Search

The aim of the work is to predict the filtration capacity of reservoirs based on core and well logs data at the stage of petrophysical study of rocks before the start of active development of the object.All the results were obtained from the data of porometric characteristics of rocks on the example of the vikulovskaya series’s deposits of the Krasnoleninsky arch. The patterns of changes in pore sizes and their contribution to the total filtration depending on the lithophysical type of the rock were established on the core plug. A classification of rocks by pore radii is proposed, and a method for assessing the filtration capacity of reservoirs based on well logs data is developed, with the calculation of the share of each layer in the planned perforation interval.

The cracking behavior of lignite during drying–wetting cycles impacts the efficiency of coal mining, underground coal gasification, and coalbed methane development. Lignite is known to have high water content, and it exhibits strong hydrophilic properties, resulting in a weak and rigid gel structure caused by water interactions with coal matrix molecules. Even at ambient temperatures, dehydration causes violent shrinkage of the lignite matrix and numerous fractures. Due to the shallow burial depth of lignite, it is often mined in open pits, and it often undergoes cycles of dehydration and rewetting in the open-air environment, resulting in significant changes to its physical structure and mechanical properties. Thus, a detailed characterization of this evolution process is necessary. In this study, lignite samples with different compositional properties were collected from the Shengli Coalfield in the Erlian Basin, and their physical structure and mechanical properties were characterized using nondestructive testing methods such as nuclear magnetic resonance, environmental scanning electron microscopy, X-ray computed tomography, and atomic force microscopy. The results provide insights into the impact of material composition on the syneresis behavior and destruction process of lignite. Upon removal of water from the coal matrix, rapid shrinkage occurs, resulting in the simultaneous formation of numerous fractures. Significant differences were observed in the contraction characteristics and fracture propagation patterns among the various lignite lithotypes. Xylite lignite exhibited the highest degree of contraction following dehydration, with the macropore reduction rate being the most significant. Matrix lignite showed a lower degree of syneresis compared to xylite lignite, while fusain-rich lignite demonstrated the weakest syneresis ability. The homogeneous xylite lignite shrinks as a whole after dehydration, and its fractures are long and straight, with good orientation. Fractures formed in the detrital humic groundmass of matrix lignite are short, convoluted, and poorly oriented. Fusain-rich lignite fractures are thin, and straight, with the best orientation. The expansion of fractures can cause geological disasters such as land subsidence, collapse, and landslides. Fusain hinders fractures' expansion and acts as a "skeleton" to support the lignite structure. The presence of fusain is advantageous to maintaining the steadiness of the lignite. The differential evolution of the physical structure of lignite during the drying–wetting cycles, which aids to avert and mitigate disasters linked to dehydration cracking in different lignite-related engineering geological fields, is discussed in this paper. [ABSTRACT FROM AUTHOR]

Studying images of a whole core (a sample of rock extracted from a well) is in demand in modern geophysics. The subject area determines the specifics of core image processing and the form of presentation of the results. A common way to represent well data is by depth-ordered measurement values. Core samples are also ordered by depth, and sample images are a collection of individual photographs or tomographic scans, often without data at some depths. A typical image of one core fragment contains a meter-long section of rock. In practice, it is often necessary to evaluate the characteristics of centimeter intervals. An approach to creating an ensemble of textural features of core images presented as depth-ordered profiles is proposed. The results can be used in conjunction with other geological and geophysical data. [ABSTRACT FROM AUTHOR]

Permo-Carboniferous oil deposit of the Usinskoye field is characterized by an extremely complex type of the void space with intense cross-sectional distribution of cavernous and fractured rock. In this study, for this production site, the process of 3D geological modeling has been implemented. At the first stage, it provided for automated identification of reservoir volumes by comparing the data of core and well logging surveys; at the second stage, identification of rock lithotypes according to Dunham classification is performed on the basis of comparison of thin sections examination and well logging data. A large array of factual information enables the use of machine learning technology on the basis of Levenberg – Marquardt neural network apparatus toward achievement of our research goals. The prediction algorithms of reservoir and rock lithotype identification using well logging methods obtained on the basis of the training samples are applied to the wells without core sampling. The implemented approach enabled complementing the 3D geological model with information about rock permeability and porosity, taking into account the structural features of the identified lithotypes. For the Permo-Carboniferous oil deposit of the Usinskoye field, the volumetric zoning of the distribution of different rock lithotypes has been established. Taking into account the lithotypes identified based on machine learning algorithms, density and openness of fractures were determined, and fracture permeability in the deposit volume was calculated. In general, during the implementation, the machine learning errors remained within 3-5 %, which suggests reliability of the obtained predictive solutions. The results of the research are incorporated in the existing 3D digital geological and process model of the deposit under study.

The reservoir properties and gas-bearing characteristics of different lithotypes of lignite are different, resulting in complex migration and accumulation laws of methane in lignite. Following systematic collections of samples of different lithotypes from the Erlian Basin, occurrence modes and storage potential of methane in lignite were explored through a series of isothermal adsorption experiments and NMR-based experiments on original water-containing samples. The maceral composition affects the reservoir characteristics and hydrophilicity of different lithotypes of lignite, which control the reservoir's gas–water competition. Xylite lignite has a strong adsorption capacity, poor development of macropores, and high irreducible water content. Therefore, among various lithotypes of lignite, xylite lignite has the highest occurrence potential for adsorbed gas and soluble gas and the lowest potential for free gas. Notably, the soluble gas in lignite is never dominant in the gas composition. Therefore, gas in xylite lignite is mainly adsorbed. Due to carbonization, the fusain-rich lignite retains many unexpanded primary plant tissue structures and has developed macropore spaces and weak hydrophilicity. Therefore, the fusain-rich lignite has high free fluid porosity and the highest free gas storage potential. When the burial depth of the matrix lignite is less than 500 m, the methane is mainly adsorbed. The storage potential of free gas gradually exceeds that of adsorbed gas as the burial depth increases. There are apparent differences in the occurrence states and accumulation patterns of methane in different lithotypes of lignite. Clarifying methane's occurrence and storage potential in different lithotypes of lignite are significant for evaluating methane resources and exploring the methane enrichment model. [ABSTRACT FROM AUTHOR]

