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"# Implementation of a Devito viscoacoustic equations\n",
"\n",
"## This tutorial is contributed by SENAI CIMATEC (2020)\n",
"\n",
"This tutorial is based on:\n",
"\n",
"
**Linear inversion in layered viscoacoustic media using a time‐domain method** (1994)\n",
"
Joakim O. Blanch and William W. Symes\n",
"
SEG Technical Program Expanded Abstracts\n",
"
https://doi.org/10.1190/1.1822695\n",
"\n",
"
**True-amplitude prestack depth migration** (2007)\n",
"
Feng Deng and George A. McMechan \n",
"
GEOPHYSICS Technical Papers \n",
"
https://doi.org/10.1190/1.2714334\n",
"\n",
"
**Attenuation compensation for least-squares reverse time migration using the viscoacoustic-wave equation** (2014)\n",
"
Gaurav Dutta and Gerard T. Schuster\n",
"
GEOPHYSICS Technical Papers\n",
"
https://doi.org/10.1190/geo2013-0414.1\n",
"\n",
"
**Multiscale viscoacoustic waveform inversion with the second generation wavelet transform and adaptive time–space domain finite-difference method** (2014)\n",
"
Zhiming Ren, Yang Liu,and Qunshan Zhang\n",
"
Geophysical Journal International, Volume 197, Issue 2, 1 May 2014, Pages 948–974\n",
"
https://doi.org/10.1093/gji/ggu024\n",
"\n",
"
**Viscoacoustic prestack reverse time migration based on the optimal time-space domain high-order finite-difference method** (2014)\n",
"
Yan Zhao, Yang Liu, and Zhi-Ming Ren \n",
"
Appl. Geophys. 11, 50–62. \n",
"
https://doi.org/10.1007/s11770-014-0414-8\n",
"\n",
"
**A stable and efficient approach of Q reverse time migration** (2018)\n",
"
Yan Zhao, Ningbo Mao, and Zhiming Ren\n",
"
GEOPHYSICS Technical Papers\n",
"
https://doi.org/10.1190/geo2018-0022.1"
]
},
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"## Introduction \n",
"\n",
"The conversion of mechanical energy to heat, occurs during the propagation of seismic waves on the subsurface, due to the viscosity of the rocks. The presence of oil and gas in these rocks causes seismic attenuations. Thus, associated effects, such as dispersion and dissipation, can significantly affect the amplitudes, as well as the phase of the seismic pulse. However, in the seismic exploration, the subsurface has still been considered as an ideal elastic/acoustic medium, that is, disregarding its mitigating effect. In practice, the propagation of seismic waves on the subsurface is in many ways different from propagation in an ideal solid. \n",
"\n",
"For example, some subsurface rocks have anisotropic properties, are heterogeneous, porous and so on. The acoustic/elastic wave equation is not sensitive enough to describe propagation in these more complicated mediums. Generally, the viscosity of materials in the subsurface causes energy dissipation and consequently a decrease in amplitude, in addition to modifying the frequency content of the waves. This phenomenon of energy dissipation of the wave is called seismic absorption or attenuation. \n",
"\n",
"The goal of this tutorial is to perform a seismic modeling taking into account the viscosity of the medium, so that it is possible to more accurately simulate the seismic data and consequently build images with better resolution in the processing of this data, in addition to extracting more detailed information on rocky materials through seismic inversion. \n",
"\n",
"This tutorial follow three main viscoacoustic approaches in time-space domain:\n",
"\n",
"- Blanch and Symes (1995) / Dutta and Schuster (2014)\n",
"\n",
"- Ren et al. (2014)\n",
"\n",
"- Deng and McMechan (2007)"
]
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"