A mud supported sandstone core sample was selected to investigate the effect of various structural parameters including anisotropic clay platelets shapes and spatial orientation, fractures volume, shape and orientation on seismic waves velocities. For the selected cylindrical core sample, the following physical parameters were measured in laboratory pressure and temperature while keeping the sample dry: total porosity, permeability, bulk density, mineral content, and acoustic waves velocities radially in 7 different azimuths as well as along the vertical axial direction. Thereafter, a primary Rock Physic model is constructed based on the visual inspection of the SEM images. In the primary dual-porosity, constructed model the clay platelets morphology and spatial orientations were considered to be model parameters along the pores (cavities with aspect ratio between 0.1 and 1) and fractures (cavities with aspect ratio between 10-5 and 10-2) morphology and spatial orientations. The conducted sensitivity analysis depicted that the seismic waves velocities are not sensitive to the considered structural parameters for the clay platelets and pores. Therefore, the primary Rock Physic model was modified to delete the uninfluential parameters. Omitting the uninfluential parameters increases the weight of the influential parameters by decreasing the unknowns and degree of freedom for the model. The interior point algorithm was used to solve the inverse problem and find the model parameters. Seismic waves velocities were regenerated using the estimated parameters in the azimuths where the waves velocities measurements were conducted. Comparing the estimated and measured waves velocities shows that the best estimation was obtained for the compressional waves velocities (root mean squared error (RMSE) – 0.5 %), the estimation error is more for fast shear waves (RMSE – 1 %) and the most erroneous results are obtained when slow shear waves are estimated (RMSE – 2.5 %). The reason for more erroneous results obtained for the slow shear waves estimation might be because of the measurement error which is more for the slow shear waves velocity measurements in the laboratory.
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