The article describes an approach to expanding the methodology for applying hydraulic fracturing in oil fields by adding the possibilities of 3D modeling with color imaging of the pore structure of the productive intervals of wells. As an applied example, the geological and geophysical section of the productive level of one of the wells of the Moscudinskoye oil field, with known data on the integrated interpretation of the results of well-logging and microcomputer tomography, was chosen. According to well-logging data, the productive reservoir in the analyzed section of the section is characterized by a high degree of heterogeneity. Tomographic studies of a full-size core made it possible to identify four lithotypes here with different pore structure features. Accounting for the identified reservoir heterogeneity, as well as data on the thickness and other characteristics of reservoir properties of individual lithotypes that make up the section, made it possible to significantly increase the detail of the final geological model of the wellbore section. A distinctive feature of this final geological model is the use of the method of enlargement of the initial data array by adding intermediate values that were calculated theoretically. The visibility of the final geological model of the borehole walls is provided by color 3D imaging of the calculated data of the enlarged massif and makes it possible to judge the presence of areas with good and weak fluid conductivity on the lateral surface of the borehole walls. According to this model, intrastratal transverse and longitudinal fluid-conducting "corridors" are observed in the circumwell zone that determine the hydro-dynamic movements of natural and artificial fluids in the space of productive reservoirs. [ABSTRACT FROM AUTHOR]

A study using high-resolution macroscopy and microscopy was conducted on the Neogene Mukah coal in Sarawak, Malaysia, to describe the changes in the coal facies, peat development and its precursors, and depositional conditions of the peat/coal. Eight coal seams from three boreholes (MC05, MC12, MC01) were analyzed. Bright, banded bright, banded dull, and dull coal lithotypes, with a predominance of the brighter lithotypes, were identified and primarily attributed to increases in huminite content and decreases in liptinite and mineral matter contents. Coals were characterized by high huminite (70.3%–91.9%), moderate liptinite (4.0%–26.3% mmf), minor inertinite (1.4%–5.9% mmf), and argillaceous mineral matter (0.0%–50.6%). Clarite (3.5%–88.7%) was observed to be the most predominant microlithotypes with carbominerite content ranging from 0.0% to 67.9%. The complete succession from topogenous to ombrogrenous peat evolution was identical between the eight coal seams, and temporary development of rheotrophic–ombrotrophic mires was suggested. The basal section of coal bench was dominated by humodetrinite/liptinite-rich coal or humocollinite/mineral matter-rich coal, whereas the middle section was characterized by humotelinite- and humocollinite/liptinite-rich coal and overlain by humotelinite-rich coal. The Mukah coal was suggested to have been deposited in a coastal floodplain within a (mainly) upper–lower delta plain setting more prone to telmatic coal facies. [ABSTRACT FROM AUTHOR]

The article describes an approach to expanding the methodology for applying hydraulic fracturing in oil fields by adding the possibilities of 3D modeling with color imaging of the pore structure of the productive intervals of wells. As an applied example, the geological and geophysical section of the productive level of one of the wells of the Moscudinskoye oil field, with known data on the integrated interpretation of the results of well-logging and microcomputer tomography, was chosen. According to well-logging data, the productive reservoir in the analyzed section of the section is characterized by a high degree of heterogeneity. Tomographic studies of a full-size core made it possible to identify four lithotypes here with different pore structure features. Accounting for the identified reservoir heterogeneity, as well as data on the thickness and other characteristics of reservoir properties of individual lithotypes that make up the section, made it possible to significantly increase the detail of the final geological model of the wellbore section. A distinctive feature of this final geological model is the use of the method of enlargement of the initial data array by adding intermediate values that were calculated theoretically. The visibility of the final geological model of the borehole walls is provided by color 3D imaging of the calculated data of the enlarged massif and makes it possible to judge the presence of areas with good and weak fluid conductivity on the lateral surface of the borehole walls. According to this model, intrastratal transverse and longitudinal fluid-conducting “corridors” are observed in the circumwell zone that determine the hydro-dynamic movements of natural and artificial fluids in the space of productive reservoirs.

The relevance of this research comes in response to the need to expand the resources of Western Siberia including Tomsk region, by the development of hard-to-recover oil reserves concentrated in the Bazhenov Suite (Tithonian-Berriasian). The aim of the research is to reveal the features of the lithologic composition and structure of the Bazhenov reservoir rocks across the potentially prospective oil-producing Tomsk region. Object: Bazhenov Suite bituminous deposits discovered by drilling at a local elevation in the Tamrat Basin (Nyurol’ sedimentary basin), the Pudinsky oil-and-gas-bearing region of the West Siberian oil and gas province (Tomsk Oblast), where an oil inflow was obtained. Methods: geophysical studies, macroscopy core description, petrographic and X-ray analyzes. Results. The paper introduces spatial distribution of decomposed rocks – oil and gas reservoirs – identified throughout the productive interval of the Bazhenov Suite. The study provides a detailed geophysical and petrographic description of rocks as well as their textural and compositional characteristics. Authors divide all rocks into seven lithotypes: 1) aleurit-silicitic argillites with rare tubicolous shells and «mud eater» fossils; 2) bituminous silicitic argillites with silicious bands and diatoms traces; 3) bituminous radiolarian argillic silicites; 4) bituminous radiolarian silicites with tubicolous shells and silicious bands; 5) bituminous radiolarian argillic silicites marked by bioturbation and crinoid traces; 6) radiolarian silicitic argillites with algae traces; 7) silicitic argillic carbonates. It was found that the accumulation of Bazhenov sediments was controlled by a low-dynamic stagnant sedimentation regime in relatively deep-sea conditions of the reducing geochemical environment. There is a correlation between both the mineral composition and the content of sapropelic organic matter with the transgressive-regressive sedimentation cyclicity: the 4th lithotype is the most enriched in siliceous material and organic matter, and the maximum amount of these components occurs at the point of inversion of the transgressive-regressive cycle. The Bazhenov collector having a mixed genesis was formed during the multi-stage lithogenesis (sedimentogenesis–catagenesis) and poststadial processes. The void space is represented by ultrathin bio-voids and pores as well as by both interlayer and intralayer fractures.

