A method and device for normalizing calculation of fluid phase equilibrium parameters in a porous medium

Abstract

The application provides a method for normalizing calculation of fluid phase equilibrium parameters in a porous medium, which comprises: calculating normalized oil saturation and gas saturation in the porous medium; calculating oil phase apparent pressure in the porous medium, gas phase apparent pressure in the porous medium, oil phase compression factor in the porous medium and gas phase compression factor in the porous medium according to oil and gas two-phase molar number normalization; and normalizing oil and gas two-phase mixture composition in each pore size to obtain apparent oil and gas two-phase mixture composition in the porous medium. The application can accurately normalize and calculate apparent oil saturation, apparent gas saturation, apparent oil phase pressure, apparent gas phase pressure, apparent oil phase compression factor, apparent gas phase compression factor, apparent oil phase mixture composition and apparent gas phase mixture composition in an oil and gas mixture system in a multiple-pore medium, and can further calculate oil and gas phase density, surface tension and other parameters, thereby providing accurate oil and gas physical property data for oil and gas field development.

Description

Technical Field

[0001] This invention relates to the technical field of oil and gas reservoir engineering methods used in oil and gas field development, and more specifically, to a method and apparatus for normalizing the calculation of fluid phase equilibrium parameters in porous media. Background Technology

[0002] Fluid phase state calculation plays a crucial role in fluid PVT analysis and fitting, reservoir numerical simulation, condensate gas reservoir development, CO2 flooding and storage, and other fields.

[0003] Conventional cubic equations of state (PR, SRK, etc.) are widely used in fluid phase calculations, and the fitted equations of state can usually accurately characterize the phase characteristics of fluids under large-space conditions (PVT reactors). However, the interaction between fluid molecules and the porous medium surface in porous media leads to significant differences in fluid phase characteristics compared to those under conventional large-space conditions.

[0004] In dense porous media, especially nanoscale porous media, the critical parameters of the fluid shift compared to the large space. The impact of this shift on phase characteristics should be considered in calculations. Heterogeneity is significant in porous media, particularly in shale where pore sizes range from 1 to 100 nm, a wide span. Different distribution patterns lead to variations in calculation results. Furthermore, the small pore radius and large capillary forces in dense porous media result in unequal pressures between the vapor and liquid phases, also affecting phase characteristics. Adsorption also exists in porous media, influencing fluid composition. The presence of adsorption layers reduces the effective pore diameter, further contributing to variations in phase equilibrium calculations, which also need to be considered.

[0005] Zhang Maolin (2004) found that adsorption lowers the dew point of condensate gas, while capillary force slightly increases it. Ma (2013) showed that in porous media, the critical temperature of the pure component increases, and the bubble point and dew point of the C1 / nC4 / nC8 mixture both increase, while the two-phase region shrinks; the shift in critical parameters has a greater impact on the heavier component. Jin (2013) found that in porous media, the bubble point of the C1-nC5 mixture decreases, while the lower dew point increases. He also found that capillary force lowers both the bubble point and lower dew point of the C1-nC5 mixture. Li Yuansheng (2015) found that when the pore throat diameter is less than 10 nm, the interaction between the pore throat and fluid molecules is significant; the smaller the pore throat, the more obvious the decrease in dew point pressure. In addition, capillary force lowers the dew point of the C1 / nC4 / nC8 mixture. Dong (2016) found that the adsorption layer increases capillary pressure, leading to a decrease in the bubble point and an increase in the dew point of the fluid; the effect is negligible when the pore size is greater than 100 nm; capillary force decreases with increasing pore size; furthermore, under porous media conditions, the dew point of Eagle Ford crude oil increases and the bubble point decreases, and the more similar the composition of the mixture, the smaller the effect of capillary force. Liu (2016) showed that adsorption has a greater impact than capillary force, with the bubble point of N2 / n-C4H10 mixtures increasing and the bubble point of CH4 / n-C4H10 mixtures decreasing; he also found that the pore size distribution affects the phase equilibrium calculation results. Lei (2017) found in his latest study that capillary force first increases and then decreases with increasing pore size, and the dew point pressure of Wolfcamp crude oil decreases in porous media.

