RU2181883C1 - Procedure measuring permeability - Google Patents

Abstract

FIELD: measurement of permeability of materials under conditions of volumetric filtration. SUBSTANCE: procedure includes measurement of initial volume of material, placement of material into chamber with liquid, rise of pressure in chamber to force liquid into material, replacement of gas present in pores of material, measurement of time of replacement of gas by liquid, measurement of volume of liquid forced into material. Then permeability of material under conditions of volumetric filtration is found with due account of additional corrections related to compressibility of liquid and deformability of material, parameter of geometric dimensions and value of volume viscosity. EFFECT: increased accuracy and speed of measurement of permeability. 17 cl, 10 dwg \

Description

 The invention relates to the study of the physical characteristics of solids and can be used to measure the permeability of materials in volumetric filtration.

 A known method of measuring the permeability of materials located directly inside the hydrocarbon reservoir [1].

This method consists in measuring the pressure of the reservoir fluid P _f , creating a hydrodynamic disturbance in the reservoir fluid by supplying the fluid to a special well with fixed dimensions in the first period of time with a flow rate of Q ₁ , measuring the pressure P _{1 of the} fluid after the first period of time, creating a second hydrodynamic disturbance in formation fluid through the fluid in the second time period at a rate Q _2, the pressure measurement P ₂ to the end of the second time period, determining the values of viscosity of the liquid in plas e and the subsequent calculation of the horizontal and vertical permeability.

 The limitations of the method include the low accuracy of determining permeability due to the inability to determine the shear viscosity parameter directly using this method, the use of viscosity values obtained using other methods, and the subsequent calculation of permeability.

 A known method of measuring the permeability of materials in an unsteady flow [2].

 This method consists in placing a core sample in a chamber with a closed fixed volume of approximately 1-4 times the volume of the pore space of the sample, crimping the sample along the side surface to eliminate the effect of gas slipping, applying fluid (usually gas) to one of the ends of this core. at a fixed pressure, measuring the time dependence of the pressure rise at the other end of the core and calculating the permeability.

 The limitation of this method is the measurement duration, due to the fact that for the correct use of the calculation formula, it is necessary to measure the time dependence of the pressure increase at the other end of the core until the pressure increases with an increment of less than 0.06 MPa.

 Another limitation of the method is its insufficient accuracy, which is due to the need to introduce a large number of free parameters when approximating the experimental pressure dependence. In addition, when calculating the permeability, it is necessary to know the shear viscosity of the fluid used at given pressures, information on the value of which is not always available.

 The closest in technical essence and the achieved result is a method of measuring permeability, including measuring the initial volume of the material, placing the material in the chamber with the liquid, increasing the pressure in the chamber to press the liquid into the material and replacing the gas in the pores of the material, measuring the time of gas replacement with liquid, measuring volume of fluid pressed into the material, determination of permeability [3].

 This method consists in placing the material in a chamber filled with liquid, applying a fixed pressure of 50 atm to the liquid in order to cause gas to replace the material in the pores of the liquid, measuring the time required to replace the gas in the pores of the material with liquid, and measuring the volume of liquid necessary for such a substitution.

где Q = ΔV/Δt - объемный расход жидкости, ΔV - объем профильтрованной жидкости за время Δt, η_s - сдвиговая вязкость жидкости, ΔP - перепад давления, L - длина материала, F - площадь поперечного сечения образца материала. Перепад давления ΔP в этом техническом решении задается в 50 ат и поддерживается вручную, что трудно осуществить на практике с высокой точностью.The limitation of the method is the possibility of only a rough estimate of the permeability of the samples of materials by the time of filling the pores. This drawback is due to the fact that the filling of the pores of the sample occurs at a variable flow rate and a variable pressure drop, which allows only approximately to use the linear Darcy filtering law in calculations:

where Q = ΔV / Δt is the volumetric flow rate of the liquid, ΔV is the volume of the filtered liquid over the time Δt, η _s is the shear viscosity of the liquid, ΔP is the pressure drop, L is the length of the material, F is the cross-sectional area of the material sample. The pressure drop ΔP in this technical solution is set at 50 atm and is maintained manually, which is difficult to implement in practice with high accuracy.

Another limitation of the method is the need to use samples of materials with large overall dimensions. The volumes of the samples ranged from 6 to 25 cm ³ , and, as a result, there is a need for large quantities of mercury, used as a liquid to fill the pores.

A further limitation of the method is that when calculating the permeability k _pr , the liquid flow rate is used without taking into account its compressibility, as well as the compressibility of the material, which introduces a significant error in the measured liquid flow rate Q and, accordingly, permeability.

 Indeed, at a pressure of 50 atm, both the liquid itself and the material undergo comprehensive compression. Therefore, in the measured volume of liquid when filling the pore space of the material, it is necessary to make appropriate corrections.

 Another significant limitation is that the moment of complete filling of the pores in the known method is not determined. In the known technical solution, it is believed that at pressures of 50 atm all the pores of the material are already filled. Therefore, in the known method, the flow rate of the liquid when filling the pores of the material is determined by the volume of liquid pressed into the material at a pressure of 50 atm. However, for most materials, the pores are completely filled at pressures significantly less than 50 atm, or for a limited number of materials at pressures greater than 50 atm. As a result, a significant error is introduced in determining the volume of fluid needed to fill the pores, and hence the flow rate of fluid Q.

Another significant limitation of the known method is that when calculating the permeability of the material used shear viscosity η _{s of the} filtered fluid; in this case, firstly, its dependence on pressure is not taken into account, and secondly, when the method is implemented, there is a volumetric indentation (compression) of the liquid into the sample material. When implementing the method under conditions of volume compression, the volumetric viscosity of the liquid η _ν , the value of which is almost always significantly greater than the shear viscosity η _s, should appear in the calculation formulas. In all of the above methods, the value η _{ν of} bulk viscosity was not taken into account when determining permeability.

 The problem solved by the invention is to increase the efficiency and quality of measurements.

 The technical result that can be obtained by implementing the inventive method is to increase the accuracy and speed of measuring the permeability of samples of materials.

 To solve the problem with the achievement of the specified technical result in a method of measuring permeability, including measuring the initial volume of the material, placing the material in the chamber with the liquid, increasing the pressure in the chamber for pressing the liquid into the material and replacing the gas in the pores of the material, measuring the time of gas replacement with liquid, measuring the volume of liquid pressed into the material, determining the permeability of the material according to the invention before placing the material in a chamber with liquid in it they place this liquid, increase the pressure in the chamber and measure the compressibility of the liquid, increase the pressure in the chamber at two different isothermal compression rates to measure the bulk viscosity of the liquid and its pressure dependence, after placing the material in the chamber, increase the pressure in the chamber when the isothermal indentation of the liquid into the material, measuring the volume of liquid pressed into the material, simultaneously measure the temporal response of the pressure change and the baric dependence of the volume of the liquid with t inflection points, which determine the moment when the material pores are completely filled with liquid, the time dependence of the change in the liquid volume to determine the liquid flow rate, after the material pores are completely filled with liquid, they additionally increase the pressure in the chamber and measure the deformability of the material, take into account additional corrections related to compressibility in the measured liquid volume fluid and deformability of the material, respectively, determine the parameter of the geometric dimensions of the material, determine the permeability of the material in terms of volume of fluid filter according to additional amendments, and geometrical dimensions of the parameter values of the bulk viscosity in the range of pressures to a pressure value of the total pore filling with liquid material.

