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Multiphysics Numerical Modeling of a Naturally Fractured Carbonate Reservoir Analogue

Abstract

Natural fractures play an important role in the numerical modelling and simulation of low permeability carbonate reservoirs. Fractures largely influence rock permeability and porosity, due to their geomechanical and hydrodynamic properties. This study focuses on the fracture characterisation applied to numerical simulation using parameters from outcrops of lacustrine laminites, Crato Formation, NE Brazil. For numerical simulations were applied a finite element code with multiphysics approach for rock response modelling considering geomechanical, hydraulic and chemical response. We collected fracture attributes (topology, length, aperture, and spatial arrangement) through scanlines (1D and 2D) and present a computer program (TopScan) that delivers geometrical and topological data from images (RBG) and scanlines. The resulting models, considering that spatial organization and topology of fractures are more reliable and realistic, are used to measure the equivalent permeability in a numerical manner. We also present results derived from numerical modelling of fracture initiation and propagation using a damage model and fragmentation mesh technique. Besides that a rock diagenesis simulation for karst generation applying a reactive transport formulation for synthetic scenarios are presented. Finally, karst collapse were modelled looking for effect in above layers and faults. We conclude that the integration between geology and engineering developments can provide a more realistic model for reservoir simulation studies and a multiphysics analysis is fundamental in prediction of fractured rock behavior due to fluid flow. The reactive transport lead to a important prediction of karsts geometries as function of fractures arrangement and interaction and its directly related to fractures topology. In the end, the karst collapse modelling led to a predict the interaction between multiple karsts and its effects in upper rocks