be described according to each step.

[0070] Step S101, obtaining the first core relaxation time of each layer before porous medium displacement based on nuclear magnetic resonance technologyT 2 distribution curve, and the second core relaxation time of each layer after the porous medium displacement T 2Distribution curve.

[0071] In some embodiments, the carrier (hereinafter referred to as the carrier) of the method for determining the permeability of the rock porous medium displacement seepage process is respectively based on the nuclear magnetic resonance technology to obtain the first core relaxation time of the same porous medium before displacement. T 2 distribution curves and the second core relaxation time after displacement T 2 distribution curve. Wherein, the porous medium includes a plurality of sheets.

[0072] In a specific implementation, the carrier can use a low-field nuclear magnetic resonance pure phase encoding pulse sequence SE-SPI to directly obtain the core relaxation time before and after displacement in the porous medium. T 2 Distribution curves, core relaxation times of different layers T 2 The distribution curve represents the water content distribution of the sheets at different positions, which indirectly reflects the pore distribution of the porous medium. The ratio of its integrated area to the volume of the sheet is the porosity of the sheet.

[0073] Among them, the carrier can be a computer program, electronic circuit, database, mobile application, electronic device, cloud computing platform, distributed system, artificial intelligence framework, mathematical model, automation tool and microcontroller, etc., which can implement software or hardware of algorithm and method flow.

[0074] Step S102, based on the first core relaxation time T 2 distribution curve to determine the porosity distribution of each layer before the porous medium displacement and the first core pore fractal dimension before the porous medium displacement; based on the porosity distribution of each layer before the porous medium displacement, determine the first tortuosity fractal dimension of each layer before the porous medium displacement.

[0075] In some embodiments, the first core relaxation time T 2 Distribution curve, including the core relaxation time of each layer before the porous medium is displaced T 2 Distribution curve; core relaxation time of the previous layer of displacement T 2 distribution curve is integrated, and the ratio of the integrally calculated pore volume to the volume of the layer is the porosity distribution of the layer.

[0076] In some embodiments, the carrier can be based on the core relaxation time T 2 Calculation of core pore fractal dimension and core relaxation time using distribution curve T 2 Relationship between distribution curves; Based on the fractal dimension of core pores and core relaxation time T2 distribution curve, the relationship between capillary pressure and pore size in porous media, and the relationship between capillary pressure and core relaxation time T 2 distribution curve; combined with the fractal theory of porous media, a fractal formula based on capillary pressure is obtained; the fractal formula of capillary pressure is fitted to obtain the fractal dimension of the core pores. That is, the core relaxation time of each layer before displacement obtained by the carrier based on nuclear magnetic resonance technology T 2 distribution curve, and the fractal dimension of the pores in the first core before displacement was obtained.

[0077] In some embodiments, the carrier can determine the first tortuosity fractal dimension of each layer of the porous medium before displacement based on the porosity distribution of each layer before displacement of the porous medium, the thickness of each layer of the porous medium, generally the thickness of each layer is the same, that is, the average value, and the minimum pore diameter before displacement.

[0078] Step S103, based on the second core relaxation time T 2 distribution curve to determine the porosity distribution of each layer after the porous medium displacement and the second core pore fractal dimension after the porous medium displacement; based on the porosity distribution of each layer after the porous medium displacement, determine the second tortuosity fractal dimension of each layer after the porous medium displacement.

[0079] In some embodiments, the method for the carrier to determine the porosity distribution of each layer after the porous medium is replaced and the second core pore fractal dimension after the porous medium is replaced, and to determine the second tortuosity fractal dimension of each layer after the porous medium is replaced is similar to step S102 and will not be repeated here.

[0080] Step S104, determining the first absolute permeability of each layer before the porous medium is displaced based on the first tortuosity, the first maximum pore diameter, the first core pore fractal dimension and the first tortuosity fractal dimension of each layer before the porous medium is displaced.

[0081] In some embodiments, the support calculates the first absolute permeability of any layer before the porous medium is flooded based on the following formula:

[0082]

[0083] in, For the i The first absolute permeability before sheet flooding, is the first tortuosity, is the thickness of each layer of the porous medium. In the calculation, the thickness of each layer is the same, and the average value is taken, that is, is the average thickness of each layer of the porous medium, is the fractal dimension of the first core pore, is the first tortuosity fractal dimension, is the maximum pore diameter of the porous medium before displacement.

[0084] Step S105, determining the second absolute permeability of each layer after the porous medium is displaced based on the second tortuosity, the second maximum pore diameter, the second core pore fractal dimension and the second tortuosity fractal dimension of each layer after the porous medium is displaced.

[0085] In some embodiments, the carrier calculates the second absolute permeability of any layer after the porous medium is flooded based on the following formula:

[0086]

[0087] in, For the i The second absolute permeability after sheet displacement, is the second tortuosity, is the average thickness of each layer of the porous medium, is the fractal dimension of the second core pore, is the second tortuosity fractal dimension, is the maximum pore diameter of the porous medium after displacement.

[0088] Step S106, based on the average thickness of each layer of the porous medium, the first tortuosity of each layer before the porous medium is displaced, the second tortuosity of each layer after the porous medium is displaced, the pore diameter before the displacement, the pore diameter after the displacement, the first core pore fractal dimension, the second core pore fractal dimension, the first tortuosity fractal dimension and the second tortuosity fractal dimension, determine the ratio of the permeability before and after the porous medium is displaced.

