bandwidth, including low- noise low frequencies, provides wavelets without side lobes so that events become single peaks or troughs, corresponding to genuine geological layers and are closer to the genuine seismic signature of formation interfaces. Tis clarifies impedance contrasts to create sharp images of small features and clear differentiation between sedimentary packages for accurate delineation of the reservoir. Ultra-low frequencies deliver more detailed facies discrimination, more quantitative seismic inversion results and therefore more reliable lithology predictions away from existing wells. Tis leads to more accurate reservoir models and better development plans. Once production is under way the benefits of broadband for 3D surveys are extended into 4D monitoring to provide better dynamic reservoir models to maximise hydrocarbon recovery.
Figure 5.49: This colour blend 3D visualisation of 2.5 Hz, 8 Hz and 15 Hz dominant frequencies, taken from data obtained in Block 22, Kwanza Basin in Angola, shows the advantages of the wide range of frequencies obtained in a broadband survey. The Upper Miocene channel systems and surrounding salt bodies are highlighted, but without the ultra-low frequencies the red channel would not be visible.
