Shale Mineralogy Research Articles

Mineralogy and geochemistry of the Cambrain Shuijingtuo Formation black shales from Western Hubei, China: implications on enrichment of critical metals and paleoenvironment

Mineralogy and geochemistry of the Cambrain Shuijingtuo Formation black shales from Western Hubei, China: implications on enrichment of critical metals and paleoenvironment

Nanoscale mineralogy and organic structure characterization of shales: Insights via AFM-IR spectroscopy

Nanoscale mineralogy and organic structure characterization of shales: Insights via AFM-IR spectroscopy

Compositional controls on the Lower Cretaceous Rodby Shale pore structure and surface area: a planned CCS top seal caprock for the Acorn storage site

Fine-grained lithologies above CCS reservoirs cannot automatically be assumed to be mineralogically stable, or high quality top-seals to highly pressured CO2 as saline aquifer have previously contained hydrostatically pressured water. We have investigated the mineralogy, pore systems and surface area characteristics of the Lower Cretaceous Rodby Shale, the caprock to the Captain Sandstone at the UK's planned Acorn/Goldeneye CCS site. Rodby Shale core was logged and analysed by XRD, light microscopy, and SEM. Grain size was measured using laser particle size analysis. Mercury intrusion porosimetry and nitrogen adsorption analysis were used to characterise the pore network. The Rodby is smectite-rich and contains abundant calcite as well as quartz silt with small quantities of chlorite and plagioclase. Calcite was sourced from benthic microfossils, locally recrystallised to create a pore-filling cement. The mean pore throat and pore body diameter are about 17 nm putting the Rodby in the mesopore range and suggesting a predominance of slit-like pores. There are three lithofacies in the Rodby Shale: (i) high surface area clay-rich shale, (ii) low surface area calcite-rich shale, (iii) intermediate surface area quartz-rich. if the second lithotype encountered CO2, then the resulting calcite dissolution would lead to increasing surface area of the remaining shale. The Rodby Shale has good potential to be an effective barrier for CO2 escape, based on assessments of diffusion rate and post-breakthrough advection rate as well as stability and sealing assessments.

Geochemistry and clay mineralogy of shales in the Sulu Orogenic Belt, East China: suggestion for continental weathering during an Early Cretaceous hyperthermal interval

ABSTRACT Understanding past weathering–climate feedback mechanisms under greenhouse conditions has significance for guiding the development of climate mitigation strategies. The continental paleoweathering state of Early Cretaceous shales in the Sulu Orogenic Belt of East China during a hyperthermal interval related to oceanic anoxic event 1a (OAE1a) was investigated via geochemical and clay mineralogical analyses of shale samples. The resulting diagrams of ternary 15Al2O3–Zr–300TiO2 discrimination, Th/Sc and Zr/Sc show that the geochemical composition was mainly controlled by source composition. This is supported by observations of low Zr contents, high indexes of compositional variability (ICV; > 1), and micropetrological characteristics. All samples showed narrow SiO2/Al2O3 and (Fe2O3 + MgO)/Al2O3 ranges that were within the predicted weathering trends of the ternary A-CN-K diagram, indicating that the shale geochemistry was not influenced by silicification and K-metasomatism. The chondrite-normalized rare-earth-element pattern suggests that all samples had the same felsic igneous parent rock. The geochemistry of whole rocks and their silicate fractions indicates that the shale had low chemical indexes of alteration (CIA) but high ICV values compared to post-Archean Australian Shale, indicating low sediment maturity and extremely weak chemical weathering in the source terrane and/or sedimentary basin under hot-dry conditions. Moreover, the clay minerals in the shale were mainly illite, suggesting low mineral weathering. Thus, during the OAE1a-related hyperthermal interval, chemical weathering was relatively weak in some mid-latitude arid inland areas. This may be mainly due to aridification decreasing water–rock reactions. Chemostratigraphic analysis suggests that the CIA, Ga/Rb, and Rb/Sr values of shales from the upper strata of the Yangjiazhuang and Shuinan formations were greater than those from lower strata. Moreover, the opposite trend in K2O/Al2O3 ratios was found. These indices suggest gradual increases in chemical weathering as the climate changed from hot-dry to warm-humid. In contrast, proxy indices of shale from the Zhifengzhuang Formation showed the opposite trend, suggesting a gradual decrease in chemical weathering as the climate changed from warm-humid to hot-dry. Considering the composition of the clay minerals, it is speculated that continental weathering was dependent on atmospheric humidity rather than temperature under the extreme greenhouse conditions, resulting in ineffective climate regulation by chemical weathering. This comprehensive study advances our understanding of the weathering–climate feedback mechanism under greenhouse regimes.