где σ₁,σ₂ - значения давлений для двух скоростей изотермического сжатия, соответственно, при одинаковых значениях объема камеры,
∂/∂t(ΔV/V)₁, ∂/∂t(ΔV/V)₂ - значения скоростей изменения деформации жидкости для двух скоростей изотермического сжатия, соответственно, при одинаковых значениях объема камеры;
- сжимаемость β_ж жидкости определяли по кривой барической зависимости объема жидкости от давления по формуле

где V_L - объем жидкости при давлении Р_ср,
ΔV_L - изменение объема жидкости при изменении давления на ΔP, где ΔP = P₂-P₁ - из всего диапазона измерения,
P_ср=(Р₂+Р₁)/2 - среднее давление жидкости в камере;
- деформируемость β_s материала определяли по формуле

где P_ср= (P₂+P₁)/2 - среднее давление жидкости в камере из диапазона давлений, больших давления Р* полного заполнения пор,
V_s - объем материала при атмосферном давлении Р_at,
ΔP(ΔP = P₂-P₁) - приращение давления, при давлениях P₁ и Р₂, соответственно, больших давления Р* полного заполнения пор,
ΔV_м - деформируемость материала при увеличении давления на ΔP,
V_Σ1,V_Σ2 - суммарные объемы, включающие объем жидкости и объем помещенного в нее материала, при давлениях P₁ и Р₂, соответственно, из диапазона давлений, больших давления Р* полного заполнения пор,
V_l ¹ - объем жидкости при давлении P₁, когда в камере размещены жидкость и материал,
V_L1, V_L2 - объемы жидкости для давлений P₁ и Р₂ соответственно, когда в камере размещена только жидкость;
- параметр α₀ геометрических размеров образца материала определяли при атмосферном давлении по формуле α₀= S₀/V_s, где
S₀ - площадь поверхности материала при атмосферном давлении Р_at,
V_s - объем материала при атмосферном давлении P_at;
- барическую зависимость параметра геометрических размеров α для материала определяли по формуле
α(P_cp) = α₀•[1+1/3•β_s(P_cp)•ΔP],
где P_ср=(p₁+p₂)/2 - среднее давление жидкости в камере для давлений p₁, р₂, меньших давления Р* полного заполнения пор,
β_s - сжимаемость материала при давлении Р_ср, полученная аппроксимацией барической зависимости β_s/ в диапазон давлений, меньших давления Р* полного заполнения пор,
ΔP(ΔP = p₂-p₁) - приращение давления за промежуток времени Δt;
- проницаемость k_pr материала при ламинарном течении жидкости определяли по формуле

где ΔV - объем жидкости, вдавленной в поры за время Δt при изменении давления на ΔP, где ΔP = (p₂-p₁) - приращение давления за тот же промежуток времени Δt из диапазона давлений, меньших давления Р* полного заполнения пор,
Р_ср=(p₂+р₁)/2 - среднее давление в промежутке времени Δt,
ΔV_n= ΔV_ж+ΔV_м - поправка на объем жидкости, вдавленной в поры при изменении давления на ΔP, обусловленная сжимаемостью ΔV_ж жидкости и деформируемостью ΔV_м материала,
ΔV_ж= β_ж•V_ж•ΔP,
ΔV_м= β_s•V_м•ΔP,
V_ж - объем жидкости при Р_ср,
V_м - объем материала при Р_ср, V_м= V_s•[1-β_s(P_cp)•ΔP],
η_ν - объемная вязкость жидкости при Р_ср,
α - параметр геометрических размеров материала при Р_ср,
- проницаемость k_pr материала при турбулентном течении жидкости определяли из формулы

где ΔV - объем жидкости, вдавленной в поры за время Δt при изменении давления на ΔP, где ΔP = (p₂-p₁) - приращение давления за тот же промежуток времени Δt из диапазона давлений, меньших давления Р^* полного заполнения пор,
Р_ср=(р₂+p₁)/2 - среднее давление в промежутке времени Δt,
ΔV_n = ΔV_ж+ΔV_м - поправка на объем жидкости, вдавленной в поры при изменении давления на ΔP, обусловленная сжимаемостью ΔV_ж жидкости и деформируемостью ΔV_м материала,
ΔV_ж= β_ж•V_ж•ΔP,
ΔV_м= β_s•V_м•ΔP,
V_ж - объем жидкости при Р_ср,
V_м - объем материала при Р_ср, V_м= V_s•[1-β_s(P_cp)•ΔP],
η_ν - объемная вязкость жидкости при Р_ср,
α - параметр геометрических размеров материала при Р_ср,
ρ - плотность жидкости при среднем давлении Р_ср, выбирается из справочных данных,
m - пористость материала, выбирается из справочных данных,
d - средний размер зерен материала, выбирается из справочных данных;
- определяли барическую зависимость проницаемости материала.When carrying out the invention, additional embodiments of the method are possible, in which it is advisable that:
- isothermal indentation of the liquid into the material was carried out at a constant flow rate;
- isothermal indentation of the liquid into the material was carried out at a flow rate ensuring a laminar flow of liquid in the material;
- isothermal indentation of the liquid into the material was carried out at a flow rate ensuring a turbulent flow of liquid in the material;
- isothermal indentation of the liquid into the material and an additional increase in pressure was performed at a constant rate of change in pressure in the chamber;
- isothermal indentation of the liquid into the material and an additional increase in pressure were made stepwise;
- the time t * of the full filling of the pores was determined by the inflection point on the time dependence of the pressure derivative ∂P / ∂t when the liquid is pressed into the material;
- pressure P * of the full filling of the pores was determined by the inflection point on the baric dependence of the derivative on the volume of the liquid ∂V / ∂t when it is pressed into the material;
- after complete filling of the pores of the material with liquid, the pressure in the chamber was additionally increased to a value exceeding the pressure of the full filling of pores by at least 5 times;
- an additional increase in pressure in the chamber was made up to pressures of 300 MPa;
- bulk viscosity of the liquid was determined by the formula

where σ ₁ , σ ₂ - pressure values for two isothermal compression rates, respectively, for the same values of the chamber volume,
∂ / ∂t (ΔV / V) ₁ , ∂ / ∂t (ΔV / V) ₂ are the values of the fluid deformation rate for two isothermal compression rates, respectively, at the same chamber volume;
- compressibility β _W fluid was determined by the curve of the baric dependence of the fluid volume on pressure by the formula

where V _L is the volume of liquid at a pressure P _cf ,
ΔV _L is the change in liquid volume when the pressure changes by ΔP, where ΔP = P ₂ -P ₁ - from the entire measurement range,
P _cf = (P ₂ + P ₁ ) / 2 - the average pressure of the liquid in the chamber;
- deformability β _{s of the} material was determined by the formula