[0006] Currently, there are relatively complete methods for calculating fluid phase states that take into account the influence of porous media. Specifically, based on the conventional cubic equation of state, the flash evaporation method calculates the phase state characteristics of fluids (oil and gas) under porous media conditions, taking into account the combined effects of capillary force, adsorption, critical parameter shift, pore size, and fluid composition.

[0007] The existing method can calculate the fluid phase equilibrium parameters within a given pore size. However, when considering the porous medium as a whole, there are multiple different pore sizes. In this case, the phase equilibrium parameters calculated for each pore size cannot represent the physical properties of the fluid in the entire porous medium. Therefore, a normalization calculation using scientific methods is required.

[0008] To address the problems of existing technologies, this invention provides a method and apparatus for normalizing the calculation of fluid phase equilibrium parameters in porous media. Summary of the Invention

[0009] To address the problems of the prior art, this invention provides a method for normalizing the calculation of fluid phase equilibrium parameters in porous media, the method comprising the following steps:

[0010] S1. The normalized oil saturation and gas saturation in the porous medium are calculated.

[0011] S2. The apparent pressure of the oil phase, the apparent pressure of the gas phase, and the compressibility factor of the oil phase in the porous medium are calculated based on the normalization of the molar number of the oil and gas phases.

[0012] S3. Normalize the composition of the oil-gas two-phase mixture within each pore size to obtain the apparent composition of the porous medium oil-gas two-phase mixture.

[0013] According to one embodiment of the present invention, in step S1, assuming all pores are spherical and the total pore volume in the porous medium is 1, the oil phase volume and the gas phase volume within each pore size are calculated using the following formula:

[0014]

[0015]

[0016] Among them, (V) o ) j This represents the volume of the oil phase within each pore size; (S) o ) j Indicates the oil phase saturation within each pore size; r j Indicates the pore radius; t j This indicates the percentage of volume occupied by pores of various sizes; (V) g ) j This represents the gas phase volume within each pore size; (S) g ) j This indicates the gas phase saturation within each pore size.

[0017] According to an embodiment of the present invention, in step S1, the oil saturation and gas saturation are calculated using the following formulas:

[0018]

[0019] (S g ) t =1-(S) o ) t

[0020] Among them, (S) o ) t Indicates oil saturation; (V) o ) j This represents the volume of the oil phase within each pore size; (V) g ) j This represents the gas phase volume within each pore size; (S) g ) tIndicates gas saturation.

[0021] According to one embodiment of the present invention, the number of moles of the oil and gas phases includes, but is not limited to: the total number of moles of fluid in each pore size, the total mole fraction of the oil phase in the porous medium, and the total mole fraction of the gas phase in the porous medium.

[0022] According to an embodiment of the present invention, in step S2, the number of moles of the oil and gas two phases is calculated using the following formula:

[0023]

[0024]

[0025] (n g ) t =1-(n o ) t

[0026] Among them, (N) j This represents the total number of moles of fluid within each pore size; (p o ) j This indicates the oil phase pressure within each pore size; (V) o ) j This represents the volume of the oil phase within each pore size; (Z) o ) j Indicates the oil phase compressibility factor within each pore size; (p g ) j This represents the gas phase pressure within each pore size; (V) g ) j This represents the gas phase volume within each pore size; (Z) g ) j Represents the gas phase compressibility factor within each pore size; R represents the gas constant; T represents the system temperature; (n o ) t Indicates the total mole fraction of the oil phase in the porous medium; (n o ) j Indicates the total mole fraction of oil phase within each pore size; (n g ) t This indicates the total mole fraction of the gas phase within the porous medium.

