Purposes for Well-Seismic Ties & Quality Business Stage Accuracy Required Seismic Quality Required Example Application Regional Mapping Within a few cycles Within ~½ cycle Wavelet character match Poor/fair Good Very good Mapping and tying a regional flooding surface across a basin Exploration Comparing a lead to nearby wells Exploitation Seismic attribute analysis Inversion SLIDE 4 The purpose and required accuracy of a well-seismic tie varies with the stage of our studies If we are doing regional mapping, e.g., mapping a significant erosional unconformity or a flooding surface, then our tie does not need to be very precise, within 1 or 2 seismic cycles (peaks or troughs) – and the seismic data quality does not have to be very good In the exploration stage, we would like to tie well data, e.g., the top of a stratigraphic horizon/marker within ½ a cycle This requires good seismic data quality In the exploitation stage (development & production), we need to not only know the seismic event within ½ a cycle, but the shape of the real and modeled seismic trace should be quite similar For this, we need very good seismic data quality If we obtain a good character (shape) tie between the real and synthetic traces, then: We would then be able to extract various seismic attributes (measures of the seismic wavelets) to predict rock and fluid properties We may also be able to use a process called inversion to transform the seismic data into an estimate of the rock properties in cross-section views or as a 3D volume (if we have 3D seismic data) Courtesy of ExxonMobil L 7 – Well-Seismic 1