where P _cf = (P ₂ + P ₁ ) / 2 - the average pressure of the liquid in the chamber from the pressure range, large pressure P * full filling of the pores,
V _s - the volume of the material at atmospheric pressure P _at
ΔP (ΔP = P ₂ -P ₁ ) is the pressure increment, at pressures P ₁ and P ₂ , respectively, large pressure P * full filling of pores,
ΔV _m - deformability of the material with increasing pressure by ΔP,
V _Σ1 , V _Σ2 - total volumes, including the volume of liquid and the volume of the material placed in it, at pressures P ₁ and P ₂ , respectively, from a pressure range greater than pressure P * full filling of pores,
V _l ¹ - the volume of liquid at a pressure P ₁ when liquid and material are placed in the chamber,
V _L1 , V _L2 - liquid volumes for pressures P ₁ and P _2, respectively, when only liquid is placed in the chamber;
- parameter α _{0 of the} geometric dimensions of the material sample was determined at atmospheric pressure according to the formula α ₀ = S ₀ / V _s , where
S ₀ - the surface area of the material at atmospheric pressure P _at
V _s is the volume of the material at atmospheric pressure P _at ;
- the pressure dependence of the geometric dimension parameter α for the material was determined by the formula
α (P _cp ) = α ₀ • [1 + 1/3 • β _s (P _cp ) • ΔP],
where P _cf = (p ₁ + p ₂ ) / 2 is the average pressure of the liquid in the chamber for pressures p ₁ , p ₂ lower than the pressure P * full filling of the pores,
β _s is the compressibility of the material at a pressure P _cr obtained by approximating the pressure dependence β _{s /} in the pressure range lower than the pressure P * of the full filling of pores,
ΔP (ΔP = p ₂ -p ₁ ) is the pressure increment over the period of time Δt;
- the permeability k _{pr of the} material in the laminar flow of liquid was determined by the formula

where ΔV is the volume of fluid pressed into the pores during the time Δt when the pressure changes by ΔP, where ΔP = (p ₂ -p ₁ ) is the pressure increment for the same time period Δt from the pressure range smaller than the pressure P * of the full filling of the pores,
P _cf = (p ₂ + p ₁ ) / 2 - average pressure in the time interval Δt,
ΔV = ΔV _n + ΔV _{w m} - correction amount of fluid forced back into the pores when the pressure on ΔP, ΔV due to the compressibility of the fluid and _{g m} ΔV deformability of the material,
ΔV _W = β _W • V _W • ΔP,
ΔV _m = β _s • V _m • ΔP,
V _W - the volume of fluid at P _cf ,
V _m - the volume of material at R _cf. , V _m = V _s • [1-β _s (P _cp ) • ΔP],
η _ν is the bulk viscosity of the liquid at P _cf ,
α is the parameter of the geometric dimensions of the material at R _cf ,
- the permeability k _{pr of the} material in a turbulent fluid flow was determined from the formula

where ΔV is the volume of fluid pressed into the pores during the time Δt when the pressure changes by ΔP, where ΔP = (p ₂ -p ₁ ) is the pressure increment for the same time period Δt from the pressure range smaller than the pressure P ^{* of the} full filling of the pores,
P _cf = (p ₂ + p ₁ ) / 2 - average pressure in the time interval Δt,
ΔV = ΔV _n + ΔV _{w m} - correction amount of fluid forced back into the pores when the pressure on ΔP, ΔV due to the compressibility of the fluid and _{g m} ΔV deformability of the material,
ΔV _W = β _W • V _W • ΔP,
ΔV _m = β _s • V _m • ΔP,
V _W - the volume of fluid at P _cf ,
V _m - the volume of material at R _cf. , V _m = V _s • [1-β _s (P _cp ) • ΔP],
η _ν is the bulk viscosity of the liquid at P _cf ,
α is the parameter of the geometric dimensions of the material at R _cf ,
ρ is the density of the liquid at an average pressure P _cf , is selected from the reference data,
m is the porosity of the material, is selected from the reference data,
d is the average grain size of the material, is selected from the reference data;
- determined the baric dependence of the permeability of the material.

 Due to the indentation of the fluid into the pore space of the material in real time, the determination of the compressibility of the fluid and the deformability of the material, as well as the bulk viscosity of the fluid, by the nature of the time and pressure dependences of the change in the volume of the fluid with the material placed in it and the time dependences of pressure during indentation, it was possible to solve the problem with the achievement of the technical result.

 These advantages and features of the present invention are illustrated by the best option for its implementation with reference to the figures.

Figure 1 depicts a device for implementing the inventive method;
FIG. 2 - baric dependence of the total fluid volume in the process of pressing into the pores of the material;
figure 3 - time dependence of changes in the volume of fluid in the process of pressing into the pores of the material;
figure 4 - time dependence of the fluid pressure in the process of pressing into the pores of the material;
FIG. 5 - time dependence of the derivative of pressure in the process of pressing into the pores of the material;
FIG. 6 - pressure dependence of the derivative of the total volume in the process of pressing into the pores of the material;
FIG. 7 - baric dependence of the relative volume of the liquid at two isothermal compression rates;
FIG. 8 - time dependences of the relative volume of the liquid at two isothermal compression rates;
FIG. 9 - dependences of the rate of change of the fluid deformation on the relative volume of the fluid at two isothermal compression rates;
figure 10 - baric dependence of the bulk viscosity of the liquid.

 The device (Fig. 1) for implementing the claimed method comprises a chamber 1 with a sample of material 3 placed in it through a hermetically sealed cover 2, a liquid 4 filling the chamber 1, volume 5, pressure b, and temperature sensors 7. A pressure generating system consists of series-connected an actuator 8 with a controlled input, an electric motor 9, a gearbox 10, a high-pressure cylinder 11 with a rod 12, the translational movement of which through the seal assembly 13 provides a pressure increase in the chamber 1. The device has a data receiving unit 14, to the input of which signals from sensors 5, 6, 7 are supplied, and the first output is connected to the data processing unit 15. The diagram also shows: a differentiating device 16 for differentiating time dependences of the volume and pressure from block 14, an information display unit 17 and a block 18 that synchronizes the operation of the entire device, controls the operation of the actuator 8 and sets the necessary conditions: liquid compression rate 4, removal rate experimental points in real time.

The rotational movement of the stepper motor 9 through the gearbox 10 is converted into the translational motion of the rod 12. The number of motor steps per revolution of the shaft is 50,000. The linear movement of the rod per revolution of the motor shaft is 2 mm. Thus, the minimum linear displacement of the motor rod in one step is 0.04 microns. As a result of this control of the engine, the pressure in the chamber 1 can vary with a constant or variable speed from 0.1 MPa / s to 57 MPa / s, volume from 10 ^-3 mm ³ / s to 30 mm ³ / s, as well as discrete jumps leading to discrete changes in the volume of liquid 4 when pressed into the pores of the material 3. In addition, such a compression mode can be realized in which isothermal conditions are ensured. Since temperature data are entered into the data processing unit 15, due to the introduction of feedback, the compression of the liquid 4 can be carried out with automatic adjustment of the compression rate and due to this isothermal conditions of the compression process (T ^o = const).

 The process of measuring permeability is performed as follows.

The chamber 1 is filled with liquid 4 and, at a fixed temperature, a measurement is made in real time of the dependence of the volume of liquid V on pressure P in the pressure range of interest. It is convenient to present the data obtained in the form of a dependence of the relative volume V / V _L (V is the current volume at a given pressure P, V _L is the initial volume of liquid 4 at atmospheric pressure equal to the volume V _{k of} chamber 1, V _L = V _k ) on pressure or from time. An example of such a dependence for kerosene in the pressure range up to 50 MPa and a temperature of 20 ^o C is shown in figure 2, curve 1.