[0027] According to an embodiment of the present invention, in step S2, the apparent pressure of the oil phase and the apparent pressure of the gas phase in the porous medium are calculated using the following formulas:

[0028]

[0029]

[0030] Among them, (p o )t This represents the apparent pressure of the oil phase within a porous medium; (p) o ) j Indicates the oil phase pressure within each pore size; (N) j This represents the total number of moles of fluid within each pore size; (n o ) j This indicates the total mole fraction of oil phase within each pore size; (p g ) t This represents the apparent pressure of the gas phase within a porous medium; (p g ) j This represents the gas phase pressure within each pore size; (n g ) j This indicates the total mole fraction of the gas phase within each pore size.

[0031] According to an embodiment of the present invention, in step S2, the oil phase compressibility factor and the gas phase compressibility factor in the porous medium are calculated using the following formulas:

[0032]

[0033]

[0034] Among them, (Z) o ) t Indicates the compressibility factor of the oil phase in porous media; (p) o ) t This represents the apparent pressure of the oil phase within a porous medium; (V) o ) j Represents the oil phase volume within each pore size; R represents the gas constant; T represents the system temperature; (n o ) t Indicates the total mole fraction of the oil phase within the porous medium; (N) j This represents the total number of moles of fluid within each pore size; (Z) g ) t Indicates the gas-phase compressibility factor within a porous medium; (p g ) t This represents the apparent pressure of the gas phase within a porous medium; (V) g ) j This represents the gas phase volume within each pore size; (n g ) t This indicates the total mole fraction of the gas phase within the porous medium.

[0035] According to an embodiment of the present invention, in step S3, the apparent oil-gas two-phase mixture composition of the porous medium is calculated using the following formula:

[0036]

[0037]

[0038] Among them, (x i ) t Indicates the composition of the oil phase mixture; (x i ) j This indicates the composition of the oil phase mixture within each pore size; (N) j This represents the total number of moles of fluid within each pore size; (n o ) j This indicates the total mole fraction of oil phase within each pore size; (y i ) t Indicates the composition of a gas-phase mixture; (y i ) j This indicates the composition of the gas-phase mixture within each pore size; (n g ) j This indicates the total mole fraction of the gas phase within each pore size.

[0039] According to another aspect of the invention, a storage medium is also provided, which includes a series of instructions for performing the steps of the method described in any of the preceding claims.

[0040] According to another aspect of the present invention, a normalization calculation apparatus for fluid phase equilibrium parameters in a porous medium is also provided, which performs the method described in any of the preceding claims, the apparatus comprising:

[0041] The saturation module is used to calculate the normalized oil saturation and gas saturation in porous media.

[0042] The apparent pressure and compressibility factor module is used to calculate the apparent pressure of the oil phase, the apparent pressure of the gas phase, and the compressibility factor of the oil phase in the porous medium based on the normalization of the molar number of the oil and gas phases.

[0043] The mixture composition module is used to normalize the composition of the oil-gas two-phase mixture within each pore size to obtain the apparent oil-gas two-phase mixture composition of the porous medium.

[0044] This invention provides a method and apparatus for normalizing the calculation of fluid phase equilibrium parameters in porous media. It can accurately normalize and calculate the apparent oil saturation, apparent gas saturation, apparent oil phase pressure, apparent gas phase pressure, apparent oil phase compressibility factor, apparent gas phase compressibility factor, apparent oil phase mixture composition, and apparent gas phase mixture composition of an oil-gas mixture system in a multi-porous medium. Based on this, parameters such as oil-gas phase density and surface tension can be further calculated, providing accurate oil and gas physical property data for oil and gas field development.

[0045] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the description, claims, and drawings. Attached Figure Description

[0046] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with the embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0047] Figure 1 A flowchart of a method for normalizing the calculation of fluid phase equilibrium parameters in a porous medium according to an embodiment of the present invention is shown.

