Method and processor for determining adsorption characteristics of pure component fluid in nanopores

Abstract

The invention discloses a method for determining adsorption characteristics of pure component fluid in nanopores and a processor, and belongs to the technical field of oil-gas field development. The method comprises the following steps: determining the volume phase fugacity of a pure component fluid in a nanopore at a current temperature and a current pressure; determining a fluid region in the nanopore according to the fluid molecule diameter of the pure component fluid and the pore channel width of the nanopore; determining the fluid fugacity of each position in the fluid area according to the volume phase fugacity; determining the fluid density distribution of the pure component fluid in the nanopores according to the fluid fugacity; and determining the excess adsorption quantity of the pure component fluid at the current temperature and the current pressure according to the fluid density distribution. According to the method and the device, the excessive adsorption quantity of any pure component fluid in the nanopores at the current temperature and the current pressure can be determined, so that the time cost of the excessive adsorption quantity determination process is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of oil and gas field development, and in particular to a method and a processor for determining adsorption characteristics of pure component fluids in nanopores. Background Art

[0002] The molecules or atoms on the solid surface have residual surface energy due to the unbalanced forces. When certain substances collide with the solid surface, they are attracted by these unbalanced forces and stay on the solid surface. This is adsorption. Adsorption is one of the most important mechanisms in the fields of coalbed methane and shale oil and gas. There are a large number of adsorbed hydrocarbon fluids in the pores of reservoir rocks, which are an important source of shale oil and gas production. For a given core sample, the existing technology usually only conducts isothermal adsorption experiments on one of the components of the oil and gas reservoir formation fluid (usually methane, carbon dioxide or nitrogen) at a preset temperature to determine the excess adsorption amount of the pure component fluid. However, the experimental process takes a lot of time, and there is a problem of high time cost. Summary of the Invention

[0003] The purpose of the embodiments of the present application is to provide a method and processor for determining the adsorption characteristics of pure component fluids in nanopores, so as to solve the problem of high time cost in determining excess adsorption amount through isothermal adsorption experiments in the prior art.

[0004] To achieve the above objectives, a first aspect of an embodiment of the present application provides a method for determining adsorption characteristics of a pure component fluid within a nanopore, comprising:

[0005] Determine the bulk fugacity of pure component fluids within nanopores at current temperature and current pressure;

[0006] Determine the fluid area within the nanopore according to the fluid molecule diameter of the pure component fluid and the pore width of the nanopore;

[0007] Determining the fluid fugacity at each location within the fluid region based on the bulk fugacity;

[0008] Determine the fluid density distribution of pure component fluid in nanopores based on the fluid fugacity;

[0009] The excess adsorption capacity of the pure component fluid at the current temperature and current pressure is determined based on the fluid density distribution.

[0010] In an embodiment of the present application, determining the bulk fugacity of a pure component fluid within a nanopore at a current temperature and a current pressure includes: determining a target compressibility factor; determining the bulk molar density of the pure component fluid based on the current temperature, the current pressure, the ideal gas constant, and the target compressibility factor; and determining the bulk fugacity of the pure component fluid within the nanopore at the current temperature and the current pressure based on the bulk molar density.

[0011] In an embodiment of the present application, determining the target compression factor includes: obtaining a compression factor state equation; determining a first state equation parameter and a second state equation parameter; determining multiple compression factors based on the compression factor state equation, the first state equation parameter and the second state equation parameter; and determining a target compression factor among the multiple compression factors based on the Gibbs free energy minimization principle.

[0012] In the embodiment of the present application, the fluid fugacity at each position in the fluid region is determined based on the bulk fugacity, including determining the fluid fugacity at any position in the fluid region according to formula (1):

[0013]

[0014] Among them, f ff (z) is the fluid fugacity at any position z in the fluid region, f bulk is the bulk fugacity, μ fs (z) is the first intermediate parameter at any position z, R is the ideal gas constant, T is the current temperature, N A is Avogadro's constant, ψ fs (z) is the second intermediate parameter at any position z, ρ atoms is the number of atoms per unit area of ​​the wall, ε fs is the interaction energy between the pure component fluid and the wall, σ fs is the average molecular diameter of pure component fluid and solid, σ ss is the distance between the molecular layers of a solid.

[0015] In an embodiment of the present application, the fluid density distribution of a pure component fluid in a nanopore is determined based on the fluid fugacity, including: determining the third state equation parameters and the fourth state equation parameters; determining the parameter correction interval corresponding to the third state equation parameters based on the fluid molecular diameter and the pore width; correcting the third state equation parameters according to the parameter correction algorithm corresponding to the parameter correction interval to obtain the corrected third state equation parameters; and determining the molar density of each position in the fluid region in combination with the fluid fugacity, the corrected third state equation parameters, and the fourth state equation parameters to obtain the fluid density distribution of the pure component fluid in the nanopore.

