High resolution seismic reflection surveys for coal

Abstract

A number of experimental high resolution seismic reflection surveys have been carried out in the Sydney Basin, using 48 trace IFP recording equipment with one millisecond sampling, single detectors per trace and small explosive charges. Generally the dominant frequency of the reflected pulse is about 120 Hz, but it can be as high as 160 Hz under favourable conditions. Wind is the most common source of noise and even low levels can seriously reduce signal-to-noise ratios because of the small explosive charges used. The most successful solution has been to record when the wind noise is minimal, such as very early in the morning. Although the resolution obtained is still not sufficient to define small faults, it still provides information not easily obtained with other seismic methods. This includes the resolution of the direction of movement with individual large faults, the determination of the separation between closely spaced faults and changes in roof conditions.