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Inversion of explosive source land seismic data to determine source signature parameters
Geophysical Prospecting ( IF 2.6 ) Pub Date : 2021-01-27 , DOI: 10.1111/1365-2478.13079
Anton Ziolkowski 1
Affiliation  

In seismic land exploration, where terrain conditions limit the use of vibrator sources, explosive sources are the preferred choice, and in situations where low‐frequency energy is essential, explosive is the preferred source, because it contains energy down to DC (0 Hz). I present a new method to estimate the source time functions of explosion source seismic data, using a modified acquisition method, data processing, modelling and inversion. Two shots of different sizes are fired into the same geophone spread with source–receiver geometry arranged such that the Green's functions are essentially the same. The spectral ratio of corresponding seismic traces is then the spectral ratio of the source time functions. A corresponding synthetic ratio filter is calculated from Blake's explosion source model for the sources within each pair. Each modelled source is defined by five parameters: the minimum radius a of the elastic zone, the internal pressure p0 at a, the density of the rock ρ and two elastic constants for an isotropic rock, the P‐wave velocity c and Poisson's ratio σ. A grid search finds the source parameters that minimise the difference between the measured and synthetic filters for each source pair, thus yielding the two source time functions, but not their absolute amplitudes. Deconvolution of the shot records within each pair for the minimum‐phase source time functions recovers the estimated earth impulse response gathers, convolved only with the response of the recording system. The improved knowledge of the source signature is then helpful in subsequent processing, especially for reverse time migration, full waveform inversion and amplitude‐versus‐offset analysis. I consider shots at different depths in the same shot hole and shots at the same depth in different shot holes. The former configuration minimises differences in geophone coupling, and, in operations, quality control procedures must be met. There is considerable variation in recovered source parameters from place to place, caused by variations in charge size, soil or rock properties and source coupling.

中文翻译:

反演爆炸源陆地震数据以确定震源特征参数

在地震土地勘探中,地形条件限制了振动源的使用,爆炸源是首选,在低频能量必不可少的情况下,爆炸源是首选源,因为爆炸源的能量低至DC(0 Hz) 。我提出了一种使用改进的采集方法,数据处理,建模和反演来估算爆炸震源数据的震源时间函数的新方法。将两个不同大小的镜头发射到相同的地震检波器中,并布置了源-接收器的几何形状,从而使格林的功能基本相同。相应的地震迹线的频谱比率就是源时间函数的频谱比率。从布雷克的爆炸源模型为每个对中的源计算出一个相应的合成比率滤波器。一个弹性区,内部压力的p 0一个,岩石的密度ρ和各向同性岩石两个弹性常数,所述P波速度Ç和泊松比σ。网格搜索可找到使每个源对的实测滤波器与合成滤波器之间的差异最小的源参数,从而得出两个源时间函数,但不能得出它们的绝对振幅。对每对镜头中最短相位源时间函数的解卷积进行反卷积可恢复估计的地球脉冲响应集,仅与记录系统的响应卷积。这样,对信号源签名的进一步了解将有助于后续处理,特别是对于反向时间偏移,全波形反演和幅度与偏移分析。我考虑在同一个射击孔中以不同深度射击,在不同射击孔中以相同深度射击。前一种配置最大程度地减少了地震检波器耦合以及操作中的差异,必须符合质量控制程序。由于装药量,土壤或岩石特性以及源耦合的变化,不同位置的采出源参数存在很大差异。
更新日期:2021-01-27
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