[0016] In the embodiment of the present application, the molar density at each position in the fluid region is determined by combining the fluid fugacity, the modified third state equation parameters, and the fourth state equation parameters, including determining the molar density at any position in the fluid region according to formula (2):

[0017]

[0018] Among them, f ff(z) is the fluid fugacity at any position z in the fluid region, P is the current pressure, ρ local (z) is the molar density at any position z in the fluid region, a ff (z) is the modified third state equation parameter, b is the fourth state equation parameter, R is the ideal gas constant, and T is the current temperature.

[0019] In an embodiment of the present application, the parameter correction interval includes a first parameter correction interval, a second parameter correction interval, a third parameter correction interval, and a fourth parameter correction interval. The parameter correction interval corresponding to the third state equation parameter is determined according to the fluid molecular diameter and the pore width, including: determining the ratio of the fluid molecular diameter to the pore width; when the ratio is greater than or equal to the first preset threshold, determining the parameter correction interval corresponding to the third state equation parameter as the first parameter correction interval; when the ratio is greater than or equal to the second preset threshold and less than the first preset threshold, determining the parameter correction interval corresponding to the third state equation parameter as the second parameter correction interval; when the ratio is greater than or equal to the third preset threshold and less than the second preset threshold, determining the parameter correction interval corresponding to the third state equation parameter as the third parameter correction interval; when the ratio is greater than or equal to the fourth preset threshold and less than the third preset threshold, determining the parameter correction interval corresponding to the third state equation parameter as the fourth parameter correction interval; wherein the first preset threshold is greater than the second preset threshold, the second preset threshold is greater than the third preset threshold, the third preset threshold is greater than the fourth preset threshold, the first parameter correction interval is greater than the second parameter correction interval, the second parameter correction interval is greater than the third parameter correction interval, and the third parameter correction interval is greater than the fourth parameter correction interval.

[0020] In the embodiment of the present application, the excess adsorption amount of the pure component fluid at the current temperature and current pressure is determined according to the fluid density distribution, including determining the excess adsorption amount according to formula (3):

[0021]

[0022] Among them, n e is the excess adsorption capacity, A s is the specific surface area of ​​the porous medium, L is the pore width, σ ff is the fluid molecular diameter, ρ local is the fluid density distribution, ρ bulk is the bulk molar density.

[0023] A second aspect of an embodiment of the present application provides a processor configured to execute the above-mentioned method for determining adsorption characteristics of pure component fluid in nanopores.

[0024] A third aspect of an embodiment of the present application provides a machine-readable storage medium having stored thereon instructions for causing a machine to execute the above-mentioned method for determining adsorption characteristics of pure component fluids in nanopores.

[0025] The above technical solution determines the bulk fugacity of the pure component fluid in the nanopore at the current temperature and current pressure, and determines the fluid area in the nanopore based on the fluid molecular diameter of the pure component fluid and the pore width of the nanopore. Then, the fluid fugacity at each position in the fluid area is determined based on the bulk fugacity. Subsequently, the fluid density distribution of the pure component fluid in the nanopore is determined based on the fluid fugacity, and finally, the excess adsorption amount of the pure component fluid at the current temperature and current pressure is determined based on the fluid density distribution. Through the above steps, the present application can determine the excess adsorption amount of any pure component fluid in the nanopore at the current temperature and current pressure, thereby reducing the time cost of the excess adsorption amount determination process.

[0026] Other features and advantages of the embodiments of the present application will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings are used to provide a further understanding of the embodiments of the present application and constitute a part of the specification. Together with the following detailed description, they are used to explain the embodiments of the present application but do not constitute a limitation on the embodiments of the present application. In the accompanying drawings:

[0028] Figure 1 A schematic diagram of a process for determining adsorption characteristics of pure component fluids in nanopores according to an embodiment of the present application is shown;

[0029] Figure 2 A schematic diagram schematically shows the fluid density distribution of methane in graphite pores at different pressures according to a specific embodiment of the present application;

[0030] Figure 3 A schematic diagram schematically illustrates the excess adsorption of methane in graphite pores at different pressures according to a specific embodiment of the present application;

[0031] Figure 4 A schematic diagram schematically illustrates the fluid density distribution of n-butane in graphite pores at different pressures according to another specific embodiment of the present application;

[0032] Figure 5 A schematic diagram illustrating the excess adsorption amount of n-butane in graphite pores at different pressures according to another specific embodiment of the present application is shown. DETAILED DESCRIPTION

[0033] To make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. It should be understood that the specific implementation methods described herein are only used to illustrate and explain the embodiments of the present application and are not used to limit the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0034] It should be noted that if the embodiments of the present application involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly.

[0035] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present application, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0036] Figure 1 The following schematically shows a flow chart of a method for determining adsorption characteristics of pure component fluid in nanopores according to an embodiment of the present application. Figure 1 As shown, the embodiment of the present application provides a method for determining the adsorption characteristics of pure component fluid in nanopores. The method is described by taking the application of the method to a processor as an example. The method may include the following steps:

[0037] Step S101: determining the bulk fugacity of the pure component fluid in the nanopore at the current temperature and current pressure.