Uranium enrichment driven by paleomarine condition and event deposition: Insights from the lower Cambrian Niutitang Formation organic-rich shales in northeastern Guizhou, South China

Organic-rich shale related uranium (U) mineralization has attracted widespread attention as a strategic and clean alternative to fossil energy and a paleoceanic redox proxy. A comprehensive study of mineralogy, organic geochemistry and elemental geochemistry of the lower Cambrian Niutitang Formation organic-rich shales in northeastern Guizhou, South China was conducted to address this issue. SEM-EDS results showed that the U occurrence state in the Niutitang Formation shales is dominated by nanoscale U minerals, mainly including coffinite, brannerite, U-bearing apatite and U-bearing xenotime. Various states of U are closely associated with organic matter, apatite, pyrite and clay minerals. Based on geochemical indexes, paleomarine condition and event deposition jointly drove the U enrichment in the Niutitang shales, in which hydrothermal activities and/or volcanic eruptions increased U fluxes in seawater and euxinic environment with high primary productivity provided a favorable condition for U reduction. The adsorption, complexation and reduction of UO22+ by organic matter and the formation of uranyl phosphate complexes by the combination of phosphate and UO22+ accelerated U immobilization and enrichment from bottom water to sediments. The microbial activities (e.g., BSR) in this process created favorable euxinic conditions and released inorganic-phase P to provide available ligands for UO22+. The U enrichment models of the lower Cambrian Niutitang shales in northeastern Guizhou were established. This paper provides a new insight into the U enrichment mechanism in organic-rich shales, and may also have implications for the applicability of U as redox proxy and the exploration of organic-rich shale related U deposits.

Mineralogy and Selenium Speciation Analysis of Early Cambrian Selenium-Rich Black Shale in Southern Shaanxi Province, China

Selenium (Se) is an essential trace element for humans and animals, and an excess of or deficiency in Se is harmful to health. Research on the selenium enrichment zone began in the late 1970s in Shuang’an, Ziyang, southern Shaanxi Province. Naore village is only one selenosis area in Shuang’an, Ziyang, China. Different scholars have conducted systematic studies on the occurrence of selenium, its organic geochemistry and biomarkers, and its content and enrichment patterns in this area. This study applied the TIMA (TESCAN integrated mineral analyzer) for the first time to conduct detailed mineralogical work. The minerals included quartz, carbonate minerals (calcite and dolomite), feldspar (plagioclase, albite, and orthoclase), biotite and muscovite, clay minerals (chlorite and kaolinite), hematite, pyrite, and accessory minerals (almandine, olivine, zircon, and apatite) in Naore village, Ziyang, Shaanxi Province. The ATi index (100 × apatite/(apatite + tourmaline)) is used to determine the source of heavy minerals and the degree of heavy minerals’ weathering. The content POS (100 × (pyroxene + olivine + spinel)/transparent heavy mineral) of olivine, pyroxene, and spinel in heavy minerals can reflect the contribution of basic and ultrabasic rocks in the source area. The ATi and POS indexes for the heavy minerals in the research area were 91.83~99.96 and 0.01~18.75, respectively, reflecting the abundance of volcanic rock material in their source. In addition, the migration, transformation, bioavailability, and toxicity of selenium in the environment are closely related to its species. The species of selenium in various selenium-rich areas (Naore, Wamiao, and Guanquan) mainly include unusable residues and organic forms, followed by humic-acid-bound selenium. The proportions of water-soluble, exchangeable, and carbonate-bound selenium are relatively small, and the proportion of Fe-Mn oxide-bound selenium is the lowest.

