Wave propagation applied to geologic imaging: acoustics

The concept of wave is recurrent in pure and applied sciences, serving as a basis to understand and describe from earthquakes, through telecommunications and electromagnetic waves, to neutron diffraction, for instance, to cite a case involving Quantum Mechanics. Thus, this concept plays a central role in fields as diverse as Geophysics and Quantum Physics, as well as in their applications. On the other hand, the wave equation is commonly studied in Physics courses, eminently using analytical solutions, where it is not possible to obtain answers in complex domains and therefore study several applications, such as Applied Geophysics and Seismic Method. This article aims to present in detail, in a simple and accessible way, the necessary tools to obtain numerical solutions of the acoustic wave equation, within the scope of Applied Seismology, using them as the basis for an image generation algorithm (reflector mapping) of geological structures in sedimentary basins. This is a beautiful and elegant application of physics, forming the basis of hydrocarbon exploration nowadays, in which huge areas of the Earth’s surface are mapped with the objective of finding configurations in which there will be a potential commercial accumulation of oil. The application described here, known in the specialized literature as Reverse-Time Migration, is applied to a realistic synthetic model. The results demonstrate an excellent quality of the image obtained. In fact, the applied technique is state-of-the-art in terms of migration method (seismic mapping), currently very in vogue and used by industry, especially in pre-salt targets.

Keywords
acoustic waves; finite-diference method; reverse-time migration; geologic structure imaging