[0038] Step S102: determining the fluid region within the nanopore according to the fluid molecule diameter of the pure component fluid and the pore width of the nanopore.

[0039] Step S103: determining the fluid fugacity at each position in the fluid region according to the bulk fugacity.

[0040] Step S104: determining the fluid density distribution of the pure component fluid in the nanopores according to the fluid fugacity.

[0041] Step S105: determining the excess adsorption capacity of the pure component fluid at the current temperature and current pressure according to the fluid density distribution.

[0042] Existing technologies usually only conduct isothermal adsorption experiments on a certain component (usually methane, carbon dioxide or nitrogen) in the oil and gas reservoir formation fluid at a preset temperature to determine the excess adsorption capacity of the pure component fluid, which is time-consuming and costly.

[0043] To solve the aforementioned problem, in an embodiment of the present application, the processor can determine the bulk fugacity of a pure component fluid located in a nanopore at a current temperature and current pressure. Nanopores are nanoscale rock pores. Furthermore, the processor can obtain the fluid molecular diameter σ of the pure component fluid. ff As well as the pore width L of the nanopore, assuming that the distance between the center of the fluid molecule of the pure component fluid and the pore wall of the nanopore is d, due to the volume of the fluid molecule itself, the fluid area can be obtained as In this way, based on the relationship between bulk fugacity and fluid fugacity, the processor can determine the fluid fugacity at each position in the fluid region based on the bulk fugacity. After determining the fluid fugacity at each position in the fluid region, the processor can determine the molar density of each position in the fluid region based on the fluid fugacity at each position in the fluid region, thereby obtaining the fluid density distribution of the pure component fluid in the nanopores. In this way, the processor can determine the excess adsorption amount of the pure component fluid at the current temperature and current pressure based on the fluid density distribution. In addition, by changing the current pressure, the embodiment of the present application can determine the excess adsorption amount of the pure component fluid at different pressures, and then obtain the isothermal adsorption curve of the pure component fluid. It should be noted that the technical solution provided by the present application is not only applicable to pure component fluids such as methane, carbon dioxide or nitrogen commonly used in isothermal adsorption experiments, but can be applied to any pure component fluid in oil and gas reservoir formation fluids, so as to meet the needs of determining the adsorption characteristics of any pure component fluid in oil and gas reservoir formation fluids.

[0044] The above technical solution determines the bulk fugacity of the pure component fluid in the nanopore at the current temperature and current pressure, and determines the fluid area in the nanopore based on the fluid molecular diameter of the pure component fluid and the pore width of the nanopore. Then, the fluid fugacity at each position in the fluid area is determined based on the bulk fugacity. Subsequently, the fluid density distribution of the pure component fluid in the nanopore is determined based on the fluid fugacity, and finally, the excess adsorption amount of the pure component fluid at the current temperature and current pressure is determined based on the fluid density distribution. Through the above steps, the present application can determine the excess adsorption amount of any pure component fluid in the nanopore at the current temperature and current pressure, thereby reducing the time cost of the excess adsorption amount determination process.

[0045] In an embodiment of the present application, determining the bulk fugacity of a pure component fluid within a nanopore at a current temperature and a current pressure may include: determining a target compressibility factor; determining the bulk molar density of the pure component fluid based on the current temperature, the current pressure, the ideal gas constant, and the target compressibility factor; and determining the bulk fugacity of the pure component fluid within the nanopore at the current temperature and the current pressure based on the bulk molar density.

[0046] Specifically, the processor can determine the bulk fugacity of the pure component fluid in the nanopore at the current temperature and current pressure using the Penn-Robinson equation of state. First, the processor can determine the target compressibility factor, and then determine the bulk molar density of the pure component fluid based on the current temperature, current pressure, ideal gas constant, and target compressibility factor. The bulk molar density of the pure component fluid satisfies formula (1):

[0047]

[0048] Among them, ρ bulk is the bulk molar density, P is the current pressure, Z is the target compressibility factor, and R is the ideal gas constant, which is 8.314472 cm 3 .MPa / (K.mol), T is the current temperature.

[0049] Then, based on the bulk molar density, the processor can determine the bulk fugacity of the pure component fluid in the nanopore at the current temperature and current pressure. The bulk fugacity satisfies formula (2):

[0050]

[0051] Among them, f bulk is the bulk fugacity, P is the current pressure, ρ bulk is the bulk molar density, a is the third state equation parameter, b is the fourth state equation parameter, R is the ideal gas constant, and Z is the current temperature.

[0052] In an embodiment of the present application, determining a target compression factor may include: obtaining a compression factor state equation; determining first state equation parameters and second state equation parameters; determining multiple compression factors based on the compression factor state equation, the first state equation parameters and the second state equation parameters; and determining a target compression factor among the multiple compression factors based on the Gibbs free energy minimization principle.

[0053] Specifically, in the process of determining the target compression factor, the processor can obtain the compression factor state equation, that is, formula (3):

[0054] Z 3 -(1-B)Z 2 +(A-2B-3B 2 )B-(AB 2-B 3 )=0 (3)

[0055] Where Z is the compression factor, which has at least one real root and at most three real roots. A is the parameter of the first state equation, and B is the parameter of the second state equation.

