Bokaro Coalfield Research Articles

Machine learning assisted model based petrographic classification: a case study from Bokaro coal field

Machine learning assisted model based petrographic classification: a case study from Bokaro coal field

Palaeodepositional environment, implications of Glossopteris flora, and organic matter characteristics from the Lower Permian, Karo Open Cast Mine, East Bokaro Coalfield, Damodar Basin, India

The present study deals with the Early Permian floral diversity, palaeoenvironment, palaeoclimate and depositional setting using a multiproxy approach that includes morphotaxonomy, palynology, and organic geochemistry of Karo OCM (Open Cast Mine), East Bokaro Coalfield, Damodar Gondwana Basin, India. The Permian sediments of Peninsular India are widely regarded as fluvial, along with some marine incursions. The macroplant fossil assemblage exhibits the presence of Glossopteridales, comprising Glossopteris, Gangamopteris, and Vertebraria, as well as Coniferales, which includes Noeggerathiopsis. The palynological assemblage encompasses the dominance of the striate bisaccate pollen Faunipollenites sp. and the sub-dominance of the non-striate bisaccate pollen Scheuringipollenites sp. with glossopterid affinities. The megafloral and palynofloral assemblage confirms the biostratigraphical age to be Late Barakar palynoflora of Kungurian affinity. The studied morphological characteristics, including small to large Glossopteris leaves exhibiting a lanceolate shape, acute apices, and acute cuneate or tapering bases, as well as entire margins with narrower lamina and narrow meshes, suggest the existence of a dense forest with the prevalence of a warm and humid climate during their deposition. The organic geochemical characterization based on functional group and biomarker analyses reveals the diagenetic effects on organic matter. Aliphatic symmetric (∼2865–2855 cm-1) and asymmetric stretching (∼2930–2910 cm-1) peaks are identifiable in coal samples, whereas they are absent in carbonaceous shale. The A-factor vs. C-factor plot suggests that the kerogen type is type III, which can generate mainly gaseous kerogen. The vitrinite reflectance studies (Rr av. 1.1%) show increased maturity of the samples, which is supported by the n-alkane distribution pattern and the absence of hopane terpenoids. The Indian floral assemblages in contemporary of southern Gondwana continents reveal a stronger inclination/affinity with the flora of Africa than that of South America, thereby supporting the age to be of Artinskian–Kungurian.

Palaeofloral assemblages from Tapin Sub-basin, West Bokaro Coalfield, Jharkhand, India and its clue on floral diversity, palaeoclimate, palaeovegetation and palaeoecology

Palaeofloral assemblages from Tapin Sub-basin, West Bokaro Coalfield, Jharkhand, India and its clue on floral diversity, palaeoclimate, palaeovegetation and palaeoecology

Multimineral Modeling and Brittleness Index Estimation Using Core and Geophysical Well Log Data in the East Bokaro Coalfield of India

Multimineral Modeling and Brittleness Index Estimation Using Core and Geophysical Well Log Data in the East Bokaro Coalfield of India

Anisotropy and fracture analysis for coalbed methane reservoir development in Bokaro coalfield, India

ABSTRACTThe low permeability of coal seams is a constraint in the efficient production of coalbed methane. However, the presence of natural fractures in coal enhances the permeability, and prior knowledge of sub‐surface fractures in coal seams is vital to identify the prospective seam. This paper investigates the anisotropy and identifies fractures by processing the advanced sonic and resistivity image logs to mitigate challenges in the reservoir. Anisotropy is estimated from the difference in the travel time between fast and slow shear waves. The application of Alford's rotation technique determines the fast shear wave polarization angle which is consistent with the fracture orientation along the NE–SW or NW–SE direction in coal seams. Moreover, the crossover of fast and slow shear waves in the slowness versus frequency plot indicates stress‐induced anisotropy that originates from fractures. Besides, drilling‐induced fractures observed along NE–SW in the resistivity image log indicate the maximum horizontal stress direction. Results from this study compare coal seams based on fractures in adopting better operational activities for optimized production and future geomechanical studies in the Bokaro coalfield situated in India.

