伊犁盆地二维地震多次反射波压制采集方法研究

Research of 2D Seismic Acquisition Parameters for Multiple Reflected Wave Compression in Yili Basin

伊犁盆地侏罗系内部煤系地层发育,地震反射能量强,连续性好,可全区对比追踪。由于煤层速度低而围岩速度高,反射系数大,与上覆白垩系底界面及地面形成多次反射波。且多次反射波类型复杂,给多次反射波压制处理带来困难,严重影响了地震资料的可靠性。因此,在资料采集和处理时,需要在工区内多次反射波特点分析的基础上,提供合适的采集和处理参数压制多次反射波。目前在资料采集上主要采用增加覆盖次数,增大采集排列长度的方法来压制干扰,但同时也会带来一些负面效应。因此,必须在多次反射波压制效果与一次反射波叠加效果之间折衷选择合适的采集参数。通过建立工区主干测线的地质模型,采用不同的地震采集观测系统参数,利用计算机正演模拟方式获得单炮地震记录,依据叠加处理效果优选合理的观测系统参数,从而达到提高地震资料的品质的目的。

In Jurassic of Yili Basin,coal measure strata were well developed and had the characteristics of strong seismic reflected energy and better continuity,the comparative tracking for sand bodies could be carried out in the whole area.However,due to the low-velocity of the coal measure strata and high-velocity of the surrounding rocks,the reflection coefficient was higher and complex reflected wave was created between the bottom of overlying Cretaceous and surface.Because of the complexity of multi-reflected wave,it was difficult for multiple reflected wave compression and it severely influenced the reliability of seismic data.Therefore,during the seismic data acquisition and processing,the characteristics of the multi-reflected wave should be analyzed in the operation area for obtaining a proper compressed multiple reflected wave.At present the method of data acquisition was to increase the number of overlying and array length for data compression,thus the signal-noise ratio of deep-layer seismic data was raised negative influence was induced.That is why proper acquisition parameters in seismic observation systems must be carefully selected.Through forward simulation,the seismic record of single shot can be acquired.Based on stacking effect,reasonable parameters in observation systems can be selected.Therefore,the geologic model of backbone lines can be established to optimize acquisition parameters,thus the quality of seismic data is improved.