Ultrahigh-resolution seismic enhancement. The use of colored inversion and seismic attributes on sub-bottom profiler data

Abstract

Companies perform acoustic surveys before installing any submarine infrastructures in the seafloor, like new wells, pipelines, manifolds, cables, or wind farms. These surveys provide high-detailed geological information about the seabed and the first one hundred meters underneath the seafloor to subsea engineers and geologists. The prime use of this information by marine geologists is in geohazards analysis. The industry always used the sub-bottom profiler data in a fast-track way, not using its full capacity of geological representation. This contribution wants to magnify the potential of the sub-bottom profiler and define it as an ultrahigh-resolution seismic method. Sub-bottom profiler data assists numerical geotechnical analysis, and despite the scaling difference, can be the initial values when modeling velocity, sedimentary layers, and the continuities of geological faults. To support it, we present some established procedures from multichannel seismic, like classical seismic attributes applied to sub-bottom data. We computed envelope, instantaneous phase, instantaneous frequency, the cosine of phase, RMS, and TecVA on it. In a seismic line acquired in South Atlantic with a sub-bottom profiler, and one geological sample drilled from the seabed and profiled with a multi-sensor core logger. We applied for the first time the colored inversion technique to enlarge the spectrum of the ultrahigh-resolution seismic, increasing the low frequencies content. The new seismic spectrum enhances geological features providing better results than obtained with the raw seismic waveform and the seismic envelope attribute provided by most sub-bottom systems. While the raw seismic waveform has more vertical resolution with more reflectors in the same vertical unit, the envelope attribute has higher amplitude values. The result achieved with colored inversion has both the vertical resolution of the seismic waveform and the amplitude intensity of the envelope attribute.