Acritarchs - Palynomorphs from the Barren Measures Formation of West Bokaro Coalfield: Implications to Depositional Environment

The Barren Measures Formation of West Bokaro Coalfield has been examined for palynological study. The present study of shale from the exposed Barren Measures Formation along the Chotha Nala section has yielded pollen, spore, AOM, phytoclast (equidimnsional and lath shaped) and acritarchs. The yield of spore, pollen, along with acritarchs and records of primary sedimentary structures attribute to a marine incursion to a fluvial setting of Barren Measure Formation. Based on the frequency distribution of acritarchs and associated palynomorphs, three zones have been proposed in which the zone II is characterised by marine incursion of high intensity as compared to zone I and II. Keywords: Acritarchs, Spore, Pollen, Phytoclast, West Bokaro Coalfield, Marine Incursion

Fracture analysis using Stoneley waves in a coalbed methane reservoir

ABSTRACTThe production of coalbed methane gas depends upon various factors such as permeability, gas content, gas saturation and seam thickness. The low permeability in coal is a constraint in the gas extraction process. However, the presence of natural fractures and cleats in coal increases the permeability; therefore, its identification is necessary to establish the prospectivity. Hence, a methodology is used to process the Stoneley waveform in the Bokaro coalfield located in India to obtain slowness magnitude from the semblance analysis. The separation of directly transmitted and reflected Stoneley waves determines the reflection coefficient and attenuation, and its analysis emphasizes the presence of fractures. In coal seams, the average reflection coefficient ranges from 0.42 to 2.44 and attenuation ranges from 0.2 dB to 12.68 dB. The Stoneley slowness versus frequency plot shows a constant slowness with increasing frequency in the non‐fractured seams, whereas a dispersive trend is observed in the fractured seams. Fractures are also distinguished from the cross‐plot of compressional/shear versus Stoneley velocity. The observation of higher reflection coefficient, attenuation and slowness‐frequency dispersion in coal seams indicates extensive fractures/cleats that corroborate with the resistivity image log correlation. Thus, the study helps to distinguish between fractured and non‐fractured coal seams from the integrated approach of reflection coefficient, attenuation and dispersion analysis of Stoneley waves supported by the identification of fractures from resistivity image log for optimization in coalbed methane production in the development phase.

Flotation behavior of metallurgical coals from different seams under electrolytic process water

ABSTRACT Various studies have reported that electrolytes present in the plant’s process water influence the coal flotation performance. However, coal fines, which are fed into the flotation circuit are from different coal seams, and their surface properties usually vary considerably. In this study, flotation experiments were conducted using coal fines from three different coal seams of the West Bokaro coalfield in plant’s process water to explore the extent of change in flotation response of each coal. Besides, flotation experiments using deionized water were parallelly examined for comparison. XRD, SEM, FTIR, BET, contact angle, wetting rate, and zeta potential measurements were performed to understand and compare the surface properties of three coals. The flotation results indicated that compared to deionized water, process water increased flotation yield, combustible recovery as well as ash recovery for all three coals at all examined collector dosages.

Early Permian Floral Diversity and Palaeoenvironment of The West Bokaro Coalfield, Damodar Basin, India

Early Permian Floral Diversity and Palaeoenvironment of The West Bokaro Coalfield, Damodar Basin, India

Floral diversity and environment during the early Permian: a case study from Jarangdih Colliery, East Bokaro Coalfield, Damodar Basin, India

Macro and miofloral analyses of coal-bearing sequences of the Jarangdih coal mine, Damodar Basin, were carried out to infer the floral diversity, age assessment, and the palaeoenvironment during the deposition of the Barakar Formation in this area. Damodar Basin, one of the five major Gondwana basins in India, is considered as the reference basin for inter-basinal age correlations. The Barakar strata of this colliery have yielded a diverse macroflora consisting of the groups Glossopteridales (Glossopteris, Vertebraria, Gangamopteris, fructifications, and stem casts) and Equisetales (Phyllotheca indica, Schizoneura gondwanensis, and Paracalamites sp.). The genus Glossopteris dominates the assemblage with 16 species viz. G. arberi, G. communis, G. churiensis, G. giridihensis, G. indica, G. intermedia, G. intermittens, G. leptoneura, G. linearis, G. mohudaensis, G. recurva, G. searsolensis, G. stenoneura, G. taenensis, G. tenuifolia, and G. tenuinervis. The leaves of Glossopteris leptoneura have impressions of male sporangia adhered on them. The groups Lycopodiales, Coniferales, Sphenophyllales, and Filicales are not represented as macrofloral remains; however, their presence is recorded in the palynoassemblage. The palynological analysis has revealed only one palynoassemblage characterised by the dominance of striate bisaccate palynomorphs mainly Faunipollenites and non-striate bisaccate pollen—Scheuringipollenites. The other stratigraphically significant palynotaxa are Striatopodocarpites, Verticipollenites, Crescentipollenites, Striatites, and Arcuatipollenites. The recovered palyno- and megafloral assemblages suggest the late early Permian (Kungurian) age to the Barakar strata of Jarangdih coal mine and prevalence of moderately warm climate during their deposition.

