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Abdul Azeez K.K.,CSIR - Central Electrochemical Research Institute | Unsworth M.J.,University of Alberta | Patro P.K.,CSIR - Central Electrochemical Research Institute | Harinarayana T.,CSIR - Central Electrochemical Research Institute | And 2 more authors.
Pure and Applied Geophysics | Year: 2013

The Central Indian Tectonic Zone (CITZ) is a major tectonic feature extending across the Indian subcontinent. It was formed in the Paleoproterozoic when the Bastar Craton and the Bundelkhand Craton were sutured together. This region is recognized in the geological record as a persistent zone of weakness with many tectonothermal events occurring over geologic time. The weakness of this region may have caused the late Cretaceous/early Tertiary Deccan volcanism to have been localized in the CITZ. The zone is still tectonically active, as evidenced by sustained levels of seismic activity. This paper presents the first systematic investigation of the resistivity structure of the CITZ using multiple magnetotelluric (MT) transects. Two-dimensional (2D) resistivity models were generated for five north-south profiles that cross the CITZ and encompass an area of ~60,000 km2. The models were based on the joint inversion of transverse electric (TE), transverse magnetic (TM) and tipper (Hz) data. All the profiles showed a low resistive (10-80 Ωm) middle to lower crust beneath the CITZ with a crustal conductance of 300-800 S. The presence of an interconnected fluid phase and/or hydrous/metallic minerals appears to be the most likely explanation for the elevated conductivity that is observed beneath the CITZ. The presence of fluids is significant because it may indicate the cause of persistent weakness at crustal depths. A northward dip of both the crustal conductive layer and coincident seismic reflections favor a northward polarity of the subduction process associated with the formation of the CITZ. © 2013 Springer Basel.

Veena Prasanna M.,National Geophysical Research Institute Council of Scientific and Industrial Research | Rasheed M.A.,Gujarat Energy Research and Management Institute GERMI | Patil D.J.,National Geophysical Research Institute Council of Scientific and Industrial Research | Dayal A.M.,National Geophysical Research Institute Council of Scientific and Industrial Research | Rajeswara Reddy B.,Osmania University
Journal of Petroleum Science and Engineering | Year: 2013

The Proterozoic Vindhyan Basin is considered to be prospective for hydrocarbons and is grouped under category III sedimentary basins of India. The major part of the study area is covered by the Deccan Traps, hindering the exploration of Mesozoic hydrocarbon targets, surface geochemical prospecting based on microseepage of hydrocarbons from subsurface accumulations, which could be advantageous in such areas. Geo-microbiological study was carried out in conjunction with different geo-scientific studies to characterize the seeping natural gases and to evaluate the hydrocarbon prospects of the study area. Total 70 soil samples were collected in reconnaissance pattern, and the study revealed the presence of high bacterial counts for methane (3.7×105cfu/g), ethane (3.2×105cfu/g), propane (3.0×105cfu/g) and butane oxidizing bacteria (2.3×105cfu/g), which signify the seepage of hydrocarbons from the subsurface. The compositional characteristics of the hydrocarbon gases desorbed from soil samples of study area indicate the presence of light gaseous hydrocarbons methane through butane, thus suggesting that hydrocarbon generation has taken place in the basin probably of thermogenic origin. The trend followed by the hydrocarbons C1>C2>C3>iC4>nC4 further confirms the petroliferous nature of the gases. The stable carbon isotope values of light hydrocarbons desorbed form the soil samples indicate a clear signature of thermogenic gas. The concentrations of TOC and TIC in the soil samples of Sagar vary from 0.09% to 0.93% and 0.003% to 0.82% respectively. The TOC and TIC correlates poorly with the adsorbed soil gases (r=0.3, r=0.2), representing a lack of association of adsorbed soil gases with the surfacial organic matter thus indicate seepage related surface anomalies. The study revealed the presence of high concentrations of hydrocarbon oxidizing bacteria and adsorbed soil gases near Sagar area of Vindhyan Basin. The integrated geo-scientific studies showed excellent correlation and suggests that the Sagar area is considered to be potential for hydrocarbon generation and entrapment.© 2013.

Naidu G.D.,Central Water and Power Research Station | Veeraswamy K.,CSIR - Central Electrochemical Research Institute | Harinarayana T.,Gujarat Energy Research and Management Institute GERMI
Earth, Planets and Space | Year: 2011

The tectonic scenario of the Narmada-Son Lineament (NSL) zone has been the subject of debate for the last few decades. It is characterized tectonically as a highly-disturbed zone in Indian geology since Precambrian times. A magnetotelluric (MT) study has been carried out across the NSL zone along a 270-km-long N-S-trending traverse, extending from Hoshangabad in the North to Ner in the South. As a part of the present study, 25 magnetotelluric soundings have been collected and the data rotated to N70°E after removing local distortions, arising from 3D galvanic effects, using the Groom-Bailey decomposition technique. 2-D inversion has been carried out using an NLCG scheme. The results derived from the 2-D inversion have brought out the highly conductive nature of the mid-lower crust at places coinciding with the known faults. The significant high heat flow and seismicity in the region associated with these faults may be caused by tectonic activity and the highly conductive nature of the mid-lower crust. This may be due to the partial melting of subsurface rocks resulting from the high temperature caused by mantle upwarping in the region. The results are also compared with the gravity and a nearby Deep Seismic Sounding (DSS). Copyright © The Society of Geomagnetism and Earth Planetary and Space Sciences (SGEPSS).

Rasheed M.A.,Gujarat Energy Research and Management Institute GERMI | Hasan S.Z.,Gujarat Energy Research and Management Institute GERMI | Srinivasa Rao P.L.S.,Gujarat Energy Research and Management Institute GERMI | Boruah A.,Gujarat Energy Research and Management Institute GERMI | And 3 more authors.
Frontiers of Earth Science | Year: 2014

Microbial prospecting of hydrocarbons is based on the detection of anomalous population of hydrocarbon oxidizing bacteria in the surface soils, indicates the presence of subsurface oil and gas accumulation. The technique is based on the seepage of light hydrocarbon gases such as C1–C4 from the oil and gas pools to the shallow surface that provide the suitable conditions for the development of highly specialized bacterial population. These bacteria utilize hydrocarbon gases as their only food source and are found enriched in the near surface soils above the hydrocarbon bearing structures. The methodology involves the collection of soil samples from the survey area, packing, preservation and storage of samples in pre-sterilized sample bags under aseptic and cold conditions till analysis and isolation and enumeration of hydrocarbon utilizing bacteria such as methane, ethane, propane, and butane oxidizers. The contour maps for the population density of hydrocarbon oxidizing bacteria are drawn and the data can be integrated with geological, geochemical, geophysical methods to evaluate the hydrocarbon prospect of an area and to prioritize the drilling locations thereby reducing the drilling risks and achieve higher success in petroleum exploration. Microbial Prospecting for Oil and Gas (MPOG) method success rate has been reported to be 90%. The paper presents details of microbial prospecting for oil and gas studies, excellent methodology, future development trends, scope, results of study area, case studies and advantages. © 2015, Higher Education Press and Springer-Verlag Berlin Heidelberg.

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