Summary
Seismic acquisition and the resulting seismic images have evolved considerably from analogue single-fold shooting, to 2D CDP shooting in the 1960s and 1970s, to 3D seismic onshore and offshore, and all the way to modern high density, wide-azimuth methods. Sources and receivers have also evolved substantially through this time period; but are the advances in acquisition equipment the main reason for the step change in data quality that we see? We believe that evolution in acquisition geometries and resulting increases in trace density have had a much bigger effect. We have seen step changes in data quality as we move from 2D to 3D, then denser and denser wide azimuth geometries which have recently been augmented with simultaneous source acquisition. So is the detail of the acquisition method the key for success, or is it a simple case of "get as many measurements per km2 as possible"?
Introduction
Indeed the development of new sensors, sources, clever processing algorithms and powerful computing have contributed significantly to the dramatic change in the quality of the subsurface image throughout the last decades, and will of course continue to do so; however, big leaps in data quality have occurred when the quantity of measurements per unit of acquisition surface coverage has jumped significantly from one generation to the next (Figure 1).
As illustrated in Figures 2 and 3, this factor – which is referred to as the trace density – correlates very well with the data quality measured in simple ways (stack image) and sophisticated ways (complex attributes) (Ourabah et al., 2015). Trace density seems to correlate best with the quality of a given survey even if the individual measurements were of lower quality or involved more blending (Dvorak et al., 2013). Moreover, these ultra-high density surveys unlock the power of a new generation of processing algorithms and tools that can take advantage of the huge redundancy of information and the fine sampling of the signal and noise, (Ourabah et al., 2014; Poulain et al., 2014). In this paper we will explore how this principle of maximizing the trace density applies for different acquisition methods and environments before going on to discuss our vision for future seismic acquisition.
