Browsing by Author "Sanjay Ojha"

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Environmental geochemistry of selected elements in lignite from Barsingsar and Gurha mines of Rajasthan, Western India
(Geological Society of India, 2015) Prakash K. Singh; P.K. Rajak; M.P. Singh; A.S. Naik; Vijay Kumar Singh; S.V. Raju; Sanjay Ojha
The present paper contains the result of investigation carried out on selected trace elements in the less studied lignite deposits of Rajasthan, Western India. The study has been made on two new lignite deposits–Barsingsar and Gurha. The former has elevated ash content (mean 20.8%) than the latter one (mean 5.1%) and both of them have high volatile matter (mean 43.7% and 49.9% respectively). The lignite samples have been studied for selected elements like Fe, Ca, Mg, Mn, K, Na, Cu, Co, Ni, Cr, Zn, Pb, Cd and As. The elements like Cd, Co, Ni, Pb and Cu occur in high concentration when compared to the Clarke values for brown coal. Ca and Mg relate positively with organic matter in Barsingsar lignite indicating their organic source while K, Cu, Co, Pb and Cd indicate their inorganic origin. Ca might have come in contact with the organic matter during humification and would have become a part of humate. The elements like Cu, Co, Ni, Cr, Cd and Pb showing strong affinity with inertinite could have got associated with the mineral matter present in the fusinite and funginite macerals. In Gurha lignites Pb and Co have shown their affinity with inorganic matter which could have been drawn from sulphides and clay minerals. © 2015, Geological Society of India.
Evolution and Evaluation of Coal-bed Methane in Cambay Basin, Western India: Insights from Stable Isotopic and Molecular Composition
(Springer, 2023) Sanjay Ojha; Naresh K. Punjrath; Amitava Chakraborty; Prakash K. Singh
Owing to a rapid rate of depletion of conventional energy resources and to keep pace with the ever increasing energy demand, scientists all over the world are looking for some alternate source. Coal bed methane (CBM) is one of them. With the discovery of coalbed gas from an oil and gas producing basin- the San Juan basin in Colorado and New Mexico by AMOCO in early 1980’s, the attention of world-wide hydrocarbon industry shifted to evaluation of CBM potential of Tertiary basins. The Tertiary Cambay basin in Gujarat is a known onland hydrocarbon province of India and has been producing oil since 1958. During drilling for petroleum, thick Eocene coal seams are encountered at varied depths in Mehsana area and further north. In 2004, few coalbed methane (CBM) blocks were awarded in northern Cambay basin and contagious Barmer Basin. The present paper entails the results of investigation carried out for CBM in the deep-seated coals of Sanchore and Tharad area in north Cambay basin. The methane content of the desorbed gases varies from 20–68%. The stable carbon isotope study (δ13C) shows that the desorbed gas is dominantly biogenic but the compositional analysis of desorbed gas reveals significant fractions of ethane (C2) and butane (C3) indicating the gases to be of mixed origin. Further, presence of high CO2 content is observed which varies from 20–45% of the total volume of desorbed gas. The estimated mean CBM resource of the study area is ∼ 46 billion cubic meters. © 2023, Geological Society of India, Bengaluru, India.
Petrogenesis and Evolution of Tharad Coals of Cambay Basin, Gujarat (Western India): An Insight
(Springer, 2023) Sanjay Ojha; Prakash K. Singh
The present paper discusses the evolution of the coal bearing sequences of Tharad Formation of Cambay Basin (Gujarat) based on coal petrological and organic geochemical signatures. Cambay Basin is a craton margin rift basin of Late Cretaceous age which is narrow and elongated. This north-south trending graben hosts huge sub-surface lignite/coal deposits of Early to Middle Eocene age. These coals have been petrographically and geochemically characterized to understand the type of flora, coal facies, depositional environment and coalification. Thickening of seams with depth is towards central part. Vitrinite rich Cambay Basin coals contain a considerable amount of liptinite indicating their derivation from the forest type of vegetation that grew under humid tropical climate while its high resin content indicates growth of conifers and gum-producing plants. High collodetrinite relates to soft woody tissues from herbaceous/bushy plant sources. Abundance of bioclasts in the western flank of the Sanchore low occur in stack indicating poor transportation and abrupt drop in bathymetry under tidal flat environment. The palynofloral assemblages indicate tidal deposition. Gas chromatography-mass spectroscopy (GC-MS) studies indicate low amount of oleanane suggesting a terrestrial source. The microlithotypes suggest limnic and telmatic mixed environment with typical forest floral input with intermittently changing water table conditions. The maceral composition of the coals indicates terrestrial origin having high tree-density. Marine influence caused influx of calcium rich water promoting decomposition of organic matter due to high bacterial activity and high pH values with depth. The ground water flow index (GWI) values indicate ombrotrophic hydrological condition while the vegetation index (VI) values support herbaceous plants. The swamp, therefore, suffered oxic and anoxic condition alternatingly with influence of reed marshes favouring the growth of anaerobic bacteria in high bathymetric region. The depth of burial of coal seams in Sanchore is extrapolated to be 1350–1800m with a temperature range of 40–80°C. © 2023, Geological Society of India, Bengaluru, India.
Prevalence of Mycobacterium tuberculosis Beijing genotype and its association with drug resistance in North India
(Elsevier Ltd, 2017) Jitendra P. Mathuria; Govind N. Srivastava; Pragya Sharma; Bharat L. Mathuria; Sanjay Ojha; Vishwa M. Katoch; Shampa Anupurba
The global presence and rapid dissemination of Beijing genotype of Mycobacterium tuberculosis, makes it an important issue of public health. Its presence and association with multi-drug resistance has been shown in many settings. In present study we tried to find its prevalence and association with drug resistance in North India. One hundred and twenty four M. tuberculosis isolates were analyzed with spoligotyping, further drug susceptibility testing was done by 1% proportional method. Out of these, 11 (8.9%) M. tuberculosis isolates were identified as Beijing and 113 (91.1%) as non-Beijing genotypes. While looking at their drug susceptibility patterns, 6 (54.5%) & 22 (19.5%) were found to be multi drug resistant (MDR) among Beijing and non-Beijing isolates respectively. Our study concluded that the Beijing strains were not so common in north India and these strains do not fully associate with MDR. © 2017 King Saud Bin Abdulaziz University for Health Sciences