[0048] Figure 2 A block diagram of a normalization calculation device for fluid phase equilibrium parameters in a porous medium according to an embodiment of the present invention is shown; and

[0049] Figure 3 The actual core pore radius distribution of the H oilfield according to an embodiment of the present invention is shown. Detailed Implementation

[0050] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0051] Figure 1 A flowchart of a method for normalizing the calculation of fluid phase equilibrium parameters in a porous medium according to an embodiment of the present invention is shown.

[0052] The present invention aims to establish a normalized calculation method for fluid phase equilibrium parameters applicable to porous media conditions, and is a method for normalizing oil and gas physical property parameters in simulated calculation cores, taking the porous media core as a whole.

[0053] Based on the calculation method of fluid phase equilibrium in porous media, and considering the influence of the distribution of multiple pore sizes in porous media, a normalized calculation method for fluid phase equilibrium parameters in porous media is established.

[0054] Assume the mixture system has a total of N c Several components are distributed in pores with radii r and r, respectively. j (j = 1, 2, ..., N) b N b In each pore, the percentage of volume occupied by pores of each size is: The fluid composition within each pore is consistent, all being z. i (i = 1, 2, ..., N) cThe system temperature and pressure are T and p, respectively.

[0055] At this point, the fluid state equation within the porous medium is established as follows:

[0056]

[0057]

[0058]

[0059] a i,j (T)=a ci,j α i,j (T) (4)

[0060]

[0061]

[0062]

[0063]

[0064]

[0065] In the formula, A m,j Indicates the phase equilibrium calculation parameters; a m,j and b m,j These are the average attractive and repulsive constants of the mixture system in the j-th capillary bundle, respectively; p j Represents the system pressure in the j-th capillary bundle; R represents the gas constant; B m,j Indicates the phase equilibrium calculation parameters; X i,j and X k,j These are component i and component k in the mixture of the j-th capillary bundle, respectively; and These are the 0.5 powers of the gravitational coefficients of components i and k in the j-th capillary bundle, respectively; a ci,j b represents the gravitational coefficient of each component in the j-th capillary bundle mixture; i,j m represents the repulsion coefficient of each component in the mixture within the j-th capillary bundle; i,j This represents the intermediate parameters in the phase equilibrium calculation; ω i,j T is the eccentricity factor of component i in the j-th capillary bundle; ci,j and p ci,j Let represent the critical temperature and critical pressure of component i in the j-th capillary bundle, respectively; For a binary interaction coefficient, in a hydrocarbon-hydrocarbon system:

[0066] The critical parameters of closed fluids in dense porous media deviate from those under conventional conditions. Zarragoicoechea and Kuz (2004) proposed a relationship between the critical parameters and pore size, but this formula only applies to... This is not applicable to macromolecules and extremely small pores. Therefore, considering the different pore sizes, the present invention adopts the following relationship:

[0067]

[0068] In the formula, σ eff D represents the effective diameter of the molecule. eff Indicates the effective diameter of the pores; T cp and T cb These represent the critical temperatures of the fluid in porous media and large spaces, respectively; p cp and p cb These represent the critical pressures of the fluid in porous media and large spaces, respectively.

[0069] like Figure 1 As shown, in step S1, the normalized oil saturation and gas saturation in the porous medium are calculated.

[0070] In one embodiment, the oil phase pressure (p) under various pore sizes is calculated based on the flash evaporation of the fluid phase in the porous medium. o ) j Gas phase pressure (p) g ) j Oil phase saturation (S) o ) j Gas phase saturation (S) g ) j Oil phase mole fraction (F) o ) j gas phase mole fraction (F g ) j Oil phase compressibility factor (Z) o ) j Gas phase compressibility factor (Z) g ) j Composition of oil phase mixture (x) i ) j (i = 1, 2, ..., N) c ), gas phase mixture composition (y i ) j (i = 1, 2, ..., N) c Based on these parameters, normalized fluid phase equilibrium parameters are calculated for the entire porous medium.

