Method and device for determining thermodynamic parameters of PVT phase characteristics of reservoir fluids

Abstract

The present invention discloses a method and device for determining thermodynamic parameters of the PVT phase characteristics of a reservoir fluid, wherein the method comprises: determining the critical temperature and critical pressure of the reservoir fluid plus component based on the specific gravity and normal pressure boiling point of the reservoir fluid plus component; determining the eccentricity factor of the reservoir fluid plus component based on the vapor pressure of the reservoir fluid plus component; determining the binary interaction coefficient between the reservoir fluid plus component and the hydrocarbon component based on the result parameters of the reservoir fluid saturation pressure experiment; determining the volume offset term of the reservoir fluid plus component based on the result parameters of the reservoir fluid density measurement; and determining the viscosity parameters of the reservoir fluid based on the result parameters of the reservoir fluid viscosity measurement. The present invention obtains experimental data through a simple experimental process, fits the experimental data step by step, and gradually determines the thermodynamic parameters of the PVT phase characteristics of the reservoir fluid. This method can more quickly obtain the thermodynamic parameters of the PVT phase characteristics of the reservoir fluid and ensure the accuracy of the obtained parameters.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas field development, and in particular to a method and device for determining thermodynamic parameters of PVT phase characteristics of oil reservoir fluid. Background Art

[0002] This section is intended to provide a background or context to the embodiments of the invention that are recited in the claims. No statement herein is admitted to be prior art by virtue of its inclusion in this section.

[0003] The study of fluid phase characteristics provides a basis for analyzing formation fluid phase changes, basic gas injection development mechanisms, and production dynamic adjustments. It is a key step in oil and gas field development and an essential step in reservoir numerical simulation. In reservoir numerical simulation, PVT fitting is required to obtain the thermodynamic parameters of the formation fluid PVT phase characteristics, thereby obtaining the fluid PVT data required by the component simulator.

[0004] Existing methods for obtaining phase-characteristic thermodynamic parameters in reservoir numerical simulations require extensive prior PVT phase-characteristic experiments to obtain data from differential degassing, isocratic expansion, isochoric depletion, separator experiments, and expansion experiments. This requires significant experimental effort and is challenging to implement. Furthermore, component merging is often performed during the PVT fitting process, which, while increasing computational speed, reduces accuracy and prevents accurate PVT phase-characteristic thermodynamic parameters from being obtained. Therefore, finding a more efficient way to obtain PVT phase-characteristic thermodynamic parameters for reservoir fluids while ensuring both reliability and accuracy has become a pressing research topic. Summary of the Invention

[0005] An embodiment of the present invention provides a method for determining thermodynamic parameters of the PVT phase characteristics of a reservoir fluid, for obtaining the thermodynamic parameters of the PVT phase characteristics of the reservoir fluid more quickly and conveniently while ensuring the accuracy of the obtained parameters. The method includes:

[0006] Determine the critical temperature and critical pressure of the reservoir fluid plus components based on the specific gravity and atmospheric boiling point of the reservoir fluid plus components;

[0007] Determine the eccentricity factor of the reservoir fluid plus component based on the vapor pressure of the reservoir fluid plus component;

[0008] Based on the result parameters of the reservoir fluid saturation pressure experiment, the binary interaction coefficient between the reservoir fluid additive component and the non-hydrocarbon component is determined;

[0009] Determine the volume offset term of the reservoir fluid plus components based on the result parameters of the reservoir fluid density measurement;

[0010] The viscosity parameters of the reservoir fluid are determined according to the result parameters of the reservoir fluid viscosity measurement.

[0011] An embodiment of the present invention further provides a device for determining thermodynamic parameters of the PVT phase characteristics of a reservoir fluid, for obtaining the thermodynamic parameters of the PVT phase characteristics of the reservoir fluid more quickly and conveniently while ensuring the accuracy of the obtained parameters. The device includes:

[0012] A module for determining critical properties of the reservoir fluid components is used to determine the critical temperature and critical pressure of the reservoir fluid components based on the specific gravity and normal pressure boiling point of the reservoir fluid components;

[0013] A component eccentricity factor determination module is used to determine the eccentricity factor of the reservoir fluid component according to the vapor pressure of the reservoir fluid component;

[0014] A binary interaction coefficient determination module is used to determine the binary interaction coefficient between the reservoir fluid plus component and the non-hydrocarbon component based on the result parameters of the reservoir fluid saturation pressure experiment;

[0015] A volume offset term determination module is used to determine a volume offset term of the reservoir fluid plus components based on the result parameters of the reservoir fluid density measurement;

[0016] The viscosity parameter determination module is used to determine the viscosity parameter of the reservoir fluid according to the result parameter of the reservoir fluid viscosity measurement.

[0017] An embodiment of the present invention also provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the method for determining the thermodynamic parameters of the PVT phase characteristics of the reservoir fluid is implemented.

[0018] An embodiment of the present invention further provides a computer-readable storage medium storing a computer program for executing the above-mentioned method for determining thermodynamic parameters of the PVT phase characteristics of reservoir fluids.

[0019] In an embodiment of the present invention, the critical temperature and critical pressure of the reservoir fluid plus component are determined based on the specific gravity and atmospheric boiling point of the reservoir fluid plus component; the eccentricity factor of the reservoir fluid plus component is determined based on the vapor pressure of the reservoir fluid plus component; the binary interaction coefficient between the reservoir fluid plus component and the hydrocarbon component is determined based on the result parameters of the reservoir fluid saturation pressure experiment; the volume offset term of the reservoir fluid plus component is determined based on the result parameters of the reservoir fluid density measurement; and the viscosity parameter of the reservoir fluid is determined based on the result parameters of the reservoir fluid viscosity measurement. Compared with the technical solution in the prior art that conducts a large number of PVT phase state experiments in advance and uniformly fits the data obtained from the experiments to determine the PVT phase state characteristic thermodynamic parameters of the reservoir fluid, the simple experimental process and step-by-step fitting based on the experimental data to gradually determine the PVT phase state characteristic thermodynamic parameters of the reservoir fluid can more quickly and conveniently obtain the PVT phase state characteristic thermodynamic parameters of the reservoir fluid while ensuring the accuracy of the obtained parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0021] Figure 1 Flowchart of a method for determining thermodynamic parameters of PVT phase characteristics of reservoir fluids according to an embodiment of the present invention;

[0022] Figure 2 This is a flow chart of a specific example of a method for determining thermodynamic parameters of PVT phase characteristics of reservoir fluids according to an embodiment of the present invention;

[0023] Figure 3 This is a flow chart of a specific example of a method for determining thermodynamic parameters of PVT phase characteristics of reservoir fluids in an embodiment of the present invention;

[0024] Figure 4 Schematic diagram of a device for determining thermodynamic parameters of PVT phase characteristics of reservoir fluids in an embodiment of the present invention;

[0025] Figure 5 It is a schematic diagram of the structure of a computer device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0026] To make the purpose, technical solutions and advantages of the embodiments of the present invention more clear, the embodiments of the present invention are further described in detail below with reference to the accompanying drawings. Here, the exemplary embodiments of the present invention and their descriptions are used to explain the present invention, but are not intended to limit the present invention.

[0027] Figure 1 FIG. 1 is a flow chart of a method for determining thermodynamic parameters of PVT phase characteristics of reservoir fluids according to an embodiment of the present invention. Figure 1 As shown, the method for determining the thermodynamic parameters of the PVT phase characteristics of the reservoir fluid in the embodiment of the present invention may include:

[0028] Step 101: Determine the critical temperature and critical pressure of the reservoir fluid plus components based on the specific gravity and normal pressure boiling point of the reservoir fluid plus components;

[0029] Step 102: determining an eccentricity factor of the reservoir fluid plus component based on the vapor pressure of the reservoir fluid plus component;

[0030] Step 103: Determine the binary interaction coefficient between the reservoir fluid additive component and the hydrocarbon component based on the result parameters of the reservoir fluid saturation pressure experiment;

[0031] Step 104: Determine a volume offset term of the reservoir fluid plus components based on the result parameters of the reservoir fluid density measurement;

[0032] Step 105: Determine the viscosity parameter of the reservoir fluid according to the result parameter of the reservoir fluid viscosity measurement.

[0033] Traditional methods for determining the PVT phase characteristic thermodynamic parameters of reservoir fluids require first conducting differential degassing, isocratic expansion, isochoric depletion, separator experiments, and expansion experiments. Numerical simulation software is then used to fit the experimental data to obtain the fluid PVT phase characteristic thermodynamic parameters. This requires a large amount of experimental data and is difficult to conduct. However, in the embodiments of the present invention, only reservoir fluid saturation pressure experiments and reservoir fluid density and viscosity measurements are required beforehand. This simple experimental process allows the acquisition of the data required to determine the PVT phase characteristic thermodynamic parameters of reservoir fluids, and the required data is far less than that acquired through traditional experimental methods.

