Ravi Shekhar

Sughosh Madhav

Virendra Bahadur Singh

Naresh Chandra Pant

Weathering and Erosion Processes in the Natural Environment An indispensable introduction to the key environmental processes of weathering and erosion Natural and human-induced weathering processes can have a great impact on soil and groundwater quality. With climate change and other environmental challenges placing increased emphasis on these resources, it has never been more important for researchers and environmental professionals to attain detailed knowledge of weathering and erosion processes. Weathering and Erosion Processes in the Natural Environment meets this need with a rigorous, systematic overview. Beginning with a description of different forces and processes that contribute to weathering, it then discusses the different kinds of landforms that can be produced by weathering and erosion processes, as well as the potential impacts of hydrogeological processes on both surface water and groundwater. The result is a volume that balances qualitative and quantitative understanding of this crucial subject. Weathering and Erosion Processes in the Natural Environment readers will also find: Documented examples in which weathering and erosion processes have led to heavy metals and other trace elements in groundwater Detailed discussion of climate change impacts, including extreme weather events and rising carbon dioxide levels Modeling approaches throughout to enable quantitative assessment and predictions of future impact Weathering and Erosion Processes in the Natural Environment is ideal for researchers and advanced students in geology, geochemistry, hydrogeochemistry and environmental science, as well as professionals dealing with water and soil management.

Weathering and Erosion Processes in the Natural Environment

Fractured reservoirs, especially in low permeable carbonate rocks, are important target for hydrocarbon exploration and production because fractures can control fluid flow inside the reservoir. Hence, quantitative knowledge of fracture attributes is important for optimal hydrocarbon production. However, in some cases fractures can cause leakage of injected CO2 during enhanced oil recovery (EOR) or CO2 sequestration. Furthermore, CO2 can geochemically interact with reservoir fluids and host rock. Hence, time-lapse monitoring of the progress of CO2 in fractured reservoirs is also very important. In order to address these challenges, I have developed an integrated approach for studying fluid flow and seismic wave propagation in fractured media using Discrete Fracture Network (DFN) models. My seismic simulation study suggests that CO2 saturated reservoir shows approximately ten times more attenuation than brine saturated reservoir. Similarly, large P-wave velocity variation in CO2 saturated reservoir and amplitude variation with offset (AVO) results for our example model predicts that CO2 is easier to detect than brine in the fractured reservoirs. The effects of geochemical processes on seismics are simulated by time-lapse modeling for t = 1000 years. My modeling study suggests that intra-aqueous reactions are more significant during injection of CO2 for t = 6 years, while slower mineral reactions dominate after pressure equilibrium is achieved that is from t = 6 to 1000 years. Overall both types of geochemical reactions cause change in reflection coefficient of 2 to 5%, which may be difficult to detect in some cases. However, the significant change in the seismic properties at the boundary of the CO2 front can be used to detect the flow path of CO2 inside the reservoirs. Finally, a method for generating stochastic fracture models was extended and improved to more realistic field model for seismic and fluid modeling. My detail analysis suggests that fractures generated by isotropic stress field favor orthogonal sets of fractures in most subsurface rocks that can be converted to seismic model, similar to DFN study. The quality and validity of the models is assessed by comparisons to DFN models, including calculations of fractal dimension measures that can help to characterize fractured reservoirs.

Ravi Shekhar

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