High-resolution surveys

Abstract

Most seismic surveys are used in the search for oil and gas reservoirs. Most of the targets are quite deep. The maximum frequency of the seismic events that are recorded from these targets is not high. The necessary resolution of the characteristics, especially those referring to their positions in 3-D space, of the seismic events, to an accuracy sufficient for most purposes in the decision about whether and where to drill for oil or gas, can, in most cases, be obtained at a reasonable cost by recording at a sample rate of 2 ms or even 4 ms. Similarly, a surface geophone trace spacing of 25 m, implying a CDP spacing of 12.5 m, is normally sufficient to provide the necessary resolution. The fold of CDP coverage does not affect the accuracy of the resolution, but does affect the quality of the final stacked sections and of those derived from them.