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3-D Pore Geometry of Carbonates and its Effects on Ultra Sonic Velocity and Permeability |
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| Investigators: Ralf Weger, Gregor Baechle, and Gregor Eberli | ||||||||
| This project is completed. |
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Patterns and Processes in Ooid Shoals around Ocean Cay, Bahamas: using the modern to predict the Pleistocene - Facies, Diagenesis and Petrophysical Properties |
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| Investigators: Eduardo Cruz, Gregor P. Eberli, Gene Rankey | ||||||||
| This project is completed. |
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4-D GPR Monitoring of Mesoscale Flow in Oolitic Carbonates |
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| Investigators: Mark Grasmueck, David A. Viggiano, Jorien Schaaf | |||||||||||||||||
| Lateral variability in carbonates often prevents a reliable prediction of connected porosity and fluid flow at scales larger than plug samples or thin sections. To improve basic understanding of flow at the reservoir scale we perform time-lapse Ground Penetrating Radar (GPR) monitored infiltration experiments at outcropping carbonate reservoir analogues. GPR is very sensitive to change in subsurface water content and can therefore be used to track wetting and drying events in the unsaturated zone. If a GPR survey is repeated with identical geometry (Grasmueck and Viggiano, 2007), variations between time-lapse radar images must be due to water content changes. As only zones with connected porosity experience water content changes, high-resolution 4-D GPR characterizes the spatio-temporal flow patterns inside a heterogeneous rock volume. A better knowledge of mesoscale flow in carbonates has the potential to improve reservoir flow prediction models, residual fluid recovery and understanding of early diagenesis processes. |
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3-D Ground-Penetrating Radar (GPR) Fracture and Shear Band Characterization in Carbonates (Cassis, France and Madonna della Mazzo, Italy) |
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| Investigators: Mark Grasmueck, Gregor Eberli, Rizky Purbayasekti, Juliette Lamarche, Francois Fournier, and Jean Borgomano | |||||||||||||||||
| Permeable fracture zones can be major fluid conduits in carbonate reservoirs. Yet characterizing fracture patterns in carbonates is not an easy task as most fracture analysis relies on two–dimensional analysis. For example, in outcrops the area method measures fractures on the surface of the bed and the scan density line method gives fracture density and spacing on the vertical exposure surface. Fractures like faults are, however, threedimensional features. Ground-Penetrating Radar has the potential to help establish the mechanical-stratigraphic relationships in three-dimensions. |
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Parameters Controlling Vp/Vs Ratio in Carbonates |
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| Investigators: Gregor P. Eberli | |||||||||||||||||
| Vp/Vs ratios in carbonates vary widely and neither traditional qualitative descriptions of pore type, texture, or percentage of micro porosity, nor more quantitative measurements such as digital image analysis derived geometric parameters are able to satisfactory explain the variations in Vp-Vs-Ratio. Likewise, variations in mineralogy or fluid composition do appear to influence Vp-Vs-Ratio only in almost negligible form (Weger 2007). Even when superimposed onto a Vp-Phi cross plot, no noticeable trends can be determined. The unpredictable nature of shear wave velocity and the Vp/Vs ratio in carbonate rocks has large implications for AVO analysis, as reliable information regarding the distribution of shear wave velocity within individual stratigraphic units is needed for such an analysis. |
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Computational Rock Physics: 3-D Carbonate Pore Networks and Simulation of Petrophysical Properties |
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| Investigators: Mark Knackstedt (Australian National University), Christoph Arns (Australian National University), Gregor Eberli | |||||||||||||||||
| Many studies have demonstrated the importance of the pore structure in carbonates on petrophysical properties (e.g. Anselmetti and Eberli, 1993, Kumar and Han, 2005; Rossebř et al., 2005). In order to quantitatively describe 2-D pore structure, we developed a digital image analysis (DIA) methodology that produces repeatable quantitative pore shape parameters (Weger, 2006). These 2D studies have added much to the understanding of the influence of the pore structure on acoustic properties, yet their 2D nature prevents a comprehensive mathematical treatment of pore shapes in simulations of petrophysical properties. In an alliance with Mark Knackstedt and his team at the Department of Applied Mathematics of the Australian National University in Canberra, Australia, we now are able to expand our 2D studies to quantitative 3D pore network topology. Their high-resolution CT scans with resolutions of 2.8 μm allow to image even micro-porous regions in 3D (Arns et al., 2002). |
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Petrophysical Characterization of Cretaceous and Tertiary Carbonate Mass Gravity Flows, Maiella Platform, Italy |
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| Investigators: Gregor Eberli, Daniel Bernoulli, Noelle van Ee and Fikril Hakiki | |||||||||||||||||
| During the two previous years we have evaluated if redeposited carbonates such as breccias and calcareous turbidites have reservoir potential by measuring the porosity and permeability of the these deposits in Cretaceous and Tertiary rocks along the Maiella Platform. In Cretaceous redeposited beds (megabreccias and turbidites) porosity does not exceed 15% and permeability is lower than 100 mD, while porosity in the nannofossil-rich background sediment is 7.5 – 27 % and permeability between 0 – 522 mD. The best reservoir potential is in coarse rudist grainstone facies(Figure 1). The goal of this project is to complement the porosity-permeability analysis with sonic velocity data. In particular to test if a correlation exists between type of mass gravity flow (turbidites, slumps, breccias, etc) and their petrophysical properties. |
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