Reservoir Characteristics and Exploration Potential Evaluation of Lower Cambrian Niutitang Shale in Northern Guizhou: A Case Study of Well QX1

The Lower Cambrian Niutitang Formation in the Northern Guizhou harbors abundant organic-rich mud shale, constituting the most significant marine shale gas reservoir in Guizhou. In this article, the reservoir characteristics of Lower Cambrian Niutitang Formation in Northern Guizhou are analyzed in terms of lithology, mineralogy, organic geochemistry, pore structure, gas content and continuous thickness of shale, and the exploration potential of shale gas in this area is evaluated. The results indicate that the content of brittle minerals in the shale of well QX1 is 65.29% to 95.22% (average of 82.10%). The total organic carbon (TOC) content ranges from 2.06% to 12.10% (average of 5.64%). The organic matter maturity (Ro) within the range of 2.29–2.67%, and the kerogen type is identified as type I. The shale samples from the Niutitang Formation have high TOC content, suitable thermal maturity, and a favorable kerogen type, suggesting good gas generation potential. The results of scanning electron microscopy (SEM) show that intergranular pores, intragranular pores and microfractures are developed in the shale of well QX1, which can provide sufficient storage space for shale gas. The shale exhibits a continuous thickness of 105.66 m in the QX1 well, comprising a gas-bearing interval of 32.89 m at the top (with an effective continuous thickness of 18 m) and a hydrocarbon source rock layer of 75.78 m at the bottom. In comparison with other shale gas regions, Niutitang Formation shale in Northern Guizhou exhibits characteristics such as favorable gas generation conditions, greater storage conditions, excellent gas-bearing, strong frackability, and substantial continuous thickness, it has greater potential for shale gas exploration.

Machine Learning Approach to Predict the Illite Weight Percent of Unconventional Reservoirs from Well-Log Data: An Example from Montney Formation, NE British Columbia, Canada

Shale mineralogy is critical for the proper design and execution of hydraulic fracturing operations and for evaluating production potential. There has been relatively little research into using artificial intelligence for mineralogical prediction for the Montney Formation. This study aims to predict the Montney Formation illite wt.% using readily available conventional logs, where illite is one of the constituents of shale and can aid in analyzing the brittle and ductile zones within the shale formation. The wt.% of illite is often determined by examining core samples or cuttings using XRD or QEMSCAN; both techniques are time-consuming, costly, and cannot be performed without physical samples. Based on conventional log readings, this study uses artificial neural networks (ANNs) and principal component analysis (PCA) to construct an accurate prediction model for illite wt.%. The feed-forward neural network (FFNN) obtained good overall performance in illite wt.% prediction (R2 = 92%) utilizing the backpropagation algorithm and the B.R. technique for eight input parameters. The ANN model was tested by randomly selecting three wells from the same log dataset excluded from the core training and testing phases. Overall, R2 = 88.5% was found in the tests, which is encouraging. This work demonstrates the viability of employing the ANN in applications involving evaluating mineralogical components of a target source rock using traditional logs, especially when geochemical data are missing or inadequate.

Mineralogy of host rocks of the Osinovskoe gold-quartz deposit (Central Urals)

The paper describes the mineralogy of mica shales of the Osinovskoe gold deposit in the Central Urals. Our studies unraveled the role of dynamometamorphism in the transformation of primary rocks and allowed the characterization of their metasomatic alteration. We showed the relationship between plastic and brittle deformations and the formation of gold-bearing mineral assemblage with major pyrite, pyrrhotite and ilmenite and subordinate and rare sphalerite, chalcopyrite, marcasite, rutile, magnetite, molybdenum, galena, altaite, hessite, melonite, petzite, calaverite, volynskite, and sylvanite. The Ag content of native gold varies from 4 to 29 wt. %. Tellurides are associated with pyrite and pyrrhotite and also form monomineral grains and intergrowths in chlorite and mica with inclusions of REE minerals (xenotime-(Y), monazite-(Ce), hydroxylbastnesite-(Ce)), allanite-(Ce)), REE-bearing minerals (epidote, apatite, zircon), Th silicate (torite), and uraninite.

