Abhijit Chaudhuri

Bio: Abhijit Chaudhuri is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Concentration polarization & Convection. The author has an hindex of 14, co-authored 44 publications receiving 656 citations. Previous affiliations of Abhijit Chaudhuri include Indian Institute of Science & University of Colorado Boulder.

Potential of $$\hbox {CO}_{2}$$CO2 based geothermal energy extraction from hot sedimentary and dry rock reservoirs, and enabling carbon geo-sequestration

Abstract: Carbon capture and sequestration (CCS) is necessary to mitigate global warming caused by anthropogenic $$\hbox {CO}_{2}$$ emissions in the atmosphere. However, due to very high storage cost, it is difficult to sustain the CCS industry. The hot sedimentary and dry rock reservoirs with very high temperature can support both geothermal energy production, and carbon geosequestration economically, provided the $$\hbox {CO}_{2}$$ is used as a heat-carrying fluid with proper optimization of injection parameters according to reservoir conditions. In this paper we have reviewed past studies discussing the working mechanisms, pressure management strategies and various advantages of energy extraction from hydrothermal reservoirs by $$\hbox {CO}_2$$ plume geothermal technology and hot dry rock— enhanced geothermal system (EGS) technology. Past studies highlighted that due to very high thermal expansivity and mobility, supercritical $$\hbox {CO}_2$$ can produce more heat than water-EGS. For low enthalpy (around 50 $$^\circ$$C) and shallow (0.5–1.5 km) reservoirs, $$\hbox {CO}_2$$ can fetch more heat than water because of higher heat capacity. Other advantages of CCS and EGS are (i) the production of brine or $$\hbox {CO}_2$$ assisting to manage the reservoir pressure and restrict the fluid interference with neighboring reservoirs, (ii) the fluid loss, which is a significant concern in a water-EGS but for $$\hbox {CO}_{2}$$-EGS it is environmentally friendly, and (iii) higher pressure and cold fluid injection induced geological deformation and microseismicity are relatively less for $$\hbox {CO}_2$$-EGS than water-EGS. In this paper, we have also discussed various challenges of $$\hbox {CO}_2$$-EGS to enable CCS in hydrothermal reservoir and hot dry rock system.

Natural analogs for improved understanding of coupled processes in engineered earth systems: examples from karst system evolution

Abstract: There is an increasing need to understand the behaviour of engineered earth systems, from the viewpoint of safe waste disposal and exploration of renewable energy sources. Often, human activities lead to significant perturbations of the earth systems, involving hydrologic, mechanical, thermal and chemical processes. Prediction of the long-term response of earth systems to large perturbations is critical for evaluating their design, performance and operation. Because many of the processes involved in system response will manifest over decades or centuries, field-testing during the design stage is infeasible. In this connection, we propose that development of coupled process simulators and testing them on natural analogs provided by geologic systems may be fruitful. As example, we illustrate our attempts to simulate the development of two types of cave systems - branchwork in meteoric environments and mazework in hypogene or hydrothermal environments. Our computational models combine hydraulic, thermal and chemical processes in limestone fractures and consider the influence of subsurface heterogeneity as well. Our computational results vividly demonstrate the mechanisms by which branchwork patterns develop in meteoric environments and demonstrate how sustained dissolution along upward flow channels can be established in hypogene environments, thus creating favourable conditions for development of maze patterns. Investigations of system sensitivities in both types of environments indicate that a surprisingly robust pattern of behaviour results, thus serving as a target for developing simplified conceptual models of these systems. We also discuss the implications of our results for design, operation and risk analysis of engineered earth systems.

Porosity–Permeability Relations for Evolving Pore Space: A Review with a Focus on (Bio-)geochemically Altered Porous Media

Abstract: Reactive transport processes in a porous medium will often both cause changes to the pore structure, via precipitation and dissolution of biomass or minerals, and be affected by these changes, via changes to the material’s porosity and permeability. An understanding of the pore structure morphology and the changes to flow parameters during these processes is critical when modeling reactive transport. Commonly applied porosity–permeability relations in simulation models on the REV scale use a power-law relation, often with slight modifications, to describe such features; they are often used for modeling the effects of mineral precipitation and/or dissolution on permeability. To predict the reduction in permeability due to biomass growth, many different and often rather complex relations have been developed and published by a variety of authors. Some authors use exponential or simplified Kozeny–Carman relations. However, many of these relations do not lead to fundamentally different predictions of permeability alteration when compared to a simple power-law relation with a suitable exponent. Exceptions to this general trend are only few of the porosity–permeability relations developed for biomass clogging; these consider a residual permeability even when the pore space is completely filled with biomass. Other exceptions are relations that consider a critical porosity at which the porous medium becomes impermeable; this is often used when modeling the effect of mineral precipitation. This review first defines the scale on which porosity–permeability relations are typically used and aims at explaining why these relations are not unique. It shows the variety of existing approaches and concludes with their essential features.