鄂尔多斯盆地南部山地几种单炮特征分析

在鄂尔多斯盆地南部山地进行地震采集的过程中,发现了三种特征非常明显的单炮--正常炮、帽子炮、高频炮,通过模型正演和大量的模型模拟后发现"帽子炮"和"高频炮"产生的原因主要与表层的速度和浅层存在一个强反射层有关系。当初至将与浅层的折射波基本平行,表层速度非常高,同时由于浅层比较薄的低速层衰减,导致后面的能量变弱被折射波所压制,形成帽子;当表层浮土缺失或者极薄,没能使其高频衰减,出高频,在致密砂岩和泥岩环境中激发形成高频炮。

Feature Analysis of Several Single Shots Adopted in Mountainous Region in South Ordos Basin

In the course of seismic acquisition in mountainous region in South Ordos Basin, three kinds of single shots have been discovered--normal shot, cap shot and high--frequency shot which have their own features. Forward modeling and a mass of model simulation have found that cap shot and high--frequency shot are related to superficial velocity and a strong reflection layer being in the shallow. When first break is generally parallel to refraction waves in the shallow, superficial velocity is very high, and meanwhile attenuation of thinner low--velocity layer in the shallow leads to a weaker subsequent energy that is kept under refraction waves. All this contributes to the shape of the cap. When superficial aggradation is missing or so thin that it cannot make the high frequency weakening, shooting in the environment of compacted sandstone and mudstone generates high--frequency shot.