If in a chamber 1 containing liquid 4 (see Fig. 1), place a sample of material 3 of known sizes and measure the pressure and time dependence of the total volume of liquid 4 with the sample placed in it (the initial volume of liquid V ₁ in this case is equal to the volume of the vessel of the high pressure V _k minus the volume of the sample V _s : V ₁ = V _k -V _s ), then from the obtained data one can obtain information on the permeability of the sample of material 3. A typical example of the obtained dependence of the relative total volume of the liquid 4 with the mat sample immersed in it rial 3 from the pressure shown in figure 2, curve 2. As the liquid 4 was also used kerosene at a temperature of 20 ^o C.

From figure 2 it can be seen that there is a significant difference between curves 1 and 2, namely: for curve 2 there is a sharp drop in the relative volume in the initial section of the curve. At pressures greater than 3 MPa, the dependence of the relative volume goes to a smooth curve similar to curve 1 for liquid 4. A sharp drop in the relative volume on curve 2 is due to the filling of the pores of material 3 with liquid 4. With a further increase in pressure over 3 MPa, the dependence of the relative total volume V _Σ from pressure goes to a smooth gentle curve, which indicates that the pore space of material 3 is already filled with liquid 4 and with a further increase in pressure, only liquid 4 and material 3 are compressed to the whole under the influence of hydrostatic pressure forces. Using the dependencies shown in curves 1 and 2, as well as the dependencies shown in FIGS. 3-6, the permeability of the sample can be calculated with high accuracy.

где ΔP - перепад давления на торцах образца материала 3 длиной L, ΔV - объем жидкости 4, профильтрованный через образец за время Δt, Δt - время фильтрации, S - площадь поперечного сечения образца материала 3, η_s - сдвиговая вязкость.In accordance with Darcy's law for the case of laminar flow of fluid 4 through the end surfaces of a sample of material 3

where ΔP is the pressure drop at the ends of the sample of material 3 with a length L, ΔV is the volume of liquid 4 filtered through the sample during Δt, Δt is the filtration time, S is the cross-sectional area of the sample of material 3, η _s is the shear viscosity.

Typically, when measuring permeability, a steady-state stationary mode is used, in which the flow rate ΔV / Δt, the average pressure in the material sample is 3 P _cf , and the pressure drop ΔP is constant in time (stationary conditions). In this case, a cylindrical or rectangular sample is used, the liquid 4 is filtered through the ends of the sample, and the shear viscosity η _{s is} used in formula (1). This mode corresponds to the laminar flow of fluid 4 and is realized at low filtration rates that satisfy the condition
Re <1, where Re = LU _ρ / η _s is the Reynolds number, U is the velocity of the fluid 4, ρ is the density of the fluid 4.

A significant difference of the proposed method compared to the existing ones is that, firstly, the proposed method uses volumetric filtration of the liquid 4 into the pore volume of the material 3 through the entire surface of the material 3, and not through the ends. Secondly, this filtration occurs under conditions of a continuously increasing pressure from atmospheric P _at to pressure P * of complete filling of the pores. Thirdly, since the indentation mode is accompanied by compression of the liquid 4 and the material 3 immersed in it, when measuring the flow rate of the liquid 4, it is possible to take into account the corrections due to the compressibility of the liquid 4 and the deformability of the material 3, and also substitute the shear viscosity η _s in the calculation formula for shear viscosity η _{s ν} . In addition, it is possible to take into account the baric dependence of the bulk viscosity η _ν when the liquid 4 is compressed to a pressure P * of completely filling the pores of the material 3.

Dependencies (Fig. 2-6) allow us to determine the permeability for any pressure P _cf from the pressure range from atmospheric P _at to P *. First, the pressure P * of the full filling of the pores and the moment t * of the full filling of the pores are determined.

As noted above, on the curve of figure 2 there is a characteristic kink that indicates the end of the filling of the pores with liquid 4. Let P * be the pressure of the full filling of pores; at this pressure, a sharp change in the nature of the pressure dependence of the relative total volume occurs (see figure 2, curve 2). This point can also be determined by a kink in the time dependence of pressure (see Fig. 4), by a jump in the first derivative of the pressure versus time (see Fig. 5) or in the first derivative of the pressure dependence of the total volume (see Fig. 6). So, for figure 2, the value of P * is approximately 3 MPa (ΔP = P ^* -P _at ). The value of the relative total volume V $\genfrac{}{}{0ex}{}{\text{*}}{\text{Σ}}$ / V _L , corresponding to pressure P *, gives information about the volume of fluid ΔV filtered into the pores. Indeed, the product of the initial total fluid volume V _L by the amount of change in the relative total volume [1-V $\genfrac{}{}{0ex}{}{\text{*}}{\text{Σ}}$ / V _L ] is equal to the volume ΔV of the liquid 4 filtered into the pores, with a pressure drop ΔP = P ^* -P _at . The filtration time t * spent on completely filling the pores with the liquid 4 is easily determined from FIG. 4 or FIG. 5.

где α - параметр геометрических размеров материала 3,
η_v - объемная вязкость жидкости.After finding the pressure P * and the moment t * when the pores are completely filled, the time dependence of the change in the volume of liquid 4 (Fig. 3) is divided into discrete time intervals Δt _j in the interval from 0 to t *. These discrete time intervals Δt _j correspond to changes in the volume ΔV _j (Fig.3). From the time dependence of the pressure (Fig. 4), discrete pressure drops ΔP _{j are} determined for the average pressures P _cpj (P _cpj = (p ₂ + p ₁ ) / 2, where p ₁ , p ₂ are the pressures from the pressure range from atmospheric P _at to P *) corresponding to the above time intervals Δt _j .
Substituting the obtained values into formula (1) for the condition of volumetric filtration of liquid 4 into the pores of material 3, we obtain the formula for calculating the permeability at a specific pressure P _cpj :

where α is the parameter of the geometric dimensions of the material 3,
η _v is the bulk viscosity of the liquid.

где ΔV - объем жидкости 4, профильтрованный при вдавливании за время Δt при изменении давления на ΔP(ΔP = p₂-p₁ - приращение давления за тот же промежуток времени Δt, p₁, p₂ - давления из диапазона от атмосферного P_at до давления Р*,
P_ср=(p₂+p₁)/2 - среднее давление в промежутке времени Δt,
η_ν - объемная вязкость жидкости 4 при данном среднем давлении Р_ср,
α - - параметр геометрических размеров материала 3 при среднем давлении Р_ср.Passing to the analytical form of mathematical expression (2), we obtain

where ΔV is the volume of liquid 4 filtered during indentation during the time Δt when the pressure changes by ΔP (ΔP = p ₂ -p ₁ is the pressure increment for the same period of time Δt, p ₁ , p ₂ is the pressure from the atmospheric P _at to pressure P *,
P _cf = (p ₂ + p ₁ ) / 2 - average pressure in the time interval Δt,
η _ν is the bulk viscosity of the liquid 4 at a given average pressure P _cf ,
α - is the parameter of the geometric dimensions of the material 3 at an average pressure P _cf.

