Thermal Evolution of Organic Matter and Secondary Hydrocarbon Generation from Upper Paleozoic Coal Deposits in Northern China

The metamorphism and hydrocarbon generation from the Upper Paleozoic coal-bearing strata in Northern China have been widely studied by Chinese geologists since the 1990s. Based on a large amount of data of Ro values,combined with geological background,we have systematically analyzed the thermal evolutionary characteristics of or-ganic matter and the stages of hydrocarbon generation from the Permo-Carboniferous coal deposits and discussed the condition of secondary hydrocarbon generation. The distribution range of secondary hydrocarbon generation in North-ern China is thus determined. It is shown that the coal ranks of the Upper Paleozoic coal deposits are higher in the southern and western belts than those in the northern and eastern belts. Really significant secondary hydrocarbon gen-eration is mainly related to the thermal evolution of organic matter during the Himalayan Period. Profitable areas for secondary hydrocarbon generation should be buried at 3000-4000 m up to the present. Maturity of the Permo-Carbon-iferous source rocks is not very high. It is suggested that the Bohai Bay depression is favourable for secondary hydro-carbon generation and has good oil and gas prospects.

Spatial analysis and evaluation of a coal deposit by coupling AHP & GIS techniques

Nowadays,the evaluation of coal deposits becomes crucial,due to many uncontrollable factors,which affect the energy sector.A comparative evaluation of coal deposits is essential for their hierarchical classification regarding their sustainable exploitation,when compared to other coal deposits or competitive fuels,which may be used as alternative solutions for electricity generation.In this paper,a method for spatial analysis and evaluation of a lignite deposit is proposed,by creating four spatial key indicators via GIS analysis,which are then aggregated by applying a weighted linear combination.The analytical hierarchy process is applied to estimate the relative weights of the indicators,in order to perform a weighted cartographic overlay.Through the synthesis of the indicators,an overall,total spatial quality indicator is calculated.The weighted analysis was shown to be more effective compared to the unweighted one,because it can provide more reliable results regarding the exploitation of the examined lignite deposit.The implementation of GIS-based analytical hierarchy process in spatial analysis and evaluation of lignite deposits,in terms of sustainable exploitation,demonstrates that this method can be extensively applied for evaluating the economic potential of mineral deposits.

Further Information of the Associated Li Deposits in the No.6 Coal Seam at Jungar Coalfield, Inner Mongolia, Northern China

Total 138 coal samples and 14 parting samples were taken from the No. 6 Seam of the Jungar Coalfield, Inner Mongolia. These samples were analysed by optical microscopy, sequential chemical extraction procedure （SCEP）, inductively coupled plasma mass spectrometry （ICP-MS）, X-ray powder diffraction （XRD）, and scanning electron microscope in conjunction with an energy-dispersive X-ray spectrometer （SEM-EDX） analysis. The results indicate that the Li contents have reached the industrial grade of the coal associated Li deposit, and the total Li reserves have reached 2406600 tons, that is, 5157000 tons Li2O in the No. 6 seam in the Jungar Coalfield. The sequential chemical extraction procedure results suggest that the Li concentration is mainly related to inorganic matter. The minerals in the coals consist of kaolinite, boehmite, chlorite-group mineral, quartz, calcite, pyrite, siderite and amorphous clay material. Some Li could be absorbed by clay minerals in the Li-bearing coal seam. The chlorite phase？could be？most likely the host for a part of Li. The Yinshan Oldland should be the most possible source of Li of the coal.

Characterization of Carbon Deposits Formed During Plasma Pyrolysis of Xinjiang Candle Coal

Carbon deposits were formed on the reactor wall during plasma pyrolysis of the Xinjiang candle coal in our V-style plasma pyrolysis pilot-plant. The carbon deposits were studied using a scanning electronic microscope （SEM） and the X-ray diffraction （XRD） method. It was found that carbon deposits located at different parts in the reactor exhibited different microscopic patterns. The formation mechanism of the carbon deposits was deduced. The downward increase in the graphitization degree of the carbon deposits was found and interpreted.

