Hydrogeophysical Methods for Analyzing Aquifer Storage and Recovery Systems     

Burke J. Minsley  Jonathan Ajo‐Franklin  Amitabha Mukhopadhyay  Frank Dale Morgan 《Ground water》2011,49(2):250-269

Hydrogeophysical methods are presented that support the siting and monitoring of aquifer storage and recovery (ASR) systems. These methods are presented as numerical simulations in the context of a proposed ASR experiment in Kuwait, although the techniques are applicable to numerous ASR projects. Bulk geophysical properties are calculated directly from ASR flow and solute transport simulations using standard petrophysical relationships and are used to simulate the dynamic geophysical response to ASR. This strategy provides a quantitative framework for determining site‐specific geophysical methods and data acquisition geometries that can provide the most useful information about the ASR implementation. An axisymmetric, coupled fluid flow and solute transport model simulates injection, storage, and withdrawal of fresh water (salinity ～500 ppm) into the Dammam aquifer, a tertiary carbonate formation with native salinity approximately 6000 ppm. Sensitivity of the flow simulations to the correlation length of aquifer heterogeneity, aquifer dispersivity, and hydraulic permeability of the confining layer are investigated. The geophysical response using electrical resistivity, time‐domain electromagnetic (TEM), and seismic methods is computed at regular intervals during the ASR simulation to investigate the sensitivity of these different techniques to changes in subsurface properties. For the electrical and electromagnetic methods, fluid electric conductivity is derived from the modeled salinity and is combined with an assumed porosity model to compute a bulk electrical resistivity structure. The seismic response is computed from the porosity model and changes in effective stress due to fluid pressure variations during injection/recovery, while changes in fluid properties are introduced through Gassmann fluid substitution.  相似文献   

Modelling the pore fluid diffusion process in aftershock initiation for 2004 Sumatra earthquake: implications for marine geohazard estimation in the Andaman region     

Basab Mukhopadhyay  Sujit Dasgupta  M. Fnais  Manoj Mukhopadhyay 《Natural Hazards》2011,57(1):39-49

The role of fluid injection on the occurrence and migration path for the aftershocks of 2004 Sumatra earthquake (Mw 9.3) and January 2005 Andaman earthquake swarm within the aftershock sequence is investigated here from the viewpoint of pore fluid diffusion process. The Sumatra earthquake created a regionally extensive crustal rupture plane exceeding 1,200 km length below the Andaman Sea. The r–t plots (Shapiro et al. 1997) are constructed for these aftershocks in order to examine the role of poroelastic effects as rupturing progressed with time. Their main results are as follows: the r–t plot corresponding to first 3 h of aftershock activity (when only 44 events of mb ≥ 4.5 originated) reveals that 95% of the data points occurred below the modelled parabola with relatively high D value of 20 m²/s, whereas a significantly low D value of 3.5 m²/s characterises the aftershock activity for the first 24 h (when 420 events of mb ≥ 4.0 occurred). Here, the Coulomb stress was transferred from the main shock with a rapid imposition of normal stress, thus inducing the pore-pressure change that started diminishing almost immediately by fluid diffusion, at a rate, defined by the diminishing D value. The modelling results for fault seismicity at far off distances from the main epicentre are interpreted here as potential indicators for large-scale sub-seabed rupturing—consequent to stress changes induced by bending of the Indian Ocean plate. Bathymetric slopes under the Andaman subduction zone are particularly amenable to sub-marine slides where crustal E–W hinge faults inferred seismically cut across the N–S trending regional thrust and strike-slip faults. Seabed rupturing appears to allow deep-slab hydration in these areas, producing pressure gradients along the normal faults. These features are important since they can herald marine geohazards in the Andaman region.  相似文献   

Role of transverse tectonics in the Himalayan collision: Further evidences from two contemporary earthquakes     

Sujit Dasgupta  Basab Mukhopadhyay  Manoj Mukhopadhyay  D. R. Nandy 《Journal of the Geological Society of India》2013,81(2):241-247

