Publication Date:
2017-12-31
Description:
High-resolution 3D images are used in Digital Rock Physics (DRP) to numerically compute rock physical properties such as permeability and elastic moduli. These images are not widely available and their preparation is both expensive and time consuming. All of these issues highlight the importance of alternative DRP methods that are based on 2D images and use different approaches to compute effective properties of 3D samples. In addition, the scale of study in both standard and alternative DRP is very small, which applications of its results are questionable at wells or reservoir scale. The aim of this study is to use 2D images and alternative DRP techniques for computing seismic wave velocity and permeability, which are compared with well and laboratory data. For this purpose, data from one well in a reservoir located in southwestern part of Iran is used. First, two clean (carbonate) and two cemented (limy-sandstone) samples were collected from well cores at different depths. Then, 2D images by Scanning Electron Microscope (SEM) and conventional microscope were captured. In the next step, two alternative DRP methods, namely empirical relations and conditional reconstruction, have been employed to compute P-wave velocity and permeability of 3D medium. Results showed that, in clean (mono-mineral) samples, velocity values were reasonably close to well data. However, permeability values are may underestimated comparing with laboratory data because laboratory data were obtained at ambient pressure, whereas alternative DRP results are more representative of reservoir pressure conditions. Nevertheless, permeability-porosity trends are valid for both samples. In the case of cemented samples, a two-scale procedure along with a method for two-scale computation and grain-cement segmentation are presented and developed. Results showed that P-wave velocity are overestimated probably due to random sampling in this method. However,velocity-porosity trends are in agreement with well data. Moreover, permeability results obtained for cemented samples were also similar to those obtained for the clean samples. This article is protected by copyright. All rights reserved
Print ISSN:
0016-8025
Electronic ISSN:
1365-2478
Topics:
Geosciences
,
Physics
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