Dual Control of Depositional Facies on Uranium Mineralization in Coal-bearing Series： Examples from the Tuanyushan Area of the Northern Qaidam Basin, NW China

The uranium deposits in the Tuanyushan area of northern Qaidam Basin commonly occur in coal-bearing series. To decipher the U-enrichment mechanism and controlling factors in this area, a database of 72 drill cores, including 56 well-logs and 3 sampling wells, was examined for sedimentology and geochemistry in relation to uranium concentrations. The results show that coal-bearing series can influence uranium mineralization from two aspects, i.e., spatial distribution and dynamic control. Five types of uranium-bearing rocks are recognized, mainly occurring in the braided river and braided delta sedimentary facies, among which sandstones near the coals are the most important. The lithological associations of sandstone-type uranium deposits can be classified into three subtypes, termed as U-coal type, coal-U-coal type, and coal-U type, respectively. The coal and fine siliciclastic rocks in the coal- bearing series confined the U-rich fluid flow and uranium accumulation in the sandstone near them. Thus, the coal-bearing series can provide good accommodations for uranium mineralization. Coals and organic matters in the coal-bearing series may have served as reducing agents and absorbing barriers. Methane is deemed to be the main acidolysis hydrocarbon in the U-bearing beds, which shows a positive correlation with U-content in the sandstones in the coal-bearing series. Additionally, the 613C in the carbonate cements of the U-bearing sandstones indicates that the organic matters, associated with the coal around the sandstones, were involved in the carbonation, one important component of alteration in the Tuanyushan area. Recognition of the dual control of coal-bearing series on the uranium mineralization is significant for the development of coal circular economy, environmental protection during coal utilization and the security of national rare metal resources.

Simulation of Ash Deposition Behavior in an Entrained Flow Coal Gasifier

Fly ash deposition is an important phenomenon associated with ash/slag handling and discharge in the entrained-flow coal gasification process. Fouling and slagging inside the gasifier may cause reliability and safety problems because they can impose strong negative effects on the gasifier wall in the way of heat transfer and chemical corrosion. For these reasons, this study focuses on investigating the ash deposition distribution inside of a two-stage entrained-flow gasifier. The computational model is developed in order to simulate the gasification process with a focus on modeling ash formation, fly ash, and ash deposition. The Eulerian-Lagrangian approach is applied to solve the reactive thermal-flow field and particle trajectories with heterogeneous reactions. The governing equations include the Navier-Stokes equations, twelve species transport equations, and ten global chemical reactions consisting of three heterogeneous reactions and seven homogeneous reactions. The coal/ash particles are tracked with the Lagrangian method. The effects of different coal/ash injection schemes and different coal types on ash deposition have been investigated. The results show that the two-stage fuel feeding scheme could distribute the ash throughout a larger gasifier’s volume and, hence, could reduce the peak ash deposition rate and make the ash distribution more uniform inside the gasifier. Gasification of a high-ash coal results in a high ash deposition rate, low syngas higher heating value (HHV), and low carbon conversion rate. The result of ash deposition rate in this study can be used as a boundary condition to provide ash particle influx distribution for use in slagging models.

The impact of depositional environment and tectonic evolution on coalbed methane occurrence in West Henan, China

