What laboratory-induced dissolution trends tell us about natural diagenetic trends of carbonate rocks
Tiziana Vanorio, Yael Ebert, Denys Grombacher, 2015. "What laboratory-induced dissolution trends tell us about natural diagenetic trends of carbonate rocks", Fundamental Controls on Fluid Flow in Carbonates: Current Workflows to Emerging Technologies, S. M. Agar, S. Geiger
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The pivotal idea of this study is to unravel the processes that control heterogeneity in the attributes of the pore space in carbonate rocks (i.e. stiffness, connectivity and tortuosity), and, in turn, in the transport and elastic properties. We use starting rocks of variable fabric (i.e. a depositional-dependent microstructure) to induce a specific process (e.g. chemical dissolution under stress) and then observe the development of the microstructure, permeability, porosity and velocity due to the induced chemomechanical processes.
We find that the changes in the two end members of the analysed rock types (mudstones and packstones) can lead to two different evolutionary trends of permeability and velocity, depending on the effectiveness of dissolution with respect to compaction. The balance between the two depends on: (a) the fraction of the carbonate phases characterized by large surface area; and (b) the pore stiffness of the rock. Packstones are characterized by low pore stiffness and compact significantly upon dissolution. This behaviour leads to a decrease in velocity because of a reduction in the stiffness at the grain contacts and a slight increase in permeability. The latter is curbed by the ongoing compaction. Mudstones are characterized by higher pore stiffness, experiencing minimal or negligible compaction. This behaviour leads to a slight change in porosity and velocity. However, large permeability changes are observed, related to enhanced connectivity or decreased tortuosity of the pathways.
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Fundamental Controls on Fluid Flow in Carbonates: Current Workflows to Emerging Technologies
This volume highlights key challenges for fluid-flow prediction in carbonate reservoirs, the approaches currently employed to address these challenges and developments in fundamental science and technology. The papers span methods and case studies that highlight workflows and emerging technologies in the fields of geology, geophysics, petrophysics, reservoir modelling and computer science. Topics include: detailed pore-scale studies that explore fundamental processes and applications of imaging and flow modelling at the pore scale; case studies of diagenetic processes with complementary perspectives from reactive transport modelling; novel methods for rock typing; petrophysical studies that investigate the impact of diagenesis and fault-rock properties on acoustic signatures; mechanical modelling and seismic imaging of faults in carbonate rocks; modelling geological influences on seismic anisotropy; novel approaches to geological modelling; methods to represent key geological details in reservoir simulations and advances in computer visualization, analytics and interactions for geoscience and engineering.