[0034] To increase computational speed, traditional methods often merge components during the PVT fitting process and uniformly input all experimental data, fitting all data in one step. This results in any experimental data problems (such as missing or incorrect data) affecting the results of determining the PVT phase characteristic thermodynamic parameters of the reservoir fluid, reducing the accuracy of the PVT phase characteristic thermodynamic parameters of the reservoir fluid. Furthermore, traditional methods fit a large amount of experimental data, which itself leads to low accuracy in determining the PVT phase characteristic thermodynamic parameters of the reservoir fluid. In the embodiments of the present invention, a small amount of experimental data obtained through reservoir fluid saturation pressure experiments and reservoir fluid density and viscosity measurements is used to perform step-by-step fitting to gradually determine the PVT phase characteristic thermodynamic parameters of the reservoir fluid. Data problems in any link only affect the parameters of the relevant link and have no impact on other parameters, thus ensuring the accuracy of the PVT phase characteristic thermodynamic parameters of the reservoir fluid.

[0035] Thermodynamic parameters of fluid PVT phase characteristics include component properties, binary interaction coefficients, viscosity parameters, coupling coefficient density exponents. Component properties include the critical pressure, critical temperature, eccentricity factor, molecular weight, volume offset term, specific gravity, and atmospheric boiling point of each formation fluid component.

[0036] In one embodiment, for example, the binary interaction coefficient can be set as BIP, the viscosity parameter, that is, the coupling coefficient density index can be set as n, and for the component properties, the critical pressure of each component of the formation fluid can be set as P c , the critical temperature is T c , eccentricity factor is ω, molecular weight is MW, volume offset term is c, specific gravity is SG, and atmospheric boiling point is T b The following content is taken as an example, but is not intended to limit the present invention.

[0037] In one embodiment, the components and composition of the reservoir fluid and injected gas are first obtained. The PVT phase characteristics and thermodynamic parameters of different components are obtained in different ways. Among them, the properties of conventional components are known quantities, such as H2S, CO2, N2, C1-C 29 , NC7-NC9 (normal alkanes), C6H6 (benzene), CC6 (cyclohexane), etc.; the added component is a mixture of hydrocarbons with a carbon number higher than a certain value, and its component properties are unknown and need to be obtained through experiments or the embodiments of the present invention. The component properties that can be obtained through experiments include molecular weight MW, specific gravity SG and normal pressure boiling point T b The component properties obtained by the embodiment of the present invention include critical properties (P c 、T c), eccentricity factor ω and volume offset term c; the binary interaction coefficient BIP between conventional components is a known quantity, the binary interaction coefficient BIP between the added component and the hydrocarbon component is a known quantity, and the binary interaction coefficient BIP between the added component and the non-hydrocarbon component is an unknown quantity, which needs to be obtained through the embodiments of the present invention; the viscosity parameter, that is, the coupling coefficient density n is an unknown quantity, which needs to be obtained through the embodiments of the present invention.

[0038] In one embodiment, the critical temperature and critical pressure of the reservoir fluid plus components are determined based on the specific gravity and atmospheric boiling point of the reservoir fluid plus components. The critical temperature of the reservoir fluid plus components can be determined first, including: determining the critical temperature of the reservoir fluid plus components based on the specific gravity and atmospheric boiling point of the reservoir fluid plus components, and the correlation between the specific gravity and atmospheric boiling point of the reservoir fluid plus components and the critical temperature of the reservoir fluid plus components.

[0039] The relationship between the specific gravity and atmospheric boiling point of the reservoir fluid plus components and the critical temperature of the reservoir fluid plus components can be determined according to the following critical temperature correlation formula:

[0040]

[0041] Among them, T c is the critical temperature of the reservoir fluid plus components; SG is the specific gravity of the reservoir fluid plus components; T b is the atmospheric boiling point of the reservoir fluid plus components.

[0042] During specific implementation, the actual situation of oil reservoir A is taken as an example for description, but it is not intended to limit the present invention.

[0043] According to the actual situation of reservoir A, the PVT phase characteristic thermodynamic parameters of a certain reservoir fluid are determined. The known values ​​are as follows:

[0044] Reservoir temperature: T 油藏 =84℃;

[0045] Formation pressure: P 油藏 =63.439MPa;

[0046] Minimum miscible pressure of injected gas and formation crude oil: P MMP-油藏 =52MPa;

[0047] Formation crude oil saturation pressure: P b-油藏 =51MPa;

[0048] The components and compositions of the formation crude oil and injected gas in the embodiment are shown in Table 1:

[0049] Table 1 Components and compositions of formation crude oil and injected gas

[0050]

[0051]

[0052] The specific composition and component properties of the reservoir fluid in the embodiment are shown in Table 2:

[0053] Table 2 Composition and properties of formation crude oil

[0054]

[0055]

[0056] In an embodiment, C 20 + For the addition component, the addition component C can be obtained according to the experiment 20 + Molecular weight MW, specific gravity SG and normal pressure boiling point T b , determine the addition of component C 20 + The critical temperature can be calculated based on the addition of component C 20 + Specific gravity SG and normal pressure boiling point T b , plus component C 20 + Specific gravity SG and normal pressure boiling point T b With component C 20 + The critical temperature T c The correlation between them determines the addition of group C 20 + critical temperature.

[0057] Add component C 20 + Specific gravity SG and normal pressure boiling point T b With component C 20 + The critical temperature T c The correlation between them can be determined according to the following critical temperature correlation formula:

[0058]

[0059] Among them, T c Add component C 20 + Critical temperature; SG is the added component C 20 + The specific gravity of the product is shown in Table 2 as follows: 0.887; T b Add component C 20 + The atmospheric boiling point is 521.94 as shown in Table 2.

[0060] The above formula can be used to calculate C 20 + The critical temperature is: T c =927.7K.

[0061] In one embodiment, the critical pressure of the reservoir fluid plus components is determined. The critical pressure of the reservoir fluid plus components can also be determined based on the specific gravity and atmospheric boiling point of the reservoir fluid plus components, including: determining the critical pressure of the reservoir fluid plus components based on the specific gravity and atmospheric boiling point of the reservoir fluid plus components, and the correlation between the specific gravity and atmospheric boiling point of the reservoir fluid plus components and the critical pressure of the reservoir fluid plus components.

[0062] The correlation between the specific gravity and atmospheric boiling point of the reservoir fluid plus components and the critical pressure of the reservoir fluid plus components can be determined according to the following critical pressure correlation formula:

[0063]

[0064] Among them, P c is the critical pressure of reservoir fluid plus components; SG is the specific gravity of reservoir fluid plus components; T b is the atmospheric boiling point of the reservoir fluid plus components.

[0065] Still taking the oil reservoir A as an example, in the embodiment, the additive component C obtained by the experiment is 20 + Molecular weight MW, specific gravity SG and normal pressure boiling point T b , determine the addition of component C 20 + The critical pressure can be determined by adding component C. 20 + Specific gravity SG and normal pressure boiling point T b , plus component C 20 + Specific gravity SG and normal pressure boiling point T b With component C 20 + The correlation between the critical pressure of 20 + critical pressure.

[0066] Add component C 20 + Specific gravity SG and normal pressure boiling point T b With component C 20 + The critical pressure T c The correlation between them can be determined according to the following critical pressure correlation formula:

[0067]

[0068] Among them, P c Add component C 20 + Critical pressure; SG is the added component C 20 + The specific gravity of the product is shown in Table 2 as follows: 0.887; T b Add component C 20 + The normal pressure boiling point is shown in Table 3: T b =521.94.

[0069] The above formula can be used to calculate the added component C 20 + The critical pressure is: P c =7.08atm.

[0070] In one embodiment, the eccentricity factor of the reservoir fluid plus component can be determined based on the vapor pressure of the reservoir fluid plus component, including determining the eccentricity factor of the reservoir fluid plus component according to the following eccentricity factor correlation:

[0071]

[0072] Where ω is the eccentricity factor; The temperature is 0.85T b The vapor pressure of the reservoir fluid plus its components.

[0073] Still taking oil reservoir A as an example, in the embodiment, according to the addition of component C 20 + The vapor pressure of component C is determined 20 + The eccentricity factor of the component C can be determined according to the following eccentricity factor correlation formula: 20 + The eccentricity factor:

[0074]

[0075] Where ω is the added component C 20 + Eccentricity factor; The temperature is 0.85T b Add component C 20 + vapor pressure.

[0076] The above formula can be used to calculate the added component C 20 + The eccentricity factor is: ω = 1.258.

[0077] In specific implementation, the critical properties of reservoir fluid plus components (P c 、Tc ), the calculation of the eccentricity factor ω can be achieved through reservoir numerical simulation software or programming software.