In the article the scientifically processed materials drilling six wells search. According to the research confirmed the lack of Selyukivskiy area of the upper strata of salt. Lower Visean Substage compiled sand and Upper Visean – clay-carbonate rocks. Parametric searching wells 304 and 2, 5 series carbonate strata of increased thickness. According to the results of research lithological rock thickness is divided into lower, middle and upper. As a result of the correlation the layers carbonate “plate” divided into 13 layers (bottom-up). In the carbonate sediments of “slab” stand analogs productive horizons B-25–B-24. They limestone predominate among three lithotype (bottom up) separated by short breaks. This shows the cyclic structure. Limestone should biogerm origin. Wells 2, 304, 4 passed through the core organic structure. Facies core are pure white and clear-gray biogerm limestone. Limestone is very central bioherm recrystallized, with porosity up to 20,7 % and permeability of 0,001–0,252 um 2. Cracks limestone multidirectional. S. V. Onufryshyn believes basement sediments bioherm inflection on the outer shelf (rukh layers, V3R) power and relatively deep entities with signs of volcanic activity.

Four lignite lithotypes (matrix coal, xylite-rich coal, mixture of matrix and mineral-rich coal and mixture of matrix and xylite-rich coal), originating from the Kovin deposit, were investigated in detail. The paper was aimed to determine the main maceral, biomarker and isotopic (δ13C) characteristics of investigated lithotypes. Based on these results the sources and depositional environment of organic matter in 4 lithotypes were established. These samples were also used as substrates for investigation of the influence of diagenetic alteration on δ13C signatures of biomarkers, as well as for assessment of the most convenient utilization for each lithotype. The investigated lithotypes differ in accordance with the composition of huminite macerals. Xylite-rich coal notably distinguishes from other lithotypes beacuse of the highest content of conifer resins vs. epicuticular waxes. The mixture of matrix and mineral-rich coal is characterised by the greatest contribution of algae and fungi and the most intense methanotrophic activity at the time of deposition. In all coal lithotypes diagenetic aromatisation influenced isotopic composition of individual biomarkers. Xylite-rich coal has the poorest grindability properties. However, this coal lithotype is the most suitable for fluidized bed gasification, whereas the mixture of matrix and mineral-rich coal has the lowest applicability for this process. The calorific value decreases in order: xylite-rich coal > matrix coal > mixture of matrix and xylite-rich coal > mixture of matrix and mineral-rich coal. The increase of organic carbon content and calorific value is controlled by the increase of contribution of wood vegetation vs. herbaceous peat-forming plants, as well as by stability of water table during peatification. [Project of the Ministry of Education, Science and Technological Development of the Republic of Serbia, Grant no. 176006 and Grant no. 451-03-01039/2015-09/05]

During the processes of methane adsorption and desorption, the internal structure of coal changes, accordingly leading to changes in electrical conductivity. In this paper, using low rank coal seams of the Yan'an Formation in the Dafosi field as the research subject, the relationship between coal resistivity, methane adsorption quantity, and equilibrium pressure is analyzed through proximate analysis, mercury injection tests, low temperature liquid nitrogen adsorption tests, and coal resistivity measurements during methane adsorption and desorption. The results show that during the process of pressure rise and methane adsorption, the conductivity of coal increases, resulting from heat release from methane adsorption, coal matrix swelling and adsorbed water molecules replaced by methane, but the resistivity reduction gradually decreases. The relationship between coal resistivity and methane adsorption quantity and equilibrium pressure can be described by a quadratic function. During the processes of depressurization and desorption, the resistivity of coal rebounds slightly, due to decalescence of methane desorption, coal matrix shrinkage and water‐gas displacement, and the relationship coincides with a linear function. Methane adsorption leads to irreversible changes in coal internal structure and enhances the coal conductivity, and resistivity cannot be restored to the initial level even after methane desorption. The resistivity and reduction rate of durain are higher than those of vitrain, with relatively greater homogeneous pore throat structure and fewer charged particles in the double electric layer. In addition, moisture can enhance the conductivity of coal and makes it change more complexly during methane adsorption and desorption. [ABSTRACT FROM AUTHOR]

Abstract New palynological analysis of the Middle Eocene to Middle Miocene Latrobe Group coals of the Gippsland Basin in Australia sheds new light on fire adaptation in Australia's modern flora. The distribution of charcoal and fire-prone flora within brown coals is entirely controlled by facies and the paleoenvironments within the peatland, and does not result from drier climates as has been previously suggested. There is therefore, no evidence of climatic drying from this Cenozoic peatland record. Charcoal and fire-prone floras are associated with emergent and meadow marsh environments that produce darker coal lithotypes. Counter-intuitively, the low-nutrient and fire-prone environments that fringed the ever-wet rainforests of the Latrobe Group peatlands may have represented an ideal setting for southeastern Australia's modern fire-adapted and sclerophyllous flora (i.e., Eucalyptus and Banksia) to evolve in. Highlights • The paleoenvironment controls the distribution of charcoal in brown coals. • Charcoal abundance in brown coals is not related to drier climates. • There is no evidence of climatic drying in the Cenozoic Latrobe Group peatlands. • Modern sclerophyllous flora likely evolved on fire-prone fringes of peatlands. [ABSTRACT FROM AUTHOR]

