Analysis of Tomographic Images of the Soil Pore Space Structure by Integral Geometry Methods

The technique of numerical analysis of three-dimensional tomographic images of the pore space of soil objects has been used in this paper. It applies methods of integral geometry, topology and morphological analysis. To characterize quantitatively the transformation of the pore space structure, tomographic images of four undisturbed soils were analyzed, i.e., heavy loamy agro-gray soil (Retic Phaeozem), agromineral (Sapric Rheic Mineralic Histosols), and hypnum (brown moss Sapric Rheic Histosols) peat soils in dry and wet conditions. For samples of the subplow horizon in agro-gray soil, a decrease in both Betty numbers was observed on wetting, where the zero number (b0) stands for the amount of topologically simple closed pores, and the first number (b1) indicates a decrease in pore connectivity, which varies in a narrower range of pore sizes as compared to b0. When a sample of agromineral peat soil is moistened, the Euler–Poincaré characteristic is negative ​in the pore range of 0.1–0.16 mm, which points to the predominating complicated branched structure of the pore space and high pore connectivity. When hypnum moss is saturated, a lot of tunnel pores get narrower (“collapse”), and the connectivity decreases due to the structural specifics of long-stemmed plant residues. The number of pores and connections between them in peat soils is an order of magnitude higher than those in the subplow horizon A of the agro-gray soil. The provided quantitative changes in the considered parameters of tomographic images of the soil pore space confirm the possibility of applying them for estimating the transformation of the pore space in soils.

Methodology for determining the average diameter of rock pores and channels by well-log data based on lithological and petrophysical studies

The paper presents a method for determining the parameters characterizing the features of the pore space structure of rocks continuously along the section, based on the results of well-log data interpretation. The results of the well-log data interpretation are presented with diagrams of average values of pore and channel diameters calculated continuously along the section, which are consistent with the results of laboratory measurements on rock samples. The proposed method is based on the use of the established correlation relationships between the slope tangent of the graph of dependence of gas permeability on reciprocal of mean pressure drop and the parameters of the pore space structure, determined from the digital processing of raster electron microscopic images.

Comparative analysis of structure and texture of industrial coke

In this work, industrial samples of coke from two different manufacturers were studied using a complex of structural methods: phase and structural analysis by powder X-ray diffraction, analytical scanning electron microscopy and adsorption porosimetry. The main structural parameters (longitudinal and transverse dimensions of packets and lamellas that fit into packets) and textural characteristics (specific surface area, pore space structure) of the studied samples of industrial coke were determined, and an analysis of the features of their microstructure was made. The results obtained in this work make it possible to unambiguously divide the studied cokes into 2 types: "anisotropic" and "isotropic". For anisotropic coke samples, the longitudinal size of the lamellas that fit into the packs is several times larger than the transverse size of these packets (La >> Lc), and this type of coke is characterized by a pronounced lamellar microstructure. Samples of “isotropic” cokes are characterized by comparable sizes of packets of lamellar layers in the longitudinal and transverse directions (La ≈ Lc) and an amorphous microstructure. Because of the work, a complete relationship was revealed between the structural parameters, shape, morphology and texture characteristics of the particles of coke samples, as well as a sufficient correspondence between the data obtained by three independent methods. The consistency of the conclusions drawn from the results of the analysis of the data of the performed complex of physicochemical studies makes it possible to consider X-ray diffraction analysis in combination with analytical electron microscopy and adsorption porosimetry as the necessary complementary tools for assessing the main properties of cokes with a view to their possible use in various technological processes.

Influence of the pore space structure and wettability on residual gas saturation

A significant part of hydrocarbon deposits in Russia is in the late stage of development. The distribution of residual oil and gas reserves is determined by the properties of the holding rocks. Estimating of deposits’ residual gas saturation is an important scientific task. The allocation of zones with the maximum undeveloped gas reserves will allow to select areas in long-developed fields for the intensification of production in the most efficient way. To search for such “sweet” zones, it is necessary to determine the factors that provide the value of the residual gas saturation. The reliance of the value of trapped in pores, residual gas saturation on such rock properties as pore space structure and wettability is studied in this article. The influence of formation pressure value and behaviour on making up of residual gas saturation during field development is not accounted in this work. The study of a wide collection of core sampled from productive deposits of the Orenburg oil and gas condensate field, the Vuktylskoe oil and gas condensate field, oil and gas field of Orenburg region, and also three areas in the East Caucasian petroleum province confirmed that the value of structure-trapped oil and gas saturation of carbonate and terrigenous rocks is directly proportional to the ratio of pore diameters and channels connecting them. Herewith the angular coefficient of the regression equation for this relationship for carbonate rocks directly depends on the quantitative characteristics of the predominant (relative) wettability. The obtained relationships make it possible to predict the value of residual gas saturation based on knowledge about the pore space structure and the surface properties of rocks.

ANALYSIS OF THE FACTORS OF INCREASING THE STRENGTH OF THE NON-AUTOCLAVE AERATED CONCRETE

non-autoclaved aerated concrete is the only real alternative to gas silicate in the organization of its release on the basis of regional production of small and medium capacity. This will help improve the competitive environment in the building materials market and optimize the cost of construction. Of particular interest is the possibility of expanding the field of application of this material due to a significant increase in strength characteristics, while maintaining its average density in acceptable, in terms of thermal insulation properties, limits - not more than 1000 ... 1100 kg/m3. At a strength level of 10 MPa and above, in combination with dispersed reinforcement or the use of traditional non-metallic reinforcing elements, such aerated concrete can be used as a lightweight structural material for creating power elements of low-rise buildings, including in promising construction printing technologies; devices distributing the load belts; non-removable formwork; porous, stiffening, filling thin-walled tubular structures. The paper presents an assessment of the effectiveness of traditional ways to increase the strength of non-autoclaved aerated concrete. New solutions for the purposeful formation of the pore space structure are proposed and tested due to the creation and use of a gas generator with normalized gas evolution, which allows the creation of pores of a given volume. The key to the economic effectiveness of the proposed solutions is the transition from traditional portland cement to composite binders based on it. The substantiated choice of the amount and composition of the mineral additive makes it possible to optimize the properties of the binder under the particularity of the problem being solved, and to minimize the consumption of cement and chemical modifiers, increase the speed of durability and the final indices of non-autoclaved aerated concrete.