Paleogeomorphology and shale distribution of Late Ordovician-Early Silurian Yangtze platform, South China: Implication for shale mineralogy and TOC content

The distribution and mineral composition of the Wufeng-Longmaxi shale on the Yangtze platform are directly influenced by the geomorphology of the Late Ordovician-Early Silurian period. This research aimed to clarify the geomorphology of the Yangtze platform during this time period and its implication on the Wufeng-Longmaxi shale. Geophysical interpretation, chronostratigraphic division, and correlation, isometric map compilation, and mineral composition analysis were utilized to achieve this objective. The results of the study showed the following findings: (1) The Wufeng-Longmaxi shale was deposited on the southeastern slope of the Leshan-Longnüsi paleo-uplift on the Yangtze platform; (2) The southeastern slope exhibited three significant slope breaks, which allowed for the division of the slope into four geomorphology units: subaqueous high, subaqueous slope, subaqueous plain, and subaqueous sag; (3) The overlying Wufeng–Longmaxi shale was fully developed in the subaqueous plain and subaqueous sag, but lacked graptolite zones LM1-4 in the subaqueous high and subaqueous slope, with the shale onlapping the southeastern slope from southeast to northwest; (4) The southeastern slope significantly affects the grain size, mineral composition, and TOC content of the overlying shale. Specifically, as the slope transitioned from the subaqueous high to the subaqueous sag, the grain size becomes finer, the contents of TOC and silica increased, and the contents of carbonate and clay minerals decreased.

Study on the Sedimentary Environments and Its Implications of Shale Reservoirs for Permian Longtan Formation in the Southeast Sichuan Basin

Marine–continental transitional shale is one of the most promising targets for shale gas exploration in the Lower Yangtze region. To investigate the sedimentary environments and the regularity of the enrichment of the Longtan shale, multiple techniques including core and thin-section observations, geochemical and elemental analyses, X-ray diffraction, scanning electron microscopy (SEM), and low-pressure nitrogen adsorption (LPNA) were used to analyze the sedimentology, mineralogy, and pore structure of the Longtan shale. The core descriptions and thin-section observations showed that the Longtan shale was deposited in marine–delta transitional environments including delta-front, shore swamp, mixed tidal flat and shallow shelf environments. The Sr/Cu, V/Cr, CIA, EF (Mo), EF (U), and other major and trace element results indicated warm and moist climates and water-reducing conditions in the Longtan period. Both the climate and water conditions were favorable for organic matter production and preservation. The geochemical results showed that the Longtan shale was in the overmature stage (Ro values ranging from 2.4% to 3.57%) and that the average total organic carbon (TOC) content was 5.76%. The pore system of the Longtan shale consisted of inorganic pores with a small number of organic pores and microfractures. The porosity and specific surface area were mainly affected by the TOC and clay mineral contents. An effective combination of brittle mineral particles, organic matter, and clay minerals provided the necessary conditions for pore preservation. The organic pores, intergranular pores in clay minerals, and brittle mineral pores formed the main network system for the Longtan shale. In summary, the lithological combinations, organic geochemistry, and pore structure system were all affected by the sedimentary environments.

Petrography, mineralogy, and geochemistry of nitrogenous shale in the Western Desert of Egypt: implications for paleoenvironment

Besides nitrate deposits located in the Atacama Desert of Chile and the Mojave Desert of California, the present work documents, for the first time, the occurrence of potassium nitrate as oval-suboval-shaped aggregations associated with the Late Maastrichtian-Early Paleocene Dakhla Shale and the Paleocene-Early Eocene Esna Shale encountered in the northeastern part of the Kharga Oasis, particularly at G. Um El-Ghanayem and G. Ghaneima. Consequently, integrated petrographic, mineralogical, and geochemical investigations were carried out for shale deposits and nitrate salts to reconstruct the paleoenvironmental conditions of shale, reveal the extent to which nitrate salts are genetically related to the paleoenvironment of shale deposits, and build up a complete scenario about the source and the formation mechanism of nitrate salts. The overall results showed that the studied shale deposits were sourced from mafic igneous and quartzose sedimentary provenances where humid climatic conditions were dominant; the transported detrital particles were then settled down under oxidizing bottom water and shallow depositional conditions. Moreover, the nitrate salts are of an epigenetic origin and sourced from the microbial nitrification of organic matter and the wet atmospheric deposition that is believed to be triggered by the active volcanic eruptions during the Late Eocene/Early Oligocene transition where warm climatic conditions prevailed.

