Trial of coal seam imaging by cross correlation analysis of drilling noise at open-pit mine based on single point 3C downhole observation
We present the field trial results of identifying the coal seam in advance of drilling based on a time-spatial cross correlation analysis of drilling noise observed by a single point three component (3C) downhole measurement at an Australian open-pit coal mine. An accurate detection of coal-seam depth is very important to improve production efficiency, in particular, for an overnight operation. We studied a method for detecting a coal seam, at an acceptable additional cost, using the seismic noise generated from drilling blasting holes at an open-pit mine. In this study, the time-spatial cross correlation analysis, with a coordinate transformation of 3C waveform, was employed to extract reflectivity in drilling noise signals in terms of delay and arrival direction. The values of cross correlation are migrated to 3D space by diffraction stack migration to estimate the subsurface structure. The characteristics of the observed drilling noise are evaluated and then the proposed imaging method is applied to these characteristics. The wave energy and frequency components change while drilling are shown. The drilling noise had enough high energy and wide frequency range. We regard all P, SV and SH wave modes were generated by the drilling. The reflection imaging results are shown. Some planer structures were detected by applying the method, and one reflector appeared near the depth of the coal seam. These results suggest the method has potential for use in open-pit mining development
Soma, 1., Tosha, T., Asanuma, H. & Karekal, S. (2013). Trial of coal seam imaging by cross correlation analysis of drilling noise at open-pit mine based on single point 3C downhole observation. Proceedings of the 11th SEGJ International Symposium (pp. 302-306). United States: Society of Exploration Geophysicists.