基于不同地表介质震源子波响应的炸药激发效果影响因素研究

发布时间：2018-04-29 05:35

本文选题：炸药激发参数 + 震源子波　；参考：《浙江大学》2017年博士论文

【摘要】：在陆地油气地震勘探中,炸药震源激发参数,包括激发介质、炸药爆速、药量、药柱直径、耦合介质和几何耦合,对地震记录中信号的振幅和频率特征有重要影响。目前,对激发参数的影响的认识主要来自实际试验,缺少对应的理论研究。本文基于爆炸力学和弹塑性力学,提出采用数值模拟与球状震源模型结合的方法,从理论上计算了炸药震源在岩土介质中产生的震源子波。本文提出的震源子波的计算过程为:首先是数值模拟炸药在岩土介质中的激发过程,分析介质中产生的塑性-弹性边界大小及压力曲线;然后,采用三角指数衰减函数(正弦函数和指数衰减函数的乘积)拟合该压力曲线,得到塑性-弹性边界压力函数;最后,基于球状震源模型,以介质弹性参数、PEB尺寸和压力函数为输入计算子波。在此基础上,对不同岩性的地表介质,计算了不同激发参数对应的子波,并研究了这些参数与子波振幅和频率的关系。研究表明,灰岩和砂岩中产生的子波主频较高而低频成分较少,可以采用高爆速炸药、大药量、大药径、水耦合增加低频成分;黄土中产生的子波主频较低而且频带宽度较小,可以采用低爆速炸药、小药量、大药径、胶泥耦合提高子波主频和频带宽度。理论计算结果与前人实际观测结果的对比表明,两者在激发岩性与子波形态、振幅和频率,炸药爆速与子波振幅,黄土中药量与子波频率、灰岩中耦合参数与子波振幅等方面基本相似。理论研究结果能解释和验证一些实践经验与采集数据,也可以为特定地表介质条件下炸药爆速、药量、药径、耦合等参数的选取提供参考。
[Abstract]:In terrestrial oil and gas seismic exploration, the excitation parameters of explosive source, including the excitation medium, explosive detonation velocity, explosive quantity, particle diameter, coupling medium and geometric coupling, have an important effect on the amplitude and frequency characteristics of the signal in seismic records. At present, the understanding of the influence of excitation parameters mainly comes from the actual experiment, and lacks the corresponding theoretical research. Based on explosive mechanics and elastoplastic mechanics, a method combining numerical simulation with spherical source model is proposed to calculate the source wavelet generated by explosive source in rock and soil media theoretically. The calculation process of the source wavelet presented in this paper is as follows: first, the excitation process of explosive in geotechnical medium is simulated, and the plastic elastic boundary size and pressure curve produced in the medium are analyzed. The triangular exponential attenuation function (the product of sinusoidal function and exponential attenuation function) is used to fit the pressure curve, and the plastic elastic boundary pressure function is obtained. The size and pressure function of PEB are taken as input to calculate wavelet. On this basis, wavelet corresponding to different excitation parameters is calculated for different lithologic surface media, and the relationship between these parameters and the amplitude and frequency of wavelet is studied. The results show that the wavelet generated in limestone and sandstone has higher main frequency and less low frequency component, so the low frequency component can be increased by high detonation rate explosive, large charge quantity, large particle diameter and water coupling, and the wavelet generated in loess has lower main frequency and smaller bandwidth. The main frequency and band width of wavelet can be improved by using low detonation rate explosive, small charge quantity, large diameter and coupling of cement. The comparison between the theoretical calculation results and the actual observation results shows that the lithology and wavelet morphology, amplitude and frequency, explosive detonation velocity and wavelet amplitude, the amount of loess traditional Chinese medicine and wavelet frequency are stimulated. The coupling parameters in limestone are basically similar to those of wavelet amplitude. The theoretical results can explain and verify some practical experience and data collection, and can also provide a reference for the selection of explosive detonation velocity, explosive quantity, particle diameter, coupling and other parameters under specific surface media conditions.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：P631.4

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