Petrology, Mineralogy, and Geochemical Characterization of Paleogene Oil Shales of the Youganwo Formation in the Maoming Basin, Southern China: Implication for Source Rock Evaluation, Provenance, Paleoweathering and Maturity

Oil shale is a crucial unconventional energy source to supplement conventional oil and gas. The oil shale in the Maoming Basin of China has excellent resource potential. In this study, through systematic geochemical testing, the industrial quality and geochemical characteristics of oil shale are revealed, and the hydrocarbon generation potential of oil shale, the parent rock type, and the tectonic setting of the source area are discussed. It is comprehensively assessed that Maoming oil shale has a medium-oil yield (avg. 6.71%) with high ash content (avg. 76.1%), a high calorific value (avg. 7.16 M J/kg), and ultra-low sulfur (avg. 0.54%). The mineralogical compositions primarily consist of clay minerals and quartz, and barely pyrite. Maoming oil shale is in an immature evolution stage, with high TOC and I-II1 kerogen type, and could be considered an excellent hydrocarbon source rock. The chemical index of alteration (CIA), the index of chemical variability (ICV), and the Th/U ratio indicate that the Maoming oil shale parent rock area is strongly weathered. Multitudinous geochemical diagrams also show that the oil shale was mainly derived from Late Cretaceous felsic volcanic rock and the granite zone, and the tectonic setting was a continental island arc environment related to the active continental margin. This is consistent with the tectonic history of southern China in the Late Cretaceous.

Influence of sequential stimulation practices on geochemical alteration of shale

Water-based hydraulic fracturing fluids (HFFs) can chemically interact with formation shale, resulting in altered porosity and permeability of the host rock. Experimental investigations of spatial and temporal shale-HFF interactions are helpful in interpreting chemical compositions of the injectate, as well as predicting alteration of hydraulic properties in the reservoir due to mineral dissolution and precipitation. Most bench-top experiments designed to study shale-HFF chemical interactions, either using batch reactors or flow-through setups, are carried out assuming that the acid spearhead has already become mixed with neutral HFFs. During operations, however, HFFs are typically injected according to a sequenced pumping schedule, starting with a concentrated acid spearhead, followed by multiple additions of near-neutral pH HFFs containing chemical amendments and proppant. In this study, we use geochemical modeling to consider whether this pre-mixed experimental protocol provides results directly comparable to a sequential discrete fluid-shale interaction protocol. Our results show that for the batch system, the transient evolution in major ion concentrations is faster with the sequential procedure. After 2 h of reaction time, the two protocols converge to the same aqueous concentrations. In a flow-through geometry, the pre-mixed model predicts extensive chemical alteration close to the injection point but negligible alteration downstream. In contrast, the sequential model predicts mineral reactions over hundreds of meters along the flow path. The extent of shale alteration in the sequential model at a given location depends on shale mineralogy and where the acid spearhead resides during the shut-in period. The predictive model developed in this study can help experimentalists to design bench-top tests and operators to better translate the results of laboratory experiments into practical applications.

Shale Wettability and Influencing Factors: A Statistical Investigation

Predicting the wetting behavior of shale rocks is important for understanding fluid flow in shales for CO2 geo-storage and enhanced oil recovery applications. However, shale rocks tend to demonstrate a much wider wettability variation compared to conventional rocks. Here, we present a new model for predicting advancing and receding contact angles for shale/CO2/brine systems. The model presented here considers shale wettability variation as a function of key influencing parameters including (a) operating conditions (i.e., pressure, temperature, and salinity), (b) shale total organic carbon (TOC), (c) thermal maturity, and (d) mineralogy of shale (including quartz, calcite, dolomite, clay, and pyrite content). The developed model shows that pressure and salinity are the most influencing parameters for both the advancing and receding contact angles. These are followed by temperature, TOC, and thermal maturity. The results of this study contribute toward predicting the wetting behavior of shale with known operating and functional properties and thus serve as an essential input in simulation models pertinent to flow behavior in shale rocks and therefore enhance hydrocarbon production from shales and CO2 storage in shale formations.