[0089] In some embodiments, the carrier determines the ratio of the permeability of the porous medium before and after displacement based on the following formula:

[0090]

[0091] in, is the ratio of the permeability before and after porous media displacement, is the first tortuosity, is the second tortuosity, is the average thickness of each layer of the porous medium, is the first tortuosity fractal dimension, is the second tortuosity fractal dimension, is the fractal dimension of the first core pore, is the fractal dimension of the second core pore, is the maximum pore diameter of the porous medium before displacement, is the maximum pore diameter of the porous medium after displacement.

[0092] Thus, the method for determining the permeability of the rock porous medium displacement seepage process provided by the embodiment of the present disclosure utilizes the fast, accurate and non-destructive detection characteristics of NMR technology to achieve accurate measurement of the rock pore structure and fluid distribution; starting from the basic principle of nuclear magnetic resonance, full use is made of T 2. The physical meaning of the distribution curve is to establish a more accurate physical model to deduce the dynamic changes of pore structure, tortuosity and permeability. For hydrates, the risk of sand production can be predicted. If the distribution shows that the pore size increases significantly and the permeability increases significantly after displacement, this may indicate that the rock structure has become unstable and the risk of sand production has increased. On the contrary, if the pore size decreases and the permeability decreases, it may indicate that the formation tends to be stable and the risk of sand production decreases. By analyzing the rock before and after displacement, the sand production risk can be predicted. T 2 distribution curve, which can guide engineers to optimize mining strategies. This technical solution introduces NMR technology to solve the problems of harsh experimental conditions, strong destructiveness of measurements before and after displacement, and difficult data analysis. The core tortuosity, porosity, average pore diameter, and relative permeability ratio before and after displacement are obtained through analysis and calculation, providing a more accurate, efficient and practical tool for fluid behavior research and reservoir optimization development in oil and gas reservoir engineering.

[0093] Figure 2 A second optional flow chart of the method for determining the permeability of a rock porous medium displacement seepage process provided by an embodiment of the present disclosure is shown. Figure 3 The porous media permeability calculation flow chart provided by the embodiment of the present disclosure is shown. Figure 2 and Figure 3 Provide explanation.

[0094] like Figure 3 As shown, first, the core NMR relaxation time of the fully saturated core is obtained by nuclear magnetic resonance technology. T 2 distribution curve, and then combine the porous media fractal theory to obtain the core pore fractal dimension and core tortuosity fractal dimension , as well as the number of core pores N and the maximum pore diameter of the core , average pore diameter , the core tortuosity is calculated Finally, the absolute permeability K of each layer in the core and the relative permeability ratio before and after core flooding are calculated by the absolute permeability formula. The total average permeability of the core is calculated for each series of slices before and after displacement , specifically:

[0095] Step S201, obtaining the core relaxation time before and after porous media displacement based on nuclear magnetic resonance technology T 2Distribution curve.

[0096] In some embodiments, the carrier obtains the core relaxation time of the same layer of porous media before and after displacement based on nuclear magnetic resonance technology. T 2Distribution curve.

[0097] In a specific implementation, the carrier uses a low-field nuclear magnetic resonance pure phase encoding pulse sequence SE-SPI to directly obtain the core relaxation time before and after displacement in the porous medium. T 2 Distribution curves, core relaxation times of different layers T 2 The distribution curve represents the water content distribution of the layers at different positions, which indirectly reflects the pore distribution of the porous medium. The ratio of its integrated area to the volume of the layer is the porosity of the layer. Set the core relaxation time before displacement T 2 Distribution curve is the first core relaxation time T 2 Distribution curve, core relaxation time after displacement T 2 Distribution curve is the second core relaxation time T 2Distribution curve.

[0098] In some embodiments, the first core relaxation time T 2 The core relaxation time before displacement of at least one layer of porous media is included in the distribution curve T 2 Distribution curve; Second core relaxation time T 2. The core relaxation time after displacement of at least one layer of porous media is included in the distribution curve T 2Distribution curve.

[0099] Step S202, determining the porosity distribution of each layer of the porous medium before and after displacement.

[0100] In some embodiments, the carriers respectively adjust the core relaxation time before displacement of each layer of the porous medium. T 2 distribution curve is integrated to obtain the porosity distribution of each layer before displacement; the core relaxation time of each layer of porous medium after displacement is determined by the carrier T 2 distribution curve is integrated to obtain the porosity distribution of each layer after displacement.

[0101] In some embodiments, the ratio of the integrated pore volume to the volume of each sheet is the porosity of the sheet.

[0102] Step S203, calculating the fractal dimension of the core pores before and after the porous medium displacement.

[0103] In some embodiments, T 2- The calculation method of fractal tortuosity is based on the core relaxation time of the porous medium of the core T 2 distribution curve, and combined with fractal theory, the fractal dimension of the core pores of porous media is calculated And other related parameters, and then find T 2- Fractal tortuosity:

[0104] The time required for the transverse magnetization vector to decay to a stable state is called the transverse relaxation time. T 2 distribution curve, can be expressed as:

[0105]

[0106] The diffusion relaxation time can be ignored when the static magnetic field gradient is very small and the time interval of the pulse sequence is short. The free relaxation time is determined by the physical properties of the fluid (hydrogen index, viscosity, etc.), but its influence is much smaller than that of the surface relaxation. Therefore, only the surface relaxation time is considered in the calculation of the embodiment of the present disclosure. T 2Distribution curve.

