TY - THES

T1 - Application of elastic properties for the discrimination of various lithologies

AU - Kuha, Alejandro

N1 - embargoed until null

PY - 2016

Y1 - 2016

N2 - In this work an attempt has been made to find a way for the discrimination of various lithologies based on their elastic parameters. A total of 577 samples from 8 different carbonate lithologies and 93 samples from 6 different magmatic-metamorphic lithologies were analyzed. Compressional and shear wave velocities, bulk and grain densities and porosities were given in a dataset for all rock samples. In the course of this thesis 19 types of cross plots were made. On the one hand the crossplots are represented as a whole (with all singular data) and on the other hand they show the mean values including the variances. The Lamé parameter λ and shear modulus μ are the most important and fundamental elastic properties of rocks. Additionally the bulk compressional modulus κ, the acoustic impedance AI and the shear impedance SI were calculated from the given data. While κ is a measure of the substances resistance to uniform pressure, AI and SI are the products of density times compressional wave velocity and shear wave velocity, respectively. Together with the given data, these parameters were used to create cross plots, which were finally interpreted and analyzed. Regarding the carbonate lithologies, the dolomites could be distinguished from limestones due to higher variances and densities in various cross plots. This variance behavior is based on the high pore diversity, which led to low compressional wave velocities. For the magmatic-metamorphic lithologies, rocks showing a schistosity and therefore anisotropy, could be distinguished due to higher variances in certain cross plots, especially for dry data. Based on the superposition of dry carbonates on dry magmatic-metamorphic rocks, a differentiation could be made. When samples are saturated, the different characteristics of the elastic properties of these rocks get lost. The various lithologies cannot be differentiated in detail based on their elastic properties, but when looking at the mean values including the variances, differences and trends can be observed. Additionally the Hashin-Shtrikman bounds were used to compute the upper, the 50% and the lower limits of elastic parameters exclusively for the limestone and dolomite samples. A total of 8 different cross plots have been made for each lithology, showing the HS-bounds together with the lithology specific values. The Hashin-Shtrikman bounds were used as an interpretational aid and show the different trends on elastic properties for the limestones and dolomites. While limestones show a “stiffer” behavior, dolomites tend to be “softer”, due to higher porosities and larger porosity ranges.

AB - In this work an attempt has been made to find a way for the discrimination of various lithologies based on their elastic parameters. A total of 577 samples from 8 different carbonate lithologies and 93 samples from 6 different magmatic-metamorphic lithologies were analyzed. Compressional and shear wave velocities, bulk and grain densities and porosities were given in a dataset for all rock samples. In the course of this thesis 19 types of cross plots were made. On the one hand the crossplots are represented as a whole (with all singular data) and on the other hand they show the mean values including the variances. The Lamé parameter λ and shear modulus μ are the most important and fundamental elastic properties of rocks. Additionally the bulk compressional modulus κ, the acoustic impedance AI and the shear impedance SI were calculated from the given data. While κ is a measure of the substances resistance to uniform pressure, AI and SI are the products of density times compressional wave velocity and shear wave velocity, respectively. Together with the given data, these parameters were used to create cross plots, which were finally interpreted and analyzed. Regarding the carbonate lithologies, the dolomites could be distinguished from limestones due to higher variances and densities in various cross plots. This variance behavior is based on the high pore diversity, which led to low compressional wave velocities. For the magmatic-metamorphic lithologies, rocks showing a schistosity and therefore anisotropy, could be distinguished due to higher variances in certain cross plots, especially for dry data. Based on the superposition of dry carbonates on dry magmatic-metamorphic rocks, a differentiation could be made. When samples are saturated, the different characteristics of the elastic properties of these rocks get lost. The various lithologies cannot be differentiated in detail based on their elastic properties, but when looking at the mean values including the variances, differences and trends can be observed. Additionally the Hashin-Shtrikman bounds were used to compute the upper, the 50% and the lower limits of elastic parameters exclusively for the limestone and dolomite samples. A total of 8 different cross plots have been made for each lithology, showing the HS-bounds together with the lithology specific values. The Hashin-Shtrikman bounds were used as an interpretational aid and show the different trends on elastic properties for the limestones and dolomites. While limestones show a “stiffer” behavior, dolomites tend to be “softer”, due to higher porosities and larger porosity ranges.

KW - elastic properties

KW - lithology discrimination

KW - elastic parameters

KW - carbonate discrimination

KW - elastic properties of rocks

KW - Hashin-Shtrikman

KW - elastische eigenschaften von gesteinen

KW - lithologie unterscheidung

KW - elastische parameter

KW - Unterscheidung von Karbonaten

KW - Hashin-Shtrikman

M3 - Master's Thesis

ER -