Prediction of gas hydrate saturation throughout the seismic section in Krishna Godavari basin using multivariate linear regression and multi-layer feed forward neural network approach     

Yudhvir Singh  Rajesh R. Nair  Harmandeep Singh  Prattya Datta  Priyank Jaiswal  Pawan Dewangan  T. Ramaprasad 《Arabian Journal of Geosciences》2016,9(5):415

Stepwise linear regression, multi-layer feed forward neural (MLFN) network method was used to predict the 2D distribution of P-wave velocity, resistivity, porosity, and gas hydrate saturation throughout seismic section NGHP-01 in the Krishna-Godavari basin. Log prediction process, with uncertainties based on root mean square error properties, was implemented by way of a multi-layer feed forward neural network. The log properties were merged with seismic data by applying a non-linear transform to the seismic attributes. Gas hydrate saturation estimates show an average saturation of 41 % between common depth point (CDP) 600 and 700 and an average saturation of 35 % for CDP 300–400 and 700–800, respectively. High gas hydrate saturation corresponds to high P-wave velocity and high resistivity except in a few spots, which could be due to local variation of permeability, temperature, fractures, etc.  相似文献   

Book review     

Subhajyoti Das  Rajesh K. Srivastava 《Journal of the Geological Society of India》2016,88(3):394-396

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Magnetic susceptibility studies of the upper Albian-Danian sediments of Cauvery basin,south India     

V. Prasannakumar  P. Pratheesh  C. Vikas  Rajesh Reghunath  R. S. Prasanth 《Journal of the Geological Society of India》2016,87(3):345-360

The Cauvery basin of the Indian Peninsular shield, formed during the fragmentation of the Gondwana Supercontinent, continued to evolve until the end of Neogene through rift, pull-apart, shelf sag and tilt processes. The basin witnessed many cycles of transgression, regression, erosion and deposition. A more or less complete succession of upper Cretaceous–Paleocene sediments is exposed in the Ariyalur–Pondicherry depression of the basin. Anisotropy of magnetic susceptibility (AMS) technique is applied in an attempt to examine the depositional and eustatic conditions prevailed during the formation of these sedimentary sequences. AMS results point to the sedimentation history dominated by marked sea level changes with several phases of transgression and regression. The sedimentation occurred mainly in a shallow epicontinental sea which has been punctuated with terrigenous supply more often. Greater utility of magnetic fabrics is suggested as a tool to trace fluvial responses to tectonic and climatic changes.  相似文献   

A Numerical Model for Water Flow and Chemical Transport in Variably Saturated Porous Media   总被引：3，自引：1，他引：3  

T.-C. Jim Yeh  Rajesh Srivastava  Amado Guzman  Thomas Harter 《Ground water》1993,31(4):634-644

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Triggering of earthquakes at Koyna,India and hammer drilling for the pilot borehole     

Madugula  Uma Anuradha  Rekapalli  Rajesh  Sudheer  K.  Jagadeesh  P.  Satyanarayana  H. V. S. 《Natural Hazards》2021,109(1):1191-1199

Natural Hazards - Koyna located near the West Coast of India is an outstanding case of artificial water reservoir-triggered seismicity. It is observed that annually earthquakes get triggered in the...  相似文献   

Phosphorus Sorption and Availability from Biochars and Soil/Biochar Mixtures   总被引：2，自引：0，他引：2       下载免费PDF全文

Rajesh Chintala  Thomas E. Schumacher  Louis M. McDonald  David E. Clay  Douglas D. Malo  Sharon K. Papiernik  Sharon A. Clay  James L. Julson 《洁净——土壤、空气、水》2014,42(5):626-634

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Evidence for Nonlinear Coupling of Solar and ENSO Signals in Indian Temperatures During the Past Century     

R. K. Tiwari  Rekapalli Rajesh  B. Padmavathi 《Pure and Applied Geophysics》2015,172(2):531-543

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Assessment of a hydrologic model's reliability in simulating flow regime alterations in a changing climate   总被引：1，自引：0，他引：1       下载免费PDF全文

Rajesh R. Shrestha  Markus A. Schnorbus  Daniel L. Peters 《水文研究》2016,30(15):2628-2643

It is a common practice to employ hydrologic models for assessing present and future states of watersheds and assess the degree of alterations for a range of hydrologic indicators. Previous studies indicate that the hydrologic model may not be able to replicate some of the indicators of interest, which raises questions on the reliability of model simulated changes. Hence, we initiated a study to evaluate the replicability of the streamflow changes by employing the widely used variable infiltration capacity hydrologic model for sub‐basins and mainstem of the Fraser River Basin, Canada. Given that the hydrologic regime of the region is known to be influenced by teleconnections to the Pacific Decadal Oscillation (PDO) and El Niño–Southern Oscillation (ENSO), we used hydrologic responses to the PDO and ENSO states as analogues for evaluating the model's ability to simulate climate‐induced changes. The results revealed that the qualitative patterns of response, such as lower flows for the warm PDO state compared to the cool state, and progressively higher flows for the warm, neutral and cool ENSO states, were generally well reproduced for most hydrologic indicators. Additionally, while the directions of change between the different PDO and ENSO states were mostly well replicated, the magnitude of change for some of the indicators showed considerable differences. Hence, replicability of both magnitude and direction of change need to be carefully examined before using the simulated indicators for assessing future hydrologic changes, and a reliable replication increases the confidence of projected changes. Copyright © 2016 Her Majesty the Queen in Right of Canada. Hydrological Processes. © 2016 John Wiley & Sons, Ltd.  相似文献   

Evidence of Higher-Order Solar Periodicities in China Temperature Record     

R. K. Tiwari  R. Rajesh  B. Padmavathi 《Pure and Applied Geophysics》2016,173(7):2511-2520

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Lithostratigraphic contact – a significant site for hydrogeological investigation in crystalline fractured-rock terrains     

Tapas Acharya  Rajesh Prasad 《Journal of Earth System Science》2017,126(1):15

Estimating the hydrogeologic control of fractured aquifers in hard crystalline and metamorphosed rocks is challenging due to complexity in the development of secondary porosity. The present study in the Precambrian metamorphic terrain in and around the Balarampur of Purulia district, West Bengal, India, aims to estimate the hydrogeologic significance of lithostratigraphic contacts using fracture characteristics obtained from surface bedrock exposures supported by hydrological data from the existing dugwells. This study involves the domain-wise analysis of the frequencies of fractures that control the fracture-porosity. The domain-wise study reveals higher fracture-frequencies adjacent to the lithostratigraphic contacts. The concurrence of lithostratigraphic contacts with the occurrences of high-discharging wells and also with the deep weathered zone in low-lying areas is clearly established, thus assigning the lithostratigraphic contact as hydrogeologically significant. An increase in frequencies of the fractures within the ‘influence zone’ of the lithocontact, is clearly visible. Among those fractures, particularly, which make the angle greater than the ‘limiting angle’ with the lithocontact are characterised by increased frequencies. However, brittle rocks like quartz biotite granite gneisses, phyllite and epidiorite show high porosity of fracture, within the ‘influence zone’ of the lithostratigraphic contact. Enhanced deepening of the weathered-zone at lower topographic region may perhaps be a plausible explanation for this increased fracture-porosity at lithocontact to assign it as a hydrogeologically significant transmissive zone within fractured rocks.  相似文献