Tóm tắt:

Seismic method has recently been used in exploration for deep coal layers thanks to its capability to accurately map subsurface layers. The main issues are to recognize the coal signatures on seismic sections; moreover, seismic data are recorded in time while coal layers need to be defined in depth. The solution is to use Vertical seismic profile (VSP) method to identify the coal layers and to convert time sections to depth. In this paper, we describe an actual case of VSP application in Red River delta to define the characteristics of reflections from coal bearing layers on seismic data. The data acquisition and processing are also briefly demonstrated. In the results, coal bearing layers show strong amplitudes with lower frequency that can be identified on VSP. The information is important to tie with conventional seismic sections for coal layer mapping and time to depth conversion. The usefulness of VSP suggests that the method should be employed more in the future for coal exploration.