A deeper understanding of the mechanisms by which geological factors(depositional environment and tectonic evolution) control the occurrence of coalbed methane(CBM) is important for the utilization of CBM resources via surface-drilled wells and the elimination of coal-methane outbursts, the latter of which is a key issue for coal mine safety. Based on drill core data, high-pressure isothermal adsorption experiments, scanning electron microscopy experiments, mercury intrusion porosimetry, and X-ray diffraction experiments, the impact of the depositional environment and tectonic evolution on CBM occurrence of the II-1 coal seam of the Shanxi Formation in West Henan was analyzed. Results showed that the depositional environment led to the epigenetic erosion of tidal flat coal-accumulating structures by shallow-delta distributary channel strata. This resulted in the replacement of the original mudstonesandy mudstone coal seam immediate roof with fine-to-medium grained sandstones, reducing methane storage capacity. Epigenetic erosion by the depositional environment also increased coal body ash content(from 6.9% to 21.4%) and mineral content, filling the cleat system and reducing porosity, reducing methane storage capacity. The maximum methane adsorption capacity of the coal body reduced from35.7 cm3/g to 30.30 cm3/g, and Langmuir pressure decreased from 1.39 MPa to 0.909 MPa. Hence, the methane adsorption capacity of the coal body decreased while its capacity for methane desorption increased. Owing to the tectonic evolution of West Henan, tectonically deformed coal is common; as it evolves from primary cataclastic coal to granulitic coal, the angle of the diffraction peak increases, d002 decreases, and La, Lc, and Nc increase; these traits are generally consistent with dynamic metamorphism.This is accompanied by increases in the total pore volume and specific surface area of the coal body, further increasing the capacity for methane storage. Increases in micropore volume and specific surface area also increase the ability of the coal body to adsorb methane.

On Lacustrine Depositional Systems and Coal Accumulation in Baise Basin

Baise basin is a semi-graben type , pan-shaped faulted basin of Early Tertiary , in which carbonate lacustrine deposits and elastic lacustrine deposits developed . The assemblages of Gilbert-type delta-lakes ,littoral ,shallow and deep water fades are recognized . Based on grain size , the clastic lacustrine deposit systems can be grouped in three kinds of depositional sequences of progressive deposition : (1)from coarse to fine , (2)from fine to coarse and (3) from fine to coarse and then to fine agan . This was controlled mainly by hydrodynamic factor of lake bottom type .Lake shore was an important place for coal accumulation and peatmoor development . It had long time for coal accumulation and there was a very little amount of minerals into the basin ,and the thick coal layer and high quality coal developed m the zone where initial lake bottom was plan-like and the surface stream flow was weak .Peat accumulation advanced from the margin to the center of basin .Carbonate lakes contained much water ,very high preponderant contenis of coagel ,low inert contents and no fusinite in the coal .

A study on the genetic relations between Permian Longtan Formation coal series strata and Carlin-type gold deposits,southwestern Guizhou Province,China

A large number of the Carlin-type gold deposits occur in the Longtan Formation in southwestern Guizhou Province.The Long-tan Formation contains abundant basalt,tuff and siliceous rocks.All rocks of the Longtan Formation are enriched in gold,which were deposited in a limited platform environment in the transition zone from marine to continental.The process of sedimentation was accompanied by the eruption of Emeishan basalt and hydrothermal deposition controlled by co-sedimentary submarine deep faults in the west,which led to the formation of a peculiar gold-bearing formation with coal series strata.This formation controlled the occurrence of the Carlin-type gold deposits in southwestern Guizhou Province.In response to the remobilization of the Emei mantle plume during the Yanshanian period,As,Au and other ore-forming materials were continuously extracted by deeply circulating waters from the Emeishan basalt and coal seams,thereafter forming ore-forming hydrothermal solutions.When these elements were transported in the coal seams,large amounts of As,Au and other elements were enriched in pyrite within the coal seams,thus forming high-As coal and Carlin-type gold deposits in the Longtan Formation coal series strata.

Theoretical insight into the enhanced CH_4 desorption via H_2O adsorption on different rank coal surfaces

The density functional theory was used to investigate the adsorption of CH4and H2O on different rank coal surfaces. The coal rank is the dominant factor in affecting the adsorption capacity of coal. In order to better understand gas and water interaction with coal of different maturity, we developed fourteen coal models to represent the different rank coal. The interactions of CH4and H2O with coal surfaces were studied and characterized by their adsorption energies, Mulliken charges and electrostatic potential surfaces. The results revealed that the interaction between coal and CH4was weak physical adsorption, and that the interaction between coal and H2O consisted of physical and chemical adsorption. Adsorption energy of coal–H2O system was larger than that of coal–CH4on all rank coals, suggesting that the adsorption priority in the coal models is H2O > CH4. Consequently, the injection of H2O into the different rank coal could effectively enhance the coal bed methane (CBM) recovery. © 2016 Science Press