[0071] In one embodiment, in step S1, assuming all pores are spherical and the total pore volume in the porous medium is 1, the oil phase volume and gas phase volume within each pore size are calculated using the following formula:

[0072]

[0073]

[0074] Among them, (V) o ) j This represents the volume of the oil phase within each pore size; (S) o ) j Indicates the oil phase saturation within each pore size; r j Indicates the pore radius; t j This indicates the percentage of volume occupied by pores of various sizes; (V) g ) j This represents the gas phase volume within each pore size; (S) g ) j This indicates the gas phase saturation within each pore size.

[0075] In one embodiment, in step S1, the oil saturation and gas saturation are calculated using the following formulas:

[0076]

[0077] (S g ) t =1-(S) o ) t

[0078] Among them, (S) o ) t Indicates oil saturation; (V) o ) j This represents the volume of the oil phase within each pore size; (V) g ) j This represents the gas phase volume within each pore size; (S) g ) t Indicates gas saturation.

[0079] like Figure 1 As shown, in step S2, the apparent pressure of the oil phase, the apparent pressure of the gas phase, the compressibility factor of the oil phase, and the compressibility factor of the gas phase in the porous medium are calculated based on the normalization of the molar number of the oil and gas phases.

[0080] In one embodiment, the number of moles of the oil and gas phases includes, but is not limited to: the total number of moles of fluid within each pore size, the total mole fraction of the oil phase in the porous medium, and the total mole fraction of the gas phase in the porous medium.

[0081] In one embodiment, in step S2, the number of moles of the oil and gas two phases is calculated according to the equation of state using the following formula:

[0082]

[0083]

[0084] (n g ) t =1-(n o ) t

[0085] Among them, (N) j This represents the total number of moles of fluid within each pore size; (p o ) j This indicates the oil phase pressure within each pore size; (V) o ) j This represents the volume of the oil phase within each pore size; (Z) o ) j Indicates the oil phase compressibility factor within each pore size; (p g ) j This represents the gas phase pressure within each pore size; (V) g ) j This represents the gas phase volume within each pore size; (Z) g ) j Represents the gas phase compressibility factor within each pore size; R represents the gas constant; T represents the system temperature; (n o ) t Indicates the total mole fraction of the oil phase in the porous medium; (n o ) j Indicates the total mole fraction of oil phase within each pore size; (n g ) t This indicates the total mole fraction of the gas phase within the porous medium.

[0086] In one embodiment, in step S2, the apparent pressure of the oil phase and the apparent pressure of the gas phase in the porous medium are calculated using the following formulas:

[0087]

[0088]

[0089] Among them, (p o ) t This represents the apparent pressure of the oil phase within a porous medium; (p) o ) j Indicates the oil phase pressure within each pore size; (N) j This represents the total number of moles of fluid within each pore size; (n o ) jThis indicates the total mole fraction of oil phase within each pore size; (p g ) t This represents the apparent pressure of the gas phase within a porous medium; (p g ) j This represents the gas phase pressure within each pore size; (n g ) j This indicates the total mole fraction of the gas phase within each pore size.

[0090] In one embodiment, in step S2, the oil phase compressibility factor and the gas phase compressibility factor in the porous medium are calculated according to the equation of state using the following formula:

[0091]

[0092]

[0093] Among them, (Z) o ) t Indicates the compressibility factor of the oil phase in porous media; (p) o ) t This represents the apparent pressure of the oil phase within a porous medium; (V) o ) j Represents the oil phase volume within each pore size; R represents the gas constant; T represents the system temperature; (n o ) t Indicates the total mole fraction of the oil phase within the porous medium; (N) j This represents the total number of moles of fluid within each pore size; (Z) g ) t Indicates the gas-phase compressibility factor within a porous medium; (p g ) t This represents the apparent pressure of the gas phase within a porous medium; (V) g ) j This represents the gas phase volume within each pore size; (n g ) t This indicates the total mole fraction of the gas phase within the porous medium.