необходимо учесть поправки, обусловленные этими факторами.Since when the liquid 4 is pressed into the pores of the material 3, the change in the volume of the liquid 4 occurs not only due to the filling of the pores, but also due to the compressibility of the liquid 4 itself and the deformability of the material 3, then in the liquid volume ΔV filtered during the pressing, during

corrections due to these factors must be taken into account.

The correction for the fluid volume ΔV _p filtered into the pores at a given average pressure P _cf , due to the compressibility of the fluid ΔV _w and the deformability of the material ΔV _m , is calculated by the formula
ΔV _n = ΔV _w + ΔV _m , (4)
where ΔV _W - correction due to the compressibility of the liquid 4 and determined by the formula
ΔV _W = β _W • V _W • ΔP, (5)
ΔV _m - correction due to the deformability of the material 3 and determined by the formula
ΔV _m = β _s • V _s • ΔP, (6)
β _W , β _s - compressibility of the fluid 4 and material 3, respectively; V _W , V _s - the volume of liquid 4 and material 3, respectively.

 The proposed method allows to determine the above amendments.

где V_L - объем жидкости 4 при заполнении камеры 1 только жидкостью 4 (кривая 1, фиг.2).The value of β _{g is} determined from the experimental data on compression for the case when the chamber 1 is filled only with liquid 4 (figure 2, curve 1). In this case, the expression for the compressibility of the liquid β _W will be calculated as follows:

where V _L is the volume of liquid 4 when filling the chamber 1 only with liquid 4 (curve 1, figure 2).

And, therefore, substituting β _g from formula (7) into formula (5), we determine the correction due to the compressibility of the liquid ΔV _g .
From formula (6) it follows that in order to find the correction due to the deformability of material 3, it is necessary to know its compressibility β _s . This value can be obtained by processing the measurement results (figure 2, curve 2).

After filling the pores (at pressures above P *), curve 2 gives the total change in the volume of liquid 4 (initial value of volume V _{1 of} liquid) and volume of material 3 (initial value of volume V _{s of} sample material 3). We use two close pressure values P ₁ and P ₂ with a small pressure difference between them ΔP in the pressure range between P * and P _max ( _figure 2). Let V _L1 , V _L2 be the volumes of liquid 4 at pressures P ₁ and P ₂ for the 1st curve, respectively (Fig. 2) is the case in which the entire chamber 1 with a volume of V _{k is} filled with liquid 4, V _l1 , V _l2 are the volumes liquid 4 at pressures P ₁ and P _2, respectively, for the case when the chamber 1 is filled with liquid 4 and contains a sample of material 3, and V _Σ1 , V _Σ2 are the total volumes, including the volume of liquid 4 and the volume of the sample of material 3 placed in it at pressures P ₁ and P _2, respectively, as shown in figure 2, curve 2.

The absolute deformation of the combined medium ΔV _Σ (liquid 4 with a sample of material 3 placed in it) is equal to (figure 2, curve 2):
ΔV _Σ | V _Σ2 -V _Σ1 | = ΔV _w + ΔV _m , (8)
where ΔV _W = V ₁₂ -V ₁₁ , ΔV _m = V _s2 -V _s1 , where V _s1 , V _s2 is the volume of the sample of material 3 at a pressure of P ₁ , P _2, respectively.

Величину V_l ¹ можно определить по формуле
V_l ¹=(1-V_s/V_L)•V_L1. (10)
Действительно, при сжатии отношение текущего объема жидкости 4 к начальному объему одинаково при равных давлениях и не зависит от начального объема жидкости 4 (то есть от того, какая часть камеры 1 заполнена жидкостью 4). Поэтому отношение V_L1/V_L (для случая, когда весь объем камеры 1 заполнен жидкостью 4) равно отношению V_l ¹/V_l (для случая, когда в жидкость 4 камеры 1 погружен образец материала 3). Тогда с учетом соотношения V_l=V_L-V_s получаем формулу (10).Then, taking into account formulas (5), (7), for pressures ΔP = P ₂ -P ₁ :

The value of V _l ¹ can be determined by the formula
V _l ¹ = (1-V _s / V _L ) • V _L1 . (10)
Indeed, under compression, the ratio of the current volume of liquid 4 to the initial volume is the same at equal pressures and does not depend on the initial volume of liquid 4 (that is, on what part of chamber 1 is filled with liquid 4). Therefore, the ratio V _L1 / V _L (for the case when the entire volume of chamber 1 is filled with liquid 4) is equal to the ratio V _l ¹ / V _l (for the case when a sample of material 3 is immersed in the liquid 4 of chamber 1). Then, taking into account the relation V _l = V _L −V _s, we obtain formula (10).

Таким образом, формулы (8)-(11) позволяют определить абсолютную деформацию ΔV_м материала 3 в любом диапазоне гидростатического давления, а также сжимаемость материала 3 в соответствии с формулой (6) равна:

Таким образом, предлагаемый способ позволяет определить деформацию ΔV_м материала 3, что используется в дальнейшем для уточнения окончательной величины проницаемости. Сжимаемость материала 3 можно определить по формуле (12) только для давлений Р_ср, больших давления Р* полного заполнения пор. В области давлений Р_ср, меньших давления Р* полного заполнения пор, используются значения β_s, полученные аппроксимацией барической зависимости β_s, рассчитанной по формуле (12). Кроме того, учитывая слабую зависимость β_s от давления, в диапазоне от P_at до Р* можно принять значение β_s равным β_s(P^*). После подстановки вычисленного значения β_s в формулу (6) и далее в (4) и (3) получим уточненную формулу определения проницаемости материала 3:

Указанная формула справедлива при медленном вдавливании жидкости 4 в материал 3, т.е. при малых скоростях фильтрации в условиях ламинарного течения.Substituting the obtained value ΔV _W from formula (9) into formula (8), we obtain for deformation ΔV _m of material sample 3

Thus, formulas (8) - (11) make it possible to determine the absolute deformation ΔV _{m of} material 3 in any range of hydrostatic pressure, as well as the compressibility of material 3 in accordance with formula (6) is equal to:

Thus, the proposed method allows to determine the deformation ΔV _{m of} material 3, which is used in the future to clarify the final value of permeability. The compressibility of the material 3 can be determined by the formula (12) only for pressures P _cf , large pressure P * full filling of the pores. In the range of pressures P _cr lower than the pressure P * of the full filling of pores, the values of β _s obtained by approximating the pressure dependence β _s calculated by formula (12) are used. In addition, given the weak pressure dependence of β _s , it is possible to take β _s equal to β _s (P ^* ) in the range from P _at to P *. After substituting the calculated value of β _s in the formula (6) and then in (4) and (3) we obtain an updated formula for determining the permeability of material 3:

This formula is valid when slowly squeezing the liquid 4 into the material 3, i.e. at low filtration rates under conditions of laminar flow.

The parameter geometric dimensions of the material α in formula (13) under atmospheric conditions will be equal to the ratio of the area of the material S ₀ to its volume V _s : α ₀ = S ₀ / V _s , where S ₀ is the surface area of the material 3 at atmospheric pressure, V _s - volume of material 3 at atmospheric pressure. Since the filtration of liquid 4 into the pore space of material 3 occurs with increasing pressure from atmospheric to full filling pressure P *, it is necessary to take into account the pressure dependence of the parameter of the geometric dimensions of the material α. The pressure dependence of the geometric dimension parameter α for an isotropic material 3 of arbitrary shape is determined by the formula
α = α ₀ • [1 + 1/3 • β _s (P _cp ) • ΔP], (14)
where β _s is the compressibility of the material 3 at a pressure P _cf determined by the formula (12).