[0078] In one embodiment, the binary interaction coefficient between the reservoir fluid plus component and the non-hydrocarbon component is determined based on the result parameters of the reservoir fluid saturation pressure experiment. The method may be as follows: based on the known PVT phase characteristic thermodynamic parameters of the reservoir fluid, saturation pressure calculation and multiple contact calculation are performed using the PR state equation to calculate the formation fluid saturation pressure and / or the minimum miscibility pressure of the injected gas and the formation fluid; and the binary interaction coefficient between the reservoir fluid plus component and the non-hydrocarbon component is determined with the goal of making the calculated formation fluid saturation pressure and / or the minimum miscibility pressure of the injected gas and the formation fluid approach the same as the formation fluid saturation pressure and / or the minimum miscibility pressure of the injected gas and the formation fluid measured by the reservoir fluid saturation pressure experiment.

[0079] The binary interaction coefficient between the reservoir fluid additive component and the hydrocarbon component can be determined according to the following formula based on the result parameters of the reservoir fluid saturation pressure experiment:

[0080] The PR state equation is:

[0081]

[0082] Where P is pressure, unit is Pa; T is thermodynamic temperature, unit is K; V is molar volume, unit is m 3 .mol -1 ; R is the universal gas constant, unit is mol -1 .K -1 ; Constants a and b are the parameters of the PR state equation, and their units are Pa.m 6 .mol -2 and m 3 .mol -1 ;

[0083] For pure components in reservoir fluid, the formulas for calculating a and b are as follows:

[0084]

[0085]

[0086] Among them, P c is the critical pressure of the pure component in the reservoir fluid, T c is the critical temperature of the pure component in the reservoir fluid, ω is the eccentricity factor of the pure component in the reservoir fluid, and R is the universal gas constant;

[0087] For mixtures, the formulas for calculating a and b are as follows:

[0088]

[0089]

[0090] Where i & j are the number of components in the mixture; x i is the mole percentage of component i; x j is the mole percentage of component j; a i is the constant a calculated according to the above formula for component i; a j is the constant a calculated by the above formula for component j; b i is the constant b calculated according to the above formula for component i; δ ij is the binary interaction coefficient between component i and component j.

[0091] In specific implementation, the calculation of formation fluid saturation pressure, minimum miscibility pressure of injected gas and formation fluid, and adjustment of interaction coefficient between added components and non-hydrocarbons can be achieved through reservoir numerical simulation software or programming software.

[0092] The calculated formation fluid saturation pressure can be set as P b-cal The calculated minimum miscible pressure of injected gas and formation fluid is P MMP-cal The formation fluid saturation pressure measured by the reservoir fluid saturation pressure experiment is P b-exp The minimum miscible pressure of injected gas and formation fluid measured by reservoir fluid saturation pressure experiment is P MMP-exp .

[0093] Still taking oil reservoir A as an example, in the embodiment, component C is added 20 + The binary interaction coefficients BIP between the non-hydrocarbon components CO2 and N2 are unknown. The binary interaction coefficients between the components of formation crude oil are shown in Table 3:

[0094] Table 3 Binary interaction coefficients between components

[0095]

[0096]

[0097] In specific implementation, the formation crude oil saturation pressure P can be calculated based on the known PVT phase characteristic thermodynamic parameters of the formation crude oil, for example, the WinProp module of the reservoir numerical simulation software CMG can be used to perform saturation pressure calculation and multiple contact calculation. b-cal and the minimum miscibility pressure P of injected gas and formation crude oil MMP-cal , if the calculated formation crude oil saturation pressure P b-calThe formation crude oil saturation pressure P measured by the reservoir fluid saturation pressure experiment b-exp tend to be the same, that is, |P b-cal -P b-exp |≤0.01, and the calculated minimum miscibility pressure of injected gas and formation crude oil P MMP-cal The minimum miscible pressure P of injected gas and formation crude oil measured by reservoir fluid saturation pressure experiment MMP-exp tend to be the same, that is, |P MMP-cal –P MMP-exp |≤0.01, the calculation ends; if not satisfied, adjust the binary interaction coefficient BIP between the additive component and the non-hydrocarbon component until the above conditions are met.

[0098] In the embodiment, the formation crude oil saturation pressure is known: P b-油藏 =51MPa, minimum miscible pressure of injected gas and formation crude oil: P MMP-油藏 =52MPa; According to the following formula, the added component C of the formation crude oil in the embodiment is determined 20 + Binary interaction coefficients with non-hydrocarbon components CO2 and non-hydrocarbon components N2:

[0099] The PR state equation is:

[0100]

[0101] Wherein, P is pressure. In the embodiment, the formation pressure is known: P 油藏 =63.439MPa; T is the thermodynamic temperature scale. In the embodiment, the reservoir temperature is known to be: T 油藏 =84℃; V is the molar volume, unit is m 3 .mol -1 ; R is the universal gas constant, unit is mol -1 .K -1 ; Constants a and b are the parameters of the PR state equation, and their units are Pa.m 6 .mol -2 and m 3 .mol -1 ;

[0102] For pure components in formation crude oil, the formulas for calculating a and b are as follows:

[0103]

[0104]

[0105] Among them, P c is the critical pressure of the pure component in the formation crude oil; T cis the critical temperature of the pure component in the formation crude oil; ω is the eccentricity factor of the pure component in the formation crude oil; R is the universal gas constant.

[0106] In the embodiment, component C is added to the formation crude oil. 20 + , the critical pressure P corresponding to the non-hydrocarbon component CO2 and the non-hydrocarbon component N2 c , critical temperature T c , eccentricity factor ω are substituted into the above formula to calculate the pure component C 20 + , constants a and b corresponding to CO2 and N2;

[0107] For mixtures, the formulas for calculating a and b are as follows:

[0108]

[0109]

[0110] Where i & j are the number of components in the mixture; x i is the mole percentage of component i; x j is the mole percentage of component j; a i is the constant a calculated according to the above formula for component i; a j is the constant a calculated by the above formula for component j; b i is the constant b calculated according to the above formula for component i; δ ij is the binary interaction coefficient between component i and component j.

[0111] In the embodiment, the calculation of the addition component C 20 + When the binary interaction coefficient BIP between the non-hydrocarbon component CO2 is i Can be added as component C 20 + The mole percentage of x j It can be the mole percentage of non-hydrocarbon component CO2; a i Can be pure component C 20 + The calculated constant a; a j The constants a and b can be calculated for the pure component CO2. i Can be pure component C 20 + The calculated constant b; δ ij Can be added as component C 20 + Binary interaction coefficient with non-hydrocarbon component CO2;

[0112] In the embodiment, the calculation of the addition component C 20 + When the binary interaction coefficient BIP between the non-hydrocarbon component N2 is i Can be added as component C 20 + The mole percentage of x j It can be the mole percentage of the non-hydrocarbon component N2; a i Can be pure component C 20 + The calculated constant a; a j The constants a and b can be calculated for the pure component N2. i Can be pure component C 20 + The calculated constant b; δ ij Can be added as component C 20 + Binary interaction coefficient with the non-hydrocarbon component N2.

[0113] Through the above steps, the formation crude oil saturation pressure P can be calculated b-cal and / or the minimum miscibility pressure P of injected gas and formation crude oil MMP-cal , and the formation crude oil saturation pressure P measured by the reservoir fluid saturation pressure experiment b-exp and / or the minimum miscibility pressure P of injected gas and formation crude oil MMP-exp The comparison results are shown in Table 4:

[0114] Table 4 Comparison of calculated and experimental results of saturation pressure and minimum miscible pressure

[0115] <![CDATA[P MMP-cal / MPa]]> <![CDATA[P MMP-exp / MPa]]> <![CDATA[P b-cal / MPa]]> <![CDATA[P b-exp / MPa]]> 52.003 52 50.997 51

[0116] As can be seen from Table 4, the formation crude oil saturation pressure calculated in the embodiment is: P b-cal =50.997MPa, the formation crude oil saturation pressure P measured by the reservoir fluid saturation pressure experiment b-exp =52.003MPa, satisfying |P b-cal -P b-exp |≤0.01; the minimum miscible pressure P of the injected gas and formation fluid calculated in the embodiment MMP-cal =52.003MPa, the minimum miscible pressure P of injected gas and formation fluid measured by reservoir fluid saturation pressure experiment MMP-exp =52MPa, satisfying |P MMP-cal –P MMP-exp |≤0.01.