Comprehensive analysis of CBM recovery in high rank coal reservoir of Jincheng area

Coalbed methane (CBM) predicting recovery in high rank coal reservoir varies greatly in Jincheng area and it seriously influences efficient and economic exploitation of CBM resource. In order to predict more accurate CBM recovery, we conducted history matching and productivity prediction of vertical well by using COMET 3 reservoir modeling software, innovatively adopted the gas desorption experiment of bulk coal at fixed test pressure, analyzed the recovery extent method of Daning multiple-hole horizontal well and Panzhuang well group, and calculated recovery by sorption isotherm method of 14 vertical CBM wells at the abandonment pressures 1.0, 0.7, 0.5 and 0.3 MPa, respectively. The results show that the reservoir simulation methods (numerical simulation method and the recovery extent method) is more reliable than the theoretical analysis of coal sample (sorption isotherm method and desorption experiment method). Also, desorption experiment method at fixed pressure is superior to sorption isotherm method. Through the comprehensive analysis and linear correction, CBM recovery ratios in high rank coal reservoir of Jincheng area were found to be 38.64%, 49.30%, 59.30%, and 69.20% at the abandonment pressures 1.0, 0.7, 0.5 and 0.3 MPa, respectively. The research results are of significant importance in the CBM exploration and development in Jincheng area.

Valency Study of Vanadium in Stone Coal of Southern China

Vanadium - bearing stone coal is a new resource of vanadium. V in stone coal mainly exists in three oxidation states: 7.84% V(III), 72.08% V(IV) and 20.08% V(V). The change and distribution of valency during oxidizing roasting shows that organic matter in the coal determines the valency at low temperatures. At about 450°C, V(III) is completely oxidized to V(IV); above 500°C, temperature is the most important factor for the oxidation of V. At 700-1000°C, 92% of V in the coal has been oxidized to V(V). At higher temperature, no more oxidation of V takes place, equilibrium being established. The role of NaCl in the recovery of V2O5 from the coal is discussed. The best conditions for roasting are an oxidation-chlorination atmosphere, temperature 800°C for 30 minutes, ore:NaCl = 100:10, ηroast reaching 90%.

Classification of Mineral Resources Associated and Accompanied with Coal Measures

The paper discusses the concept of mineral resources associated with coal measures. A rational and scientific classification of such mineral resources becomes more necessary with the development of science and technology. A classification scheme is proposed based on compositions and physical properties and the utilization of these associated minerals.

Effects of Syngas Particulate Fly Ash Deposition on the Mechanical Properties of Thermal Barrier Coatings on Simulated Film-Cooled Turbine Vane Components

Research is being conducted to study the effects of particulate deposition from contaminants in coal synthesis gas (syngas) on the mechanical properties of thermal barrier coatings (TBC) employed on integrated gasification combined cycle (IGCC) turbine hot section airfoils. West Virginia University (WVU) had been working with US Department of Energy, National Energy Technology Laboratory (NETL) to simulate deposition on the pressure side of an IGCC turbine first stage vane. To model the deposition, coal fly ash was injected into the flow of a combustor facility and deposited onto TBC coated, angled film-cooled test articles in a high pressure (approximately 4 atm) and a high temperature (1560 K) environment. To investigate the interaction between the deposition and the TBC, a load-based multiple-partial unloading micro-indentation technique was used to quantitatively evaluate the mechanical properties of materials. The indentation results showed the Young’s Modulus of the ceramic top coat was higher in areas with deposition formation due to the penetration of the fly ash. This corresponds with the reduction of strain tolerance of the 7% yttria-stabilized zirconia (7YSZ) coatings.

