# Method of determining characteristics of pore volume and thermal conductivity of matrix of porous materials

FIELD: measuring equipment.

SUBSTANCE: for determining the characteristics of pore volume and thermal conductivity of matrix of samples of porous materials, the sample of porous material is alternately saturated with at least two fluids with different known thermal conductivity. As at least one saturating fluid a mixture of fluids from at least two fluids with different known thermal conductivity is used. After each saturation of the sample the thermal conductivity of the saturated sample of the porous material is measured, and the characteristics of pore volume and thermal conductivity of the matrix of the sample of porous material is determined taking into account the results of thermal conductivity measurements.

EFFECT: increased accuracy and stability of determining the characteristics of the pore volume and the thermal conductivity of the test samples.

14 cl, 2 dwg

The technical field

The invention relates to the field of study of the physical properties of heterogeneous porous materials, namely, the characterization of the pore space and thermal conductivity of the matrix (space filled only solid substance) of these materials.

For heterogeneous porous materials can include, for example, industrial materials, unconsolidated and consolidated rock samples and minerals.

The level of technology

There is a method of determining the characteristics of the pore space and thermal conductivity of the matrix for the sample of porous material by measuring thermal conductivity of the sample, consistently busy three fluids with different thermal conductivity (Popov et al. Interrelations between thermal conductivity and other physical properties of rocks: experimental data. Pure and Appl. Geophys., 160, 2003, p.p.1137-1161). The method is based on determining the porosity of a sample of porous material, thermal conductivity of the matrix and forms of pores and cracks, which are modeled by ellipsoids of rotation and are characterized by the aspect ratio. The porosity of a sample of porous material, thermal conductivity of the matrix and the aspect ratio of the ellipsoids, simulating the pores and cracks, are determined by solving a system of three nonlinear equations with three unknowns using measurements of thermal conductivity on the sample of porous material, the reproduction is consequently busy three fluids with known different conductivity. The equations in this system are of equal theoretical and experimental values of thermal conductivity of samples of porous material, consistently busy three fluids with known different conductivity. theoretical values of thermal conductivity is determined using a known method of self-consistency of theory of efficient environments, which allows to Express thermal conductivity of a porous material, depending on thermal conductivity of the matrix, the fluid filling the pores and cracks, porosity and aspect ratios of the ellipsoid. The disadvantages of this method are as follows: (1) use the same aspect ratio for the characteristic shape as long and cracks, aspect ratio which in fact differs by several orders of magnitude, (2) the method requires sequential saturation of the sample of porous material in three different fluids, thermal conductivity of which must meet the following three conditions: a) it must be known for each fluid, b) she should have significantly different values, each of which should be selected in advance in accordance with specific requirements in accordance with the conductivity, porosity and characteristics of the pore space of the studied porous heterogeneous materials C) thermal conductivity data Tr is x fluids must be in a specific range of values, want to select in advance depending on thermal conductivity, porosity and characteristics of the pore space of the studied porous heterogeneous materials. The last three conditions is a serious problem because of the lack of ready fluids in nature. In addition, the disadvantage of this known method is not accurate characterization of the pore space and thermal conductivity of the matrix due to the fact that only limited measurements of thermal conductivity of fluid-saturated porous heterogeneous material and not use the results of additional measurements of other physical properties, which may include, for example, longitudinal or transverse elastic wave velocities, electrical conductivity, hydraulic and dielectric constant, density, volumetric heat capacity.

The closest analogue of the claimed method is a method of determining the characteristics of the pore space and thermal conductivity of the matrix (Popov et al. Physical properties of rocks from the upper part of the Yaxcopoil-1 drill hole, Chicxulub crater. Meteoritics &Planetary Science 39, Nr 6, 2004, p.p.799-812), which consists in the successive saturation of the sample of porous material at least two fluids with different known thermal conductivity and the determination of the porosity of the sample. After each saturation of the sample p is ristoro material fluid conducting the measurement of thermal conductivity of the sample. Collectively, the results of measurements of thermal conductivity and porosity of the sample of porous material at a known value to determine the characteristics of the pore space and the conductivity matrix of the sample of porous material.

The disadvantages of this method is the following: (1) more than two unknown quantities are determined from only two measurements of thermal conductivity, which leads to the possibility of the existence of a fairly wide area of different solutions for the characteristics of the pore space and thermal conductivity of the matrix; (2) the porosity must be known in advance; (3) the method requires sequential saturation of the sample of porous material in two different fluids, thermal conductivity of which must meet the following two conditions: a) it must be known for each fluid, b) she should have significantly different values in the range that should be selected in advance in accordance with the conductivity, porosity and characteristics of the pore space of the studied porous heterogeneous materials. The last two conditions is a serious problem because of the lack of ready fluids in nature. In addition, the disadvantage of this known method is not accurate characterization of the pore space and thermal conductivity of the Mat is itzá, in the that is limited only by the measurement of thermal conductivity of fluid-saturated porous heterogeneous material and not use the results of additional measurements of other physical properties, which may include, for example, longitudinal or transverse elastic wave velocities, electrical conductivity, hydraulic and dielectric constant, density, volumetric heat capacity.