[0117] In the embodiment, the added component C can be calculated 20 +The binary interaction coefficient between the non-hydrocarbon component CO2 and the added component C 20 + The binary interaction coefficients with the non-hydrocarbon component N2 are shown in Table 5:

[0118] Table 5 C 20 + Interaction coefficient with non-hydrocarbons

[0119] BIP <![CDATA[CO2]]> <![CDATA[N2]]> <![CDATA[C 20 + ]]> 0.11 0.09

[0120] In one embodiment, the volume offset term of the reservoir fluid plus components is determined based on the result parameters of the reservoir fluid density measurement. The method may be as follows: based on the known PVT phase characteristic thermodynamic parameters of the reservoir fluid, a two-phase flash calculation is performed using the PR state equation to calculate the formation fluid density; and with the goal of making the calculated formation fluid density approach the same as the formation fluid density obtained by the reservoir fluid density measurement, the volume offset term of the reservoir fluid plus components is determined.

[0121] The volume offset term of the reservoir fluid plus components can be determined based on the result parameters of the reservoir fluid density measurement according to the following formula:

[0122] The PR state equation is:

[0123]

[0124] Where P is pressure, unit is Pa; T is thermodynamic temperature scale, unit is K; V is molar volume, unit is m 3 .mol -1 ; R is the universal gas constant, unit is mol -1 .K -1 ; Constants a and b are the parameters of the PR state equation, and their units are Pa.m 6 .mol -2 and m 3 .mol -1 ;

[0125] Volume offset term for pure components in reservoir fluid:

[0126] V corrected =V EOS +c

[0127] Among them, V corrected is the volume of pure component obtained from the formation fluid density measured according to the reservoir fluid density, V EOS is the volume of the pure component obtained from the formation fluid density calculated by two-phase flash evaporation using the PR equation of state, and c is the volume offset term of the pure component in the reservoir fluid;

[0128] For mixtures, the volume offset term is given by:

[0129]

[0130] Among them, c mix is the weighted average of the molar volumes of the pure components in the reservoir fluid, x i is the mole percentage of component i, c i is the volume offset term of component i.

[0131] In specific implementation, the calculation of formation fluid density and the adjustment of the added component volume offset term can be achieved through reservoir numerical simulation software or programming software.

[0132] The calculated formation fluid density can be set to ρ cal , the formation fluid density obtained by reservoir fluid density measurement is ρ exp , plus the component volume offset term is c.

[0133] Still taking the oil reservoir A as an example, in the embodiment, the density of the formation crude oil under different pressures can be ρ o-油藏 , unit: g·cm -3 , the formation crude oil viscosity can be μ o-油藏 , unit is mPa·s; the density and viscosity of formation crude oil under different pressures are shown in Table 6:

[0134] Table 6 Density and viscosity of crude oil at different formation pressures

[0135] P / MPa <![CDATA[μ o-油藏 / mPa·s]]> <![CDATA[ρ o-油藏 / g·cm -3 ]]> 66.327 0.516 0.727 63.439 0.502 0.723 60.204 0.487 0.719 57.143 0.473 0.714 54.082 0.458 0.709 51.235 0.449 0.705

[0136] From Table 6, we can see that the formation pressure is: P 油藏 =63.439MPa, the corresponding formation crude oil density is: ρ o-油藏 =0.723g·cm -3 .

[0137] In the embodiment, based on the known PVT phase characteristic thermodynamic parameters of the formation crude oil, for example, the WinProp module of the reservoir numerical simulation software CMG can be used to perform two-phase flash calculation to calculate the formation crude oil density ρ cal , if the calculated formation crude oil density ρ cal The formation fluid density ρ obtained by measuring the reservoir fluid density exp tend to be the same, i.e. |ρ cal -ρ exp |≤0.01, calculation ends; if not satisfied, adjust and add component C 20 + The volume offset term c is calculated until the above conditions are met. The calculated formation crude oil density ρ calThe formation crude oil density ρ obtained by measuring the reservoir fluid density exp There is a certain deviation compared to the above, you can use component C 20 + The volume offset term c represents the deviation and improves the calculation accuracy. The specific formula is as follows:

[0138] The PR state equation is:

[0139]

[0140] Where P is pressure, the formation pressure is known: P 油藏 =63.439MPa; T is the thermodynamic temperature scale, the reservoir temperature is known: T 油藏 =84℃; V is the molar volume, unit is m 3 .mol -1 ; R is the universal gas constant, unit is mol -1 .K -1 ; Constants a and b are the parameters of the PR state equation, and their units are Pa.m 6 .mol -2 and m 3 .mol -1 ;

[0141] Volume offset term for pure components in formation crude oil:

[0142] V corrected =V EOS +c

[0143] Among them, V corrected is the volume of pure component obtained from the formation crude oil density measured by reservoir fluid density, V EOS is the volume of the pure component obtained from the density of the formation crude oil calculated by two-phase flash evaporation using the PR equation of state, and c is the volume offset term of the pure component in the formation crude oil;

[0144] For mixtures, the volume offset term is given by:

[0145]

[0146] Among them, c mix is the weighted average of the molar volumes of the pure components in the formation crude oil, x i is the mole percentage of component i, c i is the volume offset term of component i.

[0147] In the embodiment, the calculation of the addition component C 20 + When the volume offset term is x i Can represent the addition of component C 20+ The mole percentage of c mix It can represent the weighted average of the molar volume of the pure component parameters in the above table; c i Can represent the addition of component C 20 + The volume offset term.

[0148] The comparison results of the formation crude oil density that can be calculated in the embodiment and the formation crude oil density obtained by measuring the reservoir fluid density are shown in Table 7:

[0149] Table 7 Comparison between calculated and experimental results of formation crude oil density

[0150] P / MPa <![CDATA[ρ cal / g·cm -3 ]]> <![CDATA[ρ exp / g·cm -3 ]]> 66.327 0.730 0.727 63.439 0.725 0.723 60.204 0.720 0.719 57.143 0.714 0.714 54.082 0.708 0.709 51.235 0.702 0.705

[0151] From Table 7, we can see that the formation pressure: P 油藏 =63.439MPa, the formation crude oil density obtained by measuring the corresponding reservoir fluid density is: ρ exp =0.723g·cm -3 , the corresponding calculated formation crude oil density: ρ cal =0.725g·cm -3 , satisfying |ρ cal -ρ exp |≤0.01, through the above formula, we can calculate the added component C 20 + The volume offset term is: c = 0.342838.

[0152] In one embodiment, the viscosity parameter of the reservoir fluid is determined based on the result parameters of the reservoir fluid viscosity measurement. The method may be as follows: based on the known PVT phase characteristic thermodynamic parameters of the reservoir fluid, a two-phase flash calculation is performed using the PR state equation and the Pederson model to calculate the formation fluid viscosity; and the viscosity parameter of the reservoir fluid is determined with the goal of making the calculated formation fluid viscosity approach the same as the formation fluid viscosity obtained by the reservoir fluid viscosity measurement.

[0153] The viscosity parameters of the reservoir fluid can be determined according to the following formula based on the result parameters of the reservoir fluid viscosity measurement:

[0154] The PR state equation is:

[0155]

[0156] Where P is pressure, unit is Pa; T is thermodynamic temperature scale, unit is K; V is molar volume, unit is m 3 .mol -1 ; R is the universal gas constant, unit is mol -1 .K -1; Constants a and b are the parameters of the PR state equation, and their units are Pa.m 6 .mol -2 and m 3 .mol -1 ;

[0157] Pederson Model:

[0158]

[0159]

[0160]

[0161] Where μ0(p0,T0) is the viscosity of the known reference fluid, μ(p,t) is the viscosity of the target reservoir fluid; T c0 is the critical temperature of the known reference fluid, T c is the critical temperature of the target reservoir fluid; P c0 is the critical pressure of the known reference fluid, P c is the critical pressure of the target reservoir fluid; MW c0 is the molecular molar mass of the known reference fluid, MW c is the molecular molar mass of the target reservoir fluid; α0 is the coupling coefficient of the known reference fluid, α is the coupling coefficient of the target reservoir fluid; ρ r is the comparative density; n is the viscosity parameter of the reservoir fluid, that is, the coupling coefficient density index.

[0162] In specific implementation, the calculation of formation fluid viscosity and the adjustment of reservoir fluid viscosity parameters can be achieved through reservoir numerical simulation software or programming software.

[0163] The calculated formation fluid viscosity can be set to μ cal The formation fluid viscosity obtained by measuring the reservoir fluid viscosity is μ exp , the viscosity parameter of the reservoir fluid can be set, that is, the coupling coefficient density exponent is n.

[0164] Still taking the oil reservoir A as an example, in the embodiment, it can be seen from Table 6 that the formation pressure is: P 油藏 =63.439MPa, the corresponding formation crude oil viscosity is: μ o-油藏 =0.502mPa·s.

