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A Review of Variability of the Effective Mineral's Elastic Moduli in Sandstones
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 81st EAGE Conference and Exhibition 2019, Jun 2019, Volume 2019, p.1 - 5
Abstract
Understanding the bulk and shear moduli of the background material (κ_0, μ_0) from which the rock frame is built is crucial in rock physic models with a direct impact on rock frame modelling and Gassmann fluid substitution. Here, I describe different components of the background material and explain why the terms grain, matrix, solid or mineral do not solely represent κ_0 and μ_0 accurately. I explored the literature to gain a data-driven insight into variability of the elastic properties of the non-clay fraction of the sandstones, where quartz's elastic properties are typically used for. The results from unjacketed bulk compressibility measurements, along with two other empirical methods indicate the range of κ_0 and μ_0 vary over a rather large interval. It is shown that the effective medium theories – even using a detailed mineralogical description of the rock aggregate – do not guarantee an accurate estimation of κ_0 (and probably μ_0). It was also found that the quartz elastic properties, in particular its shear modulus, do not appear to be suitable for characterisation of the for non-clay fraction of the sandstones. Alternatively, unjacketed bulk compressibility measurements, or curve fitting is recommended for estimation of these parameters.