The decay rates of building stones and, the processes leading to their deterioration is governed by intrinsic properties such as texture, mineralogy, porosity and pore size distribution, along with other extrinsic factors related to the climate and anthropogenic activities. For urban cities such as London, the influence of extrinsic factors like temperature and rainfall, as well as the concentrations of air pollutants, such as sulphur and nitrogen oxides, along with the emissions of carbonaceous aerosols, can be particularly significant. While considering the long-term preservation of building stones used in various heritage sites in the city, it is imperative to consider how the stone could be affected by the changing air pollutant concentrations, superimposed on the effects of climate change in the region, including rising average annual temperature and precipitation with a hotter, drier summer and, warmer, wetter winter months. This paper deals with the intrinsic rock properties of the common building stones of London, including limestone, marble, granite, sandstone, slate, flint as well as bricks, building on known characteristics including strength and durability that determine how and where they are placed in a building structure. The study reviews how these stones decay due to different processes such as salt weathering in sandstone, microcracking of quartz with kaolinisation of K-feldspar and biotite in granite and dissolution of calcite and dolomite, followed by precipitation of sulphate minerals in the carbonate rocks of limestone and marble. In the urban environment of London, with progressive build up in the concentration of atmospheric nitrogen oxides leading to an increasingly acidic environment and, with predicted climate change, the diverse stone-built heritage will be affected. For example, there can be enhanced carbonate dissolution in limestone with increased annual precipitation. Due to the prolonged wetter winter, any sandstone building stone will also undergo greater damage with a deeper wetting front. On the other hand, due to predicted wetter and warmer winter months, microcracking of any plagioclase in a granite is unlikely, thereby reducing the access of fluid and air pollutants to the Ca-rich core of the zoned crystals limiting the process of sericitisation. Management of the building stones in London should include routine expert visual inspection for signs of deterioration, along with mineralogical and compositional analyses and assessment of any recession rate.

The control of coal fragmentation and fines generation during mining and processing is important in coal production. A method to characterise, model and simulate coal size degradation and fines generation based on lithotypes has been developed. This method was refined to cover both high energy single impact to mimic blasting and crushing and low energy incremental breakage to mimic coal handling, transiting, stockpiling and processing. The JKRBT was utilised to characterise high energy single impact breakage and drop shatter tests were used to characterise low energy incremental breakage. X-ray Computed Tomography (XCT) scanning was used as an undisruptive technique to estimate size distributions of drill cores in the drop shatter tests. The JK size-dependent breakage model was applied for breakage characterisation, size degradation modelling and fines generation simulation. The results indicate that coal lithotype has a significant influence on coal degradation and fines generation. This paper has demonstrated that the adaption of two distinct breakage characterisation tests and linkage via the one model is a significant advance in quantifying coal degradation and fines generation during coal production. [ABSTRACT FROM AUTHOR]

We present a method for predicting rock types. The method is based on continuous high-resolution thermal logging along full-size core samples and being applied for rocks from a major unconventional formation. The method utilizes spatial spectral decomposition and machine learning approaches allowing automatic classification of the core samples over lithological groups within an isolated stratigraphic depth interval of a wellbore. The core samples are basically classified to the particular lithotypes by means of spectral representation of profiles of thermal properties obtained by a modern contactless method. [ABSTRACT FROM AUTHOR]

Soil-gas radon concentrations and exhalation rates have generally been observed to be anomalously high along active faults in many parts of the world. The soil-gas method is based on the principle that faults and fractures in rocks are highly permeable pathways along which gases can migrate upward from deep crust and mantle to soil cover, retaining their source signatures. The present study summarizes the influence of fault zones on anomalous radon concentrations in soil by integrated geophysical and geo-structural analyses in three study areas of Central-Northern Calabria (Southern Italy). Soil-gas radon surveys have been carried out by means of an alpha scintillation counting system, at 12,509 locations between 2002 and 2004. A geostatistical approach has been used to estimate the spatial distribution of soil radon concentrations. Relations among soil-gas distribution and geo-structural features have been evaluated by ordinary multi-Gaussian kriging. Highest soil radon concentrations (ca. 90 kBq m−3) have been measured in the Rossanese sector. In the three study areas, no appreciable differences can be noticed among lithotypes, with the highest concentration values (ca. 89 kBq m−3) measured in alluvial deposit and in clay. Measurements of soil-gas radon reveal anomalies clearly connected to the tectonic structures. Increased signals are linearly distributed along regional WNW-ESE trending shear zones, with main pathways of concentration also recognizable along the E-W fault system in the Rossanese sector, the N-S fault system in the Crati Graben and the Catanzaro Trough, and the NE-SW fault system in the Catanzaro Trough. The distribution of epicentres of historical earthquakes occurred between 1184 and 2001 confirms the recent activity of the same fault systems. Soil-gas radon concentrations generally increase, as expected, with decreasing distance to the faults. [ABSTRACT FROM AUTHOR]