Geochemical and mineralogical controls on the geomechanical properties of the Eze-Aku Shale: Implications for a potential hydrocarbon reservoir

Oil and Gas Shales are becoming major contributors to the daily crude output in the global energy market. Due to permeability concerns, they require hydraulic fracturing to be commercially productive. Analysing their geomechanical properties and mineralogical influences is key to understanding the fracability and production optimization of shale reservoirs. To this regard, this study evaluates the geomechanical, geochemical and mineralogical properties of the Eze-Aku Shale. Twenty Eze-Aku Shale samples were collected from four locations (Onoli-Awgu, Lokpanta, Okopsi and Aboine) in the Southern Benue Trough. The samples were analyzed to determine composition of major oxides and minerals using Energy Dispersive X-Ray Fluorescence (EDXRF) spectrometry and X-Ray Diffraction (XRD) technology respectively. Parameters such as static Young's modulus and Poisson's Ratio were determined following the International Society for Rock Mechanics (ISRM) standard to define the brittleness and fracability of the shale samples. Average mechanical properties ranged from 0.07 to 0.13 GPa and 0.7–9.8 for Young's modulus (E) and Poisson's ratio (v) respectively. The ratio of Young's modulus to Poisson's ratio negatively relates with clay mineral presence (Illite, Kaolinite and Muscovite) in Okposi and Aboine while in Lokpanta and Onoli-Awgu these parameters however, relate positively with Calcite and Quartz. Good hydraulic fracture performance is linked to brittleness and high Young's moduli, which is favoured, by high silica and carbonate content. This research thus reveals that the mineralogy of the Eze-Aku Shale has prevailing effects on its geomechanical properties. In Lokpanta and Onoli-Awgu however, the shale can be compared most notably to the Barnett Formation (Shale), Eagle Ford Shale and Marcellus Formation.

Variation in Pore Space and Structure of Organic‐rich Oil‐prone Shales from a Non‐marine Basin: Constraints from Organic Matter and Minerals

AbstractOrganic matter (OM) and minerals are major particle components of lacustrine shales. The influence of OM and minerals on pore space and structure in organic‐rich oil‐prone shales containing a large range of total organic carbon (TOC) contents is poorly understood. In this study, we investigated the variation in pore space and structure of low mature lacustrine shales in the Songliao Basin (NE China), based on a study of the mineralogy, petrography, geochemistry, and geophysical properties of shales. Different pore types make markedly different contributions to the mineral surface area (MSA) and pore volume (PV) of the shales. There exists a negative correlation between MSA/PV and TOC in mesopores (r2 = 0.75/0.65) and macropores (r2 = 0.74/0.68), and a positive correlation in micropores (r2 = 0.59/0.64), which are associated with the variation of mineral and TOC contents. A positive relationship between the throat/pore ratio and TOC (r2 = 0.82) shows an increase in throat radius and decrease in pore radius with increasing TOC content. This relationship is supported by the reduction in mean pore diameter (MPD) for large pores and increase in MPD for small pores. These variations are related to the decreased pores by quartz plus feldspar (Q + F) content, increased throats by clay minerals, and enhanced pore‐fill by OM. We propose that the variation of OM and minerals is a key control on the pore space and structure of low mature organic‐rich oil‐prone shales.