Quantifying the Dynamics and Drivers of Landscape Change in an Opencast Coal Mining Area of Central India (East Bokaro, Jharkhand)

This paper evaluates the spatiotemporal dynamics of landscape change and identifies the primary drivers of deforestation in East Bokaro coalfields from 1972 to 2016 using grid-based change detection and spatial statistics. Landsat images for the years 1972, 2001 and 2016 were classified using a supervised maximum likelihood technique to generate the land use and land cover maps for each year. Square grids of 500 m were used to quantify the cumulative changes in land cover from 1972 to 2016. Grid-based correlation and regression analyses were used to identify the drivers of change. The results revealed that the area has undergone major changes in land cover pattern in the last 44 years due to expansion of mining activities. Forests and agriculture have reduced while settlement and barren lands have increased considerably. Extensive plantation activities on mining wastelands in the last few decades have led to an increase in the forest cover by about 8.22%. Correlations indicated that both mining and agriculture increased at the expense of forests to some degree and agricultural lands were sacrificed for the expansion of built-up areas. Regression analysis confirmed that agriculture and mining were the most influential factors driving the changes in forest cover.

Assessment of Hydrogeochemical Processes and Mine Water Suitability for Domestic, Irrigation, and Industrial Purposes in East Bokaro Coalfield, India

Mine water samples collected from the East Bokaro coalfield were analysed to assess suitability for domestic, irrigation, and industrial purposes. The pH of the samples ranged from 6.78 to 8.11 in the pre-monsoon season, 5.89–8.51 during the monsoon season, and 6.95–8.48 in the post-monsoon season. The anion chemistry was dominated by HCO3− and SO42−, with minor amounts of Cl−, NO3− and F−. The Fe concentrations exceeded the maximum permissible limit of the BIS drinking water standard in about 44% of the collected samples. Turbidity, TDS, Fe, total hardness (TH), SO42−, and Mg2+ also sometimes exceeded drinking water limits. The TDS, TH and SO42− concentrations of the mine water makes it unsuitable for domestic purposes or for industrial use; high values of %Na, SAR, RSC, and Mg-hazard at certain sites restrict its suitability for agricultural use.

Palynology and palaeoenvironment of Late Permian Sawang OCM, East Bokaro Coalfield, Damodar Basin, India

Palynodating of Sawang Open Cast Mine (OCM) section from East Bokaro Coalfield, Damodar Basin has been done. Recovered palynofossils are characterized by the dominance of Striatopodocarpites–Faunipollenites complex. The other stratigraphically significant taxa recorded from this section are Guttulapollenites hannonicus, Crescentipollenites fuscus, Rhizomaspora indica, R. triassica, Distriatites sp., Weylandites lucifer, Microfoveolatispora gondwanensis, Dictyotriletes invisus, Indotriradites spp., Arcuatipollenites pellucidus, Alisporites indicus and Klausipollenites schaubergeri. Other rare palynotaxa include Parasaccites, Corrisaccites, Dicapipollenites, Striomonosaccites, Barakarites, Plicatipollenites, Scheuringipollenites, Densipollenites, Callumispora, Tiwariasporis, Praecolpatites and Distriatites. On the basis of the total palynocomposition, the studied section has been dated as Late Permian age. This age correlation also gets support from comparative studies with similar palynoassemblages known from other coalfields of Indian Gondwana basins such as Damodar, Son–Mahanadi, Rajmahal, Wardha–Godavari and Satpura basins of India and from known Gondwanan continents. Palynofossil evidences indicate prevalence of warm and humid conditions. The dominance of conifers and subdominance of Glossopterids, cordaites and low percentage of triletes (filicopsids and lycopsids) suggests that the Inland Sawang OCM was deposited under freshwater environment.