[0165] In the embodiment, based on the known PVT phase characteristic thermodynamic parameters of the formation crude oil, for example, the WinProp module of the reservoir numerical simulation software CMG can be used to perform two-phase flash calculation to calculate the formation crude oil viscosity μ cal , if the calculated formation crude oil viscosity μ calThe formation fluid viscosity μ obtained by measuring the reservoir fluid viscosity exp tend to be the same, that is, |μ cal -μ exp |≤0.01, calculation ends; if not satisfied, adjust and add component C 20 + The viscosity parameter, that is, the coupling coefficient density index n, is adjusted until the above conditions are met. The specific formula is as follows:

[0166] PR state equation:

[0167]

[0168] Where P is pressure, the formation pressure is known: P 油藏 =63.439MPa; T is the thermodynamic temperature scale, the reservoir temperature is known: T 油藏 =84℃; V is the molar volume, unit is m 3 .mol -1 ; R is the universal gas constant, unit is mol -1 .K -1 ; Constants a and b are the parameters of the PR state equation, and their units are Pa.m 6 .mol -2 and m 3 .mol -1 ;

[0169] Pederson Model:

[0170]

[0171]

[0172]

[0173] Where μ0(p0,T0) is the viscosity of the known reference fluid, μ(p,T) is the viscosity of the target reservoir fluid; T c0 is the critical temperature of the known reference fluid, T c is the critical temperature of the target reservoir fluid; P c0 is the critical pressure of the known reference fluid, P c is the critical pressure of the target reservoir fluid; MW c0 is the molecular molar mass of the known reference fluid, MW c is the molecular molar mass of the target reservoir fluid; α0 is the coupling coefficient of the known reference fluid, α is the coupling coefficient of the target reservoir fluid, characterizing the influence of molecular size and density; ρ r is the relative density, which can be calculated by the PR equation, and n is the viscosity parameter of the reservoir fluid: coupling coefficient density index.

[0174] In the embodiment, according to the known PVT phase characteristic thermodynamic parameters in Table 2, and the additive component C gradually obtained by the above method, 20 + The critical properties (P c 、T c ), eccentricity factor ω, volume offset term c, C 20 + The binary interaction coefficient BIP with non-hydrocarbons (CO2, N2) determines the viscosity parameter of the formation crude oil, that is, the coupling coefficient density index n.

[0175] In the embodiment, the formation crude oil viscosity μ can be calculated. cal , and the formation crude oil viscosity μ obtained by measuring the viscosity of the reservoir fluid exp The comparison results are shown in Table 8:

[0176] Table 8 Comparison between calculated and experimental results of formation crude oil viscosity

[0177] P / MPa <![CDATA[μ cal / mPa·s]]> <![CDATA[μ exp / mPa·s <!-- 15 -->]]> 66.327 0.511 0.516 63.439 0.500 0.502 60.204 0.490 0.487 57.143 0.479 0.473 54.082 0.461 0.458 51.235 0.450 0.449

[0178] From Table 8, we can see that the formation pressure: P 油藏 =63.439MPa, the corresponding reservoir fluid viscosity is measured to obtain the formation crude oil viscosity: μ exp =0.502mPa·s, the corresponding calculated formation crude oil viscosity is: μ cal =0.500mPa·s, satisfying |μ cal -μ exp |≤0.01, through the above formula, the viscosity parameter of the formation crude oil, that is, the coupling coefficient density index, can be calculated: n=1.847.

[0179] Figure 2 This is a flow chart of a specific example of a method for determining thermodynamic parameters of PVT phase characteristics of reservoir fluids in an embodiment of the present invention. Figure 2 The specific example process of the method for determining the thermodynamic parameters of the PVT phase characteristics of the reservoir fluid in the embodiment of the present invention includes:

[0180] Step 201: Obtain the components and composition of the reservoir fluid;

[0181] Step 202: determine whether the reservoir fluid contains the added component. If so, execute step 203; if not, jump to step 209;

[0182] Step 203: Obtain the molecular weight, specific gravity, and normal pressure boiling point of the added component through experiments;

[0183] Step 204: Calculate the critical temperature, critical pressure, and eccentricity factor of the added component using a correlation equation based on the molecular weight, specific gravity, and normal-pressure boiling point of the added component;

[0184] Step 205: Based on the known PVT phase characteristic thermodynamic parameters of the reservoir fluid, saturation pressure calculation and multiple contact calculation are performed using the PR state equation to calculate the formation fluid saturation pressure and / or the minimum miscibility pressure of the injected gas and the formation fluid;

[0185] Step 206: Determine the binary interaction coefficient between the reservoir fluid plus component and the non-hydrocarbon component with the goal of making the calculated formation fluid saturation pressure and / or the minimum miscibility pressure of the injected gas and the formation fluid approach the same as the formation fluid saturation pressure and / or the minimum miscibility pressure of the injected gas and the formation fluid measured by the reservoir fluid saturation pressure experiment;

[0186] Step 207: Based on the known PVT phase characteristic thermodynamic parameters of the reservoir fluid, a two-phase flash calculation is performed using the PR state equation to calculate the formation fluid density;

[0187] Step 208: determining a volume offset term of the reservoir fluid plus components with the goal of making the calculated formation fluid density approach the same as the formation fluid density obtained by reservoir fluid density measurement;

[0188] Step 209: Based on the known PVT phase characteristic thermodynamic parameters of the reservoir fluid, two-phase flash calculation is performed using the PR state equation and the Pederson model to calculate the formation fluid viscosity;

[0189] Step 210 , with the goal of making the calculated formation fluid viscosity and the formation fluid viscosity obtained by reservoir fluid viscosity measurement approach the same, the viscosity parameter of the reservoir fluid is determined, and the process ends.

[0190] Figure 3 This is a flow chart of a specific example of a method for determining thermodynamic parameters of the PVT phase characteristics of oil reservoir fluids according to an embodiment of the present invention. This process is described using a certain oil reservoir layer A in the above specific embodiment as an example. The specific process may include:

[0191] Step 301: Obtain the components and compositions of formation crude oil and injected gas;

[0192] Step 302: Obtaining the additive component C through experiments 20 + Molecular weight MW, specific gravity SG and normal pressure boiling point T b ;

[0193] Step 303: Add component C 20 + Molecular weight MW, specific gravity SG and normal pressure boiling point T b , using the correlation formula to calculate the added component C 20 + The critical temperature Tc , critical pressure P c and eccentricity factor ω;

[0194] Step 304: Based on the known PVT phase characteristic thermodynamic parameters of the formation crude oil, the PR state equation is used to perform saturation pressure calculation and multiple contact calculation to calculate the formation crude oil saturation pressure P b-cal and / or the minimum miscibility pressure P of injected gas and formation crude oil MMP-cal ;

[0195] Step 305: Using the calculated formation crude oil saturation pressure P b-cal and / or the minimum miscibility pressure P of injected gas and formation crude oil MMP-cal , and the formation crude oil saturation pressure P measured by the reservoir fluid saturation pressure experiment b-exp and / or the minimum miscibility pressure P of injected gas and formation crude oil MMP-exp The goal is to make them similar, and then determine the addition group C. 20 + Binary interaction coefficient BIP with non-hydrocarbon components CO2 and N2;

[0196] Step 306: Based on the known PVT phase characteristic thermodynamic parameters of the formation crude oil, the PR state equation is used to perform two-phase flash calculation to calculate the formation crude oil density ρ cal ;

[0197] Step 307: Using the calculated formation crude oil density ρ cal , and the formation crude oil density ρ obtained by measuring the reservoir fluid density exp The goal is to make the formation crude oil plus component C 20 + The volume offset term c;

[0198] Step 308: Based on the known PVT phase characteristic thermodynamic parameters of the formation crude oil, the PR state equation and the Pederson model are used to perform two-phase flash calculation to calculate the formation crude oil viscosity μ cal ;

[0199] Step 309: Using the calculated formation crude oil viscosity μ cal , and the formation crude oil viscosity μ obtained by measuring the viscosity of the reservoir fluid exp With the goal of making them similar, the viscosity parameters of the formation crude oil are determined: coupling coefficient density index n, and the process ends.

[0200] Figure 4 Schematic diagram of the device for determining the thermodynamic parameters of the PVT phase characteristics of the reservoir fluid in an embodiment of the present invention. Figure 4 As shown, the apparatus for determining thermodynamic parameters of PVT phase characteristics of reservoir fluid in an embodiment of the present invention may include:

[0201] The critical property determination module 401 is used to determine the critical temperature and critical pressure of the reservoir fluid plus component based on the specific gravity and normal pressure boiling point of the reservoir fluid plus component;

[0202] A component eccentricity factor determination module 402 is configured to determine an eccentricity factor of a reservoir fluid component based on a vapor pressure of the reservoir fluid component;

[0203] A binary interaction coefficient determination module 403 is used to determine the binary interaction coefficient between the reservoir fluid plus component and the non-hydrocarbon component based on the result parameters of the reservoir fluid saturation pressure experiment;

[0204] The volume offset term determination module 404 is used to determine the volume offset term of the reservoir fluid plus components based on the result parameters of the reservoir fluid density measurement;

[0205] The viscosity parameter determination module 405 is used to determine the viscosity parameter of the reservoir fluid according to the result parameter of the viscosity measurement of the reservoir fluid.

