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Evaluation of Coal Quality and Geomechanical Moduli using Core and Geophysical Logs: Study from Middle Permian Barakar Formation of Gondwana Coalfield

ICRMEG: 20th International Conference on Rock Mechanics and Engineering Geology, Sydney, Australia, Mar 29-30, 2018

Middle Permian Barakar formation is the major economic coal bearing unit of vast east-west trending Damodar Valley basin of Gondwana coalfield. Primary sedimentary structures were studied from the core holes, which represent majorly four facies groups: sandstone dominated facies, sandstone-shale heterolith facies, shale facies and coal facies. Total eight major coal seams have been identified with the bottom most seam being the thickest. Laterally, continuous coal seams were deposited in the calm and quiet environment of extensive floodplain swamps. Channel sinuosity and lateral channel migration/avulsion results in lateral facies heterogeneity and coal splitting. Geophysical well logs (Gamma-Resistivity-Density logs) have been used to establish the vertical and lateral correlation of various litho units field-wide, which reveals the predominance of repetitive fining upwards cycles.

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Geophysical log based coal characterization of middle Permian Barakar formation from North Karanpura coal field, India

Journal of the Geological Society of India, Springer, 2018, Vol 92, pp 36-44, Sydney, Australia, Mar 29-30, 2018

North Karanpura coal field is the western most marginal coal bearing segment of east-west trending Damodar valley basin. It consists of middle Permian Barakar Formation with sandstone, siltstone, coal and shale being the dominant lithofacies, deposited in a fluvial meandering environment, giving rise to repetitive fining upwards cycles. Study of geophysical logs, the drilled core holes were used to identify lithofacies, correlate coal seams with splitmerge behavior; which has been used to understand lateral and vertical facies disposition. Geophysical logs have been employed to compute various coal assay parameters–ash, fixed carbon, moisture, volatile content, cleat porosity, vitrinite reflectance seam wise. Study of log based coal assay parameters, calibrated with lab based values depicts lateral coal quality variation, i.e. decreasing ash content, higher fixed carbon from east to west, which can be a great proxy for future development of field or mine planning.

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Sequence Stratigraphic Model of Middle Permian Barakar Formation from a Marginal Gondwana Basin, India

Journal of Earth Science, Springer, 2018, Vol. 29, No. 4, pp 745-754

Gondwana deposits are extensively found across the continents. Here we study the Middle Permian Barakar Formation from the marginal Gondwana Basin, eastern India, being deposited in a normal fault setting. Availability of extensive cores as well as geophysical log suites (gamma-resistivity-density from drilled wells) from the study area helped us achieving high resolution interpretation. Core study identifies fluvial sedimentary architectures, which were correlated with the geophysical logs and modeled field-wide to understand vertical and horizontal facies disposition. The facies analysis has been used to establish a sequence stratigraphic model of the cyclic Barakar deposition. Four major fining upward depositional sequences were identified, each sequence comprises of low accommodation system tract (LAST) at base and high accommodation system tract (HAST) at top. LAST is characterized by vertically stacked, multistory amalgamated channel sandstone dominated facies, while floodplain dominated facies characterizes HAST, reflecting a gradual shift from braided to meandering depositional system from bottom to top of each cycle. Study reveals depocenter to be in the western part, supported by eastward thinning of sediment packets, all being deposited in a half-graben setting.

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Impact of Bioturbation on Reservoir Quality and Production – A review

Journal of the Geological Society of India, Springer, 2017, Vol. 89, Issue 4, pp 460-470

Bioturbation is a typically small scale yet potentially significant geological process altering rock properties by reworking. For many years, bioturbation studies found application in exploration geology to estimate paleobathymetry, interpreting depositional environment and identifying key stratigraphic surfaces. These act as vital inputs to the geological models, for determination of source rock potential, reservoir quality and modeling of petroleum systems. Recently geologists extended the application of bioturbation studies to address production related challenges. Recognizing the bioturbation effects and incorporating them in reservoir simulation models can improve production predictions and enhanced oil recovery operations. This paper discusses bioturbation and its effects on reservoir quality, its performance and production.

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Facies analysis and depositional model of Late Permian Raniganj Formation: Study from Raniganj Coal bed methane block, India

Journal of the Geological Society of India, Springer, 2016, Vol. 88, Issue 4, pp 503-516

The Raniganj Formation (late Permian) forms the uppermost economic coal-bearing unit of the Gondwana succession. The dominant facies interpreted from analysis of cores from the Raniganj formation are classified as Sandstone dominated facies, Sandstone - shale heterolith facies, Shale facies and Coal facies. The natural Gamma response of Raniganj Formation shows predominance of repetitive fining upwards cycles. Integration of core analysis and geophysical log data of the Raniganj formation indicates meandering fluvial environment. The lower part of Raniganj Formation is channel dominated which corresponds to thick amalgamated sand bodies while the upper part represent overbank shows predominance of channel avulsion indicating a gradual change in accommodation space. Five major fining upward depositional sequences, bounded by sub-aerial unconformities (sequence boundaries) have been dentified in Raniganj formation, based on changes in depositional style that are correlated regionally. Each sequence comprises of Low accommodation system tract (LAST) at base and high accommodation system tract (HAST) at top. LAST is characterized by vertically stacked, multistory amalgamated channel sandstone dominated facies, while floodplain dominated facies characterize HAST. The coal seams deposited in LAST are thicker and relatively more continuous than the frequent thin seams of HAST. Such facies distribution study would be helpful for the development strategy for CBM blocks based on production priority.