[0056] The first state equation parameter A satisfies formula (4):

[0057]

[0058] The second state equation parameter B satisfies formula (5):

[0059]

[0060] Among them, A is the first state equation parameter, B is the second state equation parameter, a is the third state equation parameter, b is the fourth state equation parameter, p is the working fluid pressure, R is the ideal gas constant, and T is the current temperature.

[0061] In this way, the processor can determine multiple compressibility factors based on the compressibility factor state equation, the first state equation parameters and the second state equation parameters, and then determine the target compressibility factor among the multiple compressibility factors based on the Gibbs free energy minimization principle.

[0062] In the embodiment of the present application, determining the fluid fugacity at each position within the fluid region based on the bulk fugacity may include determining the fluid fugacity at any position within the fluid region according to formula (6):

[0063]

[0064] Among them, f ff (z) is the fluid fugacity at any position z in the fluid region, f bulk is the bulk fugacity, μ fs (z) is the first intermediate parameter at any position z, R is the ideal gas constant, T is the current temperature, N A is Avogadro's constant, ψ fs (z) is the second intermediate parameter at any position z, ρ atoms is the number of atoms per unit area of ​​the wall, ε fs is the interaction energy between the pure component fluid and the wall, σ fs is the average molecular diameter of pure component fluid and solid, σ ss is the distance between the molecular layers of a solid.

[0065] Specifically, based on the relationship between bulk fugacity and fluid fugacity, ie, formula (6), the processor can determine the fluid fugacity at each position in the fluid region according to the bulk fugacity.

[0066] In an embodiment of the present application, determining the fluid density distribution of a pure component fluid in a nanopore based on the fluid fugacity may include: determining third state equation parameters and fourth state equation parameters; determining a parameter correction interval corresponding to the third state equation parameters based on the fluid molecular diameter and the pore width; correcting the third state equation parameters according to a parameter correction algorithm corresponding to the parameter correction interval to obtain corrected third state equation parameters; and determining the molar density of each position in the fluid region in combination with the fluid fugacity, the corrected third state equation parameters, and the fourth state equation parameters to obtain the fluid density distribution of the pure component fluid in the nanopore.

[0067] Specifically, the processor can determine the fluid density distribution of the pure component fluid in the nanopore based on the fluid fugacity. In this process, the processor can first determine the third state equation parameters and the fourth state equation parameters. Among them, the third state equation parameters satisfy formula (7):

[0068]

[0069] Where a is the third state equation parameter, R is the ideal gas constant, T is the current temperature, T c is the critical temperature, p c is the critical pressure, m is the third intermediate parameter, and the third intermediate parameter satisfies formula (8):

[0070]

[0071] Among them, m is the third intermediate parameter, ω is the eccentricity factor, and it is dimensionless.

[0072] The fourth state equation parameters satisfy formula (9):

[0073]

[0074] Where b is the fourth state equation parameter, R is the ideal gas constant, T c is the critical temperature, p c is the critical pressure.

[0075] After determining the third state equation parameters and the fourth state equation parameters, since the third state equation parameters are only applicable to conventional conditions, the third state equation parameters need to be corrected for the pure component fluid in the nanopore. In the process of correcting the third state equation parameters, the processor needs to determine the parameter correction interval corresponding to the third state equation parameters based on the ratio of the fluid molecular diameter and the pore width. The parameter correction interval includes the first parameter correction interval, the second parameter correction interval, the third parameter correction interval and the fourth parameter correction interval. If the parameter correction interval is the first parameter correction interval, then the third state equation parameters can be corrected according to formula (10):

[0076]

[0077] If the parameter correction interval is the second parameter correction interval, then the third state equation parameters can be corrected according to formula (11):

[0078]

[0079] If the parameter correction interval is the third parameter correction interval, then the third state equation parameters can be corrected according to formula (12):

[0080]

[0081] If the parameter correction interval is the fourth parameter correction interval, then the third state equation parameters can be corrected according to formula (13):

[0082]

[0083] Among them, a ff (z) is the modified third state equation parameter, a is the third state equation parameter, L is the channel width, σ ff is the diameter of the fluid molecule, and z is any position in the fluid region.

[0084] Subsequently, the processor can determine the molar density at each location within the fluid region by combining the fluid fugacity, the modified third state equation parameters, and the fourth state equation parameters, thereby obtaining the fluid density distribution of the pure component fluid within the nanopore. The molar density at any location within the fluid region can be determined according to formula (14) and numerically solved using the Newton iteration method:

[0085]

[0086]

[0087] Among them, f ff (z) is the fluid fugacity at any position z in the fluid region, P is the current pressure, ρ local (z) is the molar density at any position z in the fluid region, a ff (z) is the modified third state equation parameter, b is the fourth state equation parameter, R is the ideal gas constant, and T is the current temperature.

