Study On Seismic Tomography In In-seam Seismicexploration In Coal Field

Coal is a significant type of energy in China. With the rapid development of national economy, the demand of coal is gradually rising. As a result,the scale of coal mining is expanding. However,he geological structures of large coal fields in China are complicated, resulting in different scales of the geological anomalous body developed. In the process of coal mining, if the geological anomalous body is not prospected clearly and positively, coal safety issues would happen in the process of coal mining, which would cause casualties and financial loss. In order to get through the complicated geological conditions, it is significant to know the geological structure in advance. In-seam seismic exploration(ISS) is an effective mean to detect the small structure, the anomalous body and the variation of the coal thickness developed underground in the coal field. It is effective for computerized tomography(CT) to reform the underground geological structures.Based on the study status of in-seasm wave seismic exploration around the world, the basic theory of ISS is introduced, including the formation mechanism, categories and three exploration means of in-seam wave.Dispersion is the significant characteristic of in-seam wave. Group velocity and phase velocity are the key to study the theory of dispersion. Airy phase is the extreme value position on the dispersion wave, which contain high energyand high frequency. Dispersion wave is influenced by several factors,especially the coal seam thickness. And, dispersion analysis methods are also introduced, including moving window method and phase diversity method.The inverse algorithm methods of seismic tomography is summarized in this paper. Algebraic Reconstruction Techniques(ART) and Simultaneous Iterative Reconstruction Techniques(SIRT) are widely used in seismic tomography.In the research area, data collection of in-seam wave is proceeded underground in Dongpang coal field. SCT, an in-seam seismic data processing software, is used as the main data processing tool. Moving window method is used in the dispersion analysis. SCT chooses SIRT as The inverse algorithm methods of seismic tomography. According to the integrated interpretation, the positions of the two faults known before is correct.In conclusion, Rayleigh wave, the certainty of ISS prospecting the scale of the geological body, the research and development of ISS equipment are still the hot pots of future ISS study.