Two contemporary earthquakes originating in the central Himalayan arc and its foredeep (Sikkim earthquake of 18.09.2011, M_w 6.9, h: 10–60 (?) km and Bihar-Nepal earthquake of 20.08.1988, Mw 6.8, h: 57 km) are commonly associated with transverse lineaments/faults traversing the region. Such lineaments/faults form active seismic blocks defining promontories for the advancing Indian Craton. These actually produce conjugate shear faulting pattern suggestive of pervasive crustal interplay deep inside the mountains. Focal mechanism solutions allow inferring that large part of the current convergence across the central Himalayan arc is accommodated by lateral slip. Similar slip also continues unabated in the densely populated foredeep for distances up to several tens of kilometers south of the Main Boundary Thrust (MBT).  相似文献   

Feasibility of red mud neutralization with seawater using Taguchi’s methodology   总被引：2，自引：0，他引：2  

S. Rai  K. L. Wasewar  D. H. Lataye  J. Mukhopadhyay  C. K. Yoo 《International Journal of Environmental Science and Technology》2013,10(2):305-314

In this study, feasibility of using seawater to neutralize alkaline red mud for its safe disposal has been studied using Taguchi’s design of experimental methodology. Parameters such as weight of red mud, volume of seawater, stirring time and temperature were tested at three levels to study their effect on response characteristic, i.e., pH of the neutralized slurry. The analysis of variance showed that volume of seawater added and quantity of red mud are the two significant parameters with 53.59 and 44.92 % contribution each, respectively. Under the optimized parameters, pH value of red mud slurry reaches to about 8.0 which is within disposable limits. When seawater or other Ca- and Mg-rich brines are added to caustic red mud, the pH of the mixture is reduced causing hydroxide, carbonate or hydroxy carbonate minerals to be precipitated. This mechanism of neutralization process has been explained with emphasis on chemical analysis, mineralogy and morphology of the neutralized red mud. The process improved the physical characteristics of red mud with entrained liquor becoming non-hazardous water with reduced alkalinity. The results would be extremely useful in the process of safe disposal of red mud.  相似文献   

Variation of intrinsic and scattering attenuation with depth in NW Himalayas     

S. Mukhopadhyay  C. Tyagi 《Geophysical Journal International》2008,172(3):1055-1065

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Understanding the Role of Cloud and Convective Processes in Simulating the Weaker Tropical Cyclones over Indian Seas     

Radhika D. Kanase  P. Mukhopadhyay  P. S. Salvekar 《Pure and Applied Geophysics》2015,172(6):1751-1779

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On northward movement of convergence zones along west coast of India in a real-time forecast     

S. Taraphdar  J. Sanjay  P. Mukhopadhyay 《Meteorology and Atmospheric Physics》2009,104(3-4):177-189

The present study addresses the depiction of regional features in the National Centers for Environmental Prediction (NCEP) Global Forecast System (GFS) real-time products associated with the onset of Indian summer monsoon 2006 along the west coast of India. This study attempts to understand some atmospheric dynamical processes that give rise to the northward shifting of the convergence zones in the sub-daily scale leading to the onset over Mumbai. The comparison of analysis and forecast shows that NCEP GFS appears to follow the analysis till 24 h, but deviates thereafter. The most notable feature in analyses is the distinct meridional asymmetries in the vorticity field with respect to the convection center. It is identified that the equivalent barotropic structure of vorticity north of the convection center is the main forcing for the northward movement of convergence zones. The composite meridional–vertical structure of each term in the vorticity budget reveals the importance of convective term in the upper atmosphere (700–200 hPa) and the stretching term in the lower atmosphere (1,000–700 hPa) with a lesser contribution of the tilting term. From an analysis of a simplified vorticity equation by retaining these dominant terms and by comparing the evolution of the diabatic heating, it is concluded that the inaccuracies in the model’s representation of convection led to the weakening of barotropic westerlies in the forecast.  相似文献   

The economics of mining seabed manganese nodules: A case study of the Indian Ocean nodule field     

Ranadhir Mukhopadhyay  Sankalp Naik  Shawn De Souza  Ozinta Dias  Sridhar D Iyer  Anil K Ghosh 《Marine Georesources & Geotechnology》2013,31(7):845-851

Abstract

Because of ever-growing demand for strategic metals, the focus of the international community has fallen on deep sea manganese nodules occurring at a water depth of more than 4500?m. We present an economic appraisal and strategy for mining of nodules from the Indian Ocean Nodule Field- one of the four economically potential areas in the world oceans. In contrast to the prevailing perception of non-viability of nodule mining, our analysis indicates a fair degree of economic feasibility and commercial sustainability to mine the deep-sea manganese nodules.  相似文献   