[0107] Figure 4 An optional flow chart for calculating the fractal dimension of core pores before and after porous media displacement provided by an embodiment of the present disclosure is shown, and will be explained according to each step.

[0108] Step S2031, based on the core relaxation time T 2 Calculation of core pore fractal dimension and core relaxation time using distribution curve T 2 The relationship between the distribution curves.

[0109] In some embodiments, the core pore fractal dimension and the core relaxation time T The relationship between the 2 distribution curves is as follows:

[0110]

[0111] in, is the transverse relaxation strength of the pore surface, is the pore surface area of ​​the porous medium, is the pore volume of the porous medium, is the shape factor, is the pore radius of the porous medium.

[0112] Step S2032, calculating the relationship between the capillary pressure and the pore size in the porous medium.

[0113] In some embodiments, based on rock physics, the relationship between capillary pressure and pore size in porous media is as follows:

[0114]

[0115] in, is the capillary pressure, σ is the surface tension of the fluid, and θ is the contact angle between the fluid and the pore.

[0116] Step S2033, based on the relationship between the core pore fractal dimension and the core relaxation time T 2 distribution curve, and the relationship between capillary pressure and pore size in the porous medium, obtain the capillary pressure and the core relaxation time T 2 distribution curve.

[0117] In some embodiments, combining Equation (2) and Equation (3) can obtain:

[0118]

[0119] Step S2034, combining the porous medium fractal theory, obtain the fractal formula based on capillary pressure.

[0120] In some embodiments, according to the porous medium fractal theory, derive the fractal formula based on capillary pressure (i.e., rock capillary pressure):

[0121]

[0122] Wherein, is the core relaxation time T 2 maximum value of the distribution curve, is the core pore fractal dimension.

[0123] Among them, the derivation process of formula (5) is as follows:

[0124] According to the fractal geometry principle, if the pore size distribution conforms to the fractal structure, then the number of pores N(>r) with a pore size greater than r in the reservoir has the following power function relationship with r:

[0125]

[0126] Wherein, is the maximum pore radius in the reservoir, is the pore distribution density function, and a is a proportional constant.

[0127] Taking the derivative of r gives the pore size distribution function Expression:

[0128]

[0129] Wherein, = is a proportional constant.

[0130] Substituting (4-2) into (4-3) for integration, obtain the expression of the cumulative volume V(<r) of pores with a pore size less than r in the reservoir:

[0131]

[0132] Wherein, = / (3- ), is a constant related to the pore shape, (the pore is a cube, , is a sphere, then =4π / 3, is the minimum pore radius of the porous medium. Similarly, the total pore volume V is:

[0133]

[0134] Substituting (4-3) (4-4) into (4-5), we can obtain the cumulative pore volume fraction of pores smaller than r The expression is:

[0135]

[0136] because , r, (4-5) can be simplified as:

[0137]

[0138] From this, we can obtain the fractal geometry formula for the distribution of porous media.

[0139] Porous media obey the Laplace formula. Then:

[0140]

[0141] Substituting formula (4-7) into (4-6) yields:

[0142]

[0143] In the formula, is the maximum pore size in the porous medium The corresponding capillary pressure; Capillary pressure The percentage of the pore volume occupied by the fluid in the pores of a porous medium.

[0144] Step S2035, fitting the fractal formula of the capillary pressure to obtain the fractal dimension of the core pores.

[0145] In some embodiments, the fractal dimension of the core pore is obtained by fitting based on equation (4-8): .

[0146]

[0147] In some embodiments, the carrier can calculate the core pore fractal dimension before and after the porous medium displacement based on the above steps S2031 to S2035; the core pore fractal dimension before displacement is the first core pore fractal dimension, and the core pore fractal dimension after displacement is the second core pore fractal dimension.

[0148] Step S204, calculating the fractal dimension of the tortuosity of the porous medium before and after displacement.

[0149] In some embodiments, the fractal dimension of the porous medium tortuosity Calculation: Through the relationship between tortuosity fractal dimension and porosity, and porosity The relationship can be expressed as:

[0150]

[0151] in, is the average thickness of each layer of the porous medium, is the minimum pore diameter of the core of porous media.

[0152] In some embodiments, the carrier can calculate the tortuosity fractal dimension of the porous medium before and after displacement based on the above formula (7); the core pore fractal dimension before displacement is denoted as the first core pore fractal dimension, and the porosity before displacement and the minimum pore diameter of the core are substituted into formula (7) during calculation; the core pore fractal dimension after displacement is denoted as the second core pore fractal dimension, and the porosity after displacement and the minimum pore diameter of the core are substituted into formula (7) during calculation.

[0153] Step S205, calculating the average pore diameter of the porous medium.

[0154] In some embodiments, the average pore diameter of the porous medium is When calculating, it is necessary to combine fractal theory to obtain the total number of pores N in the porous medium, and use the pore distribution probability density function equation The average pore diameter can be obtained by integrating the number of pores N: :

[0155]

[0156]

[0157] in, is the maximum pore diameter of the core of the porous medium.

[0158] In some embodiments, the carrier can calculate the average pore diameter of the porous medium before and after displacement based on the above formulas (8) and (9), respectively; the average pore diameter before displacement is referred to as the first average pore diameter, and the relevant parameters before displacement are substituted into formulas (8) and (9) during calculation; the average pore diameter after displacement is referred to as the second average pore diameter, and the relevant parameters after displacement are substituted into formulas (8) and (9) during calculation.