Coal-Forming Model in the Context of Non-marine Sequence Stratigraphy:A Case Study of Jurassic Coal Measures in Northern Qaidam Basin,Northwestern China

Previous studies of coal sequence stratigraphy have concentrated on coals associated with paralic depositional systems.Little attention has been paid to their counterparts in non-marine intra-mountain coal basins.The northern Qaidam Basin of northwestern China has been extensively developed with abundant oil and gas as well as coal resources in its Jurassic non-marine successions.A total of six sedimentary systems of the Early and Middle Jurassic

Sequence Stratigraphy of the Jurassic Coal Measures in Northwestern China

The sequence stratigraphy of the Jurassic coal measures of northwestern China has been studied based on data from outcrop and borehole sections. Because of the geological background and the diversity of basin types, such as isochronisms of coal seams and recognition of key sequence boundaries, it is rare to summarize and correlate sequence structure and framework. The types and recognition characteristics of the sequence boundaries of the Jurassic coal measures are revealed by comparing climatic characteristics, structural styles and the base level cycle. A total of five third-order sequences and 15 systems tracts have been subdivided and the sequence stratigraphic framework has been reconstructed confirming that the thick coals accumulated in the late stage of transgression system tracts of sequence I （SQ I） and sequence III （SQ III）. This idea is of important academic significance for instructing coal resources exploration, and enhancing geological effects of prospecting engineering. It is also of practical significance for guaranteeing construction of the large-scale coal production base in northwestern China, accelerating the westward development of the coal industry stratagem.

Microstructural Degradation of Thermal Barrier Coatings on an Integrated Gasification Combined Cycle (IGCC) Simulated Film-Cooled Turbine Vane Pressure Surface Due to Particulate Fly Ash Deposition

Research is being conducted to study the degradation of thermal barrier coatings (TBC) employed on IGCC turbine hot section airfoils due to particulate deposition from contaminants in coal syn-thesis gas (syngas). West Virginia University (WVU) had been working with US Department of Energy, National Energy Technology Laboratory (NETL) to simulate deposition on the pressure side of an IGCC turbine first stage vane. To simulate the contaminant deposition, several TBC coated, angled film-cooled test articles were subjected to accelerated coal fly ash, which was injected into the flow of a combustor facility with a high pressure (approximately 4 atm) and a high temperature (1560 K) environment. To investigate the degradation of the TBCs due to particulate deposition, non-destructive tests were performed using scanning electron microscopy (SEM) evaluation and energy dispersive X-ray spectroscopy (EDS) examinations. The SEM evaluation was used to display the microstructure change within the layers of the TBC system directly related to the fly ash deposition. The SEM micrographs showed that deposition-TBC interaction made the YSZ coating more susceptible to delamination and promoted a dissolution-reprecipitation mechanism that changed the YSZ morphology and composition. The EDS examination provided elemental maps of the shallow infiltration depth of the fly ash and chemical composition spectrum results which showed yttria migration from the YSZ into the deposition.

Genetic Stratigraphic Sequences of Late Tertiary Brown Coal Basins in Central Yunnan,China

There are a number of small -scale brown coal basins in the central part of Yunnan. The coal-bearing strata are made up of alluvialfan-lacustrine-swamp genetic Seguences’ On the basis of the detialedgenatic stratigraphic analyses with some basins, three types of chronestratigraphic interfaces and second grade or the geneticstratigraphic units are defined. This paper reveals inherent relationswith regrad to the genetic stratigraphic evolution and coal formation of the small-scale fault basins’

河南偃龙地区晚石炭世风化作用与铝土矿成矿过程

通过对偃龙地区铝土矿成矿的古地理环境特征、含矿岩系的岩相学特征、岩石矿物特征、成矿元素富集特征的研究,分析了晚石炭世本溪组铝土矿风化成矿作用的三个阶段脱硅富铝的动态变化过程,进而探讨了本区晚石炭世风化作用条件下的铝土矿成矿过程。研究结果认为,在风化作用为主的铝土矿成矿过程中,含矿母岩首先生成黏土矿物,然后当岩石中Al_(2)O_(3)含量接近35%时,开始生成以三水铝石为主的最初铝土矿,最后铝土矿在盖层覆盖下,在一定的温度压力条件下三水铝石转化为一水硬铝石,并最终形成“煤-黏土-铝土-铁质黏土”这种本溪组铝土矿系的典型结构。