[0094] like Figure 1 As shown, in step S3, the composition of the oil-gas two-phase mixture within each pore size is normalized to obtain the apparent composition of the porous medium oil-gas two-phase mixture.

[0095] In one embodiment, in step S3, the apparent oil-gas two-phase mixture composition of the porous medium is calculated using the following formula:

[0096]

[0097]

[0098] Among them, (xi ) t Indicates the composition of the oil phase mixture; (x i ) j This indicates the composition of the oil phase mixture within each pore size; (N) j This represents the total number of moles of fluid within each pore size; (n o ) j This indicates the total mole fraction of oil phase within each pore size; (y i ) t Indicates the composition of a gas-phase mixture; (y i ) j This indicates the composition of the gas-phase mixture within each pore size; (n g ) j This indicates the total mole fraction of the gas phase within each pore size.

[0099] The present invention provides a method and apparatus for normalizing the calculation of fluid phase equilibrium parameters in porous media. This method and apparatus can also be used in conjunction with a computer-readable storage medium storing a computer program. Executing the computer program runs the method for normalizing the calculation of fluid phase equilibrium parameters in porous media. The computer program can execute computer instructions, which include computer program code. The computer program code can be in the form of source code, object code, executable file, or some intermediate form.

[0100] Computer-readable storage media can include: any entity or device capable of carrying computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc.

[0101] It should be noted that the contents of computer-readable storage media may be appropriately added to or subtracted from the contents according to the requirements of legislation and patent practice in a jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable storage media may not include electrical carrier signals and telecommunication signals.

[0102] Figure 2 A block diagram of a device for normalizing fluid phase equilibrium parameters in a porous medium according to an embodiment of the present invention is shown.

[0103] like Figure 2 As shown, a normalized calculation device 200 for fluid phase equilibrium parameters in porous media includes: a saturation module 201, an apparent pressure and compressibility factor module 202, and a mixture composition module 203.

[0104] In one embodiment, the saturation module 201 is used to calculate the normalized oil saturation and gas saturation in the porous medium.

[0105] In one embodiment, the apparent pressure and compressibility factor module 202 is used to calculate the apparent pressure of the oil phase, the apparent pressure of the gas phase, the compressibility factor of the oil phase, and the compressibility factor of the gas phase in the porous medium based on the normalization of the molar number of the oil and gas phases.

[0106] In one embodiment, the mixture composition module 203 is used to normalize the composition of the oil-gas two-phase mixture within each pore size to obtain the apparent oil-gas two-phase mixture composition of the porous medium.

[0107] Figure 3 The actual core pore radius distribution of the H oilfield according to an embodiment of the present invention is shown.

[0108] Taking crude oil from the H oilfield as an example, this paper applies a normalized calculation method for fluid phase equilibrium parameters in porous media. The composition of saturated CO2 crude oil from the H oilfield is shown in Table 1, and the actual core pore distribution is as follows: Figure 3 As shown.

[0109] Table 1. Composition and Equation of State Parameters of Saturated CO2 Crude Oil from Oilfield H

[0110] Components <![CDATA[Z i (mol%)]]> <![CDATA[M i (g / mol)]]> <![CDATA[p cb (MPa)]]> <![CDATA[T cb (K)]]> <![CDATA[w i ]]> <![CDATA[CO2]]> 41.177 44.01 7.376 304.2 0.225 <![CDATA[C1]]> 7.503 16.043 4.600 190.6 0.008 <![CDATA[C2]]> 2.631 30.07 4.884 305.4 0.098 <![CDATA[C3]]> 3.321 44.097 4.246 369.8 0.152 <![CDATA[iC4]]> 0.830 58.124 3.648 408.1 0.176 <![CDATA[nC4]]> 1.180 58.124 3.800 425.2 0.193 <![CDATA[iC5]]> 0.820 72.151 3.384 460.4 0.227 <![CDATA[nC5]]> 0.470 72.151 3.374 469.6 0.251 <![CDATA[C6]]> 1.621 86 3.289 507.5 0.275 <![CDATA[C7 + _1]]> 19.637 119.4151 2.318 606.4 0.273 <![CDATA[C7 + _2]]> 17.233 252.3154 1.158 776.9 0.484 <![CDATA[C7 + _3]]> 3.575 535 0.584 938.9 1.160