Disclosure of inventions

Technical result achieved during the implementation of the present invention is to improve the sustainability of the characterization of the pore space and thermal conductivity of the matrix due to the use as an additional nourishing substances mixtures of two or more fluids with different thermal conductivity. This leads to the possibility of saturation of the studied porous heterogeneous materials fluids with pre-defined thermal conductivity and increase the number of experimental values of the physical properties (thermal conductivity and other properties, including, for example, elastic wave velocities, electrical conductivity, hydraulic and dielectric constant, density, volumetric heat capacity, which are used to determine unknown parameters - characteristics of the pore space and thermal conductivity of the matrix. The conductivity brewed this about what atom mixtures can be determined by measurement or by calculation) and known for each mixture. In addition, the conductivity of such mixtures can have significantly different values, each of which may be selected in advance in accordance with specific requirements in accordance with the conductivity, porosity and characteristics of the pore space of the studied porous heterogeneous materials. In addition, it may be made a condition under which thermal conductivity data of mixtures of fluids is in a certain range of values that can be selected in advance depending on thermal conductivity, porosity and characteristics of the pore space of the studied porous heterogeneous materials. The possibility of increasing the number of nourishing substances through the use of mixtures of two or more fluids of different, including pre-defined, the conductivity also allows you to not require that the porosity of the porous material was known in advance, and to include it among the determined values along with the characteristics of the pore space and the conductivity of the matrix.

This technical result is achieved due to the fact that the sample of porous material alternately saturate at least two fluids with different known conductivity, and as at least one saturated fluid, a mixture of fluids from at least two f is widow with different known conductivity. After each saturation of the sample is measured saturated conductivity of the sample of porous material and define the characteristics of the pore space and thermal conductivity of the matrix of the sample of porous material based on the results of measurements of thermal conductivity. Characteristics of the pore space include porosity and geometrical parameters of the pore space. In another embodiment of the invention the porosity of the samples of porous materials can be determined in advance.

thermal conductivity of the mixture of fluids can be determined in advance according to the known values of thermal conductivity of each of the mixed fluids and volumes or masses of mixed fluids. In accordance with another embodiment of the invention, the conductivity of the mixture of fluids can be determined by measuring thermal conductivity of the mixture after mixing of fluids.

In accordance with another embodiment of the invention, thermal conductivity or the range of thermal conductivity of the mixture of fluids set in advance.

As fluids can be used with oil and water.

As at least one of the fluid mixture can be used a gas with a known thermal conductivity, for example, air. When using at least two mixtures of fluids containing gas with a known t what proposedvalue, different thermal conductivity of the mixtures provided by the use of the same gas with different humidity.

In accordance with one embodiments of the invention pre-determine the required values of thermal conductivity of the fluid, the number of prepared mixtures of fluids and thermal conductivity values prepared mixtures of fluids.

In accordance with another embodiment of the invention after each saturation of the sample of porous material is measured at least one physical property of a sample, and the results of the determination of additional physical properties of the sample of porous material is used together with the results of determination of thermal conductivity of the sample of porous material for the characterization of the pore space and thermal conductivity of the matrix of the sample of porous materials.

Additionally is determined by the physical property of a sample of porous material may be at least one property from the following groups: elastic wave velocities, electrical conductivity, permeability, density, volumetric heat capacity.

The saturated conductivity of the sample can be determined by optical scanning.

Brief description of drawings

The invention is illustrated by drawings, shown in figure 1 and figure 2. Figure 1 illustrates the location is adelene volume of voids on the aspect relationship, built on detected parameters of the Beta distribution (α=3.0, β=1.1), when the porosity of the sample was unknown, and was the target parameter along with the Beta distribution and matrix conductivity. Figure 2 shows the distribution of volume of voids on the aspect of otnosheniy built on detected parameters of the Beta distribution (α=7.1, β=1.8), in the case where the porosity of the sample was known in advance.

The implementation of the invention

In accordance with the proposed method, in addition to the saturation of the sample of porous material one or more fluid with a known conductivity and conducted following this, the measurement of thermal conductivity of saturated porous sample material the sample is saturated with at least one mixture of two or more fluids with a variety of known thermal conductivity. Every time after saturation of the sample of porous material measure its conductivity. The measured values of thermal conductivity of the sample of porous material saturated with one or more mixtures of two or more fluids are used to determine the characteristics of the pore space and thermal conductivity of the matrix of the sample of porous material. Characteristics of the pore space include porosity and geometrical parameters of the pore space (for example, TSA is ktoe the ratio of the ellipsoids, modeling of emptiness, the parameters of the distribution function of the aspect ratios of the pores and cracks or any other quantities characterizing the shape of the pores and cracks, the amount, orientation, or size).

Porosity, geometrical parameters of the pore space and the conductivity matrix for the sample of porous material is determined so that the discrepancy between experimental values of thermal conductivity obtained at each saturation of the sample of porous material, and theoretical values of thermal conductivity of the sample of porous material does not exceed the specified value. theoretical value of thermal conductivity of the sample of porous material, depending on the porosity of the geometrical parameters of the pore space and thermal conductivity of the matrix is determined using known relationships between thermal conductivity of the sample of porous material with a porosity values, geometrical parameters of the pore space and thermal conductivity of the matrix. For example, for this purpose can be used with the known composition of methods of theory of efficient environments, is shown below.

Let the measurement of thermal conductivity are carried out in a direction that is specified in the master coordinate system by the vector n=(n_{1}n_{2}n_{3}). The main coordinate system is defined by the elements of symmetry the sample of porous material and the effective conductivity tensor is diagonal.
Then in this direction, thermal conductivity is determined by the known formula:

where λ^{*}effective conductivity tensor in the principal coordinate system associated with the porosity ϕ, geometrical parameters of the pore space defined by the tensor g and the tensor of thermal conductivity of the matrix λ^{M}as follows (Popov et al., Interrelations between thermal conductivity and other physical properties of rocks: experimental data. Pure Appl. Geophys., 160, 2003, pp.1137-1161):

In the formula (2) the angular brackets denote volume averaging, which in the case of statistically homogeneous medium can be replaced by statistical averaging over the ensemble.