162 Seismic Imaging The second example describes the use of hybrid seismic refracted and surface waves. The processing of surface waves, extracted from a seismic survey, was performed in the f-k domain with SWIP, an open-source MATLAB-based package. The inversion of the dispersion curves produced pseudo 2D models of S-wave velocity with an estimated depth of investigation of around 10 m. A P-wave velocity model was extracted from the refraction arrivals by a tomography algorithm. The Poisson’s ratio was estimated from this information. The distribution of this parameter, more particularly its contrasts, clearly highlights gas pathways in the subsurface consistent with degassing observed at the surface. The good results obtained in the case studies reveal that it is possible to obtain complementary information from the combination of different wave types from the same seismic survey. Thus, these hybrid seismic methods open up new perspectives for more applications. References Hagedoorn G.J., 1959, The Plus–Minus method of interpreting seismic refraction sections, Geophysical Prospecting, 7, 158-182. Mendes M., Mari J.L., Hayet M., 2014, Imaging geological structures up to the acquisition surface using a hybrid refraction-reflection seismic method, Oil & Gas Science Technology, 69 (2), 351-361, http://dx.doi.org/10.2516/ogst/2012095. Pasquet S., Bodet, L., 2017, SWIP: An integrated workflow for surface-wave dispersion inversion and profiling, Geophysics, 82 (6), WB47-WB61.
RkJQdWJsaXNoZXIy NjA3NzQ=