Published in Australian Longwall Magazine
The basic technique of seismic exploration involves imaging the sub-surface using artificially generated sound waves. Surface receiving devices, or geophones, are used to detect the seismic energy that originates from a seismic source, travels down into the earth, and gets partially reflected back to the surface at geological boundaries.
Three-dimensional seismic exploration involves using a grid of surface receivers to detect the reflected seismic energy generated by each seismic source in an exploration area, rather than using a single line of receivers (2D seismic). In this way significantly more information can be obtained about the sub-surface, and the accuracy of mapping small-scale features in target coal seams is increased.
The most significant advances in 3D coal-seismic technology over the past five years have been related to improvements in data interpretation and 3D visualisation methods. Since Newlands first used 3D seismic in the Southern underground mine area in 1998, computers have become much more powerful, and 3D seismic interpretation software has evolved to take advantage of this.
Brisbane-based 3D seismic survey specialist Velseis said coal mines had benefited most from the emphasis now given to ways in which mine geologists and seismic interpreters work together to integrate knowledge. For example, geophysical logs and borehole picks are now easily imported and tied to 3D seismic volumes, enabling more accurate depth surfaces to be generated from seismic data.
Many new seismic attributes have been developed to help geologists extract meaningful stratigraphic information from their seismic data, in addition to the more traditional structural maps.
Advances in visualisation software mean seismic interpreters can consider 3D variations in the seismic data when interpreting the geological significance of anomalies in the seismic volume. Also, high speed network connections enable mine staff to remotely access seismic data to improve utilisation.
