| According to the 13 th Five-Year Plan,there will be no change in the energy policy that focuses on coal and diversifies development.As the main energy and industrial raw materials of the country,coal remains the country ’s main resource for a long time to come,which is related to the destiny of the country’s economy and society.In recent years,coal mine safety accidents have occurred frequently.How to guarantee the safe and effective production of coal source has become a problem urged from being rolled.Small fault is a major factor affecting safe and efficient mining of coal mine.In recent years,seismic wave identification of minor faults has made great progress,but it is still difficult to identify small faults within 5m of coalfield drop.The southern coal fields are generally characterized by complex topography and developed faults.In order to promote seismic exploration of small faults in the southern coalfield,the Liupanshui coalfield in Guizhou Province,a typical coalfield in southern China,is selected as the research area in this paper.Due to the difficulty and particularity of the production of small faults,the spatial size ratio of 1:2000 is used,and for the first time in China,the construction of a physical model of a small fault with a burial depth of 800 m,1000m and 1200 m with a drop of 5m,3m and 1m has been systematically realized.Finally,the physical seismic model of small fault in coal measure strata in south China is completed.Then,seismic data are collected on the seismic physical model,processed and interpreted,and compared with the numerical simulation model data.From the perspective of seismic wave kinematics and dynamics,small faults with different burial depth drops of 5m,3m and 1m are identified.Seismic data of Shanjiaoshu mining area in Liupanshui coalfield,Guizhou province were used for numerical simulation,and the seismic wave field characteristics of small faults in the study area were analyzed.The physical model was established and compared with the numerical simulation seismic data.found that the numerical simulation of seismic data is too idealistic,acquisition of data and physical model consistent with the wild field collecting data,numerical simulation is incomparable.It is difficult to identify minute faults with a drop of 1 to 5m by seismic wave kinematic method because the coal seam is in a low-velocity layer on the surface.However,a variety of seismic attributes are extracted and analyzed by using dynamic method,and it is found that amplitude envelope,amplitude first derivative,amplitude second derivative and amplitude imaginary part are sensitive to the characteristic response of small faults,and have strong resolution ability.On this basis,the correlation between seismic attributes and drop is established.The results show that when the small fault drop of coal seam is less than or equal to 5m,there is a linear relationship not only with the traditional amplitude attribute,but also with the phase and frequency related seismic attributes,which provides a stronger basis for identifying small faults in coal seam by using seismic attributes.The current research results also show that the amplitude envelope has a high correlation with the imaginary part of the amplitude.Instantaneous frequency,first derivative of amplitude,cosine instantaneous phase,second derivative of the amplitude and amplitude envelope have a relatively low correlation and are relatively independent.Meanwhile,all the five attributes have geological significance of faults.So based on the seismic physical model research gap between 5 m or less seismic response characteristics of small fault reveals the geological factors(buried depth,head)of the influence law of seismic wave to identify small fault in the study area,saves the cost of field exploration,and the wild have great significance in guiding practical seismic data processing,fine for the southern coalfield seismic exploration to provide theoretical and technical support. |
