4D seismic data acquisition method during coal mining

Abstract

In order to observe overburden media changes caused by mining processing, we take the fully-mechanized working face of the BLT coal mine in Shendong mine district as an example to develop a 4D seismic data acquisition methodology during coal mining. The 4D seismic data acquisition is implemented to collect 3D seismic data four times in different periods, such as before mining, during the mining process and after mining to observe the changes of the overburden layer during coal mining. The seismic data in the research area demonstrates that seismic waves are stronger in energy, higher in frequency and have better continuous reflectors before coal mining. However, all this is reversed after coal mining because the overburden layer has been mined, the seismic energy and frequency decrease, and reflections have more discontinuities. Comparing the records collected in the survey with those from newly mined areas and other records acquired in the same survey with the same geometry and with a long time for settling after mining, it clearly shows that the seismic reflections have stronger amplitudes and are more continuous because the media have recovered by overburden layer compaction after a long time of settling after mining. By 4D seismic acquisition, the original background investigation of the coal layers can be derived from the first records, then the layer structure changes can be monitored through the records of mining action and compaction action after mining. This method has laid the foundation for further research into the variation principles of the overburden layer under modern coal-mining conditions.