The effect of extraction temperature on the solubility of 4 Victorian brown coals (a Yallourn Woody coal and three Loy Yang lithotypes -Dark, Medium Light and Light) in the ionic liquid DIMCARB was investigated using a 100 mL autoclave. The solubility of coal at room temperature is in the order of Light > Medium > Dark > Woody coal, but the effect of temperature on the solubility is related to coal properties. For the Woody, Dark and Medium lithotypes, with higher aromaticity, the soluble yield significantly increased with extraction temperature to 80 °C, then slightly further improved at 120 °C. Elemental analysis, FT-IR and solid 13 C NMR analyses indicated that increasing temperature promoted interactions between DIMCARB and the coal and improved the solubilisation. The soluble fractions have higher H/C ratios and aliphaticities than the corresponding residue fractions and raw coals. The extraction temperature affected the distribution of pyrolysis products from the resultant solubles and residues. The solubles have high relative abundance of polycyclic compounds (including diterpenoids and triterpenoids) relative to the corresponding residues and the parent coals. However, increasing extraction temperature leads to decreasing selectivity for triterpenoids and increasing selectivity for long-chain alkanes and alkenes in the pyrolysis products of the soluble fraction. The solubles extracted at 120 °C have similar pyrolysis product distribution to the corresponding raw coals. In the case of the Light lithotype, with high aliphaticity, the highest soluble yield was obtained at room temperature. Extraction at 80 °C reduced the yield significantly, while at 120 °C, the yield slightly increased to be close to that at room temperature. For this case, the soluble fractions have lower H/C molar ratios than the corresponding residues. The relative abundance of triterpenoids in the pyrolysis products of the solubles exhibited the same trend as the soluble yield in DIMCARB versus temperature. [ABSTRACT FROM AUTHOR]

The Middle Eocene lignites of the Zeitz-Weißenfels coal mining area in central Germany hosted one of the most economically successful lithotypes of lignite deposits utilised in the paraffin industry of the 19th century, i.e. the pyropissite deposits. However, due to their economic significance, these rare lithotypes were almost completely mined out, such that presently only a few remnant deposits are known. Apart from the Zeitz-Weißenfels coal mining district, other pyropissite deposits were also encountered in other lignite mines, for instance, in the Hessian and Subhercynian Basins. Pyropissite is a whitish and bitumen-rich variety of soft brown coal (lignite) lithotypes, dominated by a homogeneous matrix with loosely embedded organic and inorganic components. Fresh exposure of pyropissite at Grana was logged and studied petrographically and geochemically, along with samples obtained from archival collections. Results were compared with those from the 19th and 20th century to derive general conclusions regarding origin and formation of pyropissite. Microscopically, the main constituent of this special lignite lithotype is amorphous to detrital in appearance. According to W. Schneider the term xanthinite is applied to this component, which forms the groundmass of the pyropissite. It contains high proportions of liptinitic substances with contributions of formless huminitic material and minor amounts of mineral matter. Geochemically, pyropissite is characterised by an increased H/C atomic ratio and a very high content of bitumen (in terms of toluene-soluble components) as well as low-temperature carbonisation tar. The obtained data revealed that the extraordinarily high content of liptinite and the paucity of huminitic material of the pyropissite deposits of the Zeitz-Weißenfels coal mining area are not related to primary depositional processes but rather are the result of dissipation of high condensed huminites and the consequent enrichment of liptinitic substances. The mechanism involves oxidation by groundwater and is related to glaciation processes operating during the Pleistocence. Such glacially derived processes also account for both vertical and horizontal distributions of the pyropissite. Thus, recent research activities may also serve as an innovative inspiration to fundamental understanding of the formation of lignites with extremely high liptinite content. [ABSTRACT FROM AUTHOR]

The relevance of the discussed issue is caused by the fact that really all geological issues are solved on the basis of the models which accuracy increases considerably when using sedimentological component.. Sedimentalogical factors control the conditions of formation, placement and quality of a reservoir and caps. It means that consideration of sedimentological models increases the efficiency of exploration for oil and gas, especially, preparation of deposits to development and development drilling. The main aim of the research is justification of importance of J1 a formation deposition (formed by sandstones of Upper Jurassic deposits) of T condensate field (Yamal-Nenets Autonomous District) according to the coredata performed on two wells. Research methods: Lithological composition analysis of the rocks, separation of rocks on lithological characteristics on lithotypes, facies analysis, complex analysis of lithological and petrophysical data. Results. Based on the coredata analysis the authors have selected six lithotypes and six sedimentary environments (facies) of deposits of J1 a. All lithotypes have different reservoir (permeability and porosity) properties. The lithofacies were grouped into larger sedimentary complexes - facies associations. Complex associations allocated within the T field of the studied formation allowed justifying the sedimentological model of deposit formation. Formation of J1 a sediment accumulated in the barrier-island environment complex from the west to the east. It is shown that lithotypes 3 and 4 have the best filtration-capacitive properties, and lithotype 1 has the worst quality. Litotiype 3 was formed in a Flood Tidal Delta marine and tidal inlet, deposits litotype 4 was formed in shallow-marine environment during transgression, influenced by moderate activity wave processes.

Coal permeability has been identified as one of the key factors affecting coalbed methane (CBM) extraction. CBM drainage and hydraulic fracturing usually lead to coal fines output. Some of these coal fines passed through wellbore discharged of coal bed, and some of them were compacted in fractures during the closing of fractures (or cleats) under the confining pressure. The pore distribution and seepage path of those compacted coal fines are different from natural coal. In this study we used reconstituted coal as a research material to study porosity and permeability characteristics of compacted coal fines in coal reservoir fractures. We use different macrolithotype coal particles with size of 0.2–0.4 mm, a heat-shrinkable tube and two guide blocks to make a reconstituted coal sample. In order to investigate the behavior of reconstituted coal permeability changing with effective stress and the influence of lithotype effect on permeability of reconstituted coal, reconstituted coal cores porosity and permeability test with helium gas in net confining stress were measured in laboratory. And pore distribution of different macrolithotype natural coals and reconstituted coals were analyzed by low-temperature nitrogen adsorption experiment and low-field nuclear magnetic resonance (NMR) measurement. Both porosity and permeability of reconstituted coal decrease exponentially with the increase of effective stress. Initial permeability and permeability damage rate of reconstituted coal have a negative correlation and a positive correlation with quality proportion of clarain and vitrain, respectively. The proportion of seepage channels of dull reconstituted coal is larger than that of bright reconstituted coal. [ABSTRACT FROM AUTHOR]

