不同纵波速度介质中炸药震源激发数值模拟研究

震源激发是影响地震勘探效果的一个重要因素,在油气勘探中需要选择合适的震源参数以获取较好的地震记录。本文以数值模拟方法为基础,通过使用ANSYS/LS-DYNA软件,对单井条件下不同岩土介质中柱状炸药震源激发进行了对比研究,计算得到相应的地震子波。通过对比分析各组参数对应的地震子波振幅和频谱,选择合适的激发参数。研究结果表明,在纵波速度较低的介质中,中低爆速、细长药柱炸药激发产生的地震子波频率高、能量大,而在纵波速度较高的介质中,高爆速、短粗药柱炸药激发产生的地震子波频率高、能量大。该研究结果与实际勘探结果比较符合,可为实际勘探中激发参数的选择提供参考。

Numerical Simulation of Excitation Source with Medium of Different P-wave Velocity

Source excitation is an important factor of the effects of seismic exploration. Choosing the appropriate excitation parameters in oil and gas exploration in order to get better seismic record is necessary. By using the software ANSYS/LS-DYNA, we adopted Lagrange algorithm based on the finite element method to simulate the seismic source of the cylindrical explosive. In this paper we focus on the frequency component of excited seismic waves in single well. Through the study of explosive detonation velocity and explosive shape we conclude that the dynamite with low detonation velocity and elongated grains has high excitation frequency and energy in the medium with low P-wave velocity, but the dynamite with high detonation velocity and short-thick shape has high excitation frequency and energy in the medium with high P-wave velocity. We want to provide references for the choices of excitation parameters in actual exploration to save exploration costs.