碳酸盐岩表层结构对地震波能量的影响

为研究在层状结构表层激发时地震波能量及频率的变化规律，进行了激发物理模拟试验，认为：当岩石表层结构存在薄互层时，将对某些频率成分产生调谐放大作用，如果适合爆破地震勘探的频率成分在这些放大的频率范围内，则该表层结构的地震地质条件较好，可得到能量较强的地震信号。为了研究灰岩裸露区复杂的地表接收条件对地震波能量的影响，进行了灰岩表层结构接收试验，认为：①爆炸应力波的主要能量集中在几千至上万赫兹频率范围内，应力波的高频部分迅速衰减，而占其中份额很少的低频信号被接收；②地表地层在炸药爆炸的激励作用下产生相应的低频振幅响应，它和应力波混合在一起，成为地震激发的地震子波，灰岩地层由于岩层厚度和岩石密度大，导致地震子波能量弱，因此在碳酸盐岩中采集到的地震波能量较弱；③在灰岩裸露地区，岩石表层条件一致性很差，导致爆炸反射波的振幅、频率和相位产生很大差异，增加了在碳酸盐岩地区爆炸地震勘探采集技术的复杂性。研究成果对碳酸盐岩介质中油气资源勘探、开发的震源设计具有借鉴意义。

Influence of carbonate near-surface structures on seismic wave energy

In order to study the change of seismic wave energy and frequency in layered near-surface,we carry out physical simulation tests.Based on this simulation,certain frequency components have tuned amplification effects when the near-surface consists of rock inter-beds,and if seismic frequency components have tuned amplification strong seismic energy will be recorded in good near-surface conditions.In order to study the influence of bare limestone on seismic energy,we conduct some field tests.The following observations are obtained:A.The main explosive stress energy concentrates in several thousand MHz which attenuates rapidly,while low-frequency energy is recorded; B.Low-frequency mixed with stress wave forms seismic wavelet.Seismic wavelet energy is rather weak due to limestone thickness and density,so recorded seismic wave energy is weak in carbonate areas; C.In limestone near-surface areas,reflection quality is very poor with the distortion of amplitude,frequency and phase,which makes more difficult in carbonate exploration.Our research results might be a reference for hydrocarbon exploration and development in carbonate areas.