Late Permian palynomorphs from the West Bokaro Coalfield, Damodar Basin, Jharkhand, India

Palynological studies were carried out for samples collected from the Bokaro River section near Danea area from West Bokaro Coalfield, Damodar Basin. The recovered palynomorphs are characterized by the dominance of monosaccate pollen mainly Densipollenites (D. magnicorpus, D. invisus, D. indicus and D. densus) and subdominance of Faunipollenites spp.–Striatopodocarpites spp. complex. The other stratigraphically significant taxa recorded from this section are Guttulapollenites hannonicus, Crescentipollenites fuscus, Arcuatipollenites (A. pellucidus, A. ovatus and A. damudicus), Alisporites asansolensis, Verticipollenites gibbosus, Striatites rhombicus, Platysaccus densicorpus, Chordasporites sp., Parasaccites (P. perfectus and P. densicorpus) and Horriditriletes sp. On the basis of the total palynocomposition, the studied section has been dated as late Permian in age. This age correlation also gets support from comparative studies with similar palynoassemblages known from other coalfields of Indian Gondwana basins such as Damodar, Satpura, Son–Mahanadi, Rajmahal and Wardha–Godavari basins. The dominance of Cordaites and subdominance of conifers of Glossopterids suggests that the deposition of the sedimentary sequences took under freshwater environment.

Assessment of Sulphate and Iron Contamination and Seasonal Variations in the Water Resources of a Damodar Valley Coalfield, India: A Case Study.

The aim of the present study was to assess the sulphate [Formula: see text] and iron (Fe) contamination and seasonal variations in the water resources (groundwater, surface water, and mine water) of the West Bokaro coalfield region, India. One hundred and twenty-four water resources samples were collected from the coalfield during the post- and pre-monsoon seasons. The concentrations of [Formula: see text] were determined using ion chromatography and Fe concentrations were analyzed using inductively coupled plasma mass spectrometry. A statistical analysis was used to easily understand the seasonal variations of the elements in the water resources of the area. The concentrations of [Formula: see text] and Fe in the water resources were higher in the pre-monsoon season than in the post-monsoon season, irrespective of location. The water resources of the coalfield were contaminated with high concentrations of [Formula: see text] and Fe, and would require suitable treatment before drinking, domestic and industrial uses.

Prediction of Compressional Wave Velocity Using Regression and Neural Network Modeling and Estimation of Stress Orientation in Bokaro Coalfield, India

Velocity of compressional wave (V P) of coal and non-coal lithology is predicted from five wells from the Bokaro coalfield (CF), India. Shear sonic travel time logs are not recorded for all wells under the study area. Shear wave velocity (Vs) is available only for two wells: one from east and other from west Bokaro CF. The major lithologies of this CF are dominated by coal, shaly coal of Barakar formation. This paper focuses on the (a) relationship between Vp and Vs, (b) prediction of Vp using regression and neural network modeling and (c) estimation of maximum horizontal stress from image log. Coal characterizes with low acoustic impedance (AI) as compared to the overlying and underlying strata. The cross-plot between AI and Vp/Vs is able to identify coal, shaly coal, shale and sandstone from wells in Bokaro CF. The relationship between Vp and Vs is obtained with excellent goodness of fit (R 2) ranging from 0.90 to 0.93. Linear multiple regression and multi-layered feed-forward neural network (MLFN) models are developed for prediction Vp from two wells using four input log parameters: gamma ray, resistivity, bulk density and neutron porosity. Regression model predicted Vp shows poor fit (from R 2 = 0.28) to good fit (R 2 = 0.79) with the observed velocity. MLFN model predicted Vp indicates satisfactory to good R2 values varying from 0.62 to 0.92 with the observed velocity. Maximum horizontal stress orientation from a well at west Bokaro CF is studied from Formation Micro-Imager (FMI) log. Breakouts and drilling-induced fractures (DIFs) are identified from the FMI log. Breakout length of 4.5 m is oriented towards N60°W whereas the orientation of DIFs for a cumulative length of 26.5 m is varying from N15°E to N35°E. The mean maximum horizontal stress in this CF is towards N28°E.

Identification of artificial groundwater recharging zone using a GIS-based fuzzy logic approach: a case study in a coal mine area of the Damodar Valley, India

The West Bokaro coalfield is a richest coal-mining belt in the Damodar Valley, India. The extensive mining of the area has resulted in disruption of the groundwater availability in terms of both quantity and quality. This has led to a drinking water crisis, especially during the pre-monsoon period in the West Bokaro coalfield area. The characterization of the hydrogeological system and the artificial recharging of the aquifers might help to better manage the problem of the groundwater-level depletion. For this purpose, seven important hydrogeological factors (water depth, slope, drainage, soil, infiltration, lithology, and landuse) have been considered to define the most suitable locations for artificial groundwater recharging in the mining area. Different thematic maps were prepared from existing maps and data sets, remote-sensing images, and field investigations for identification of the most suitable locations for artificial recharge. Thematic layers for these parameters were prepared, classified, weighted, and integrated into a geographic information system (GIS) environment by means of fuzzy logic. The results of the study indicate that about 29 and 31% of the area are very suitable and suitable for recharging purposes in the West Bokaro coalfield. However, the rest of the area is moderate to unsuitable for recharging due to the ongoing mining and related activities in the study area. The groundwater recharging map of the study area was validated with measured electrical conductivity (EC) values in the groundwater, and it indicated that validation can be accepted for the identification of groundwater recharging sites. These findings are providing useful information for the proper planning and sustainable management of the groundwater resources in the study area.

