Micromechanical modeling of ultrasonic velocity for pore-structure and porosity characterization considering anisotropy in carbonate samples
Abstract This work presents an approach to characterize the pore-structure and anisotropy in carbonate samples based on the Effective Medium Method (EMM). It considers a matrix with spheroidal inclusions which induce a transverse anisotropy. The compressional wave (VP), vertical (VSV) and horizontal (VSH ) shear wave velocities are estimated, taking into account parameters as characteristic length, frequency, wave incidence angle, aspect ratio, mineralogy, and pore-filling fluid to predict pore shape in carbonates. Ranges of aspect ratios are shown to discriminate different pore types: intercrystalline, intergranular, moldic, and vuggy. The wave incidence angle is a determinant parameter in the estimation of VP (0°,45°,90°), VSV (0°) and VSH (90°) to calculate dynamic anisotropic Young's modulus (E33) and Poisson's ratio (v31), together with the Thomsen parameters, ε, γ, and δ for quantification of the anisotropic pore-structure. The obtained results establish that the size and the pore-structure have a more significant impact on the elastic properties when the porosity takes values greater than 4% for the three ranges of frequency, ultrasonic, sonic, and seismic. This investigation predicts the pore-structure and pore-size to improve the characterization and elastic properties modeling of carbonate reservoirs. The validation of results includes porosity measurements and ultrasonic velocity data of different carbonate samples.
| Main Authors: | , , , |
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| Format: | Digital revista |
| Language: | English |
| Published: |
Universidad Nacional Autónoma de México, Instituto de Geofísica
2021
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| Online Access: | http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S0016-71692021000400294 |
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