Search

The Upper Devonian shales are predominantly carbonate, carbonate-siliceous thin-layer rocks with a high content of organic matter. Considered formation is widespread within the Volga-Ural and Timan-Pechora basins in the European part of Russia. Various estimations show that the hydrocarbon resources of the Upper Devonian shales range between hundreds of millions to billions of tons of oil. However, recovery of such hydrocarbons is significantly constrained due to the high heterogeneity and complex structure of rocks and its pore space. The paper presents the results of complex lithological studies of Upper Devonian shales based on core material from two wells located in the northern part of the Verkhnekamsk depression. Study includes data obtained with a scanning electron microscopy (SEM), X-ray structural analysis, optical microscopy, nuclear magnetic resonance (NMR) and Rock-Eval pyrolysis method. Analyzed rock samples mainly represent mixed carbonate-siliceous differences with a significant content of organic matter. A total of 11 lithotypes were identified and grouped by the predominant component (carbonate, siliceous), structure, and probable genesis. Within each group, a specific set of void space types were allocated. Only minor part of pores was associated with a mineral matrix; it was shown that the majority of void space is concentrated in the organic-mineral association (a polymer compound of organic matter and mineral component). Images obtained from scanning electron microscope show that the pore size in rock samples varies from 1 to 10 μm. And there is a strong connection between amount of organic matter and porosity coefficient. [ABSTRACT FROM AUTHOR]

Advances in a low field NMR made possible registration of very short relaxation times. It is very useful tool for investigation of tight materials, applicable in many fields of science including geology. In this paper complex characterization of the pore structure and petrophysical properties of flysch sandstones was done by means of several H¹ NMR methods. The following standard experiments corresponding to NMR well-logging were carried out: T1IR (Inversion-recovery), T2CPMG (The Carr-Purcell-Meiboom-Gill sequence) and T1-T2 relaxation correlation. Additionally, T2 spatially resolved measurements were conducted. Complementary images of proton density were registered using 2D and 3D Single Point Imaging (SPI). The measurements were performed on cylindrical core samples of medium-grained arenites from the Outer Carpathians. The obtained results were compared with Mercury Intrusion Capillary Pressure (MICP), microscopic and SEM/BSE observations of thin sections. Based on the T2 experiments, the pore size distribution, the total and effective NMR porosities and the content of different types of water occupying the pores (Free Fluid Index (FFI), Bulk Volume Irreducible (BVI), Clay-bound Water (CBW)) were determined. The NMR permeability was estimated in accordance to a theoretical model. The T1-T2 maps allowed us to determine the content and mobility of water in the samples. The porosity changes within the samples were observed due to the T2 relaxation time distribution registered for selected slices. 2D and 3D projections of the proton density acquired as SPI images gave additional information characterizing the pore space. In some samples, zones of reduced and enhanced porosity related to the tectonic structures were observed. The presented results show that the complexity of NMR approach enables good and non-invasive insight into the pore structure and other petrophysical parameters of sandstones. [ABSTRACT FROM AUTHOR]

The particle size distribution of phosphorus slag powder was determined by using of the laser particle size analyzer, and the fractal dimension of the ultra fine phosphorus slag powder had been calculated according to the tested results. The effects of fractal dimension on the particle size distribution characteristic value, compressive strength of mortars, and pore structure of the ultra fine phosphorus slag power had been systematically investigated. Results indicated that, the grinding efficiency of phosphorus slag decreased with the increase of grinding time. And the grinding efficiency reached the limit when the grinding time was 3 hours. The compressive strengths of mortars linearly increased with the particle size distributional fractal dimensions of phosphorus slag powder. The results derived from nitrogen adsorption method revealed that the ultrafine phosphorus slag power can reduce both the characteristic pore size and the porosity, thus, increased the density of hardened cement paste. In addition, the later strengths of mortars was more sensitive to the particle size distributional fractal dimension of phosphorus slag than the early strengths. [ABSTRACT FROM AUTHOR]