Water–Rock interactions in the basement beneath Long Valley Caldera: an oxygen isotope study of the Long Valley Exploratory Well drill cores     

Biswajit Mukhopadhyay 《Journal of Volcanology and Geothermal Research》2002,116(3-4)

The Long Valley Exploratory Well, at the center of the Resurgent Dome of Long Valley caldera, penetrated pre-caldera basement rocks at a depth of 2101.72–2313.0 m, beneath the caldera-forming Bishop Tuff and post-caldera Early Rhyolite. The basement rocks contain prominent quartzites, with ubiquitous milky white quartz veins (with minor calcite and pyrite) and fractures of varied orientation and geometry. The other members of the basement sequence are very fine-grained quartz-rich graphitic pelites with calcite veins, spotted hornfels, and shallow intrusive rocks. Previous studies established the presence of a post-caldera, paleohydrothermal system (500–100 ka) to a depth of 2000 m that affected the Bishop Tuff and a recent (40 ka to present) hydrothermal system at shallow depth (<1 km). The deeper extent of these hydrothermal activities is established in this paper by a detailed oxygen isotope analysis of the drill core samples. 238 analyses of δ¹⁸O in 50 quartz veins within the 163.57 m depth interval of basement rocks reveal extreme heterogeneity in δ¹⁸O values (8–19.5‰). Majorities of the 84 bulk analyses of quartzites show variation of δ¹⁸O within a narrow range of 14–16‰. However, certain samples of these quartzites near the contacts with veins and fractures exhibit sharp drops in δ¹⁸O. The interbedded pelitic rocks and spotted hornfels have whole-rock δ¹⁸O ranging from 2.2 to 11.8‰. Clear, euhedral vuggy quartz that partially fills earlier open fractures in both the quartzites and quartz veins, has distinctive δ¹⁸O, ranging between −3.2 and +8.4‰. Low values of δ¹⁸O are also found in the hydrothermal minerals and whole rocks adjacent to the thin veins, clearly indicating infiltration of meteoric water. Three distinct observed patterns of fractionation in δ¹⁸O between veins and host quartzites are analyzed with the principles of mass balance, equilibrium oxygen isotope fractionation in closed system, and kinetically controlled oxygen isotope exchange in an open system. This analysis suggests that the early quartz veins formed due to a magmatic-hydrothermal activity with no influx of external water once the system comprising the sedimentary envelope and a magmatic-hydrothermal fluid phase became closed. Two-stage isotopic exchange processes caused fractionation in the δ values that originally formed arrays with slope 1 in a δ_{vein quartz}–δ_{host quartzite} space. Another array in the same space, with near zero slope was also formed due to variation in temperature, initial isotopic compositions of the quartzite sequence and the fluid phase. Variation in temperature was mostly in the range of 300–400°C giving Δ (=δ_{vein quartz}–δ_{host quartzite})≈−2.8 to +2.8. The δ¹⁸O of the fluid could range from −5 to +10; however a narrower range of +5 to +10 can explain the data. This episode of hydrothermal activity could take place either as a single pulse or in multiple pulses but each as a closed system. A later, fracture-controlled, meteoric water (δ¹⁸O−0.46 to −12.13) flow and interaction (at 250°C) is interpreted from the analysis of δ¹⁸O values of the coexisting quartz and calcite pairs and existence of markedly ¹⁸O-depleted pelitic horizons interbedded with ¹⁸O-enriched quartzite layers. Thus, the interpreted earlier magmatic-hydrothermal activity was overprinted by a later meteoric-hydrothermal activity that resulted in steep arrays of δ¹⁸O values in the δ_{vein quartz}–δ_{host quartzite} space. Calculations show that the likely life span of the post-caldera, hydrothermal activity in the depth range of 2.1–2.3 km beneath Long Valley was 0.08–0.12 Ma. Diffusive ±advective transport of oxygen isotopes from fracture-channelized meteoric water to nearly impermeable wall rocks caused a lowering of δ¹⁸O values in the quartz over short distances and in calcites over greater distances. Thus, the hydrothermal activity appears pervasive even though the meteoric water flow was primarily controlled by fractures.  相似文献   

Densitometeric Scanning of Electrophoregrams of Egg Proteins in Five Carps     

S. K. Mukhopadhyay  A. K. Bose 《洁净——土壤、空气、水》1982,10(2):193-198

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