松辽盆地地层吸收特性和地震波衰减规律研究

选取有代表性的岩石样本，实验室模拟地下岩层的实际物理状态，对P波的品质因素Q和波速进行了测试，结果表明，松辽盆地地下岩层的P波Q和波速皆随压力的增中呈线性增加，随温度的增加呈线性减小；且Q与波速符合幂律关系，粘弹介质地震波场正演模拟表明，导致地震波衰减的主要是第四系低速带的影响，通过对震测井资料估算，按目前的地震采集方式，即潜水面（低速带）以下激发，检波器地面接收，从激发到接收，地震波在第四系中高频成分将损失170Hz，在最理想情况下，爆炸震源激发的初始子波频宽为402Hz，经过第四系和下伏地层吸收，第四系以下的反射波频带宽度不会超过232Hz，这是松辽盆地受地层吸收限制的高频采集极限。

A STUDY ON THE ABSORPTION CHARACTERISTCS OF ROCKS AND THE RULE OF WAVE ATTENUATION IN SONGLIAO BASIN

Bying simulating the actual physical conditions of rocks underground in laboratory,P wave Q and velocity of the rock samples in the SongLiao Basin have been tested.The experimental result shows that both Q and velocity of the rocks in the SongLiao Basin will increase with the pressure going up and decrease with the temperature going up as the linear rule.The result also verify that there is a power function relation between Q and velocity.Seismic modelling to the real strata indicates that wave attenuation occurs mainly in the Quarternary,and the lower velocity zone up the Quarternary take a large portion of the attenuation.Calculating derived from the seismic logging data proves that if the Source is below the lower velocity zone and geophone on the surface which has been a conventional seismic acqusition way in the SongLiao Basin,seismic wave will lose its high frequency amounts to 170Hz in the Quarternary.Under the favourable conditions,the explosive source can creates a wavelet with the maximum frequency band width of 402Hz.So,the reflected wave finally received from any layer below the Quarternary only has a frequency band width less than 232Hz.That is, in SongLiao Basin, owing to the wave attenuation, the limit of the highest frequency of the seismic reflection is 232Hz.