[0159] Step S206, calculating the tortuosity of the porous medium.

[0160] In some embodiments, the tortuosity It is defined as the actual length of the pore fluid. The average thickness of each layer of porous media The ratio of reflects the complexity of the porous medium tortuosity:

[0161]

[0162] Where A is the cross-sectional area of ​​the core.

[0163] In some embodiments, the carrier can calculate the tortuosity of the porous medium before and after displacement based on the above formula (10); the tortuosity before displacement is referred to as the first tortuosity, and the relevant parameters before displacement are substituted into formula (10) during calculation; the tortuosity after displacement is referred to as the second tortuosity, and the relevant parameters after displacement are substituted into formula (10) during calculation.

[0164] Step S207, calculating the absolute permeability of the porous medium before and after displacement.

[0165] In some embodiments, the absolute permeability of the porous medium before and after displacement can be calculated by combining the tortuosity, maximum pore diameter and fractal dimension calculated above:

[0166]

[0167] In some embodiments, the carrier can calculate the absolute permeability of the porous medium before and after displacement based on the above formula (11); the absolute permeability before displacement is recorded as the first absolute permeability, and the relevant parameters before displacement are substituted into the formula (11) during calculation; the absolute permeability after displacement is recorded as the second absolute permeability, and the relevant parameters before and after displacement are substituted into the formula (11) during calculation, as follows:

[0168]

[0169] in, For the i The first absolute permeability before sheet flooding, is the first tortuosity, is the fractal dimension of the first core pore, is the first tortuosity fractal dimension, is the maximum pore diameter of the porous medium before displacement.

[0170]

[0171] in, For the i The second absolute permeability after sheet displacement, is the second tortuosity, is the fractal dimension of the second core pore, is the second tortuosity fractal dimension, is the maximum pore diameter of the porous medium after displacement.

[0172] Step S208, calculating the permeability ratio of the porous medium before and after displacement.

[0173] In some embodiments, the permeability ratio of the porous medium before and after displacement is calculated based on the following formula:

[0174]

[0175] Step S209, calculating the total average permeability of the porous medium.

[0176] In some embodiments, the porous medium core is entirely serially displaced linearly, and for the selected slice positions from m to n, one of the slices is i (in, i Not 0, when i When it is 0, is the thickness of each layer of the porous medium. In the calculation, the thickness of each layer is the same, that is, the average value ), the thickness of the sheet Sum them up and then calculate the total average permeability of the core series :

[0177]

[0178] Where, K is the total average permeability, For porous media i The thickness of the layer, m is the layer mark of the displacement inlet, n is the layer mark of the displacement outlet, is the first i The absolute permeability of the layer. Furthermore, when calculating the total average permeability before displacement, the following formula can be used:

[0179]

[0180] in, is the total average permeability before displacement, or the total average permeability of the series before displacement, For the i First absolute permeability before sheet flooding.

[0181] When calculating the total average permeability after displacement, the following formula can be used:

[0182]

[0183] in, is the total average permeability after displacement, or the total average permeability of the series after displacement, For the i Second absolute permeability after sheet flooding.

[0184] Thus, the permeability determination method of the rock porous medium displacement seepage process provided by the embodiment of the present disclosure realizes the calculation of the tortuosity and average pore diameter of the porous medium before and after displacement, and obtains the change law of the permeability. The nuclear magnetic resonance measurement of the change law before and after displacement in the porous medium of the present invention first uses the low-field nuclear magnetic resonance pure phase encoding pulse sequence SE-SPI to directly obtain the permeability before and after displacement. T 2 distribution curves, based on fractal theory, the fractal dimensions of porous media are calculated respectively and the fractal dimension of porous media tortuosity , average pore diameter, tortuosity The absolute permeability and relative permeability ratio of the porous media before and after displacement objectively reflects the impact of the fluid on the porous media before and after displacement. T 2 The distribution curve is directly integrated to obtain the value of the porosity in the porous medium, that is, the porosity of different layers is accurately calculated separately, so the value obtained will be more accurate. Through the above method, only the core relaxation time of the porous medium needs to be measured by nuclear magnetic resonance. T 2 distribution curve, the permeability at a certain position or a certain moment can be obtained, which is of great help in the subsequent calculation of relative permeability and the treatment of oil production flow problems and hydrate sand production.

[0185] Figure 5 A third optional flow chart of the method for determining the permeability of the rock porous medium displacement seepage process provided by the embodiment of the present disclosure is shown, and will be explained according to each step.

[0186] Step S401, obtaining the core relaxation time before and after porous media displacement based on nuclear magnetic resonance technology T 2Distribution curve.

[0187] Figure 6 Shows core displacement schematic and core relaxation time T2Distribution curve.

[0188] like Figure 6 As shown, the core length is 49 mm and the diameter is 38 mm. Two injection liquids, brine and deionized water, are injected from bottom to top to obtain the spatial core relaxation time. T 2 Distribution curve, core relaxation time T 2 The oblique coordinates in the distribution curve represent the slice identification of the porous medium, i.e., slice 0 to slice 15, and the vertical coordinate represents the signal intensity.

[0189] Figure 7 Shows the core relaxation time before and after the first sheet of porous media is displaced. T 2Distribution curve.

[0190] like Figure 7 As shown, each data point on the curve represents the signal intensity at a different position. The Berea core was selected, and the total porosity of the core was 19.1%. The embodiment of the present disclosure selected 10 slices, and the relaxation time of each slice was T 2 The porosity of the sheet can be obtained by integrating the distribution curve.

