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根据安徽淮南某煤矿的地质构造特点及煤层赋存形态,在三维地震测区中部选择了一条典型地质剖面,据此建立了陡倾角二维地震数学模型,并从波动方程出发确立了模型的三维地震观测系统。通过对正演模拟得到的炮集记录、叠加剖面、偏移剖面上的波场特征的分析,确定了适合勘探区地质条件的采集和处理方法。对该二维模型数据的处理结果表明,叠后偏移手段不适合陡倾角区煤层地震资料的处理,而叠前时间偏移可有效保证陡倾角勘探区块的地质目标成像。根据陡倾角目的层及逆掩断层区域开展地震勘探的难点问题,提出了适当调整观测系统、提高空间采样密度等措施。根据多年在淮南矿区开展采区三维地震勘探的工作经验,认为该区最佳观测系统为方位角特性好、共面元道集内炮检距分布均匀的八线八炮制束状规则观测系统。
According to the geological structure of a coalmine in Huainan city, Anhui province and the occurrence pattern of coal seam, a typical geological profile was selected in the middle of the 3D seismic survey area. Based on this, a mathematical model of two-dimensional earthquake with steep dip was established, and the three- Seismic observation system. Through the analysis of the wave field characteristics of the shot record, the superimposed profile and the offset profile obtained by the forward modeling, the methods of acquisition and processing suitable for the geological conditions in the exploration area are determined. The results of processing the two-dimensional model data show that the post-migration offsetting method is not suitable for the processing of coalbed seismic data in steeply dipping areas, and the prestack time migration can effectively ensure the geological target imaging in the steeply dipping exploration blocks. According to the difficulty of seismic exploration in steeply dipping target zone and reverse overthrust zone, measures such as adjusting the observation system and increasing the spatial sampling density are proposed. According to many years’ experience in carrying out 3D seismic exploration in mining area in Huainan mining area, the best observation system in this area is that the eight-line and eight-beam regular observation system with good azimuth characteristic and uniform offset within the coplanar set is available.