где σ₁,σ₂ - значения давлений при двух скоростях изотермического сжатия и одинаковых значениях объема камеры 1; ∂/∂t(ΔV/V)₁,∂/∂t(ΔV/V)₂ - значения скоростей изменения деформации жидкости 4 при двух скоростях изотермического сжатия и одинаковых значениях объема камеры 1.Instead of shear viscosity η _s for the proposed method should be used bulk viscosity η _ν . Indeed, the comprehensive compression of liquid 4 when filling the pores of material 3 is accompanied by dissipative losses, which are phenomenologically associated with the bulk viscosity parameter (see L. D. Landau, V. M. Lifshits. Hydrodynamics, M .: Nauka, T.6, 1988, 730 s.). To determine the bulk viscosity of the fluid η _ν , fluid 4 is placed in chamber 1 and isothermally compressed at two different pressure increase rates (see Fig. 7). At the same time, the time dependences of changes in the volume of liquid 4 under compression are measured (see Fig. 8) and the time derivatives of these dependencies are determined at two compression rates. So, Fig. 8 shows the time dependences of the relative volume of liquid 4 at two compression rates: 0.7 MPa / s (curve 1) and 7 MPa / s (curve 2), and Fig. 9 shows the dependences of the first derivatives of the relative volume of liquid 4 (rate of change of volumetric deformation) at two compression rates from the relative volume (position of the translationally moving rod 12 in the chamber 1). The subsequent calculation of the values of bulk viscosity η _ν and its baric dependence is performed according to the formula

where σ ₁ , σ ₂ - pressure values at two speeds of isothermal compression and the same values of the volume of the chamber 1; ∂ / ∂t (ΔV / V) ₁ , ∂ / ∂t (ΔV / V) ₂ are the values of the rates of change of the deformation of fluid 4 at two speeds of isothermal compression and the same values of the volume of chamber 1.

Thus, the measurement of the relative volume of liquid 4 at various isothermal compression rates in real time allows us to calculate the bulk viscosity of fluid 4 at any P _cf , to calculate the pressure dependence of the bulk pressure and use this data to correctly calculate the permeability of samples of materials 3 by the formula (13) .

As follows from formulas (3) - (13), the accuracy of determining the permeability of material 3 is mainly determined by the accuracy of determining the volume of liquid V and pressure R. The accuracy of determining V is ~ 10 ^-3 mm ³ and is ensured by the correspondingly selected high resolution of volume, pressure sensor 5 6 and high accuracy of the data processing unit 15.

11) разбивают временную зависимость объема жидкости (фиг.3) на такие же дискретные отрезки времени Δt_j, которым соответствуют дискретные значения изменения объема ΔV_j. Для данной операции можно использовать барическую зависимость объема (фиг.2), разбивая ее на те же, как и в пункте 10, дискретные участки ΔP_j;
12) для каждого дискретного участка ΔP_j по формулам (4)-(6) рассчитывается поправка ΔV_n и параметр геометрических размеров α по формуле (14);
13) для каждого среднего значения Р_ср (из диапазона от P_at до Р*) и каждого интервала ΔP_j рассчитывается значение проницаемости по формуле (13).The following sequence of operations is proposed for measuring the permeability of material 3:
1) the placement of the liquid 4 in the chamber 1 and the measurement of the pressure dependence of its volume (curve 1, figure 2), the determination of the compressibility of the liquid β _W and its pressure dependence;
2) the deformation of the fluid 4 during two cycles of isothermal compression with a small and high compression rate (Fig.7);
3) measurement of time dependences of volume changes during two cycles of isothermal compression of a liquid 4 (Fig. 8);
4) measuring the rate of change of the deformation of the liquid 4 in two cycles of isothermal compression (Fig.9) and the calculation of bulk viscosity according to the formula (15) (Fig.10);
5) measurement of the volume of the material V _m and its surface area S ₀ under atmospheric conditions, calculation of the parameter of the geometric dimensions of the material 3 at atmospheric pressure;
6) placing the material 3 in the chamber 1 with the liquid 4 and measuring the pressure dependence of the volume of the pressed liquid 4 (figure 2, curve 2). Determination of the compressibility of the material β _s according to the formula (12);
7) measuring the time dependence of volume and pressure when indenting fluid 4 into the pores of material 3 (Figs. 3, 4);
8) determination of the pressure of the complete filling of the pores of material 3 with liquid P * at the inflection point on the baric dependence of the total volume (Fig. 2, curve 2) or on the baric dependence of the rate of change of volume (Fig. 6);
9) determining the moment when the pores of material 3 are completely filled with liquid t * on the time dependence of pressure (Fig. 4) or on the time dependence of the derivative of pressure ∂P / ∂t (Fig. 5);
10) dividing the time dependence of pressure (Fig. 4) from the interval from P _at to P * into discrete sections ΔP _j = (p _{j + 1-} p _j ), which correspond to discrete time intervals Δt _j from the interval from 0 to t * sec . Determine the average pressure P _cf = (p _{j + 1} + p _j ) / 2 in each time interval

11) divide the time dependence of the liquid volume (Fig. 3) into the same discrete time intervals Δt _j , to which the discrete values of the volume change ΔV _j correspond. For this operation, you can use the pressure dependence of the volume (figure 2), dividing it into the same, as in paragraph 10, discrete sections ΔP _j ;
12) for each discrete section ΔP _j using the formulas (4) - (6), the correction ΔV _n and the geometric dimension parameter α are calculated by the formula (14);
13) for each average value of P _cf (from the range from P _at to P *) and each interval ΔP _j , the permeability value is calculated by the formula (13).

When dividing the time dependence of pressure, you can use the option of dividing P (from the interval from P _at to P *) into equal segments ΔP _j (in this case, the time intervals Δt _j may not necessarily be equal) or the option of dividing t - time (from the interval from 0 to t * sec) into equal segments. In the second case, ΔP _j may turn out to be unequal.

 The proposed method allows to determine the parameter P *, at which the pores of the material 3 are completely filled with liquid 4, with a high degree of accuracy by the characteristic fracture in the pressure dependence of the total volume (Fig. 2) or pressure dependence of the derivative ∂V / ∂t on the total volume (Fig. 6), as well as at the time t * of the complete filling of the pores of the material 3 with the liquid 4 (the time t * uniquely corresponds to the pressure P * of the full filling of the pores) on the time dependence of the pressure (Fig. 4), or at the inflection point (sharp break) at time curl imosti first ∂P / ∂t pressure derivative (5).

The differentiating device 16 introduced to the input of the data processing unit 15 makes it possible to determine the moment t * with high accuracy from a characteristic break in the time dependence. The value of t * is sent to the data processing unit 15, in which P * is found. Similarly, the data processing unit 15 calculates the volume ΔV _{j of the} liquid 4 pressed into the pores of the material 3, corrects ΔV _n for the compressibility of the liquid 4 and the deformability of the material 3, calculates the bulk viscosity, the geometric dimension parameter, and also the final calculation of the permeability of the material 3 by the formula ( 13) and the issuance of data in tabular and graphical form on the display unit 17. Block 18 synchronizes the operation of the device, controls the operation of the actuator 8 and sets the necessary conditions for the implementation of the method: the compression rate of the liquid 4, the frequency of removal of experimental points in real time.