[0191] Step S402, calculating the porosity before and after displacement.

[0192] In some embodiments, the core relaxation time T 2 distribution curve is integrated, and the ratio of the integrated pore volume to the volume of each layer is the porosity of the layer.

[0193] Figure 8 A schematic diagram showing the porosity changes of each layer before and after displacement is shown.

[0194] like Figure 8 As shown, the horizontal axis is the slice identification, and the vertical axis is the porosity. The porosity of slice 9 remains unchanged before and after displacement, while the others either become higher or lower. There is no obvious regularity between the porosities of the slices before and after displacement.

[0195] Step S403, calculating the fractal dimension of the core porosity before and after displacement.

[0196] The specific steps of step S403 are the same as those of step S203 and will not be repeated here.

[0197] It should be noted that the logarithm of equation (4-8) is obtained to obtain equation (5), and then the fractal dimension of the core pores before and after displacement is calculated based on equation (5): , .

[0198] Step S404, calculating the fractal dimension of tortuosity before and after displacement.

[0199] The specific steps of step S404 are the same as those of step S204 and will not be repeated here.

[0200] The fractal dimension of tortuosity before and after displacement can be calculated based on formula (6): , .

[0201] Step S405, calculating the average pore diameter before and after displacement.

[0202] The specific steps of step S405 are the same as those of step S205 and will not be repeated here.

[0203] Fig. 9 The figure shows the comparison of the average pore diameter of each layer before and after displacement. Fig.10 A schematic diagram showing the comparison of the changes in the maximum pore diameter of each layer before and after displacement is shown.

[0204] Fig. 9 and Fig.10 In the figure, the horizontal axis is the lamella identification or lamella position, and the vertical axis is the pore diameter.

[0205] Step S406, calculating the tortuosity before and after displacement.

[0206] The specific step flow of step S406 is the same as that of step S206 and will not be repeated here.

[0207] Fig.11 A schematic diagram showing the comparison of the tortuosity changes of each layer before and after displacement is shown.

[0208] Fig.11 In the figure, the horizontal axis is the slice identification or slice position, and the vertical axis is the tortuosity.

[0209] Step S407, calculating the absolute permeability before and after displacement.

[0210] The specific steps of step S407 are the same as those of step S207 and will not be repeated here.

[0211] Fig.12 A schematic diagram showing the comparison of absolute permeability changes of each layer before and after displacement is shown.

[0212] Fig.12 In the figure, the horizontal axis is the layer identification or layer position, and the vertical axis is the absolute permeability, in square meters (m 2 ).

[0213] Step S408, calculating the absolute permeability ratio before and after displacement.

[0214] The specific step flow of step S408 is the same as that of step S208 and will not be repeated here.

[0215] Fig.13 A schematic diagram of the permeability ratio of each layer before and after displacement is shown.

[0216] Fig.13 In the figure, the horizontal axis is the lamella identification or lamella position, and the vertical axis is the permeability ratio.

[0217] Step S409, calculating the total average permeability before and after the displacement.

[0218] In the embodiment of the present disclosure, the selected slices are slice 10 to slice 5, and the length of the core slices is , according to formula (13):

[0219]

[0220] Furthermore, the calculated results showed that the total average permeability of the core before displacement was 8.79 mD, and the total average permeability of the core after displacement was 2.75 mD.

[0221] Thus, the experimental accuracy is improved by using the NMR technique to measure T 2 relaxation time distribution, more accurately analyze the pore structure and fluid distribution of rocks, and reduce measurement errors; achieve non-destructiveness: the disclosed embodiment can measure multiple times without destroying the core, provide guarantee for long-term experiments and continuity, and reduce experimental costs; simplify the experimental process; compared with traditional high-pressure and high-temperature experiments, the disclosed embodiment can be carried out under more relaxed conditions, reducing the complexity of the experiment; improve data processing capabilities: the disclosed embodiment can more accurately interpret T 2 distribution data, and calculate the permeability of the core. Compared with the prior art, the disclosed embodiment has the following advantages: through precise and non-destructive means, this solution greatly improves the reliability of data and provides strong technical support for oil and gas reservoir development.

[0222] Fig.14 An optional structural schematic diagram of a device for determining permeability in a rock porous medium displacement seepage process provided by an embodiment of the present disclosure is shown, and will be described according to each part.

[0223] In some embodiments, the permeability determination device 500 for the rock porous medium displacement seepage process includes a nuclear magnetic resonance unit 501, a first processing unit 502, a second processing unit 503, a first absolute permeability determination unit 504, a second absolute permeability determination unit 505 and a permeability ratio determination unit 506.

