Integrando estratigrafia, petrofísica e rede de fraturas carstificadas em um modelo digital 3D unificado: exemplo da Caverna Cristal (Cráton São Francisco, Nordeste do Brasil)
Digital Outcrop Models (DOMs) are visual representations of geological sites in a virtual environment. DOMs are constantly evolving and widely used tools for geological investigations. However, in contrast with their broad applications, the full potential of DOMs is still underexplored in terms of t...
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| Tipo de recurso: | tesis de maestría |
| Estado: | Versión publicada |
| Fecha de publicación: | 2022 |
| País: | Brasil |
| Institución: | Universidade Federal do Rio Grande do Norte (UFRN) |
| Repositorio: | Repositório Institucional da UFRN |
| Idioma: | portugués |
| OAI Identifier: | oai:repositorio.ufrn.br:123456789/50838 |
| Acceso en línea: | https://repositorio.ufrn.br/handle/123456789/50838 |
| Access Level: | acceso abierto |
| Palabra clave: | Geodinâmica Modelo digital de afloramento Redes de fraturas discretas Carste Reservatórios carbonáticos CNPQ::CIENCIAS EXATAS E DA TERRA::GEOCIENCIAS |
| Sumario: | Digital Outcrop Models (DOMs) are visual representations of geological sites in a virtual environment. DOMs are constantly evolving and widely used tools for geological investigations. However, in contrast with their broad applications, the full potential of DOMs is still underexplored in terms of their integration with other data. We present an integrative approach by combining a DOM with stratigraphic, petrophysical, fracture distribution and karst dissolution information into a single 3D georeferenced digital model. Fracture aperture enlargement due to karstic dissolution are implemented on a Discrete Fracture Network (DFN) to generate a Discrete Fracture and Karst Network (DFKN), where it is possible to compose different karstification intensity scenarios. The used DOM is based on photogrammetric data obtained inside a segment of the Cristal Cave. This cave developed in Mesoproterozoic carbonate rocks of the Caboclo Formation, in the Chapada Diamantina Group, São Francisco Craton, Northeastern Brazil, and has been used as a structural and diagenetic outcrop analogue for the Brazilian pre-salt carbonate reservoirs. The described Integrative Model combines both deterministic (stratigraphy and petrophysics) and stochastic (DFN and DFKN) elements. The framework of the Integrative Model reproduces the stratigraphy of the outcrop as 22 parallel layers, which were populated with porosity, permeability and uniaxial compressive strength measurements. Resorting to a stochastic approach, we obtained a 3D DFN by solving the stereology inverse problem, where statistical measurements of the fracture traces (power law and P21 persistences) on the walls and ceiling of the cave are honored. Petrophysical parameters of the Integrative Model can be easily changed, while it is also possible to modify the power law that relates aperture and fracture length to implement different karstification stages of the fracture apertures. As a result, different scenarios of primary and secondary porosities can be easily composed, which can be used in fluid flow simulations, thus facilitating the understanding of the multiple factors affecting the behavior of carbonate reservoirs. |
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