Inorganic geochemical, mineralogical and methane sorption capacities of Paleozoic shale formations from Western Peninsular Malaysia: Implication of shale gas potential

An experimental study comprising methane sorption capacity (MSC), inorganic geochemical and mineralogical analysis was conducted to assess the shale gas potential, depositional environments, and tectonic settings in the Western Peninsula (WP) Malaysia. Here, we report 146 shale samples from seven Paleozoic formations in WP Malaysia, divided into four groups based on their ages. The results indicate MSC ranging between 0.054 and 0.065, 0.034 and 0.109, 0.032 and 0.069 and 0.021 and 0.100 mmol/g rock for Silurian-Devonian (S-D), Devonian, Carboniferous, and Permian shales, respectively. By comparison, the MSC of the WP Malaysia shale is close to obtainable values for Longmaxi (China) and Barnett (USA) shales. Geochemical characterization reveals that the studied Paleozoic shales were deposited mainly in continental island arc and active continental margin (ACM) under a reducing marine depositional environment. Sr/Cu, Rb/Sr,Sr/Ba ratios, and C-values reveal warm, humid to hot arid paleoclimate for the S-D and Carboniferous shale samples, and warm, humid paleoclimate for the Devonian and Permian shales. The PIA, CIW, and CIA values indicate the source rocks have been subjected to moderate to strong chemical weathering. Al2O3/TiO2, Zr/TiO2, and LREE/HREE ratio, Eu anomalies, and the binary plot of Zr/Sc and Th/Sc denote that the shales from WP Malaysia are derived from intermediate to felsic igneous source rock. Mineralogical analysis reveals that S-D and Permian shales generally possess less clay and more siliceous minerals than the Devonian and Carboniferous shales. Comparatively, the mineral content of the Paleozoic shales is close to the mineralogy of Niutitang and Longmaxi shales. The geochemical analysis indicates that the pyrobitumen reflectance of Paleozoic shale samples is overmatured. Overall, based on the derived geological data and comparative analysis with hot gas shale reservoirs around the world, high, moderate and low shale gas potentials were obtained for the Devonian and Permian shales, S-D shales and Carboniferous shales in WP Malaysia, respectively.

UV IDENTIFICATION FOR TARFAYAS OIL SHALE AND ASHING AT LOW TEMPERATURE OF Z1 LAYER (MOROCCO)

In order to elucidate our knowledge of oil shale, this work has been initiated. Morocco has large oil shale reserves, the most important deposits of which are in Timahdit, Tarfaya and Tangiers .As oil shale is first-round energy materials that can be used to further valorize these resources, we are interested in the research and development of oil shale-based materials capable of retaining pollutants present in wastewater. In this study, we discuss the role that oil shale can play in inhibiting the infiltration of micro pollutants into the water table. The part of this work presents a bibliographical study on the mineralogy, geochemistry and petro chemistry of oil shale. The use of these materials in the field of environmental protection is discussed. Firstly, an experimental identification work was carried out using the spectroscopic apparatus of our establishment to study the Z1 layer of the Tarfaya deposit in its raw state and in the screen solubilized with chloroform. The Z1 layer has a percentage of organic matter of 12.3% and mineral matter of 29.4% for a heating rate of 21°C/min (A.Attaoui:1999).Then, within the framework of a clean use of the material as an absorbent or depolluting(He.G.Liang et al:2019,S.Gamoudi et al :2019) we carried out the ashing at low temperature of the oil shale, which consists in carrying out combustions on this shale, more precisely on the organic part and not altering the mineral part. In this context, we carried out this incineration on the oil shale of Tarfaya (Z1) at temperatures ranging from ambient to 227°C. The samples were then subjected to HCl acid attacks, and the remaining part was measured and the quantity of the constituents sensitive to this acid attack was evaluated. Pure calcite was taken as a reference and the PH-meter was used to analyses the phenomenon.

Mineralogy, geochemistry and paleoweathering characteristics of Paleogene-Miocene oil shales in Azerbaijan

The Paleogene-Miocene oil shales studied in the paper were taken from the outcrops and ejecta of mud volcanoes in Shamakhi-Gobustan and Absheron regions. The geological age, mineralogy, and chemical composition of the samples were studied by analytical investigations. Minerals found oil shales were described in detail in the relevant categories. Some appropriate classifications were made in connection with the chemical composition of samples. The indices such as CIA, CIW, PIA, "RR = SiO2/Al2O3" - chemical weathering index, the diagrams like "(Al2O - K2O) – CaO – Na2O", "A-CN-K", and also reflecting mobility characteristics of elements, and estimates on large-ion lithophile elements were used to study the paleoweathering characteristics. Keywords: oil shale; geochemistry; mineral; paleoweathering.