[0224] The NMR unit 501 is used to obtain the first core relaxation time of each layer before the porous medium is displaced. T2 distribution curve, and the second core relaxation time of each layer after the porous medium displacement T 2Distribution curve;

[0225] The first processing unit 502 is used to calculate the first core relaxation time based on the first core relaxation time. T 2 distribution curve to determine the porosity distribution of each layer before the porous medium displacement and the first core pore fractal dimension before the porous medium displacement; based on the porosity distribution of each layer before the porous medium displacement, determine the first tortuosity fractal dimension of each layer before the porous medium displacement;

[0226] The second processing unit 503 is used to calculate the second core relaxation time based on the second core relaxation time. T 2 distribution curve to determine the porosity distribution of each layer after the porous medium displacement and the second core pore fractal dimension after the porous medium displacement; based on the porosity distribution of each layer after the porous medium displacement, determine the second tortuosity fractal dimension of each layer after the porous medium displacement;

[0227] The first absolute permeability determination unit 504 is used to determine the first absolute permeability of each layer before the porous medium is displaced based on the first tortuosity of each layer before the porous medium is displaced, the first maximum pore diameter, the first core pore fractal dimension and the first tortuosity fractal dimension;

[0228] The second absolute permeability determination unit 505 is used to determine the second absolute permeability of each layer after the porous medium is displaced based on the second tortuosity of each layer after the porous medium is displaced, the second maximum pore diameter, the second core pore fractal dimension and the second tortuosity fractal dimension.

[0229] The permeability ratio determination unit 506 is used to determine the ratio of the permeabilities before and after the porous medium is displaced based on the thickness of each layer of the porous medium, the first tortuosity of each layer before the porous medium is displaced, the second tortuosity of each layer after the multi-block medium is displaced, the pore diameter before the displacement, the pore diameter after the displacement, the first core pore fractal dimension, the second core pore fractal dimension, the first tortuosity fractal dimension and the second tortuosity fractal dimension.

[0230] The permeability ratio determination unit 506 is specifically used to determine the ratio of the permeabilities of the porous medium before and after displacement based on the following formula:

[0231]

[0232] in, is the ratio of the permeability before and after porous media displacement, is the first tortuosity, is the second tortuosity, is the average thickness of each layer of the porous medium, is the first tortuosity fractal dimension, is the second tortuosity fractal dimension, is the fractal dimension of the first core pore, is the fractal dimension of the second core pore, is the maximum pore diameter of the porous medium before displacement, is the maximum pore diameter of the porous medium after displacement.

[0233] The first absolute permeability determination unit 504 is specifically used to calculate the first absolute permeability of any layer before the porous medium is flooded based on the following formula:

[0234]

[0235] in, For the i The first absolute permeability before sheet flooding, is the first tortuosity, is the average thickness of each layer of the porous medium, is the fractal dimension of the first core pore, is the first tortuosity fractal dimension, is the maximum pore diameter of the porous medium before displacement.

[0236] The second absolute permeability determination unit 505 is specifically used to calculate the second absolute permeability of any layer after the porous medium is displaced based on the following formula:

[0237]

[0238] in, For the i The second absolute permeability after sheet displacement, is the second tortuosity, is the average thickness of each layer of the porous medium, is the fractal dimension of the second core pore, is the second tortuosity fractal dimension, is the maximum pore diameter of the porous medium after displacement.

[0239]

[0240] In some embodiments, the rock porous medium displacement seepage process permeability determination device 500 further includes a total average permeability determination unit 507 .

[0241] The total average permeability determination unit 507 is used to determine the second total average permeability after the porous medium is displaced based on the thickness of each layer after the porous medium is displaced and the second absolute permeability.

[0242] The total average permeability determination unit 507 is specifically used to determine the total average permeability of the porous medium based on the following formula:

[0243]

[0244] in, is the second overall average permeability after displacement, For porous media i The thickness of the layer, m is the layer mark of the displacement inlet, n is the layer mark of the displacement outlet, For the i Second absolute permeability after sheet flooding.

[0245] The total average permeability determination unit 507 is specifically configured to determine the first total average permeability before the porous medium is displaced based on the thickness of each layer after the porous medium is displaced and the first absolute permeability.

[0246] The total average permeability determination unit 507 is specifically used to determine the first total average permeability of the porous medium before displacement based on the following formula:

[0247]

[0248] in, is the first total average permeability before displacement, For porous media i The thickness of the layer, m is the layer mark of the displacement inlet, n is the layer mark of the displacement outlet, For the i First absolute permeability before sheet flooding.

[0249] According to an embodiment of the present disclosure, the present disclosure also provides an electronic device and a readable storage medium.

[0250] Fig.15A schematic block diagram of an example electronic device 800 that can be used to implement an embodiment of the present disclosure is shown. The electronic device is intended to represent various forms of digital computers, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device can also represent various forms of mobile devices, such as personal digital processing, cellular phones, smart phones, wearable devices, and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely examples and are not intended to limit the implementation of the present disclosure described and / or required herein.

[0251] like Fig.15 As shown, the electronic device 800 includes a computing unit 801, which can perform various appropriate actions and processes according to a computer program stored in a read-only memory (ROM) 802 or a computer program loaded from a storage unit 808 to a random access memory (RAM) 803. In the RAM 803, various programs and data required for the operation of the electronic device 800 can also be stored. The computing unit 801, the ROM 802, and the RAM 803 are connected to each other via a bus 804. An input / output (I / O) interface 805 is also connected to the bus 804.

[0252] Multiple components in the electronic device 800 are connected to the I / O interface 805, including: an input unit 806, such as a keyboard, a mouse, etc.; an output unit 807, such as various types of displays, speakers, etc.; a storage unit 808, such as a disk, an optical disk, etc.; and a communication unit 809, such as a network card, a modem, a wireless communication transceiver, etc. The communication unit 809 allows the electronic device 800 to exchange information / data with other devices through a computer network such as the Internet and / or various telecommunication networks.