[0206] The component critical property determination module 401 is specifically used for:

[0207] The critical temperature of the reservoir fluid plus components is determined based on the specific gravity and atmospheric boiling point of the reservoir fluid plus components and the correlation between the specific gravity and atmospheric boiling point of the reservoir fluid plus components and the critical temperature of the reservoir fluid plus components.

[0208] The component critical property determination module 401 is specifically used for:

[0209] The relationship between the specific gravity and atmospheric boiling point of the reservoir fluid plus components and the critical temperature of the reservoir fluid plus components is determined according to the following critical temperature correlation formula:

[0210]

[0211] Among them, T c is the critical temperature of the reservoir fluid plus components; SG is the specific gravity of the reservoir fluid plus components, T b is the atmospheric boiling point of the reservoir fluid plus components.

[0212] The component critical property determination module 401 is specifically used for:

[0213] The critical pressure of the reservoir fluid plus components is determined based on the specific gravity and atmospheric boiling point of the reservoir fluid plus components and the correlation between the specific gravity and atmospheric boiling point of the reservoir fluid plus components and the critical pressure of the reservoir fluid plus components.

[0214] The component critical property determination module 401 is specifically used for:

[0215] The relationship between the specific gravity and atmospheric boiling point of the reservoir fluid plus components and the critical pressure of the reservoir fluid plus components is determined according to the following critical pressure correlation formula:

[0216]

[0217] Among them, P c is the critical pressure of reservoir fluid plus components, SG is the specific gravity of reservoir fluid plus components, T b is the atmospheric boiling point of the reservoir fluid plus components.

[0218] The component eccentricity factor determination module 402 is specifically used for:

[0219] Determining an eccentricity factor of the reservoir fluid plus component based on the vapor pressure of the reservoir fluid plus component includes determining the eccentricity factor of the reservoir fluid plus component according to the following eccentricity factor correlation:

[0220]

[0221] Where ω is the eccentricity factor, The temperature is 0.85T b The vapor pressure of the reservoir fluid plus its components.

[0222] The binary interaction coefficient determination module 403 is specifically used for:

[0223] Based on the known PVT phase characteristic thermodynamic parameters of the reservoir fluid, the PR state equation is used to perform saturation pressure calculation and multiple contact calculation to calculate the formation fluid saturation pressure and / or the minimum miscibility pressure of the injected gas and formation fluid;

[0224] With the goal of making the calculated formation fluid saturation pressure and / or the minimum miscibility pressure of the injected gas and formation fluid approach the same as the formation fluid saturation pressure and / or the minimum miscibility pressure of the injected gas and formation fluid measured by the reservoir fluid saturation pressure experiment, the binary interaction coefficient between the reservoir fluid plus component and the non-hydrocarbon component is determined.

[0225] The binary interaction coefficient determination module 403 is specifically used for:

[0226] The binary interaction coefficient between the reservoir fluid plus component and the non-hydrocarbon component is determined according to the following formula based on the result parameters of the reservoir fluid saturation pressure experiment:

[0227] The PR state equation is:

[0228]

[0229] Where P is pressure, unit is Pa; T is thermodynamic temperature scale, unit is K; V is molar volume, unit is m 3 .mol-1 ; R is the universal gas constant, unit is mol -1 .K -1 ; Constants a and b are the parameters of the PR state equation, and their units are Pa.m 6 .mol -2 and m 3 .mol -1 ;

[0230] For pure components in reservoir fluid, the formulas for calculating a and b are as follows:

[0231]

[0232]

[0233] Among them, P c is the critical pressure of the pure component in the reservoir fluid; T c is the critical temperature of the pure component in the reservoir fluid; ω is the eccentricity factor of the pure component in the reservoir fluid; R is the universal gas constant;

[0234] For mixtures, the formulas for calculating a and b are as follows:

[0235]

[0236]

[0237] Where i & j represent the number of components in the mixture; x i is the mole percentage of component i; x j is the mole percentage of component j; a i is the constant a calculated according to the above formula for component i; a j is the constant a calculated by the above formula for component j; b i is the constant b calculated according to the above formula for component i; δ ij is the binary interaction coefficient between component i and component j.

[0238] The volume offset item determination module 404 is specifically configured to:

[0239] Based on the known PVT phase characteristic thermodynamic parameters of the reservoir fluid, the PR state equation is used to perform two-phase flash calculation to calculate the formation fluid density;

[0240] With the goal of making the calculated formation fluid density approach the same as the formation fluid density obtained from reservoir fluid density measurements, the volume offset term of the reservoir fluid plus components is determined.

[0241] The volume offset item determination module 404 is specifically configured to:

[0242] The volume offset term of the reservoir fluid plus components is determined based on the parameters of the reservoir fluid density measurement results according to the following formula:

[0243] The PR state equation is:

[0244]

[0245] Where P is pressure, unit is Pa; T is thermodynamic temperature scale, unit is K; V is molar volume, unit is m 3 .mol -1 ; R is the universal gas constant, unit is mol -1 .K -1 ; Constants a and b are the parameters of the PR state equation, and their units are Pa.m 6 .mol -2 and m 3 .mol -1 ;

[0246] Volume offset term for pure components in reservoir fluid:

[0247] V corrected =V EOS +c

[0248] Among them, V corrected is the volume of pure component obtained from the formation fluid density measured according to the reservoir fluid density, V EOS is the volume of the pure component obtained from the formation fluid density calculated by two-phase flash evaporation using the PR equation of state, and c is the volume offset term of the pure component in the reservoir fluid;

[0249] For mixtures, the volume offset term is given by:

[0250]

[0251] Among them, c mix is the molar volume weighted average of the parameters of the pure components in the reservoir fluid, x i is the mole percentage of component i, c i is the volume offset term of component i.

[0252] The viscosity parameter determination module 405 is specifically used for:

[0253] Based on the known PVT phase characteristic thermodynamic parameters of the reservoir fluid, the PR state equation and Pederson model are used to perform two-phase flash calculation to calculate the formation fluid viscosity;

[0254] The viscosity parameters of the reservoir fluid are determined with the goal of making the calculated formation fluid viscosity and the formation fluid viscosity obtained by reservoir fluid viscosity measurement approach the same.

[0255] The viscosity parameter determination module 405 is specifically used for:

[0256] The viscosity parameters of the reservoir fluid are determined according to the following formula based on the result parameters of the reservoir fluid viscosity measurement:

[0257] The PR state equation is:

[0258]

[0259] Where P is pressure, unit is Pa; T is thermodynamic temperature scale, unit is K; V is molar volume, unit is m 3 .mol -1 ; R is the universal gas constant, unit is mol -1 .K -1 ; Constants a and b are the parameters of the PR state equation, and their units are Pa.m 6 .mol -2 and m 3 .mol -1 ;

[0260] Pederson Model:

[0261]

[0262]

[0263]

[0264] Where, μ0(p0,t0) is the viscosity of the known reference fluid, μ(p,t) is the viscosity of the target reservoir fluid; T c0 is the critical temperature of the known reference fluid, T c is the critical temperature of the target reservoir fluid; P c0 is the critical pressure of the known reference fluid, P c is the critical pressure of the target reservoir fluid; MW c0 is the molecular molar mass of the known reference fluid, MW c is the molecular molar mass of the target reservoir fluid; α0 is the coupling coefficient of the known reference fluid, α is the coupling coefficient of the target reservoir fluid, characterizing the influence of molecular size and density; ρ r is the comparative density; n is the viscosity parameter of the reservoir fluid, that is, the coupling coefficient density index.

[0265] Based on the above invention concept, Figure 5As shown, the present invention also proposes a computer device 500, including a memory 510, a processor 520, and a computer program 530 stored in the memory 510 and executable on the processor 520, wherein the processor 520 implements the aforementioned method for determining thermodynamic parameters of the PVT phase characteristics of reservoir fluids when executing the computer program 530.

[0266] Based on the aforementioned inventive concept, an embodiment of the present invention further provides a computer-readable storage medium storing a computer program for executing the aforementioned method for determining thermodynamic parameters of the PVT phase characteristics of reservoir fluids.