[0088] In an embodiment of the present application, the parameter correction interval may include a first parameter correction interval, a second parameter correction interval, a third parameter correction interval, and a fourth parameter correction interval. Determining the parameter correction interval corresponding to the third state equation parameter according to the fluid molecular diameter and the pore width may include: determining the ratio of the fluid molecular diameter to the pore width; when the ratio is greater than or equal to the first preset threshold, determining the parameter correction interval corresponding to the third state equation parameter as the first parameter correction interval; when the ratio is greater than or equal to the second preset threshold and less than the first preset threshold, determining the parameter correction interval corresponding to the third state equation parameter as the second parameter correction interval; when the ratio is greater than or equal to the third preset threshold and less than the second preset threshold, determining the parameter correction interval corresponding to the third state equation parameter as the third parameter correction interval; when the ratio is greater than or equal to the fourth preset threshold and less than the third preset threshold, determining the parameter correction interval corresponding to the third state equation parameter as the fourth parameter correction interval; wherein the first preset threshold is greater than the second preset threshold, the second preset threshold is greater than the third preset threshold, the third preset threshold is greater than the fourth preset threshold, the first parameter correction interval is greater than the second parameter correction interval, the second parameter correction interval is greater than the third parameter correction interval, and the third parameter correction interval is greater than the fourth parameter correction interval.

[0089] Specifically, the processor may determine the ratio of the fluid molecular diameter to the pore width and, based on the ratio, determine a parameter correction interval corresponding to the third state equation parameter. The parameter correction interval may include a first parameter correction interval, a second parameter correction interval, a third parameter correction interval, and a fourth parameter correction interval. If the ratio is greater than or equal to a first preset threshold, the processor may determine the parameter correction interval corresponding to the third state equation parameter as the first parameter correction interval. If the ratio is greater than or equal to a second preset threshold and less than the first preset threshold, the processor may determine the parameter correction interval corresponding to the third state equation parameter as the second parameter correction interval. If the ratio is greater than or equal to a third preset threshold and less than the second preset threshold, the processor may determine the parameter correction interval corresponding to the third state equation parameter as the third parameter correction interval. If the ratio is greater than or equal to a fourth preset threshold and less than the third preset threshold, the processor may determine the parameter correction interval corresponding to the third state equation parameter as the fourth parameter correction interval. If the first preset threshold is greater than the second preset threshold, the second preset threshold is greater than the third preset threshold, the third preset threshold is greater than the fourth preset threshold, the first parameter correction interval is greater than the second parameter correction interval, the second parameter correction interval is greater than the third parameter correction interval, and the third parameter correction interval is greater than the fourth parameter correction interval. In one example, the processor may determine that the value of the first preset threshold is 3, the value of the second preset threshold is 2, and the value of the third preset threshold is 1.5. When the ratio of the pore width to the fluid molecule diameter is less than 1, there are no fluid molecules in the nanopore, and the value of the fourth preset threshold must be greater than or equal to 1. Therefore, the value of the fourth preset threshold can be 1. This facilitates subsequent correction of the third state equation parameters according to the parameter correction algorithm corresponding to the parameter correction interval.

[0090] In the embodiment of the present application, determining the excess adsorption amount of the pure component fluid at the current temperature and current pressure according to the fluid density distribution may include determining the excess adsorption amount according to formula (15):

[0091]

[0092] Among them, n e is the excess adsorption capacity, A s is the specific surface area of ​​the porous medium, L is the pore width, σ ff is the fluid molecular diameter, ρ local is the fluid density distribution, ρ bulk is the bulk molar density.

[0093] Specifically, after determining the fluid density distribution, the processor can determine the excess adsorption capacity of the pure component fluid at the current temperature and current pressure based on the fluid density distribution and the bulk molar density. The excess adsorption capacity satisfies formula (15).

[0094] In a specific embodiment of the present application, for methane in graphite pores with a pore width of 5 nm, the critical temperature T c is 190.56K, and the critical pressure p c is 4.6 MPa, the eccentricity factor ω is 0.011, and the interaction energy ε between the pure component fluid and the wall is fs 2.0516×10 -21 J, solid molecular layer spacing σ ss is 0.335nm, the diameter of the fluid molecule σ ff is 0.3758 nm, and the number of atoms per unit area of ​​the wall is ρ atoms 38.2 / nm 2 , the specific surface area A of the porous medium s 3.01×10 8 cm 2 / kg. If the current temperature is 358.15K, the current pressure is adjusted to 1MPa, 2MPa, 5MPa, 10MPa, 15MPa and 20MPa. When the current pressure is 1MPa, taking the 2.5nm position in the graphite pore as an example, the bulk molar density can be determined to be 3.3964×10 -4 mol / cm 3 , and further determined the bulk fugacity to be 0.9887MPa based on formula (2) and bulk molar density. Since the ratio of pore width to fluid molecular diameter is greater than 3, the third state equation parameter a can be corrected to a by formula (10) ff (z=2.5)=1.8223×10 5 , and then according to formula (6), the fluid fugacity at 2.5 nm is determined to be 1.0069 MPa. Thus, according to the fluid fugacity at 2.5 nm, the molar density at 2.5 nm can be determined to be 3.4604×10 - 4 mol / cm 3 Repeating the above steps can determine the molar density at each location within the fluid region, and thus obtain the fluid density distribution. In this way, the fluid density distribution when the current pressure is 1 MPa can be determined. Figure 2 The schematic diagram of the fluid density distribution of methane in graphite pores at different pressures according to a specific embodiment of the present application is shown schematically. Figure 2 As shown, the current pressure is adjusted to 2MPa, 5MPa, 10MPa, 15MPa and 20MPa, and the fluid density distribution when the current pressure is 2MPa, 5MPa, 10MPa, 15MPa and 20MPa can be determined respectively according to the above steps. Figure 3The following schematically shows the excess adsorption of methane in graphite pores at different pressures according to a specific embodiment of the present application. Figure 3 As shown, according to the fluid density distribution and formula (15), the excess adsorption amount when the current temperature is 358.15K and the current pressure is 1MPa, 2MPa, 5MPa, 10MPa, 15MPa and 20MPa respectively can be obtained.