Commercially available hyperspectral drill core scanning systems in the Visible and Near-Infrared (VNIR), Short-Wave Infrared (SWIR) and Long-Wave Infrared (LWIR) regions, along with a handheld spectrometer for the Middle-Wave Infrared (MWIR) region, were used to characterise a rank suite of coal samples (0.45% to 1.76% Rr) with different preparations (slabbed surface, outer core and compressed powder pellets). The samples used in this study came from Australian basins of Permian and Jurassic ages. The spectral characteristics of the coals measured using these scanning systems were compared to those obtained using well-established spectroscopy techniques that operate in the same region of the electromagnetic spectrum, such as Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy. The observed spectral features of the coals changed with increasing coalification. The features occurring at 1910 nm in the SWIR region and 2940 nm in the MWIR region tended to disappear as rank increased; these features arise from OH bonds related to structural water and hence correlate with the moisture content. The CH stretching fundamentals at 3280 nm correspond to the aromatic fraction of the coal, while the spectral region between 3380 nm and 3500 nm corresponds to the CH 2 and CH 3 stretching fundamentals occurring in the aliphatic fraction of the coal. The ratio of the area of the aromatic absorption feature to that of the aliphatic absorption features, herein called Rank Spectral Index, displayed a strong linear correlation with coal rank parameters, such as vitrinite reflectance. Other spectral features in the SWIR and MWIR regions also correlated with coal rank parameters. In addition to rank, trends in the magnitudes of the spectral features were influenced by maceral composition, particularly in low rank samples with abundant liptinite or inertinite group macerals. The variable spectral features related to composition were mapped onto the slabbed core surface, discriminating bright and dull bands and fusain lenses enabling the classification of coal lithotypes, regardless of rank. Among the less banded lithotypes, it was established that high liptinite content coals can be distinguished by their aliphatic spectral features in core samples. Overall, this study has shown that hyperspectral drill core scanners can be used to characterise coal and non-destructively classify rank and lithotype. • Non-destructive hyperspectral scanning systems were applied to coal characterisation. • Wavelengths covered 450 nm to 14,500 nm or visible near to thermal infrared. • Rank related features structural water, aliphatic and aromatic features were identified in the spectra. • A Rank Spectral Index was created from spectral features in the Middle-Wave Infrared. • High resolution spectral maps distinguished banding and coal lithotypes. [ABSTRACT FROM AUTHOR]

Two major earthquakes occurred on October 23rd, 2011 (M=7.1) and November 9th, 2011 (M=5.6) in Tabanli and Edremit districts of Van province in Turkey, respectively. New settlement areas for Van city were determined after these destructive earthquakes. One of the most important areas for new settlements to be built was Edremit region, consisting travertine where nearly 80% of new housing units (12.384) were built by TOKI (Housing Development Administration of Turkey). Travertines have different lithotypes depending on their depositional process such as crystalline crust, shrub, reed which can affect mechanical and engineering properties of travertine and each level has different handicaps. The purpose of this study is to investigate the relationship between lithotype and physico-mechanical properties of travertines. According to the results, lithotype has an effect on physical, mechanical and rock mass properties of travertine. It is ascertained by several research methods that various handicaps may occur on such areas when the active tectonic structure of the area is evaluated along with the karstic cavities within the travertine and different lithotype qualities. [ABSTRACT FROM AUTHOR]

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The cyclic succession of brown coals in the Latrobe Valley, Gippsland Basin, Australia, records an exceptional floral and charcoal record from the Late Oligocene to Middle Miocene. New palynological, geological and charcoal data are consistent with existing colourimetry, carbon isotope, and organic geochemical and palaeobotanical data, indicating that the repeated lithotype cycles represent relative drying (terrestrialization). Based on this detailed palynological study, the vegetation succession within the Latrobe Valley peatlands is interpreted to have begun with a fire-prone emergent marsh of bulrushes (Typhaceae), which grades landward into a fire-prone meadow marsh of rushes (Restionaceae), heaths (Ericaceae) and coral-ferns (Gleicheniaceae). This marsh environment then developed into a forested bog, with gymnosperms (e.g. the Podocarpaceae Dacrycarpus and Dacrydium ) as the dominant trees, until an ombrogenous forest bog developed, predominantly consisting of angiosperms (e.g. Nothofagus , Quintinia ). The similarity between vegetation successions in New Zealand and the lightening-upwards cycles from the Latrobe Valley coals suggests that New Zealand's modern vegetation communities represent a floral analogue for the successions preserved in the Latrobe Valley coals. High abundances of micro and macro charcoal recorded in the darker lithotypes, within the lithotype cycles of the M1B and M2A seams, suggest that the Latrobe Valley peatlands were subject to repeated fires during the Late Oligocene to Early Miocene. [ABSTRACT FROM AUTHOR]

