Research on key techniques for coalfield seismic data acquisition in thick loess area

Complicated conditions in thick loess-covered area cause many serious problems to the coal field seismic prospecting, which is characterized with loose soil structure, lower wave velocity, severe absorption and attenuation, serious secondary disturbances, extremely poor S/N ratio and resolution.Among these problems, field acquisition techniques are the key problems.So, some solutions are proposed, including:(1) fine portraying the loess velocity structure using Rayleigh-Wave inversion method restrained by micro-logging data, to reasonably select the excitation location; (2) applying long excite/geophone array to enhance S/N ratio of raw data and suppress the strong low speed regular interfaces; (3) adopting the low frequency geophones in order to adapt the propagation attenuation characteristics of thick loess; (4) using the multi-lines and long layout observation to improve the effective folds for targeted coal seam.The full-scale test in the thick loess area of Wanrong and Hongdong county in Shanxi indicated that through the system and comprehensive application of the above 4 key techniques, the reflection wave can be clearly recognized from raw records, and the seismic stack-profiles with events of high S/N ratio, good continuity can be obtained.The geological results have been proved perfect by 3 wells data.The application of these key techniques will basically solve the technical problems which coal field seismic acquisition work has faced in the similar areas with thick loess.