[0095] In another specific embodiment of the present application, for n-butane in graphite pores with a pore width of 4 nm, the critical temperature T c is 425.21K, and the critical pressure p c is 3.7997 MPa, the eccentricity factor ω is 0.199, and the interaction energy ε between the pure component fluid and the wall is fs is 2.9197×10 -21 J, solid molecular layer spacing σ ss is 0.34nm, the fluid molecule diameter σ ff is 0.464 nm, and the number of atoms per unit area of ​​the wall is ρ atoms 38.2 / nm 2 , the specific surface area A of the porous medium s 3.01×10 8 cm 2 / kg. If the current temperature is 25 degrees Celsius, the current pressure is adjusted to 0.01MPa, 0.05MPa, 0.1MPa, 0.15MPa and 0.2MPa respectively. When the current pressure is 0.1MPa, taking the 2nm position in the graphite pore as an example, the bulk molar density can be determined to be 4.1492×10 -4 mol / cm 3 , and further determined the bulk fugacity to be 0.0973 MPa based on formula (2) and bulk molar density. Since the ratio of pore width to fluid molecular diameter is greater than 3, the third state equation parameter a can be corrected to a by formula (10) ff (z=2)=9.2455×10 5 , and then according to formula (6), the fluid fugacity at 2nm is determined to be 0.1115MPa. Thus, according to the fluid fugacity at 2nm, the molar density at 2nm can be determined to be 4.7916×10 -4 mol / cm 3 Repeating the above steps can determine the molar density at each location within the fluid region, and thus obtain the fluid density distribution. In this way, the fluid density distribution when the current pressure is 0.1 MPa can be determined. Figure 4 The schematic diagram of the fluid density distribution of n-butane in graphite pores at different pressures according to another specific embodiment of the present application is shown schematically. Figure 4 As shown, the current pressure is adjusted from 0.1 MPa to 0.01 MPa, 0.05 MPa, 0.15 MPa and 0.2 MPa, and the fluid density distribution when the current pressure is 0.01 MPa, 0.05 MPa, 0.15 MPa and 0.2 MPa can be determined respectively according to the above steps. Figure 5 The following schematically shows the excess adsorption of n-butane in graphite pores at different pressures according to another specific embodiment of the present application. Figure 5 As shown, according to the fluid density distribution and formula (15), the excess adsorption capacity when the current temperature is 25 degrees Celsius and the current pressure is 0.01MPa, 0.05MPa, 0.1MPa, 0.15MPa and 0.2MPa respectively can be obtained.

[0096] An embodiment of the present application further provides a processor configured to execute the above method for determining adsorption characteristics of pure component fluid in nanopores.

[0097] Specifically, in an embodiment of the present application, the processor can be configured to: determine the bulk fugacity of the pure component fluid in the nanopore at the current temperature and current pressure; determine the fluid region in the nanopore based on the fluid molecule diameter of the pure component fluid and the pore width of the nanopore; determine the fluid fugacity at each position in the fluid region based on the bulk fugacity; determine the fluid density distribution of the pure component fluid in the nanopore based on the fluid fugacity; and determine the excess adsorption amount of the pure component fluid at the current temperature and current pressure based on the fluid density distribution.

[0098] In one embodiment, the processor is further configured to: determine a target compressibility factor; determine a bulk molar density of the pure component fluid based on the current temperature, the current pressure, the ideal gas constant, and the target compressibility factor; and determine a bulk fugacity of the pure component fluid within the nanopores at the current temperature and the current pressure based on the bulk molar density.

[0099] In one embodiment, the processor is further configured to: obtain a compression factor state equation; determine a first state equation parameter and a second state equation parameter; determine multiple compression factors based on the compression factor state equation, the first state equation parameter and the second state equation parameter; and determine a target compression factor among the multiple compression factors based on the Gibbs free energy minimization principle.