An integrated analysis of megascopic lithotype, microscopic maceral and mineral composition, stable carbon isotope and interburden sedimentology from a single well was used to interpret the response of the Late Permian Fort Cooper Coal Measures (FCCM) to regional and global environmental influences. The FCCM are differentiated from underlying, relatively high vitrinite Moranbah Coal Measures, and overlying higher inertinite Rangal Coal Measures in the Bowen Basin by their intercalation with abundant tuff and siliciclastic partings and interbeds. Besides this, there is little described about the variation in the organic composition of the FCCM and its causes. The FCCM can be subdivided into a lower aggradational Fair Hill Formation, transgressed by the shallow marine-derived Black Alley Shale that interfinger with/is overlain by the progradational Middle Main Seams and Burngrove Formation coal measures. The coals are dominantly dull with minor bright bands that are more abundant in the Burngrove Formation representing a change in plant composition. The maceral analysis shows that the coals in the Fair Hill Formation and Middle Main Seams are vitrinite-rich (80–90% mmf) albeit with high mineral matter suggesting the formation of precursory peat under rising water levels and with high sediment (tuff) influx and preservation. The coals in the Burngrove Formation have an increased inertinite content (30% mmf) but are also high in mineral matter suggesting a shift to increased decomposition arising from a fluctuating water table, possibly increased aridity and/or microbial activity. Tuffs occur throughout, and although their frequency is higher in the lower Fair Hill Formation, the preservation of thicker tuffs in the upper Burngrove Formation indicates increased intensity of volcanism that could have modified the environment. Variation in carbon isotope compositions show a parabolic trend, from around − 24.1‰ in the Fair Hill Formation to more variable values in the Middle Main Seams with an overall 13 C-enrichment upwards in the Burngrove Formation, prior to the δ 13 C values becoming negative (depleted between − 1 to − 4% from the average − 24.1‰) in the top seams and into the overlying Rangal Coal Measures. The 13 C-depletion trend in the upper part of the section is unexpected in view of corresponding increase in inertinite content of the coals indicating that the δ 13 C values/plant composition and inertinite content are decoupled, unless the inertinite origin is from intense microbial decay. Similar stable carbon isotope depletion trends have been observed elsewhere in an equivalent stratigraphic interval of the Bowen Basin suggesting that the carbon isotope values are responding to global conditions that cause negative excursions in carbon isotopes before the P-T boundary. Overall, the basin was continuously subsiding and peats accumulated with constant interruptions from excessive sedimentation and volcanic eruptions. The low proportion of visible thick bright bands coupled with high telovitrinite (mmf) content suggests a marsh to fen environment, with an open canopy and ponding able to preserve volcanic ash falls. [ABSTRACT FROM AUTHOR]

The stone artefacts from Sirmium, held at the Museum of Srem, were sampled and analyzed in order to establish an archaeological database connected with Roman quarries and possible transport routes along the Sava and Danube Rivers. Of the artefacts made of Neogene limestone three lithotypes were identified. Two of them were determined as originating from the known Roman quarry in the Drina Valley (NE Bosnia). For the third lithotype and its subtypes a model of the hypothetical quarry is proposed, the location of which is suggested to be outside the Drina river basin. Beside limestone, the sampled artefacts also revealed two types of porous volcanoclastic rocks of andesitic composition, which supposedly originate from two different microlocations in the Drina river basin.

Ionic liquids formed by association of carbon dioxide (CO 2 ) with low molecular weight secondary amines to form carbamate salts (e.g. N,N-dimethylammonium N′,N′-dimethylcarbamates, or DIMCARB) as solvents have been identified as ‘distillable’ as they reform their volatile precursor components upon heating at relatively low temperature and, thus, can be recovered by condensation. DIMCARB was selected for the solubilisation of a number of Victorian brown coals including Loy Yang coal, a dark, a medium light and a light lithotype and a Yallourn woody coal. The coal was mixed with DIMCARB at a mass ratio of 1:20 for 24 h at room temperature. The soluble product was recovered by centrifugation followed by acid washing to remove residual DIMCARB. The solubilisation yields achieved were between 10% and 63% in the order of woody coal < dark lithotype < medium light lithotype < Loy Yang < light lithotype. The soluble and non-soluble products were characterised by FTIR, NMR and pyrolysis GC–MS. Results revealed a positive correlation between the solubility and aliphatic content in the coals. Polycyclic aliphatic and aromatic compounds, specifically the triterpenoid group, were selectively dissolved by DIMCARB. [ABSTRACT FROM AUTHOR]

Travertine deposits have an economic value due to their chemical composition and widespread use in the construction industry. Travertines reveal different lithotypes depending on their depositional process and this can affect mechanical and engineering properties of travertine. Edremit travertine displays various structural features in lateral and vertical distributions. In this study, Edremit travertine is firstly differentiated into three different levels such as crystalline crust, shrub and reed based on the mechanical, physical properties and field observations. A strength map of different lithotypes is prepared and crystalline crust level is investigated for using in marble industry. For this purpose, the long-term performance/durability of crystalline crust travertine is investigated against various environmental processes by using several accelerated weathering tests. Accordingly, compared to the crystalline crust other levels of travertine (shrub and reed) are much more affected from atmospheric conditions. Among these levels, the crystalline crust level is recommended to be used as marble according to laboratory test results whereas other levels are appropriate for cement industry. [ABSTRACT FROM AUTHOR]

Abstract: A high-resolution study (n=66) was conducted on Late Permian coal measures of the Bowen Basin, Australia, to observe palynofacies changes during peat accumulation over time. Palynofacies were determined using polytopic vector analysis (PVA) to derive end members with variable compositions that reflected fine scale environmental changes, within and between seams, of the Kaloola Member. Palynofacies reflect a three-stage succession within the palaeo- peat-forming environments from stable, anoxic conditions at the base, progressing to variable, oxic conditions toward the top of each seam. In cases where a seam was capped by tuff, rather than siliciclastic sediment, anoxic conditions similar to the bottom of each seam occurred. The results corroborate previous interpretations of palaeofloral communities and provide a new palynofacies model that integrates environmental progression within the coal seams in the Late Permian coal measures of the Bowen Basin. A complementary study of palynological assemblages recognised a shift from Dulhuntyspora sp., to Protohaploxypinus sp. in the lower Kaloola Member, indicating a change in pollen/spore source. Associations between dispersed palynomorphs and coal phyterals of parent flora remain tenuous beyond class rank, due to poor preservation and taxonomic bias inherent within the sample space. This is the first such palynofacies study to be conducted in the Bowen–Sydney–Gunnedah basin complex, thus opening the way for future work examining regional changes in palynofacies, expressed in both coal and siliciclastic sediments. [Copyright &y& Elsevier]