[0253] The computing unit 801 may be a variety of general and / or special processing components with processing and computing capabilities. Some examples of the computing unit 801 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various dedicated artificial intelligence (AI) computing chips, various computing units running machine learning model algorithms, digital signal processors (DSPs), and any appropriate processors, controllers, microcontrollers, etc. The computing unit 801 performs the various methods and processes described above, such as a method for determining the permeability of a rock porous medium displacement seepage process. For example, in some embodiments, the method for determining the permeability of a rock porous medium displacement seepage process may be implemented as a computer software program, which is tangibly contained in a machine-readable medium, such as a storage unit 808. In some embodiments, part or all of the computer program may be loaded and / or installed on the electronic device 800 via the ROM 802 and / or the communication unit 809. When the computer program is loaded into the RAM 803 and executed by the computing unit 801, one or more steps of the method for determining the permeability of a rock porous medium displacement seepage process described above may be executed. Alternatively, in other embodiments, the computing unit 801 may be configured to execute the method for determining the permeability of a rock porous medium displacement seepage process in any other appropriate manner (for example, by means of firmware).

[0254] Various implementations of the systems and techniques described above herein can be implemented in digital electronic circuit systems, integrated circuit systems, field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), systems on chips (SOCs), load programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various implementations can include: being implemented in one or more computer programs that can be executed and / or interpreted on a programmable system including at least one programmable processor, which can be a special purpose or general purpose programmable processor that can receive data and instructions from a storage system, at least one input device, and at least one output device, and transmit data and instructions to the storage system, the at least one input device, and the at least one output device.

[0255] The program code for implementing the method of the present disclosure may be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general-purpose computer, a special-purpose computer, or other programmable data processing device, so that the program code, when executed by the processor or controller, enables the functions / operations specified in the flow chart and / or block diagram to be implemented. The program code may be executed entirely on the machine, partially on the machine, partially on the machine and partially on a remote machine as a stand-alone software package, or entirely on a remote machine or server.

[0256] In the context of the present disclosure, a machine-readable medium may be a tangible medium that may contain or store a program for use by or in conjunction with an instruction execution system, device, or equipment. A machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, or device, or any suitable combination of the foregoing. A more specific example of a machine-readable storage medium may include an electrical connection based on one or more lines, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0257] To provide interaction with a user, the systems and techniques described herein can be implemented on a computer having: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user; and a keyboard and pointing device (e.g., a mouse or trackball) through which the user can provide input to the computer. Other types of devices can also be used to provide interaction with the user; for example, the feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including acoustic input, voice input, or tactile input).

[0258] The systems and techniques described herein may be implemented in a computing system that includes back-end components (e.g., as a data server), or a computing system that includes middleware components (e.g., an application server), or a computing system that includes front-end components (e.g., a user computer with a graphical user interface or a web browser through which a user can interact with implementations of the systems and techniques described herein), or a computing system that includes any combination of such back-end components, middleware components, or front-end components. The components of the system may be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include: a local area network (LAN), a wide area network (WAN), and the Internet.

[0259] A computer system may include a client and a server. The client and the server are generally remote from each other and usually interact through a communication network. The relationship of client and server is generated by computer programs running on respective computers and having a client-server relationship with each other. The server may be a cloud server, a server of a distributed system, or a server combined with a blockchain.

[0260] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps recorded in this disclosure can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solutions disclosed in this disclosure can be achieved, and this document does not limit this.

[0261] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present disclosure, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0262] The above is only a specific embodiment of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any person skilled in the art who is familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present disclosure, which should be included in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be based on the protection scope of the claims.

Claims

1. A method for determining the permeability of a porous rock medium displacement seepage process, characterized in that: The method comprises: Obtaining the first core relaxation time of each layer before porous media displacement based on nuclear magnetic resonance technology T 2 distribution curve, and the second core relaxation time of each layer after the porous medium displacement T 2Distribution curve; Based on the first core relaxation time T 2 distribution curve to determine the porosity distribution of each layer before the porous medium displacement and the first core pore fractal dimension before the porous medium displacement; based on the porosity distribution of each layer before the porous medium displacement, determine the first tortuosity fractal dimension of each layer before the porous medium displacement; Based on the second core relaxation time T 2 distribution curve to determine the porosity distribution of each layer after the porous medium displacement and the second core pore fractal dimension after the porous medium displacement; based on the porosity distribution of each layer after the porous medium displacement, determine the second tortuosity fractal dimension of each layer after the porous medium displacement; Determine the first absolute permeability of each layer before the porous medium is replaced based on the first tortuosity, the first maximum pore diameter, the first core pore fractal dimension and the first tortuosity fractal dimension of each layer before the porous medium is replaced; including calculating the first absolute permeability of any layer before the porous medium is replaced based on the following formula: in, For the i The first absolute permeability before sheet flooding, is the first tortuosity, is the average thickness of each layer of the porous medium, is the fractal dimension of the first core pore, is the first tortuosity fractal dimension, is the maximum pore diameter of the porous medium before displacement; Determine the second absolute permeability of each layer after the porous medium displacement based on the second tortuosity, the second maximum pore diameter, the second core pore fractal dimension and the second tortuosity fractal dimension of each layer after the porous medium displacement; including calculating the second absolute permeability of any layer after the porous medium displacement based on the following formula: in, For the i The second absolute permeability after sheet displacement, is the second tortuosity, is the average thickness of each layer of the porous medium, is the fractal dimension of the second core pore, is the second tortuosity fractal dimension, is the maximum pore diameter of the porous medium after displacement; Based on the average thickness of each layer of the porous medium, the first tortuosity of each layer before the porous medium is displaced, the second tortuosity of each layer after the porous medium is displaced, the pore diameter before the displacement, the pore diameter after the displacement, the first core pore fractal dimension, the second core pore fractal dimension, the first tortuosity fractal dimension and the second tortuosity fractal dimension, the ratio of the permeability before and after the porous medium is displaced is determined, specifically including determining the ratio of the permeability before and after the porous medium is displaced based on the following formula: in, is the ratio of the permeability before and after porous media displacement, is the first tortuosity, is the second tortuosity, is the average thickness of each layer of the porous medium, is the first tortuosity fractal dimension, is the second tortuosity fractal dimension, is the fractal dimension of the first core pore, is the fractal dimension of the second core pore, is the maximum pore diameter of the porous medium before displacement, is the maximum pore diameter of the porous medium after displacement.

