Analysis And Application Of Seismic Azimuth After Stacking Of Small Faults In Coalfield

Fault is a structure in which the strata or rock mass displaces obviously along the fracture surface,which has an important impact on the safe and efficient mining of coal.In this thesis,according to the distinction of fault distance and dip angle,we build a model and numerical simulation for the small fault of Ordovician limestone roof in coal field,analyze the characteristics of seismic response,and study its azimuth seismic attributes,so as to provide theoretical basis and analysis method for seismic exploration of Ordovician limestone fault.In this thesis,based on the elastic property test of limestone samples,the model of Ordovician limestone top small fault in coal field is constructed,and the finite difference method is used for numerical simulation;Through the analysis of forward azimuth seismic section,it is found that the existence of small faults will cause the distortion of the reflection phase axis of Ordovician limestone top.The analysis of seismic attributes shows that the main amplitude,the maximum amplitude,the coherence coefficient and the main frequency are attenuated at the fault,while the minimum amplitude and the bandwidth are increased at the fault.Through the least square fitting of the azimuth seismic attributes,it is found that the ellipse fitting accuracy between the azimuth attributes and the azimuth angles of the maximum amplitude and the minimum amplitude at the fault is high,and the fitting results can be used to judge the location and plane characteristics of the fault;The short axis of the ellipse is perpendicular to the fault strike,and the long axis is the fault strike.When the fault dip angle is constant,the eccentricity e of ellipse can be used as an index to qualitatively judge the fault distance.The larger the eccentricity e is,the larger the fault distance is.When the fault distance is constant,the eccentricity e can be used as the basis to qualitatively judge the fault dip angle.The larger the eccentricity e is,the larger the fault dip angle is.Finally,the effectiveness of the method is verified by inversion of actual seismic data using post stack azimuth seismic attribute analysis.This thesis has 86 figures,10 tables and 85 references.