Macroscale Young’s Moduli of Shale Based on Nanoindentations
- Wenfeng Li (The University of Oklahoma) | A. Sakhaee-Pour (The University of Oklahoma)
- Document ID
- Society of Petrophysicists and Well-Log Analysts
- Publication Date
- December 2016
- Document Type
- Journal Paper
- 597 - 603
- 2016. Society of Petrophysicists & Well Log Analysts
- 2 in the last 30 days
- 349 since 2007
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It remains difficult to relate shale nanoscale measurements to core- and block-scale properties because of the heterogeneous structure of shale. One of the main reasons for this difficulty is the heterogeneity of natural nanogranular media, which is scale dependent. In this study, we propose a new conceptual model for the elastic deformation of a shale formation. The conceptual model accounts for the effective stiffness of small-scale constitutive entities at a large scale. We use the proposed model to determine macroscale Young’s moduli by analyzing nanoindentations. Independent macroscale measurements corroborate our model.
The petrophysical characterization of a shale formation, which can be considered to be a natural nanogranular composite, remains a challenging problem because of its heterogeneous structure. The heterogeneity exists at different scales, which makes it even more difficult for us to understand the pore space and the solid phases forming the matrix (Gupta et al., 2013; Sakhaee-Pour and Bryant, 2015).
The elastic properties of shale play critical roles in formation stimulation, well-log interpretation, drilling design, and production estimation. Determining these properties by conventional methods is time consuming and may even become impractical for shales. A large shale sample usually breaks into pieces during recovery due to the lack of mechanical stability. Hence, the notion of finding large-scale (core-scale, block-scale, or log-scale) properties from relevant properties of forming entities, such as organic and clay minerals, has gained attention among researchers (Bobko and Ulm, 2008; Kumar et al., 2012; Bennett et al., 2015). The key assumption is that knowing the elastic properties of the forming entities can enable us to predict the elastic properties of shale at a larger scale.
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