2. The method according to claim 1, characterized in that: The method further comprises: The second total average permeability after the porous medium is flooded is determined based on the thickness of each layer after the porous medium is flooded and the second absolute permeability.

3. The method according to claim 2, characterized in that The determining of the second total average permeability after the porous medium is displaced based on the thickness of each layer after the porous medium is displaced and the second absolute permeability comprises: The second overall average permeability of the porous medium is determined based on the following formula: in, is the second overall average permeability after displacement, For porous media i The thickness of the layer, m is the layer mark of the displacement inlet, n is the layer mark of the displacement outlet, For the i Second absolute permeability after sheet flooding.

4. The method according to claim 1, characterized in that: The method further comprises: Based on the thickness of each layer after the porous medium is flooded and the first absolute permeability, the first total average permeability before the porous medium is flooded is determined.

5. The method according to claim 4, characterized in that The step of determining the first total average permeability of the porous medium before displacement based on the thickness of each layer after displacement of the porous medium and the first absolute permeability comprises: The first overall average permeability of the porous medium before displacement is determined based on the following formula: in, is the first total average permeability before displacement, For porous media i The thickness of the layer, m is the layer mark of the displacement inlet, n is the layer mark of the displacement outlet, For the i First absolute permeability before sheet flooding.

6. A device for determining the permeability of a porous rock medium displacement seepage process, characterized in that: The device comprises: NMR unit, used to obtain the first core relaxation time of each layer before porous media displacement T 2 distribution curve, and the second core relaxation time of each layer after the porous medium displacement T 2Distribution curve; a first processing unit, for determining a first core relaxation time based on the first core relaxation time; T 2 distribution curve to determine the porosity distribution of each layer before the porous medium displacement and the first core pore fractal dimension before the porous medium displacement; based on the porosity distribution of each layer before the porous medium displacement, determine the first tortuosity fractal dimension of each layer before the porous medium displacement; a second processing unit for processing a second core relaxation time based on the second core relaxation time T 2 distribution curve to determine the porosity distribution of each layer after the porous medium displacement and the second core pore fractal dimension after the porous medium displacement; based on the porosity distribution of each layer after the porous medium displacement, determine the second tortuosity fractal dimension of each layer after the porous medium displacement; The first absolute permeability determination unit is used to determine the first absolute permeability of each layer before the porous medium is replaced based on the first tortuosity, the first maximum pore diameter, the first core pore fractal dimension and the first tortuosity fractal dimension of each layer before the porous medium is replaced; including calculating the first absolute permeability of any layer before the porous medium is replaced based on the following formula: in, For the i The first absolute permeability before sheet flooding, is the first tortuosity, is the average thickness of each layer of the porous medium, is the fractal dimension of the first core pore, is the first tortuosity fractal dimension, is the maximum pore diameter of the porous medium before displacement; The second absolute permeability determination unit is used to determine the second absolute permeability of each layer after the porous medium is displaced based on the second tortuosity, the second maximum pore diameter, the second core pore fractal dimension and the second tortuosity fractal dimension of each layer after the porous medium is displaced; including calculating the second absolute permeability of any layer after the porous medium is displaced based on the following formula: in, For the i The second absolute permeability after sheet displacement, is the second tortuosity, is the average thickness of each layer of the porous medium, is the fractal dimension of the second core pore, is the second tortuosity fractal dimension, is the maximum pore diameter of the porous medium after displacement; The permeability ratio determination unit is used to determine the ratio of the permeabilities before and after the porous medium is displaced based on the thickness of each layer of the porous medium, the first tortuosity of each layer before the porous medium is displaced, the second tortuosity of each layer after the multi-block medium is displaced, the pore diameter before the displacement, the pore diameter after the displacement, the first core pore fractal dimension, the second core pore fractal dimension, the first tortuosity fractal dimension and the second tortuosity fractal dimension, specifically including determining the ratio of the permeabilities before and after the porous medium is displaced based on the following formula: in, is the ratio of the permeability before and after porous media displacement, is the first tortuosity, is the second tortuosity, is the average thickness of each layer of the porous medium, is the first tortuosity fractal dimension, is the second tortuosity fractal dimension, is the fractal dimension of the first core pore, is the fractal dimension of the second core pore, is the maximum pore diameter of the porous medium before displacement, is the maximum pore diameter of the porous medium after displacement.

7. An electronic device, characterized in that: include: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute the method according to any one of claims 1 to 5.

8. A non-transitory computer-readable storage medium storing computer instructions, characterized in that: The computer instructions are used to make a computer execute the method according to any one of claims 1-5.

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