 The compressibility of the fluid 4 by the formula (7) is determined for a given fluid 4 only once, and then it is stored and used by the data processing unit 15 as a constant for this fluid 4.

 Since the device (Fig. 1) is equipped with a temperature sensor 7, due to automatic control it is possible to increase the pressure in the chamber 1 and / or additionally increase the pressure in the chamber 1 at a speed that provides isothermal indentation of the liquid 4 into the material 3. Moreover, the isothermal indentation of the liquid 4 into the pores of material 3 can be produced at a constant flow rate, which provides both stationary filtration at low flow rates and the absence of the influence of flow acceleration in laminar flow, as well as non-stationary filtration at large lower filtration rates and turbulent flow of fluid 4. In addition, the indentation of fluid 4 into the pores can be performed at a constant rate of increase in pressure, as well as with a sudden change in pressure.

 At low filtration rates, the condition of laminar filling of pores with liquid 4 is observed and formula (13) is used to calculate the permeability and its pressure dependence. The baric dependence of permeability is calculated only up to pressures P * corresponding to the full filling of pores. At pressures greater than P *, the flow of fluid 4 into the pores is absent.

где ΔV - объем жидкости 4 при вдавливании за время Δt при изменении давления на ΔP, где ΔP = (p₂-p₁) - приращение давления за тот же промежуток времени Δt из диапазона давлений, меньших давления Р* полного заполнения пор,
P_cp = (p₂-p₁)/2 - среднее давление в промежутке времени Δt,
ΔV_n = ΔV_ж+ΔV_м - поправка на объем жидкости 4, вдавленной в поры при изменении давления на ΔP, обусловленная сжимаемостью ΔV_ж жидкости 4 и деформируемостью ΔV_м материала 3,
ΔV_ж = β_ж•V_ж•ΔP,
ΔV_м = β_s•V_м•ΔP,
V_ж - объем жидкости 4 при Р_ср,
V_м - объем материала 3 при Р_ср, V_м = V_s•[1-β_s(P_cp)•ΔP],
η_ν - объемная вязкость жидкости 4 при Р_ср,
α - параметр геометрических размеров материала 3 при Р_ср,
ρ - плотность жидкости 4 при среднем давлении Р_ср, выбирается из справочных данных,
m - пористость материала 3, выбирается из справочных данных,
d - средний размер зерен материала 3, выбирается из справочных данных.At high filtration rates, which are realized at high rates of liquid 4 being pushed into the pores (i.e., at high ΔV / Δt flow rates), formula (13) ceases to be valid, since due to a number of expansions and narrowings of the liquid flow 4 when filling the pore space material 3 possible formation of twists. In this case, the proposed method uses a two-term filtration equation, similar to the Reynolds equation in a straight pipe, but taking into account the bulk viscosity of the liquid 4 and the presence of volumetric, rather than linear filtration, filtration geometry. The permeability k _pr is determined from the formula

where ΔV is the volume of liquid 4 during indentation during the time Δt when the pressure changes by ΔP, where ΔP = (p ₂ -p ₁ ) is the pressure increment over the same time period Δt from the pressure range smaller than the pressure P * of the full filling of pores,
P _cp = (p ₂ -p ₁ ) / 2 - average pressure in the time interval Δt,
ΔV _n = ΔV _W + ΔV _m is the correction for the volume of liquid 4 pressed into the pores when the pressure changes by ΔP, due to the compressibility ΔV _{W of} liquid 4 and deformability ΔV _{m of} material 3,
ΔV _W = β _W • V _W • ΔP,
ΔV _m = β _s • V _m • ΔP,
V _W - the volume of fluid 4 at P _cf ,
V _m - the volume of material 3 at P _cf , V _m = V _s • [1-β _s (P _cp ) • ΔP],
η _ν is the bulk viscosity of the liquid 4 at P _cf ,
α is the parameter of the geometric dimensions of the material 3 at P _cf ,
ρ is the density of the liquid 4 at an average pressure P _cf , is selected from the reference data,
m is the porosity of the material 3, is selected from the reference data,
d is the average grain size of the material 3, is selected from the reference data.

При Re_v≤10^-13 скорость движения штока 12 составляет ~ 1 мм/с, в этом случае реализуется ламинарное течение жидкости 4, и проницаемость рассчитывается по соответствующей формуле (13). При Re_v>10^-13 нарушается условие ламинарного вдавливания жидкости 4, и в этом случае необходимо пользоваться нелинейной формулой (16) определения проницаемости.By analogy with the flow of fluid 4 through pipes for the conditions of indentation (flow) of fluid 4, the dimensionless coefficient Re _v (Reynolds number for the volume flow of fluid) is introduced into the pores of material 3, which characterizes the resistance to fluid flow 4:

When Re _v ≤10 ^{-13, the} speed of the rod 12 is ~ 1 mm / s, in this case a laminar flow of liquid 4 is realized, and the permeability is calculated by the corresponding formula (13). When Re _v > 10 ^-13, the condition of laminar indentation of fluid 4 is violated, and in this case it is necessary to use the nonlinear formula (16) for determining permeability.

 The table presents comparative data on the measurement of permeability of the claimed method and the traditional method.

 The comparison results indicate the high accuracy of the proposed method. It should be noted that to improve the accuracy of determining permeability and reduce the time of the experiment, it is better to use a liquid 4 that does not wet the sample. When using a wetting liquid 4, the material 3 must be coated with a special gel before immersion in the chamber 1, which protects the sample from wetting at atmospheric pressure, but allows the liquid 4 to be filtered through the surface of the material 3 with an increase in pressure above atmospheric. The time of the experiment for measuring permeability of the proposed method is significantly reduced and is only a few minutes in case of high costs.

 The proposed method can also be used to measure the phase permeability of partially saturated samples. In this case, the material 3 is partially saturated for some time with the first liquid, for example water, and then the phase permeability of the second liquid, for example oil, is determined using it as a liquid 4 for filtering into the pores of the material 3 in accordance with the specified method.

 The most successfully claimed method of measuring permeability can be industrially used in geology, geophysics, soil science in studying the process of permeability of clays, soils, in the mining and oil and gas industry in determining the permeability of rocks, in construction, as well as in other areas in which capillary is used porous media.

