Key techniques and method for deep seismic data acquisition in hard-rock environment

Deep reflection seismic survey is the main method to explore the deep geological structure,in which the high quality data is the basis of reasonable geological interpretation.Due to very irregular and heterogeneous strata in hard-rock environment,the seismic scattering effect is obvious,leading to complexity of the seismic wave field.On the other hand,as non-ideal elastic media,hard-rock rigidity is not conducive to elastic wave energy conversion,so explosive energy is too limited to transfer to elastic waves.Low frequency characteristics of seismic dataassociated with the deeper exploration target can be seriously disturbed by environmental noise,resulting in low signal-to-noise ratio in hard-rock environment.Based on the seismic reflection data acquisition in the middle and lower reaches of the Yangtze River metallogenic belt from 2009 to 2014,this work focused on how to improve seismic raw data quality and signal-to-noise ratio with fine design and careful implementation in hard-rock environment.We have conducted a series of experiments on new methods such aslongitudinal non-coupling exploding,wide band receivingin the very low SNR region andwide line acquisitionto improve seismic data quality.The results show that these techniques can enhance the energy of elastic waves propagating downward,expand frequency bands of received seismic signals,and raise coverage times and SNR,which effectively improve the quality of raw data and imaging profiles.It provides the experience and reference for deep seismic data acquisition in hard-rock environment in the future.