[0111] Based on the existing method for calculating oil and gas flash evaporation in porous media, the oil and gas phase equilibrium parameters and normalized results in each pore under reservoir temperature (65℃) and pressure of 5MPa are calculated and shown in Table 2.

[0112] Table 2. Oil-gas phase equilibrium parameters and normalized results in each pore.

[0113]

[0114] The composition and normalization results of the oil phase and gas phase mixture in each pore under the same conditions are shown in Tables 3 and 4, respectively.

[0115] Table 3. Composition and normalization results of oil phase mixture in each pore.

[0116]

[0117]

[0118] Table 4. Composition and normalization results of gas phase mixtures in each pore.

[0119]

[0120]

[0121] In summary, the present invention provides a method and apparatus for normalizing the calculation of fluid phase equilibrium parameters in porous media. This method can accurately normalize and calculate the apparent oil saturation, apparent gas saturation, apparent oil phase pressure, apparent gas phase pressure, apparent oil phase compressibility factor, apparent gas phase compressibility factor, apparent oil phase mixture composition, and apparent gas phase mixture composition of an oil-gas mixture system in a multi-porous medium. Based on this, parameters such as oil-gas phase density and surface tension can be further calculated, providing accurate oil and gas physical property data for oil and gas field development.

[0122] It should be understood that the embodiments disclosed herein are not limited to the specific structures, processing steps, or materials disclosed herein, but should be extended to equivalent substitutions of these features as understood by those skilled in the art. It should also be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

[0123] In the description of this invention, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," "tail," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0124] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0125] The phrase "an embodiment" or "an embodiment" used in this specification means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Therefore, the phrase "an embodiment" or "an embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment.

[0126] The embodiments of the present invention are given for illustrative and descriptive purposes only, and are not intended to be exhaustive or to limit the invention to the forms disclosed. Many modifications and variations will be apparent to those skilled in the art. The embodiments were chosen and described in order to better illustrate the principles and practical application of the invention, and to enable those skilled in the art to understand the invention and to design various embodiments with various modifications suitable for a particular purpose.

[0127] While the embodiments disclosed in this invention are as described above, the content is merely for the purpose of facilitating understanding of the invention and is not intended to limit the invention. Any person skilled in the art to which this invention pertains may make any modifications and variations in form and detail of the implementation without departing from the spirit and scope disclosed herein; however, the scope of patent protection for this invention shall still be determined by the scope defined in the appended claims.

Claims

1. A method for normalizing the calculation of fluid phase equilibrium parameters in porous media, characterized in that, The method includes the following steps: S1. The normalized oil saturation and gas saturation in the porous medium are calculated. S2. The apparent pressure of the oil phase, the apparent pressure of the gas phase, the compressibility factor of the oil phase, and the compressibility factor of the gas phase in the porous medium are calculated based on the normalized molar number of the oil and gas phases. The molar number of the oil and gas phases includes: the total number of moles of fluid in each pore size, the total mole fraction of the oil phase in the porous medium, and the total mole fraction of the gas phase in the porous medium. S3. Normalize the composition of the oil-gas two-phase mixture within each pore size to obtain the apparent composition of the oil-gas two-phase mixture in the porous medium. In step S2, the number of moles of the oil and gas two phases is calculated using the following formula: in, This indicates the total number of moles of fluid within each pore size; This indicates the oil phase pressure within each pore size; This indicates the volume of the oil phase within each pore size; Indicates the compressibility factor of the oil phase within each pore size; This indicates the gas phase pressure within each pore size; This indicates the volume of the gas phase within each pore size; Indicates the gas phase compressibility factor within each pore size; Represents the gas constant; Indicates the system temperature; This indicates the total mole fraction of the oil phase within the porous medium; This indicates the total mole fraction of oil phase within each pore size; This indicates the total mole fraction of the gas phase within the porous medium; Indicates the number of pores; In step S2, the apparent pressure of the oil phase and the apparent pressure of the gas phase in the porous medium are calculated using the following formulas: in, This indicates the apparent pressure of the oil phase within a porous medium. This represents the apparent pressure of the gas phase within a porous medium. This indicates the total mole fraction of the gas phase within each pore size.