[0100] In one embodiment, the processor is further configured to determine the fluid fugacity at any location within the fluid region according to formula (6):

[0101]

[0102] Among them, f ff (z) is the fluid fugacity at any position z in the fluid region, fbulk is the bulk fugacity, μ fs (z) is the first intermediate parameter at any position z, R is the ideal gas constant, T is the current temperature, N A is Avogadro's constant, ψ fs (z) is the second intermediate parameter at any position z, ρ atoms is the number of atoms per unit area of ​​the wall, ε fs is the interaction energy between the pure component fluid and the wall, σ fs is the average molecular diameter of pure component fluid and solid, σ ss is the distance between the molecular layers of a solid.

[0103] In one embodiment, the processor is further configured to: determine the third state equation parameters and the fourth state equation parameters; determine the parameter correction interval corresponding to the third state equation parameters based on the fluid molecular diameter and the pore width; correct the third state equation parameters according to the parameter correction algorithm corresponding to the parameter correction interval to obtain the corrected third state equation parameters; combine the fluid fugacity, the corrected third state equation parameters and the fourth state equation parameters to determine the molar density of each position in the fluid area to obtain the fluid density distribution of the pure component fluid in the nanopores.

[0104] In one embodiment, the processor is further configured to determine the molar density at any location within the fluid region according to formula (14):

[0105]

[0106] Among them, f ff (z) is the fluid fugacity at any position z in the fluid region, P is the current pressure, ρ local (z) is the molar density at any position z in the fluid region, a ff (z) is the modified third state equation parameter, b is the fourth state equation parameter, R is the ideal gas constant, and T is the current temperature.

[0107] In one embodiment, the processor is further configured to: determine the ratio of the fluid molecular diameter to the pore width; when the ratio is greater than or equal to the first preset threshold, determine the parameter correction interval corresponding to the third state equation parameter as the first parameter correction interval; when the ratio is greater than or equal to the second preset threshold and less than the first preset threshold, determine the parameter correction interval corresponding to the third state equation parameter as the second parameter correction interval; when the ratio is greater than or equal to the third preset threshold and less than the second preset threshold, determine the parameter correction interval corresponding to the third state equation parameter as the third parameter correction interval; when the ratio is greater than or equal to the fourth preset threshold and less than the third preset threshold, determine the parameter correction interval corresponding to the third state equation parameter as the fourth parameter correction interval; wherein, the first preset threshold is greater than the second preset threshold, the second preset threshold is greater than the third preset threshold, the third preset threshold is greater than the fourth preset threshold, the first parameter correction interval is greater than the second parameter correction interval, the second parameter correction interval is greater than the third parameter correction interval, and the third parameter correction interval is greater than the fourth parameter correction interval.

[0108] In one embodiment, the processor is further configured to determine the excess adsorption amount according to formula (15):

[0109]

[0110] Among them, n e is the excess adsorption capacity, A s is the specific surface area of ​​the porous medium, L is the pore width, σ ff is the fluid molecular diameter, ρ local is the fluid density distribution, ρ bulk is the bulk molar density.

[0111] The above technical solution determines the bulk fugacity of the pure component fluid in the nanopore at the current temperature and current pressure, and determines the fluid area in the nanopore based on the fluid molecular diameter of the pure component fluid and the pore width of the nanopore. Then, the fluid fugacity at each position in the fluid area is determined based on the bulk fugacity. Subsequently, the fluid density distribution of the pure component fluid in the nanopore is determined based on the fluid fugacity, and finally, the excess adsorption amount of the pure component fluid at the current temperature and current pressure is determined based on the fluid density distribution. Through the above steps, the present application can determine the excess adsorption amount of any pure component fluid in the nanopore at the current temperature and current pressure, thereby reducing the time cost of the excess adsorption amount determination process.

[0112] An embodiment of the present application further provides a machine-readable storage medium having stored thereon instructions for causing a machine to execute the above-mentioned method for determining adsorption characteristics of pure component fluids in nanopores.

[0113] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0114] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the steps in the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0115] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0116] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0117] In a typical configuration, a computing device includes one or more processors (CPUs), input / output interfaces, network interfaces, and memory.

[0118] The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0119] Computer-readable media includes permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. The information can be computer-readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassettes, magnetic disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer-readable media does not include transitory computer-readable media (transitory media), such as modulated data signals and carrier waves.

[0120] It should also be noted that the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, commodity, or apparatus that includes a series of elements includes not only those elements but also other elements not explicitly listed, or includes elements inherent to such process, method, commodity, or apparatus. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not exclude the presence of other identical elements in the process, method, commodity, or apparatus that includes the element.

[0121] The above are merely embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should all be included within the scope of the claims of the present application.

Claims

1. A method for determining the adsorption characteristics of pure component fluids in nanopores, characterized in that: include: Determine the bulk fugacity of pure component fluids within nanopores at current temperature and current pressure; determining a fluid region within the nanopore according to a fluid molecule diameter of the pure component fluid and a pore width of the nanopore; determining the fluid fugacity at each position within the fluid region based on the bulk fugacity; determining a fluid density distribution of the pure component fluid within the nanopores according to the fluid fugacity; The excess adsorption amount of the pure component fluid at the current temperature and the current pressure is determined according to the fluid density distribution.

