The Time-frequency Characteristic of a Large Volume Airgun Source Wavelet and Its Influenc

The Time?frequency Characteristic of a Large Volume Airgun Source Wavelet and Its Influencing

Factors1

Xia Ji1，2），Jin Xing1，2，3），Cai Huiteng3），and Xu Jiajun3） 【期刊名称】中国地震研究（英文版） 【年(卷),期】2016(030)003 【总页数】16

【关键词】Key words：Airgun wavelet Time?frequency characteristic Wavelet parameters Gun depth Firing pressure

Through analyzing the near?field hydrophone records of the airgun experiment in the Jiemian reservoir，Fujian，we study the time?frequency characteristic of airgun source wavelet and the influence of gun depth and firing pressure，and explain the process of bubble oscillation based on the Johnson（1994）bubble model.The data analysis shows that：（1）Airgun wavelet is composed of primary pulse and bubble pulse.The primary pulse，which is of large amplitude，short duration and wide frequency band，is usually used in shallow exploration.The bubble pulse，which is concentrated in the low?frequency range，is usually used in deep exploration with deep vertical penetration and far horizontal propagation.（2）The variation of primary pulse amplitude with gun depth is very small，bubble pulse amplitude and the dominant frequency increase，and peak?bubble