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...
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| Formato: | Dissertação |
| Idioma: | pt_BR |
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Universidade Federal do Rio Grande do Norte
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| Endereço do item: | https://repositorio.ufrn.br/handle/123456789/50838 |
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| Resumo: | 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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