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Discussion on the concepts in palaeoenvironmental reconstruction from coal macerals and petrographic indices, Marine and Petroleum Geology

Elsevier, 2016, Vol. 73, pp 371-391

Organic facies analyses quantify the coal constituents and plot various associations to discriminate the paleoenvironment for coal bearing successions. This allows the relation of coal composition to mire ecosystems or environments. Coal petrographic models are used extensively to reconstruct the nature of ancient peat forming environments. Many authors proposed relations between specific maceral assemblages and/or micro-lithotypes and peat forming environments. The key controlling factors which affect peat environment include hydrogeology, redox, pH, vegetation type, clastic influx, sedimentation and peat accumulation rate etc. Recent advancements in coal maceral study and organic petrology reveal the pros and cons of the available indices and models. The main reasons for the failure of the petrographic models are – oversimplification of the effects of humification on tissue preservation vs. destruction, the use of post-diagenetic processes (e.g. geochemical gelification) in determining depositional environments, changes in petrographic composition related to floral evolution, geological age, rank increase and compaction, lack of distinction between different inertinite maceral in some models. Here the widely used petrographic indices and models are reviewed based on the observations of several workers and the applicability and concepts of paleo-environmental reconstruction are discussed. A multi-disciplinary approach including petrography, palynology, chemistry etc. has been recommended, which is more logical and scientific than the exclusive use of petrographic composition for paleoenvironmental interpretation.

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Review on coal petrographic indices and their applicability in paleoenvironmental interpretation

Geosciences Journal, Springer, 2015, Vol. 20, Issue 5, pp 719-729

Organic facies analyses quantify the coal constituents and plot various associations to discriminate the paleoenvironment for coal bearing successions. This allows the relation of coal composition to mire ecosystems or environments. Coal petrographic models are used extensively to reconstruct the nature of ancient peat forming environments. Many authors proposed relations between specific maceral assemblages and/or micro-lithotypes and peat forming environments. The key controlling factors which affect peat environment include hydrogeology, redox, pH, vegetation type, clastic influx, sedimentation and peat accumulation rate etc. Recent advancements in coal maceral study and organic petrology reveal the pros and cons of the available indices and models. The main reasons for the failure of the petrographic models are–over-simplification of the effects of humification on tissue preservation vs. destruction, the use of post-diagenetic processes (e.g., geochemical gelification) in determining depositional environments, changes in petrographic composition related to floral evolution, geological age, rank increase and compaction, lack of distinction between different inertnite maceral in some models. Here the widely used petrographic indices and models are reviewed based on the observations of several workers and the applicability and concepts of paleo-environmental reconstruction are discussed. A multi-disciplinary approach including petrography, palynology, chemistry etc. has been recommended, which is more logical and scientific than the exclusive use of petrographic composition for paleoenvironmental interpretation.

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Bridging the Industry-Academia Gap and Knowledge Management: Hour of Need

Paper ID-2009894

Industry-academia interface has always been under extensive discussions in many ways. A developed common area of interest strengthens the relationship between universities or research institutes and industry in a bigger resolution and on a precise basis between scientists and professionals in industries. Management of knowledge and communication makes a sense of newer outlook of the hydrocarbon sectors. To boost the growth of oil and gas industry globally, trained workforce and continuous strategic methods are needed which is only possible through mutual conjunction of academic and industrial human resource. Shortage of high quality collaboration in reality climbs list of discussions these days. This article gives an insight on bridging the gap between academia-industry interaction for a better way of the look of oil & gas industry scenario. The most core sector of a research institute or a university is its teaching. Many of the institutes have really phenomenal high-end applied courses which is the subject that fascinates the industry. Industry looks for human resource with proper dimension of knowledge in the field. To rectify the theoretical knowledge into the practical industrial problems proper training is needed for the newly recruited trainee. The trainee plays the most important role in this system to establish the academia-industry relation. More and more involvement of undergraduate students with the industry makes a proper hit to reduce the gap. Another part of interest for the industry is the really outstanding faculties and scientists who are doing globally acclaimed research in the field of hydrocarbon and its sciences. Along with betterment of corporate level strategies industries need to have technological advancements, which are largely benefited by growing research. So, extensive collaboration with cutting edge researchers working on applied sciences is expected. In addition government should have a proper assistance for the synergy between academics and industry in the oil and gas sector to fuel the need of the hour.

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