[0267] In summary, in the embodiments of the present invention, the critical temperature and critical pressure of the reservoir fluid plus component are determined based on the specific gravity and normal pressure boiling point of the reservoir fluid plus component; the eccentricity factor of the reservoir fluid plus component is determined based on the vapor pressure of the reservoir fluid plus component; the binary interaction coefficient between the reservoir fluid plus component and the hydrocarbon component is determined based on the result parameters of the reservoir fluid saturation pressure experiment; the volume offset term of the reservoir fluid plus component is determined based on the result parameters of the reservoir fluid density measurement; and the viscosity parameter of the reservoir fluid is determined based on the result parameters of the reservoir fluid viscosity measurement.

[0268] When determining the PVT phase characteristic thermodynamic parameters of reservoir fluids using traditional methods, it is first necessary to conduct differential degassing, isocratic expansion, isochoric depletion, separator experiments, and expansion experiments. Numerical simulation software is then used to fit the experimental data to obtain the fluid PVT phase characteristic thermodynamic parameters. The large amount of data obtained from these complex experiments is then uniformly fitted, resulting in low accuracy in determining the PVT phase characteristic thermodynamic parameters of reservoir fluids. The method for determining the PVT phase characteristic thermodynamic parameters of reservoir fluids in an embodiment of the present invention, however, obtains a small amount of data through a simple experimental process, then fits the obtained data step by step to gradually determine the PVT phase characteristic thermodynamic parameters of reservoir fluids. This allows for faster and more convenient acquisition of the PVT phase characteristic thermodynamic parameters of reservoir fluids while ensuring the accuracy of the obtained parameters.

[0269] It will be understood by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take 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.) containing computer-usable program code.

[0270] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, 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 processes in the flowcharts and / or block diagrams. 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.

[0271] 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.

[0272] 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.

[0273] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for determining thermodynamic parameters of PVT phase characteristics of reservoir fluids, characterized by: include: Determine the critical temperature and critical pressure of the reservoir fluid plus components based on the specific gravity and atmospheric boiling point of the reservoir fluid plus components; Determine the eccentricity factor of the reservoir fluid plus component based on the vapor pressure of the reservoir fluid plus component; Based on the result parameters of the reservoir fluid saturation pressure experiment, the binary interaction coefficient between the reservoir fluid additive component and the non-hydrocarbon component is determined; Determine the volume offset term of the reservoir fluid plus components based on the result parameters of the reservoir fluid density measurement; Determining the viscosity parameters of the reservoir fluid according to the result parameters of the reservoir fluid viscosity measurement; Determining an eccentricity factor of the reservoir fluid plus component based on the vapor pressure of the reservoir fluid plus component includes determining the eccentricity factor of the reservoir fluid plus component according to the following eccentricity factor correlation: Where ω is the eccentricity factor; The temperature is 0.85T b When the vapor pressure of the reservoir fluid plus components; Determining the binary interaction coefficient between the reservoir fluid plus component and the non-hydrocarbon component based on the result parameters of the reservoir fluid saturation pressure experiment, including: performing saturation pressure calculation and multiple contact calculation using the PR equation of state based on known PVT phase characteristic thermodynamic parameters of the reservoir fluid to calculate the formation fluid saturation pressure and / or the minimum miscibility pressure of the injected gas and the formation fluid; determining the binary interaction coefficient between the reservoir fluid plus component and the non-hydrocarbon component with the goal of making the calculated formation fluid saturation pressure and / or the minimum miscibility pressure of the injected gas and the formation fluid approach the same as the formation fluid saturation pressure and / or the minimum miscibility pressure of the injected gas and the formation fluid measured by the reservoir fluid saturation pressure experiment; The binary interaction coefficient between the reservoir fluid plus component and the non-hydrocarbon component is determined according to the following formula based on the result parameters of the reservoir fluid saturation pressure experiment: The PR state equation is: Where P is pressure, unit is Pa; T is thermodynamic temperature scale, unit is K; V is molar volume, unit is m 3 .mol -1 ; R is the universal gas constant, unit is mol -1 .K -1 ; Constants a and b are the parameters of the PR state equation, and their units are Pa.m 6 .mol -2 and m 3 .mol -1 ; For pure components in reservoir fluid, the formulas for calculating a and b are as follows: Among them, P c is the critical pressure of the pure component in the reservoir fluid, T c is the critical temperature of the pure component in the reservoir fluid, ω is the eccentricity factor of the pure component in the reservoir fluid, and R is the universal gas constant; For mixtures, the formulas for calculating a and b are as follows: Where i & j represent the number of components in the mixture; x i is the mole percentage of component i; x j is the mole percentage of component j; a i is the constant a calculated according to the above formula for component i; a j is the constant a calculated by the above formula for component j; b i is the constant b calculated according to the above formula for component i; δ ij is the binary interaction coefficient between component i and component j; The added component is a mixture of hydrocarbons with a carbon number higher than a predetermined value, and the properties of the components are unknown.

2. The method according to claim 1, wherein Determine the critical temperature of the reservoir fluid plus components based on their specific gravity and atmospheric boiling point, including: The critical temperature of the reservoir fluid plus components is determined based on the specific gravity and atmospheric boiling point of the reservoir fluid plus components and the correlation between the specific gravity and atmospheric boiling point of the reservoir fluid plus components and the critical temperature of the reservoir fluid plus components.

3. The method according to claim 2, wherein The relationship between the specific gravity and atmospheric boiling point of the reservoir fluid plus components and the critical temperature of the reservoir fluid plus components is determined according to the following critical temperature correlation formula: Among them, T c is the critical temperature of the reservoir fluid plus components; SG is the specific gravity of the reservoir fluid plus components; T b is the atmospheric boiling point of the reservoir fluid plus components.

4. The method according to claim 1, wherein Determine the critical pressure of the reservoir fluid plus components based on the specific gravity and atmospheric boiling point of the reservoir fluid plus components, including: The critical pressure of the reservoir fluid plus components is determined based on the specific gravity and atmospheric boiling point of the reservoir fluid plus components and the correlation between the specific gravity and atmospheric boiling point of the reservoir fluid plus components and the critical pressure of the reservoir fluid plus components.

5. The method according to claim 4, wherein The correlation between the specific gravity and atmospheric boiling point of the reservoir fluid plus components and the critical pressure of the reservoir fluid plus components is determined according to the following critical pressure correlation formula: Among them, P c is the critical pressure of reservoir fluid plus components; SG is the specific gravity of reservoir fluid plus components; T b is the atmospheric boiling point of the reservoir fluid plus components.

6. The method according to claim 1, wherein Based on the parameters of the reservoir fluid density measurement results, the volume offset term of the reservoir fluid plus components is determined, including: Based on the known PVT phase characteristic thermodynamic parameters of the reservoir fluid, the PR state equation is used to perform two-phase flash calculation to calculate the formation fluid density; With the goal of making the calculated formation fluid density approach the same as the formation fluid density obtained from reservoir fluid density measurements, the volume offset term of the reservoir fluid plus components is determined.

7. The method according to claim 6, wherein The volume offset term of the reservoir fluid plus components is determined based on the parameters of the reservoir fluid density measurement results according to the following formula: The PR state equation is: Where P is pressure, unit is Pa; T is thermodynamic temperature scale, unit is K; V is molar volume, unit is m 3 .mol -1 ; R is the universal gas constant, unit is mol -1 .K -1 ; Constants a and b are the parameters of the PR state equation, and their units are Pa.m 6 .mol -2 and m 3 .mol -1 ; Volume offset term for pure components in reservoir fluid: In corrected =V EOS +c Among them, V corrected is the volume of pure component obtained from the formation fluid density measured according to the reservoir fluid density, V EOS is the volume of the pure component obtained from the formation fluid density calculated by two-phase flash evaporation using the PR equation of state, and c is the volume offset term of the pure component in the reservoir fluid; For mixtures, the volume offset term is given by: Among them, c mix is the weighted average of the molar volumes of the pure components in the reservoir fluid, x i is the mole percentage of component i, c i is the volume offset term of component i.

8. The method according to claim 1, wherein According to the result parameters of the reservoir fluid viscosity measurement, the viscosity parameters of the reservoir fluid are determined, including: Based on the known PVT phase characteristic thermodynamic parameters of the reservoir fluid, the PR state equation and Pederson model are used to perform two-phase flash calculation to calculate the formation fluid viscosity; The viscosity parameters of the reservoir fluid are determined with the goal of making the calculated formation fluid viscosity and the formation fluid viscosity obtained by reservoir fluid viscosity measurement approach the same.

