Characterization of gas‐bearing sediments in the coastal environment using geophysical and geotechnical data

Seismic investigation in marine gas-bearing sediments often fails to get information below the acoustic mask created by free gas. To circumvent this problem, we combined collocated multichannel ultra-high resolution seismic imaging, electrical resistivity tomography and core sampling study physical properties of Bay Concarneau (France). We obtained sections compression (P-) wave velocity ( V P ${V_P}$ ) from processing 2D models data inversion. observed low (∼0.5 Ω·m) (∼1200 m/s) values where gas was identified data. tested a joint workflow combining 1D inversion with P-wave through structural coupling between velocity. series fitting whilst agreement The resulting showed continuity geological units fronts, which are associated paleo-valley sediment infilling. were able demonstrate relationships differing superficial deeper sediments. established these at geophysical scale then compared results porosity). inferred porosity distribution At locations, good both within outside This demonstrated that could be used as proxy for no available caps. In regions, high (60%–70%) down about 10–20 m depth, contrast surrounding medium has less than 55%. These support hypothesis failures inside control migration.