THREE-DIMENSIONAL IMAGING AHEAD OF MINING

摘要

The National Mining Association (NMA) Technology Committee and the Department ofEnergy (DOE) Office of Industrial Technologies (OIT) developed the technology roadmap forthe Mining Industry of the Future (MOF) program. Imaging ahead of mining was ranked withinthe top ten needed technologies. Mines will be deeper and coal seams will be thinner and moredifficult to mine. Because coal seams are natural waveguides for transmission of electromagnetic(EM) waves, EM waves can be applied in tomographic imaging. Since EM waves are highlysensitive to the physical structure of the coal seam waveguide and its electrical parameters, EMwaves can be used in the tomographic imaging of anomalies in the coal seam. EM waves arerefracted, reflected, and absorbed along transmission paths through geologically disturbed zones.The degree of EM change is dependent on the anomaly. Because EM energy does not travelalong a straight ray path, tomographic image reconstruction algorithms based upon straight raypath assumptions cannot be used. Furthermore, instrumentation capable of accurate total phaseshift and absorption measurements is needed. This paper describes newly developed threedimensional(3-D) imaging algorithms and instrumentation that can be applied between gateroads and degas holes more than 2000 feet apart. In-mine imaging of geologic anomalies hasproven effective in improving mine planning and reducing risk. Imaging between degas holesholds promise of increasing coal bed methane (CBM) production. The images, when combinedwith ground control science and engineering, will increase safety in mining.