Sources of information
1. European application EP 0520903, E 21 B 49/00, publ. 1992

 2. Application of Great Britain 2127559, G 01 N 13/08, publ. 1984 year

 3. US patent 2327642, 73-38, publ. 1943

Claims (18)

 1. A method of measuring permeability, including measuring the initial volume of the material, placing the material in the chamber with the liquid, increasing the pressure in the chamber to press the liquid into the material and replacing the gas in the pores of the material, measuring the time it takes for the gas to replace the liquid, measuring the volume of liquid pressed into the material, determining the permeability of the material, characterized in that before placing the material in the chamber with the liquid in this fluid is placed in it, increase the pressure in the chamber and measure the compressibility of the fluid increase the pressure in the chamber at two different speeds of isothermal compression to measure the bulk viscosity of the liquid and its pressure dependence, after placing the material in the chamber, increase the pressure in the chamber when isothermally indenting the liquid into the material, while measuring the volume of the liquid pressed into the material, the temporal characteristic of the pressure change is simultaneously measured and the baric dependence of the liquid volume with finding the inflection point in them, by which the moment of complete filling of the pores of the liquid material is determined Accordingly, the time dependence of the change in the volume of the liquid to determine the liquid flow rate, after the pores of the material are completely filled with liquid, the pressure in the chamber is additionally increased and the deformability of the material is measured; , determine the permeability of the material in terms of volumetric fluid filtration, taking into account additional amendments, parameter and geometric sizes and quantities of bulk viscosity in the range of pressures to a pressure value of the total pore filling with liquid material.  2. The method according to p. 1, characterized in that the isothermal indentation of the liquid into the material is carried out at a constant flow rate.  3. The method according to p. 1, characterized in that the isothermal indentation of the liquid into the material is carried out at a cost that provides a laminar flow of liquid in the material.  4. The method according to p. 1, characterized in that the isothermal indentation of the liquid into the material is carried out at a cost that ensures a turbulent flow of liquid in the material.  5. The method according to p. 1, characterized in that the isothermal indentation of the liquid into the material and an additional increase in pressure are produced at a constant rate of change of pressure in the chamber.  6. The method according to p. 1, characterized in that the isothermal indentation of the liquid into the material and an additional increase in pressure are produced stepwise. 7. The method according to p. 1, characterized in that the moment t ^{* of the} full filling of the pores is determined by the inflection point on the time dependence of the pressure derivative ∂P / ∂t when the liquid is pressed into the material. 8. The method according to p. 1, characterized in that the pressure P ^* full filling of the pores is determined by the inflection point on the pressure dependence of the derivative of the volume of the liquid ∂V / ∂t when it is pressed into the material.  9. The method according to p. 1, characterized in that after the pores are completely filled with liquid, the pressure in the chamber is additionally increased to a value that exceeds the pore filled pressure by at least 5 times.  10. The method according to p. 1, characterized in that the additional increase in pressure in the chamber is produced up to pressures of 300 MPa. 11. The method according to p. 1, characterized in that the bulk viscosity of the liquid is determined by the formula

where σ ₁ , σ ₂ - pressure values for two isothermal compression rates, respectively, at the same chamber volume;
∂ / ∂t (ΔV / V) ₁ , ∂ / ∂t (ΔV / V) ₂ are the values of the fluid deformation rate for two isothermal compression rates, respectively, for the same chamber volume. 12. The method of claim. 1, characterized in that the fluid compressibility β _w is determined by the pressure dependence of the liquid volume curve of pressure according to the formula

where V _L is the volume of liquid at a pressure P _cf ;
ΔV _L is the change in the volume of the liquid when the pressure changes by ΔP (ΔP = P ₂ -P ₁ ), P ₁ , P ₂ - from the entire range of pressure measurement;
P _cf = (P ₂ + P ₁ ) / 2 - the average pressure of the liquid in the chamber. 13. The method according to p. 1, characterized in that the deformability β _{s of the} material is determined by the formula

where P _cf = (P ₂ + P ₁ ) / 2 - the average pressure of the liquid in the chamber from the pressure range, large pressure P ^* full filling of pores;
V _s - the volume of the material at atmospheric pressure P _at
ΔP (ΔP = P ₂ -P ₁ ) is the pressure increment, at pressures P ₁ and P _2, respectively, greater than pressure P ^{* of the} full filling of pores;
ΔV _m - deformability of the material with increasing pressure by ΔP;
V _Σ1 , V _Σ2 - total volumes, including the volume of liquid and the volume of the material placed in it, at pressures P ₁ and P _2, respectively, from a pressure range greater than pressure P ^{* of} full filling of pores;
V _l ¹ is the volume of liquid at a pressure of P ₁ when liquid and material are placed in the chamber;
V _L1 , V _L2 - fluid volumes for pressures P ₁ and P _2, respectively, when only liquid is placed in the chamber. 14. The method according to p. 1, characterized in that the parameter α _{0 the} geometric dimensions of the sample material is determined at atmospheric pressure by the formula
α ₀ = S ₀ / V _s ,
where S ₀ is the surface area of the material at atmospheric pressure P _at ;
V _s - the volume of the material at atmospheric pressure P _at . 15. The method according to p. 14, characterized in that the pressure dependence of the parameter of geometric dimensions α for the material is determined by the formula
α (P _cf ) = α ₀ • [1 + 1/3 • β _s (P _cf ) • ΔP],
where P _cf = (p ₁ + p ₂ ) / 2 - the average pressure of the liquid in the chamber for pressures p ₁ , p ₂ less than the pressure P ^* full filling of pores;
β _s is the compressibility of the material at a pressure P _cr obtained by approximating the pressure dependence β _s to a pressure range lower than the pressure P ^{* of the} full filling of pores;
ΔP = (p ₂ -p ₁ ) is the pressure increment. 16. The method according to p. 3, characterized in that the permeability k _{pr of the} material during a laminar flow of liquid is determined by the formula

where ΔV is the volume of liquid pressed into the pores of the material during the time Δt when the pressure changes by ΔP, where ΔP = (p ₂ -p ₁ ) is the pressure increment for the same time period Δt from the pressure range smaller than the pressure P ^{* of the} full filling of the pores;
P _cf = (p ₂ + p ₁ ) / 2 - average pressure in the time interval Δt;
ΔV = ΔV _n + ΔV _{w m} - correction amount of fluid forced back into the pores when the pressure on ΔP, ΔV due to the compressibility of the fluid and _{g m =} ΔV deformability of the material;
ΔV _W = β _W • V _W • ΔP;
ΔV _m = β _s • V _m • ΔP;
V _W - the volume of fluid at P _cf ;
V _m - the volume of material at R _cf , V _m = V _s • [1-β _s (P _cf ) • ΔP];
η _ν is the bulk viscosity of the liquid at P _cf ;
V _s is the volume of the material at atmospheric pressure P _at ;
α is the parameter of the geometric dimensions of the material at R _cf. 17. The method according to p. 4, characterized in that the permeability k _{pr of the} material in a turbulent fluid flow is determined from the formula

where ΔV is the volume of liquid pressed into the pores of the material during the time Δt when the pressure changes by ΔP, where ΔP = (p ₂ -p ₁ ) is the pressure increment for the same time period Δt from the pressure range smaller than the pressure P ^{* of the} full filling of the pores;
P _cf = (p ₂ + p ₁ ) / 2 - average pressure in the time interval Δt;
ΔV = ΔV _n + ΔV _{w m} - correction amount of fluid forced back into the pores when the pressure on ΔP, ΔV due to the compressibility of the fluid and _g ΔV _m deformability of the material;
ΔV _W = β _W • V _W • ΔP;
ΔV _m = β _s • V _m • ΔP;
V _W - the volume of fluid at P _cf ;
V _m - the volume of material at R _cf , V _m = V _s • [1-β _s (P _cf ) • ΔP];
η _ν is the bulk viscosity of the liquid at P _cf ;
α is the parameter of the geometric dimensions of the material at R _cf ;
ρ is the density of the liquid at an average pressure P _cf , is selected from the reference data;
m is the porosity of the material, is selected from the reference data;
d is the average grain size of the material, is selected from the reference data.  18. The method according to p. 1, characterized in that they determine the baric dependence of the permeability of the material.

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