Abstract: Four lithotypes (vitrain, bright clarain, clarain, and fusain) of a high volatile bituminous Springfield Coal from the Illinois Basin were characterized using advanced solid-state 13C nuclear magnetic resonance (NMR) spectroscopy. The NMR techniques included quantitative direct polarization/magic angle spinning (DP/MAS), cross polarization/total sideband suppression (CP/TOSS), dipolar dephasing, CHn selection, and recoupled C–H long-range dipolar dephasing techniques. The lithotypes that experienced high-pressure CO2 adsorption isotherm analysis were also analyzed to determine possible changes in coal structure as a result of CO2 saturation at high pressure and subsequent evacuation. The main carbon functionalities present in original vitrain, bright clarain, clarain and fusain were aromatic carbons (65.9%–86.1%), nonpolar alkyl groups (9.0%–28.9%), and aromatic C–O carbons (4.1%–9.5%). Among these lithotypes, aromaticity increased in the order of clarain, bright clarain, vitrain, and fusain, whereas the fraction of alkyl carbons decreased in the same order. Fusain was distinct from other three lithotypes in respect to its highest aromatic composition (86.1%) and remarkably small fraction of alkyl carbons (11.0%). The aromatic cluster size in fusain was larger than that in bright clarain. The lithotypes studied responded differently to high pressure CO2 saturation. After exposure to high pressure CO2, vitrain and fusain showed a decrease in aromaticity but an increase in the fraction of alkyl carbons, whereas bright clarain and clarain displayed an increase in aromaticity but a decrease in the fraction of alkyl carbons. Aromatic fused-rings were larger for bright clarain but smaller for fusain in the post-CO2 adsorption samples compared to the original lithotypes. These observations suggested chemical CO2–coal interactions at high pressure and the selectivity of lithotypes in response to CO2 adsorption. [Copyright &y& Elsevier]

The lithology change patterns between sections on the northern slope of Caucasus and in Ciscaucasia wells must be taken into account in addition to geophysical and biostratigraphic characteristics during detailed correlation of Aptian and Albian sediments. This paper discusses rock lithologic types (LT), rock distribution patterns in the covered territories, and their formation conditions. It includes a facies profile showing these patterns. [ABSTRACT FROM AUTHOR]

A relict mound of Holocene barite (BaSO4) tufa underlies the Flybye Springs, a small, barium-rich, cold sulphur spring system in the Northwest Territories of Canada. The tufa is composed of relatively pure barite with ≤0·34 wt% Ca2+ and ≤0·77 wt% Sr2+. The mound is made up of coated bubble, raft, undulatory sheet, stromatolitic, coated grain and detrital conglomerate barite tufa. Although previously unreported in barite, these lithotypes are akin to facies found in many carbonate spring deposits. Raft and ooid-coated grain tufa was formed via ‘inorganic’ barite precipitation in spring water ponds and tributaries where rapid oxidation of sulphide to sulphate established barite supersaturation. Undulatory sheet tufa may have formed by the reaction of dissolved barium with sulphate derived from the oxidation of extracellular polysaccharide-rich colloidal sulphur films floating in oxygenated, barite-saturated spring water ponds. Coated bubble, oncoid-coated grain and stromatolitic tufa with filamentous microfossils was formed in close association with sulphur-tolerant microbes inhabiting dysoxic and oxygenated spring water tributaries and ponds. Adsorption of dissolved barium to microbial extracellular polysaccharide probably facilitated the development of these ‘biogenic’ lithotypes. Detrital conglomerate tufa was formed by barite cementation of microdetrital tufa, allochthonous lithoclasts and organic detritus, including caribou hair. Biogenic textures, organic artefacts and microfossils in the Flybye barite tufa have survived diagenetic aggradational recrystallization and precipitation of secondary cements, indicating the potential for palaeoecological information to be preserved in barite in the geological record. Similarities between the Flybye barite tufa and carbonate spring deposits demonstrate that analogous textures can develop in chemical sedimentary systems with distinct mineralogy, biology and physiochemistry. [ABSTRACT FROM AUTHOR]

Despite the economic importance of coal to the Australian economy, detailed studies of controls on variation in coal type are remarkably few. However, important contributions have been made in the understanding of coal facies development. Tertiary lignite deposits of the Gippsland Basin provide key insights into the development of lithotype cyclicity and its relationship to relative sea-level changes, with individual paling-up cycles being correlated to parasequences. Studies of Permian hard coals have identified relationships between coal type and surrounding sediments. Unfortunately, these relationships have been widely over-interpreted in a manner that has diminished their real value. [Copyright &y& Elsevier]

A range of lower rank coals from Australia, Indonesia, and the USA have been dried under hydrothermal dewatering conditions at 320 °C for 30 min in a 500 ml autoclave using a 1:3 dry coal/water mixture. The hydrothermally dewatered (HTD) products were characterised by elemental analysis (both organic and inorganic components), volatile matter determinations, moisture holding capacity, calorific value and mercury porosimetry. The total organic carbon (TOC) and the concentrations of inorganics in the waste waters were also determined. The coals fell into two broad groups, the lower rank Australian brown coals with gross calorific values in the range 10–16 MJ/kg (afm) and the higher rank Indonesian and US coals with gross calorific values in the range 18–25.5 MJ/kg (afm). Rank was the major factor influencing the properties of the HTD products but lithotype was also important. TOC values of the waste water from drying of the low rank Australian coals were much higher than those of the waste water from the higher rank coals. Important variations in the amount of leached calcium, magnesium, and iron were noted. [Copyright &y& Elsevier]

In this paper the distribution of sulfur in different lithotypes in Assam coal is reported and an attempt is made for organic desulfurization of Assam coal by directly using original run-of-mine coal as well as by taking its sulfur-rich lithotypes, using sequential solvent extraction to obtain cleaner fuel. More than 80% organic sulfur was found to have been removed by this treatment. The vitrinite content of the coal seemed to play no significant role on the organic desulfurization of the coal and sulfur-rich lithotypes. Successive sequential extraction of coal may help in desulfurization of high sulfur coals to obtain cleaner fuels. [ABSTRACT FROM AUTHOR]