2. The method for normalizing the calculation of fluid phase equilibrium parameters in porous media as described in claim 1, characterized in that, In step S1, assuming all pores are spherical and the total pore volume in the porous medium is 1, the oil phase volume and gas phase volume within each pore size are calculated using the following formula: in, This indicates the volume of the oil phase within each pore size; Indicates the oil phase saturation within each pore size; Indicates the pore radius; This indicates the percentage of volume occupied by pores of each size; This indicates the volume of the gas phase within each pore size; This indicates the gas phase saturation within each pore size.

3. The method for normalizing the calculation of fluid phase equilibrium parameters in porous media as described in claim 1, characterized in that, In step S1, the oil saturation and gas saturation are calculated using the following formulas: in, Indicates oil saturation; This indicates the volume of the oil phase within each pore size; This indicates the volume of the gas phase within each pore size; Indicates gas saturation.

4. The method for normalizing the calculation of fluid phase equilibrium parameters in porous media as described in claim 1, characterized in that, In step S2, the compressibility factor of the oil phase and the compressibility factor of the gas phase in the porous medium are calculated using the following formulas: in, Indicates the compressibility factor of the oil phase in a porous medium; This indicates the apparent pressure of the oil phase within a porous medium. This indicates the volume of the oil phase within each pore size; Represents the gas constant; Indicates the system temperature; This indicates the total mole fraction of the oil phase within the porous medium; This indicates the total number of moles of fluid within each pore size; Indicates the gas-phase compressibility factor within a porous medium; This represents the apparent pressure of the gas phase within a porous medium. This indicates the volume of the gas phase within each pore size; This indicates the total mole fraction of the gas phase within the porous medium.

5. The method for normalizing the calculation of fluid phase equilibrium parameters in porous media as described in claim 1, characterized in that, In step S3, the apparent oil-gas two-phase mixture in the porous medium is calculated using the following formula. composition: in, Indicates the composition of the oil phase mixture; This indicates the composition of the oil phase mixture within each pore size; This indicates the total number of moles of fluid within each pore size; This indicates the total mole fraction of oil phase within each pore size; Indicates the composition of a gas-phase mixture; This indicates the composition of the gas phase mixture within each pore size; This indicates the total mole fraction of the gas phase within each pore size; Indicates the quantity of components.

6. A storage medium, characterized in that, It includes a series of instructions for performing the method steps as described in any one of claims 1-5.

7. A device for normalizing the calculation parameters of fluid phase equilibrium in porous media, characterized in that, The apparatus for performing the method as described in any one of claims 1-6 comprises: The saturation module is used to calculate the normalized oil saturation and gas saturation in porous media. The apparent pressure and compressibility factor module is used to calculate the apparent pressure of the oil phase, the apparent pressure of the gas phase, and the compressibility factor of the oil phase in the porous medium based on the normalization of the molar number of the oil and gas phases. The mixture composition module is used to normalize the composition of the oil-gas two-phase mixture within each pore size to obtain the apparent oil-gas two-phase mixture composition of the porous medium.

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