Sandstones, clastic sedimentary rocks, were used as load-bearing materials for centuries. Even though nowadays these natural materials are usually used as decorative or facing materials, sandstones still belong to the group of building materials. Rocks, which can be called sandstones (from a geological point of view), vary widely. All properties depend mainly on the mineralogical composition, granularity and pore system of an individual material. Because the aim of this study was to find out the relationship between hygric properties and pore size distribution, selected materials differ mainly in their porosity. Mostly quartzose sandstones with an irregular granularity, which are quarried in the Czech Republic, were chosen and experimentally characterised for the purpose of this study. The dependencies of water vapour transport properties on the porosity of quartzose sandstones were found in a form of a power function, while in the case of liquid water transport exponential function fitted best. [ABSTRACT FROM AUTHOR]

High pressure supercritical CO2 (HP-ScCO2) geochemical reactor was designed to study the interaction between coal and HP-ScCO2 in order to simulate the CO2 geo-sequestration into and/or enhancement of coalbed methane recovery from deep coal, focusing on the characterization of the pore structure of coal and its changes. Four coal samples with different coal rank were chosen for the HP-ScCO2 tests using the geochemical reactor under around 40 °C and 9.8 MPa for 72 hours. The coal samples with and without the ScCO2-H2O treatment were further investigated using the mercury porosimetry, providing the mercury intrusion data for characterization of the pore structure of coals. Fractal analysis was used to distinguish inter- and intraparticle pores at lower mercury intrusion pressure and to define the initial pressure associated coal compressibility. The fractal dimension phenomena corresponding to three pressure ranges were observed associated with three different mercury intrusion processes. These fractal dimension phenomena can be described by means of the fractal dimensions. The fractal dimensions in relatively low pressure are not change much, mainly resulted from the accumulation mode of particle samples in the penetrometer and the roughness of samples which caused by crushing and grinding process. In the higher pressure range, the fractal dimensions decreases with increasing pressure as the coal rank increased, which probably related to the hardness of coal. In general, CO2 sequestration process makes all the samples become easier to be compressed than the raw samples. Moreover, coal rank and ash content may play more important role in maintaining the pore structure. After reacted with HP-ScCO2, the higher rank samples exhibit larger pore structure changes than the lower rank ones. [ABSTRACT FROM AUTHOR]

Based on the capillary pressure curves measured at lab, the pore structures distribution features were analyzed for cores with several permeability. The comparison between methods of the single-line and two-line fitting indicated the multi-fractal characteristics of the heterogeneous pore distribution. The study shows that the fractal dimension could be used to describe such characteristics. The greater the pore structure heterogeneity of a core, the bigger the fractal dimension calculated by single-line fitting, and the larger difference between the two fractal dimensions calculated by the two-line fitting method. [ABSTRACT FROM PUBLISHER]

Natural resources have been widely used for production of building materials in many countries in the entire world. Use of local minerals, such as materials on foam gypsum basis, in construction material production and usage in sound and heat isolation in building structures, is a significant benefit in national economy. The current research in foam gypsum shows that such possibilities exist (Skujans et al., 2010). Varying at the process of manufacturing with the ratio of gypsum and water, as well as the volume of the surface active stuff, foam gypsum of different volume density can be obtained but it has to be noted that the low bending strength of foam gypsum is a disadvantage. Material modification with fibrous reinforcement (hemp reinforcement) can serve as improvement of foam gypsum bending strength but it depends on the measure and amount of hemp reinforcement. Shorter fibers of hemps increase the material strength but longer fibers increase the sound absorption coefficient. Both fiber types have an impact on the pore structure of foam gypsum as it is on foam gypsum without fibrous reinforcement manufactured with the same technology. [ABSTRACT FROM AUTHOR]

A methodological framework designed/developed under the form of an algorithmic procedure (including 20 activity stages and 10 decision nodes) has been applied for multicriteria ranking of models. The criteria used are: fitting to experimental data, agreement with theoretical aspects, model simplicity, experimental falsifiability, progressiveness, and relation to other ISs, as proved by a common path/rationale of deduction. An implementation is presented referring to the selection of pore ideal structure of anodized aluminium among the alternatives: cylindrical (A1), truncated-cone-like (A2), trumpet-like (A3), vesica-like (A4), multiple-base (A5), and tilted-cylinder-like (A6). The alternative A2 (implying corresponding specific surface estimation of the anodic film) was ranked first and the solution was proved to be robust. [ABSTRACT FROM AUTHOR]