Seismic exploration problems in the Bass region ? some recent results

Abstract

The diversity of geological regimes in the Bass region, the location of a recent Bureau of Mineral Resources (BMR) seismic survey (Fig. 1), is paralleled by a diversity of seismic exploration problems. Within the Bass Basin the economically significant lower part of the Eastern View Coal Measures, and deeper undrilled strata, have historically been difficult to explore seismically due to acoustic shadowing by, and multiple generation within, the coal-bearing upper part. Furthermore, the overlying section is host to volcanogenic complexes which can be efficient acoustic scatterers. The seismic response of sedimentary sequences in the two continental slopes that were traversed, the upper parts of which are potentially of economic significance, can be partly degraded by a strong water-layer multiple, and by processing flows which fail to compensate for departure from Common Depth Point (CDP) ray path geometry below the rough submarine topography. Limitations of resolution (loss of high frequencies and low signal to noise ratios) in some older seismic data can be related to the practice of summing adjacent traces or consecutive shot records, and to an inadequate energy source (Figs 2 and 3).