9. The method according to claim 8, wherein The viscosity parameters of the reservoir fluid are determined according to the following formula based on the result parameters of the reservoir fluid viscosity measurement: The PR state equation is: Where P is pressure, unit is Pa; T is thermodynamic temperature scale, unit is K; V is molar volume, unit is m 3 .mol -1 ; R is the universal gas constant, unit is mol -1 .K -1 ; Constants a and b are the parameters of the PR state equation, and their units are Pa.m 6 .mol -2 and m 3 .mol -1 ; Pederson Model: Where μ0(p0,T0) is the viscosity of the known reference fluid, μ(p,T) is the viscosity of the target reservoir fluid; T c0 is the critical temperature of the known reference fluid, T c is the critical temperature of the target reservoir fluid; P c0 is the critical pressure of the known reference fluid, P c is the critical pressure of the target reservoir fluid; MW c0 is the molecular molar mass of the known reference fluid, MW c is the molecular molar mass of the target reservoir fluid; α0 is the coupling coefficient of the known reference fluid, α is the coupling coefficient of the target reservoir fluid; ρ r is the comparative density; n is the viscosity parameter of the reservoir fluid, that is, the coupling coefficient density index.

10. A device for determining thermodynamic parameters of PVT phase characteristics of oil reservoir fluid, characterized by: include: A module for determining critical properties of the reservoir fluid components is used to determine the critical temperature and critical pressure of the reservoir fluid components based on the specific gravity and normal pressure boiling point of the reservoir fluid components; A component eccentricity factor determination module is used to determine the eccentricity factor of the reservoir fluid component according to the vapor pressure of the reservoir fluid component; A binary interaction coefficient determination module is used to determine the binary interaction coefficient between the reservoir fluid plus component and the non-hydrocarbon component based on the result parameters of the reservoir fluid saturation pressure experiment; A volume offset term determination module is used to determine a volume offset term of the reservoir fluid plus components based on the result parameters of the reservoir fluid density measurement; A viscosity parameter determination module is used to determine the viscosity parameter of the reservoir fluid according to the result parameter of the viscosity measurement of the reservoir fluid; The component eccentricity factor determination module is specifically used to determine the eccentricity factor of the reservoir fluid plus component according to the vapor pressure of the reservoir fluid plus component, including determining the eccentricity factor of the reservoir fluid plus component according to the following eccentricity factor correlation formula: Where ω is the eccentricity factor, The temperature is 0.85T b When the vapor pressure of the reservoir fluid plus components; The binary interaction coefficient determination module is specifically used to: calculate the formation fluid saturation pressure and / or the minimum miscibility pressure of the injected gas and the formation fluid based on the known PVT phase characteristic thermodynamic parameters of the reservoir fluid, using the PR state equation to perform saturation pressure calculation and multiple contact calculation; determine the binary interaction coefficient between the reservoir fluid plus component and the non-hydrocarbon component with the goal of making the calculated formation fluid saturation pressure and / or the minimum miscibility pressure of the injected gas and the formation fluid approach the same as the formation fluid saturation pressure and / or the minimum miscibility pressure of the injected gas and the formation fluid measured by the reservoir fluid saturation pressure experiment; The binary interaction coefficient determination module is specifically used to determine the binary interaction coefficient between the reservoir fluid plus component and the non-hydrocarbon component according to the following formula based on the result parameters of the reservoir fluid saturation pressure experiment: The state equation is: Where P is pressure, unit is Pa; T is thermodynamic temperature scale, unit is K; V is molar volume, unit is m 3 .mol -1 ; R is the universal gas constant, unit is mol -1 .K -1 ; Constants a and b are the parameters of the PR state equation, and their units are Pa.m 6 .mol -2 and m 3 .mol -1 ; For pure components in reservoir fluid, the formulas for calculating a and b are as follows: Among them, P c is the critical pressure of the pure component in the reservoir fluid; T c is the critical temperature of the pure component in the reservoir fluid; ω is the eccentricity factor of the pure component in the reservoir fluid; R is the universal gas constant; For mixtures, the formulas for calculating a and b are as follows: Where i & j are the number of components in the mixture; x i is the mole percentage of component i; x j is the mole percentage of component j; a i is the constant a calculated according to the above formula for component i; a j is the constant a calculated by the above formula for component j; b i is the constant b calculated according to the above formula for component i; δ ij is the binary interaction coefficient between component i and component j; The added component is a mixture of hydrocarbons with a carbon number higher than a predetermined value, and the properties of the components are unknown.

11. The device according to claim 10, wherein The module for determining the critical properties of additive components is specifically used for: The critical temperature of the reservoir fluid plus components is determined based on the specific gravity and atmospheric boiling point of the reservoir fluid plus components and the correlation between the specific gravity and atmospheric boiling point of the reservoir fluid plus components and the critical temperature of the reservoir fluid plus components.

12. The device according to claim 11, wherein The module for determining the critical properties of additive components is specifically used for: The relationship between the specific gravity and atmospheric boiling point of the reservoir fluid plus components and the critical temperature of the reservoir fluid plus components is determined according to the following critical temperature correlation formula: Among them, T c is the critical temperature of the reservoir fluid plus components, SG is the specific gravity of the reservoir fluid plus components, T b is the atmospheric boiling point of the reservoir fluid plus components.

13. The device according to claim 10, wherein The module for determining the critical properties of additive components is specifically used for: The critical pressure of the reservoir fluid plus components is determined based on the specific gravity and atmospheric boiling point of the reservoir fluid plus components and the correlation between the specific gravity and atmospheric boiling point of the reservoir fluid plus components and the critical pressure of the reservoir fluid plus components.

14. The device according to claim 13, wherein The module for determining the critical properties of additive components is specifically used for: The relationship between the specific gravity and atmospheric boiling point of the reservoir fluid plus components and the critical pressure of the reservoir fluid plus components is determined according to the following critical pressure correlation formula: Among them, P c is the critical pressure of reservoir fluid plus components, SG is the specific gravity of reservoir fluid plus components, T b is the atmospheric boiling point of the reservoir fluid plus components.

15. The device according to claim 10, wherein The volume offset item determination module is specifically used to: Based on the known PVT phase characteristic thermodynamic parameters of the reservoir fluid, the PR state equation is used to perform two-phase flash calculation to calculate the formation fluid density; With the goal of making the calculated formation fluid density approach the same as the formation fluid density obtained from reservoir fluid density measurements, the volume offset term of the reservoir fluid plus components is determined.

16. The device according to claim 15, characterized in that The volume offset item determination module is specifically used to: The volume offset term of the reservoir fluid plus components is determined based on the parameters of the reservoir fluid density measurement results according to the following formula: The PR state equation is: Where P is pressure, unit is Pa; T is thermodynamic temperature scale, unit is K; V is molar volume, unit is m 3 .mol -1 ; R is the universal gas constant, unit is mol -1 .K -1 ; Constants a and b are the parameters of the PR state equation, and their units are Pa.m 6 .mol -2 and m 3 .mol -1 ; Volume offset term for pure components in reservoir fluid: In corrected =V EOS +c Among them, V corrected is the volume of pure component obtained from the formation fluid density measured according to the reservoir fluid density, V EOS is the volume of the pure component obtained from the formation fluid density calculated by two-phase flash evaporation using the PR equation of state, and c is the volume offset term of the pure component in the reservoir fluid; For mixtures, the volume offset term is given by: Among them, c mix is the weighted average of the molar volumes of the pure components in the reservoir fluid, x i is the mole percentage of component i, c i is the volume offset term of component i.

17. The device according to claim 10, wherein The viscosity parameter determination module is specifically used for: Based on the known PVT phase characteristic thermodynamic parameters of the reservoir fluid, the PR state equation and Pederson model are used to perform two-phase flash calculation to calculate the formation fluid viscosity; The viscosity parameters of the reservoir fluid are determined with the goal of making the calculated formation fluid viscosity and the formation fluid viscosity obtained by reservoir fluid viscosity measurement approach the same.

18. The device according to claim 17, wherein The viscosity parameter determination module is specifically used for: The viscosity parameters of the reservoir fluid are determined according to the following formula based on the result parameters of the reservoir fluid viscosity measurement: The PR state equation is: Where P is pressure, unit is Pa; T is thermodynamic temperature scale, unit is K; V is molar volume, unit is m 3 .mol -1 ; R is the universal gas constant, unit is mol -1 .K -1 ; Constants a and b are the parameters of the PR state equation, and their units are Pa.m 6 .mol -2 and m 3 .mol -1 ; Pederson Model: Where μ0(p0,T0) is the viscosity of the known reference fluid, μ(p,T) is the viscosity of the target reservoir fluid; T c0 is the critical temperature of the known reference fluid, T c is the critical temperature of the target reservoir fluid; P c0 is the critical pressure of the known reference fluid, P c is the critical pressure of the target reservoir fluid; MW c0 is the molecular molar mass of the known reference fluid, MW c is the molecular molar mass of the target reservoir fluid; α0 is the coupling coefficient of the known reference fluid, α is the coupling coefficient of the target reservoir fluid; ρ t is the comparative density; n is the viscosity parameter of the reservoir fluid, that is, the coupling coefficient density index.

19. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the method according to any one of claims 1 to 9 is implemented.

20. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method according to any one of claims 1 to 9 is implemented.

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