2. The method according to claim 1, characterized in that The determining of the bulk fugacity of the pure component fluid in the nanopore at the current temperature and the current pressure comprises: Determine the target compression factor; determining the bulk molar density of the pure component fluid according to the current temperature, the current pressure, the ideal gas constant, and the target compressibility factor; The bulk fugacity of the pure component fluid in the nanopore at a current temperature and a current pressure is determined based on the bulk molar density.

3. The method according to claim 2, characterized in that Determining the target compression factor includes: Obtain the compressibility factor state equation; determining a first state equation parameter and a second state equation parameter; determining a plurality of compressibility factors based on the compressibility factor state equation, the first state equation parameter, and the second state equation parameter; A target compression factor among the plurality of compression factors is determined according to the Gibbs free energy minimization principle.

4. The method according to claim 1, wherein Determining the fluid fugacity at each position within the fluid region based on the bulk fugacity includes determining the fluid fugacity at any position within the fluid region according to formula (1): Among them, f ff (z) is the fluid fugacity at any position z within the fluid region, f bulk is the bulk fugacity, μ fs (z) is the first intermediate parameter at the arbitrary position z, R is the ideal gas constant, T is the current temperature, N a is Avogadro's constant, ψ fs (z) is the second intermediate parameter at the arbitrary position z, ρ atoms is the number of atoms per unit area of ​​the wall, ε fs is the interaction energy between the pure component fluid and the wall, σ fs is the average molecular diameter of pure component fluid and solid, σ ss is the distance between the molecular layers of a solid.

5. The method according to claim 1, wherein The determining of the fluid density distribution of the pure component fluid in the nanopores according to the fluid fugacity includes: determining a third state equation parameter and a fourth state equation parameter; Determining a parameter correction interval corresponding to the third state equation parameter according to the fluid molecule diameter and the pore width; Correcting the third state equation parameters according to the parameter correction algorithm corresponding to the parameter correction interval to obtain corrected third state equation parameters; The molar density of each position in the fluid region is determined by combining the fluid fugacity, the modified third state equation parameters, and the fourth state equation parameters to obtain the fluid density distribution of the pure component fluid in the nanopores.

6. The method according to claim 5, characterized in that Determining the molar density at each position within the fluid region by combining the fluid fugacity, the modified third state equation parameters, and the fourth state equation parameters includes determining the molar density at any position within the fluid region according to formula (2): Among them, f ff (z) is the fluid fugacity at any position z in the fluid region, P is the current pressure, ρ local (z) is the molar density at any position z in the fluid region, a ff (z) is the modified third state equation parameter, b is the fourth state equation parameter, R is the ideal gas constant, and T is the current temperature.

7. The method according to claim 5, characterized in that The parameter correction interval includes a first parameter correction interval, a second parameter correction interval, a third parameter correction interval, and a fourth parameter correction interval. The parameter correction interval corresponding to the third state equation parameter is determined according to the fluid molecular diameter and the pore width, including: determining a ratio of the fluid molecule diameter to the pore width; When the ratio is greater than or equal to a first preset threshold, determining the parameter correction interval corresponding to the third state equation parameter as the first parameter correction interval; When the ratio is greater than or equal to a second preset threshold and less than the first preset threshold, determining the parameter correction interval corresponding to the third state equation parameter as the second parameter correction interval; When the ratio is greater than or equal to a third preset threshold and less than the second preset threshold, determining the parameter correction interval corresponding to the third state equation parameter as a third parameter correction interval; When the ratio is greater than or equal to a fourth preset threshold and less than the third preset threshold, determining the parameter correction interval corresponding to the third state equation parameter as a fourth parameter correction interval; Among them, the first preset threshold is greater than the second preset threshold, the second preset threshold is greater than the third preset threshold, the third preset threshold is greater than the fourth preset threshold, the first parameter correction interval is greater than the second parameter correction interval, the second parameter correction interval is greater than the third parameter correction interval, and the third parameter correction interval is greater than the fourth parameter correction interval.

8. The method according to claim 1, characterized in that Determining the excess adsorption amount of the pure component fluid at the current temperature and the current pressure according to the fluid density distribution includes determining the excess adsorption amount according to formula (3): Among them, n e is the excess adsorption capacity, A s is the specific surface area of ​​the porous medium, L is the pore width, σ ff is the molecular diameter of the fluid, ρ local is the fluid density distribution, ρ bulk is the bulk molar density.

9. A processor, characterized in that: The device is configured to perform the method for determining adsorption characteristics of pure component fluids within nanopores according to any one of claims 1 to 8.

10. A machine-readable storage medium, characterized in that The machine-readable storage medium stores instructions for causing a machine to execute the method for determining adsorption characteristics of pure component fluids in nanopores according to any one of claims 1 to 8.

Images