Chemical and mineralogical composition of Kathara Coal, East Bokaro Coalfield, India

Utilisation of any coal primarily depends on its organic constituents. However, the inorganic constituents i.e., mineral matter present in the coal can decide its end uses. Therefore, the study of mineral matter in coal is an inevitable and such type of studies in India is very scanty. In this paper, we present the characters of a relatively low-ash non-coking coal from Kathara mines, East Bokaro coalfield, India with emphasis on its inorganic constituents and mineral matter. The coal is characterised by 22.56wt% ash (dry basis), 28.78wt% volatile matter (dry basis), and 48.66wt% fixed carbon (dry basis). Modal analysis by optical microscopy revealed 53.6vol% vitrinite, 38.3vol% inertinite, 8.1vol% liptinite on the mineral matter free basis (mmf), and 25.1vol% mineral matter. The minerals present in this coal are dominantly clay, quartz and siderite with a minor quantity of hematite, magnetite, goethite and pyrite. Electron micro-probe studies revealed trace presence of sphalerite, baddeleyite, and some altered magnesium silicate. The total sulphur content of this coal is found to be 1.16wt% on dry ash free basis (daf). Since the majority of the minerals, although fine in size, occur as independent phases with distinct and weak grain boundaries with the macerals, the coal shall be susceptible for beneficiation and the cleaner product can find applications in metallurgical industries for partial substitution in coke making because the mean vitrinite reflectance of this coal is 0.70%.

Quantitative assessment of groundwater resource potential in a coalfield of Damodar River Basin India

The present study was carried out for the quantitative assessment of groundwater resource potentials in East Bokaro Coalfield of Damodar River Basin. The rise and fall of groundwater table is closely related to the hydro-meteorological conditions, water level, landform, geology and morphological factors. Average annual rainfall for the entire period of 35 years is 1366 mm in which annual maximum rainfall was 2544 mm in the year 2001 and minimum was 733 mm in the year 2004. The fluctuation of groundwater level ranged between 0.15 and 2.87 mbgl in the study area. Rainfall is the main source to replenish the groundwater by percolation through deep soil zones. Besides rainfall, the mine water discharges from the local mining areas and existing water bodies including water logged in abundant mine quarries. Mine water also contributed to the groundwater recharge as return flow. The study area is highly disturbed and the permeabilities of individual geological units are spatially variable and depend on lithology, fracturing and attenuation with depth. The total annual replenishable recharge was calculated to be 48.5 million m3/year and net annual groundwater availability was estimated to be 13.7 million m3 by rainfall infiltration method. The stage of groundwater development was calculated as per GEC-1997 guideline, which falls under the safe category (i.e., 67%). But water resource conservation for sustainable water management is urgently required in the study area.

Assessment of Mine Water Quality Using Heavy Metal Pollution Index in a Coal Mining Area of Damodar River Basin, India.

A total no. of 16 mine water (underground and opencast coal mine pump discharges) samples were collected from East Bokaro coalfield during pre-monsoon, monsoon and post-monsoon seasons. The concentrations of Fe, Mn, Cu, Pb, Zn, Ni, As, Se, Al, Cd and Cr were determined using inductively coupled plasma mass spectrometry for the assessment of spatio-temporal variations, source apportionment and heavy metal pollution indexing. The results demonstrated that concentrations of the metals showed significant seasonality and most variables exhibited higher levels in the pre-monsoon season. The principle component analysis for ionic source identification was synthesized into three factors with eigen values cut off at greater than unity and explained about 64.8% of the total variance. The extracted factors seemed to be associated to the geogenic, extensive mining and allied transportation sources of the elements. The heavy metal pollution index (HPI) of the mine water calculated for the individual locations varied from 7.1 to 49.5. Most of the locations fall under low to medium classes of HPI except few locations which are under the influence of surface mining and associated transportation.